WO2016181405A1

WO2016181405A1 - A reciprocating piston concrete pump having a force multiplier cum automatic overload protection & disengaging device separate from its drive mechanism

Info

Publication number: WO2016181405A1
Application number: PCT/IN2015/000444
Authority: WO
Inventors: Amit Arun Gokhale; Anand Arun Gokhale
Original assignee: Individual
Current assignee: Individual
Priority date: 2015-05-08
Filing date: 2015-12-09
Publication date: 2016-11-17
Anticipated expiration: 2017-11-08

Abstract

In accordance with the present invention, "A reciprocating piston concrete pump having a Force Multiplier Cum automatic overload protection & disengaging device separate & independent of its drive mechanism" which typically & essentially consists of an improved reciprocating piston concrete pump having an additional hydraulic cylinder (7) separate from its drive mechanism, mechanically installed between the reciprocating piston (1) and the mechanical linkages (10) wherein the said hydraulic cylinder (7) is provided with a static fluid (18) confined and enclosed between two differential areas ( 11 & 12 ) and the smaller area is mechanically connected to the mechanical linkage (10) for application of input force and the bigger area is mechanically connected to the reciprocating piston (1) for exerting force on concrete. The said hydraulic cylinder (7) performs various functions such as multiplication of force in accordance with the Pascal's principle; overload protection and manual disengagement of pumping action.

Description

! : "A reciprocating piston concrete pump having a Force Multiplier Cum automatic overh protection & disengaging device separate from its drive mechanism"

[001] TECHNICAL FIELD OF INVENTION:

This invention specifically relates to a high pressure concrete pump used for placement of concrete. To be precise, this invention relates to a reciprocating piston pump driven through mechanical linkages such as a crank and connecting rod which is lacking in effective automatic overload protection & disengaging of pump action and has no other mechanism to increase the pressure on concrete and hence is fast becoming obsolete.

This invention therefore relates to concrete pumps which use reciprocating pistons driven through mechanical linkages in the context of overload protection & disengagement of pump action from the prime mover. The invention however also relates to a hydraulically driven reciprocating piston concrete pump only in the context of further multiplication of available reciprocating force.

[002] BACKGROUND OF THE INVENTION & DESCRIPTION OF PRIOR ART:

Concrete pump is an apparatus used for pumping concrete. Since the material qnder pumping js concrete, the basic design of any concrete pump differs from any other reciprocating pump used for pumping any other materials. In other words, the characteristics of concrete make the entire process of pumping concrete very unique due to high bulk density & presence of various ingredients which include sand & various sizes of aggregates. Therefore the concrete pumps are completely different from any other available reciprocating pumps.

There have been many efforts to make a simple concrete pump having a simple mechanical drive wherein the pumps have been driven through a crank & connecting rod mechanism. Some pumps have also been driven through cam and fojipwer mechanisms. Especially in the period 1930 to 1940, before the advent of hydraulically driven concrete pumps.

However these early efforts could not address some critical issues effectively which were addressed by hydraulically operated concrete pumps after 1950.

It is very important to note here that all the present hydraulically driven concrete pumps use ^■ a conventional hydraulic pump and are driven through hydraulic drives. Some of the limitations of the mechanically driven concrete pumps developed since 1914 are listed hereunder:

1. Low concrete pressures developed due to low reciprocating force :

The mechanical concrete pumps developed since 1914 use mechanical linkages such as crank and connecting rod mechanism to convert the rotary motion of the prime mover into a linear reciprocating motion which is in turn is used for pumping of concrete. The pressure developed in the pipeline of concrete is called concrete pressure which depends upon the cross sectional area of the reciprocating piston and the amount of reciprocating force behind the reciprocating piston. A detailed method of calculation of the actual reciprocating force and the concrete pressure is explained ahead.

As of today most of the concrete pumps are driven hydraulically with the help of a hydraulic pump. The hydraulically driven pumps are having advantage as the maximum concrete pressure in the pipeline of the pump can be controlled by controlling the hydraulic pressure in the drive system and the force on the piston could be multiplied by using conventional hydraulics & high displacement hydraulic pumps.

2. No protection in case sudden overloading due to pipeline blockages:

As of today most of the concrete pumps are driven hydraulically with the help of a hydraulic pump. The hydraulically driven pumps are having advantage as the maximum concrete pressure in the pipeline of the pump can be controlled by controlling the hydraulic pressure in the drive system. The hydraulic systems are provided with safety relief valves which can easily and reliably control the maximum operating hydraulic pressure in the system and in turn control the maximum concrete pressure in the ^' pipeline. Thus any damage to the pumping system and the prime mover is avoided. Further these safety relief valves can be set & reset which enables the end user to operate within the prescribed working limit. This feature is not available in the mechanically driven pumps especially using diesel engines as prime movers.

3. Manual Disengagement of pumping action :

The earlier developed mechanical pumps were called direct drive pumps and were not provided with any dis-engaging mechanism. Today there are mechanically driven concrete pumps suc as ball valve pump which are mainly used to pump grouts are provided with a CLUTCH in between the prime-mover and the reciprocating piston. Therefore in order to disengage the pumping action, the operator has to declutch the prime mover by means of a mechanical lever or a electromagnetic actuator. However the frequent engaging & disengaging causes high wear & tear and the method is not as smooth as in a hydraulically driven reciprocating concrete pump.

[003] TECHNICAL PROBLEM ASSOCIATED WITH THE EXISTING PRIOR ARTS: Prior art 1: Mechanically driven concrete pumps:

The Fig no. 1 on sheet no. 1 shows a simple mechanically driven reciprocating piston pump using a diesel engine the closest art being the J.C. Kooyman Pump developed in 1935. Alternatively there are many pumps are presently also in use which use cranks & cams to convert the rotary motion of the prime mover into the linear to & from motion of the piston.

As shown in the Fig. 1 on sheet 1 , The Concrete pump uses a reciprocating piston (5), which is made to reciprocate to and from by converting the rotary motion into the linear motion by using crank (6) & connecting rod (7) mechanism. The crankshaft rpm decides the no. of strokes. The crank (6) is connected to the prime mover through a series of reduction pulleys & gears so as to reduce the prime mover rpm and increase the torque at the crank. The fig. also shows the hopper (1), valves(2 & 3) and delivery line 3.

Technical problems in mechanically driven concrete pumps:

As discussed earlier, there were found three major limitations in all the mechanically driven concrete pumps since 1914.

These limitations are discussed in detail one by one.

A. LOW PRESSURE ON CONCRETE DUE TO LOW RECIPROCATING FORCE:

The conventional Mechanical drive pumps, precisely the pumps which used mechanical linkages such as crank and connecting rod could not develop a very high pressure on concrete in the pipeline for higher outputs due to lower reciprocating force available.

The fig. 1 on sheet no. 1 shows the J.C. Kooyman Concrete pump, the mechanically driven reciprocating Piston is made to reciprocate in the pumping cylinder by converting the rotary motion of the prime mover into linear motion by using mechanical means such as a crankshaft & connecting rod. Alternatively a cam & follower & spring mechanism are other mechanical linkages which can convert rotary motion into the linear motion.

Since the reciprocating piston ( more popularly called as RAM) is made to reciprocate to and fro by converting the rotary motion of the prime mover in to a linear motion by using purely mechanical linkages, the pressure developed by the said reciprocating piston on the concrete being pumped ( in pounds per square inch or PSI) essentially depends upon the following factors :

1. The horsepower of the prime mover ( In Kw)

2. The operating rpm of the crankshaft (revolutions per minute)

3. The operating torque of the crankshaft (in NM)

4. The offset distance of the crank (in meter)

5. The resultant linear force implied by the piston ( In Newton)

6. The resultant linear force implied by the piston (In Pound)

7. The area of the reciprocating piston (In square inches).

Thus one can calculate the actual concrete pressure developed by a mechanically driven concrete pump in following steps:

1. Calculation of torque in (Newton-Meter) at the crank :

The operating Torque on the crank in (Newton-Meter) can be easily calculated by considering the power of the prime mover and the rpm of the crankshaft.

Thus for example if the prime mover power is say 19 KW, the operating torque at the crank rotating at an rpm of 30 can be easily calculated as 6047.88 NM.

2. Calculation of linear force in Newton:

The linear force (in Newton) developed depends upon the offset distance of the crank which can be easily calculated y di vid i ng the - torque (in Newton-meter) by the offset distance (in meter). Let us assume that the crank is off-set by say 90 mm or 0.090 meter. This will typically result in a stroke-length of 180 mm (0.180 meter) of the reciprocating piston.

Then the linear force in Newton can be calculated by dividing the torque 6047.88 Newton- Meter by the offset distance 0.090 meter, which comes to 67198.66 Newton.

3. Conversion of the linear force from Newton to Pound:

In this step, the Linear force is converted into pounds which can be easily calculated by the conversion formula and comes to 15106 Pound.

4. Calculation of the actual pressure on concrete developed by the reciprocating piston face:

Now the actual pressure developed by the reciprocating piston can be easily calculated by dividing the linear force in Pound by the area of the reciprocating piston in Square Inches. Let us assume that the piston diameter is 180 mm (0.180 Meter) and the area of the piston face works out to 40.69 Square inch. Now the actual pressure can be easily calculated by dividing the linear force of 15106 Pound by the area of the piston which is 40.69 Square Inch. So finally the actual pressure on concrete can be calculated as 371.24 PSI (Pounds per Square Inch) or 25.80 bar.

CONCLUSION:

So in this example, it can be easily calculated that a concrete pump driven through mechanical linkages by a prime mover power of say 19 KW can develop a maximum piston face pressure of approx. 374.24 PSI or 25.80 bar when a crank offset by 90 mm operates at a rpm of 30 so as to have 30 strokes of 180mm stroke-length of a reciprocating piston having a diameter of 180 mm or a piston face area of 40.69 square inch. The concrete output resulted by such reciprocating motion can be easily calculated by calculating the displacement caused by the reciprocating piston which comes to 8.24 pubic meter of concrete per hour.

If we increase the output, we have to increase the RPM at which the crank rotates. However any increase in the RPM of the Crankshaft shall result in reduction of the torque and hence subsequently result in lower force acting on the piston. This means that the pressure developed by the piston face on concrete shall be reduced. Therefore due to this mechanical limitation in above case, there is only one way to have higher output at the same 25.80 bar concrete pressure, which is to increase the size of the prime mover so as to increase the power. However even the concrete pressure of 25.80 bar is low and the pump cannot be used for high rise buildings where the typical heights would be 80-100 meters and above.

The actual required concrete pressure to pump concrete through the pipeline however depends upon the following factors:

1. The Tenacity Factor :

The tenacity factor depends upon the slump and spread of the concrete. Thus the tenacity factor is 1.18 for a concrete mix having a slump of 120 mm or spread of 500 mm.

2. The water / Cement factor:

It is a well known fact that the concrete mix in order to be pumped must have a water/Cement factor of more than 0.42.

3. Length of pipeline through which the concrete is to be pumped (in meter) .

4. Diameter of the pipeline (in mm)

5. Required concrete output (in cubic meter per hour)

6. The vertical height difference ( in meter)

So it is obvious that the required concrete pump pressure depends upon the output in cubic meter per hour. However in conventional mechanical pumps if the output is increased the concrete pressure has to come down as the crank has to rotate at a higher rpm so as to give more working strokes of the reciprocating piston. It also means that since the crank rotates at a higher rpm, the torque comes down and hence the force comes down and as a result the pressure on concrete comes down. "In conventional mechanical pumps developed till date over the entire century since 1914, there has been no other mechanism to increase the concrete pressure at a constant or higher output by increasing the reciprocating force apart from increasing the prime mover power. However it is still grossly insufficient even after the power is increased by a huge margin ".

Due to mechanical limitations of power & torque, there is no way to increase the reciprocating force beyond a certain fixed value.

Due to which the mechanically driven pumps cannot develop high reciprocating forces as compared to the hydraulically operated concrete pumps and are becoming obsolete due to this very serious limitation which has not been overcome till this invention.

B. NO OVERLOAD PROTECTION IN CASE OF SUDDE OVERLOADS DUE TO PIPELINE BLOCKAGES.

As shown in the fig. 1 on sheet no. 1, which shows a mechanically driven concrete pump invented by J.C. Kooyman; the mechanically driven Piston (5) is made to reciprocate in the pumping cylinder by converting the rotary motion of the prime mover into linear motion by using mechanical means such as a crankshaft (6) & connecting rod (7) or alternatively by using a cam & follower & spring, mechanism. Thus the reciprocating piston cannot be disengaged unless & until the clutch is provided between the reciprocating piston and the prime mover further the clutch has to be manually operated.

Therefore presently available mechanically driven concrete pumps are provided with a clutch between the engine & the crankshaft, therefore the engine can be disengaged manually and the pumping operation can be stopped.

In case of concrete pumps, the line pressure may increase suddenly beyond the designed limit due to line blockage as concrete pipelines can be blocked within a very short period due to the nature of the material under pumping. Now this sudden overload is directly working on the mechanical linkages and the prime mover. Once the concrete pressure increases to more than the maximum pressure which can be put by the reciprocating piston on concrete which depends upon the engine HP, torque, off-set distance of the crank & the area of the piston. Thus once the piston is blocked due to blockage of delivery line, the engine is still pushing the piston through the mechanical linkage and if the engine is not dis-engaged completely by manually operating the clutch, the mechanical linkages are damaged and Or the engine is overloaded & stalls.

Now while pumping concrete, this overload situation can come across many times & every time it may not be possible to disengage manually and hence a full proof automatic system without any human intervention is required to avoid the damage to the mechanical linkages & prime mover.

Presently, some very sophisticated engines are provided with electronic engine management systems (EMS). These systems are provided with sensors which can detect any overloading of engine. However these systems are very costly and are not available with normal engines. Further these systems have sensors which measure the exhaust temperatures & compare with the data available so as to decide whether the engine is overloaded or not. Thus these systems can be used to prevent a gradual overload but cannot prevent a sudden unexpected shock load in the mechanical drive which is experienced suddenly and cannot be predicted. Further in case of such sudden shock load, the engine might be operating at the normal temperature and hence the sensors cannot detect the overloading which actually may happen in a fraction of a second.

The mechanically driven concrete pumps however are easy to manufacture, simple to service, have higher efficiency than hydraulic drives and have low capital & operating cost.

Therefore if the overloading issue is resolved, the mechanically driven concrete pumps can be used as reliably as hvdraulicallv driven concrete pumps.

C: MANUAL DISENGAGEMENT OF THE PRIME MOVER FROM PUMP ACTION:

As discussed earlier, the initially developed mechanically driven concrete pumps were direct drive concrete pumps and were not equipped with a mechanism to allow the operator to disengage the pump-action from the prime mover. Such disengagements are required frequently in concrete pumping operation as time intervals are required for transit mixer trucks as well as the pipeline crew to add or remove pipes. The today available mechanically driven pumps also called as ball valve pumps which are mainly used for pumping grouts are provided with mechanical or electromagnetic clutches. The operator can therefore disengage the pumping action by disengaging the clutch between the prime-mover and the reciprocating piston.

However due to the frequent engaging & disengaging, these clutches have a high wear & tear and require maintenance. Further the operation is not as smooth as the one in a hydraulically driven concrete pump wherein the prime-mover can be completely disengaged from the reciprocating piston.

Prior art No. 2 : Hydraulically drive reciprocating pisto concrete pump:

As discussed earlier, the majority of the concrete pumps used today are hydraulically driven through a drive mechanism which typically uses a conventional hydraulic pump and hydraulic cylinders to have the reciprocating motion of the pumping piston.

The use of hydraulics enables these pumps to have higher stroke-lengths and hence hjgher outputs. The hydraulically driven concrete pumps are able to develop high concrete pressures in the pipeline mainly due to the hydraulic drive mechanism used by them due to force multiplication.

The hydraulically driven concrete pumps as discussed earlier provide a very reliable overload protection compared to the mechanically driven concrete pumps. However the hydraulically operated concrete pumps are also having some limitations which are discussed hereunder:

1. Optimum output and maximum pressure on concrete cannot be achieved at the same time. One can refer to the nomograph of a hydraulically operated concrete pump. Which is a graph of output vs the pressure on concrete. It can be easily seen that the output comes down as the concrete pressure goes up.

2. Maximum reciprocating force is developed outside the pumping cylinder, i.e. in the hydraulic cylinders. Which is in turn is transferred to the reciprocating rubber pistons. The resulting concrete pressure therefore depends upon the differential areas of the hydraulic piston and the concrete piston. [004] OBJECT OF INVENTION & SOLUTION TO THE PROBLEM

After going through all the three very serious limitations of mechanically driven pumps, it is amply clear why the mechanically driven concrete pumps were replaced by hydraulically operated concrete pumps which used advance hydraulics & high displacement hydraulic pumps especially after 1950.

The presently available almost all high pressure concrete pumps are operated hydraulically through sophisticated hydraulic circuits and hydraulic pumps. These pumps can develop high pressures on concrete, have higher outputs, have 100% reliable overload protection & can be engaged or disengaged very smoothly without any wear & tear at will.

However, if we keep away the above three serious limitations for a moment, the mechanically driven concrete pumps have some very clear advantages over the hydraulically operated concrete pumps.

These advantages are:

1. Simplicity of construction ;

The mechanically operated concrete pumps have a very simple mechanism such as a reciprocating piston made to reciprocate to and fro by using simple mechanical crank & connecting rod mechanism. Whereas the hydraulically operated concrete pumps are highly complex and use a very complex hydraulic circuit to operate the reciprocating pistons & the gate valve mechanisms.

2. Low cost of manufacturing & easy to manufacture:

Due to a very simple mechanism, the mechanically driven concrete pumps are comparatively very easy to manufacture and cost effective. Further the no. of parts are very limited and the components need not be as precisely machined as the hydraulic components. The operating parts are mainly made up of steel and can be easily replaced and replacement cost is very low.

Whereas the hydraulic components such as hydraulic cylinders, valve-banks, directional control valves, safety valves & flow control valves and hydraulic pumps need very complex & precise manufacturing & hence the cost calculation is compounding. 3. No requirement of consumables such as hydraulic oil, etc:

Since the mechanically operated concrete pumps generate the reciprocating force through mechanical linkages such as crank & connecting rod mechanism, they do not require hydraulic oil. Whereas the presently available hydraulically operated concrete pumps use very heavy duty hydraulic pumps having very high displacements per revolution. In order to keep the hydraulic oil temperature low, these hydraulically operated pumps are provided big capacity hydraulic oil tanks such as 250 to 300 Its or many times more than that. Since the power is transmitted through hydraulic oil, it needs to be replaced at certain intervals. Which adds to the preventive maintenance cost. Further for transmitting the power, a no. of high pressure hoses are required. These hoses also have a working life and need to be replaced or cause loss of oil through leakages & bursting. The mechanically driven pumps on the other hand do not have any rubber items except the reciprocating piston and v-belts used for mechanical power transmission. Both of these have very low replacement costs.

4. High service life due to limited parts:

Since the majority of the components used in a mechanically driven concrete pump are made up of steel without as precise manufacturing as the hydraulic components, they all have very low replacement cost, which means the equipment life can be enhanced by repairing or replacing all the steel parts to almost any duration. Whereas the hydraulic components are high cost items and the replacement cost is uneconomical and sometimes is so high that replacement of the entire equipment seems to be a better option.

5. High mechanical efficiency :

The mechanically operated pumps are also called as direct drive pumps as the pumps are operated through simple mechanical linkages. Theoretically the mechanical drive has a higher efficiency compared to the hydraulic drives provided the power is transmitted at a small distance & through a very few components. However on the other hand even the most advanced hydraulic drives have lower efficiencies generally upto 80%. Whereas a simple belt drive can provide a much higher mechanical efficiency. The above comparison is only limited to the field of concrete pump technology & not for any other equipment, where the hydraulics might be very techno- commerciallv more advantageous over the mechanical drives.

Hence the primary object of this invention is to have a simple mechanically driven concrete pump with a single low cost device so as to make available: a. A fully automatic overload protection as reliable as a hydraulically operated concrete pumps.

b. A user-friendly manual disengagement mechanism as smooth and reliable as a hydraulically operated concrete pump

c. a amplified very high reciprocating force acting only on the reciprocating piston and not on the mechanical linkages, wherein such a force can develop even higher pressures on concrete compared to hydraulically operated concrete pumps.

Another object of this invention is to make the mechanically driven concrete pump 100% reliable such as a hydraulically operated concrete pump.

Another object of this invention is to make available a concrete pump which has a higher working life, requires very less consumables & has a very low operation & maintenance cost compared to the presently available hydraulically driven concrete pumps.

Another object of this invention is to have a concrete pump having low capital cost when compared to the presently available hydraulically operated concrete pumps.

One more objective of this invention is to have a concrete pump which can develop a very high concrete pressure irrespective of the output. Which means that the output does not come down with respect to the increase in the concrete pressure, which is a common case in hydraulically operated concrete pumps.

Another very important objective of this invention is to have higher concrete pressures at constant optimum output without increasing the size of the prime mover.

Another objective of this invention is to have a very high reciprocating force only on the reciprocating piston which does not work backwards on the mechanical linkages; Another very important obiective of this invention is to increase the reciprocating force on the reciprocating piston without increasing the torgue on the crank and without increasing the horse power.

Another very important obiective of this invention is to have higher diameter pumping cylinders which in turn shall contribute to higher concrete pressures which is contrary to the presently available hydrau!ically driven concrete pumps where the concrete pressure is inversely proportional to the diameter of the pumping cylinder. Which means any increase in the pumping cylinder diameter reduces the resultant concrete pressure if reciprocating force is constant.

Another far reaching obiective of this invention is to have a means of multiplying the reciprocatin force by using this invention in hvdraulically operated pumps as well, wherein the drive system can be kept entirely separate from the force multiplying unit.

[005] SUMMARY & DISCLOSURE OF THE INVENTION:

In accordance with the present invention, "A reciprocating piston concrete pump having a Force Multiplier Cum automatic overload protection & disengaging device separate from its drive mechanism" is disclosed as under and typically & essentially consists of the foilowings. a. A reciprocating piston concrete pump wherein the reciprocating piston (1) is made to reciprocate by using mechanical linkages or alternatively by using hydraulic pump drive mechanism.

b. A hydraulic force multiplier cum overload protection & disengaging device which independently works on Pascal's principle, mechanjcally installed between the reciprocating piston (1) & the mechanical linkage (10) wherein the hydraulic force multiplier cum overload protection and disengaging device is an "add on" unit completely separate & independent from the pump's drive mechanism and is typically & essentially made up off:

(i) A custom designed hydraulic cylinder (7) having :

a confined or enclosed static fluid filled (18) enclosed o confined between two differential areas (11) & (12) arid the two differential areas are typically obtained either by -having a hollow enlarged but closed section on one side with the extreme wall (11) having a larger cross-sectional area than the small piston (12) wherein the hollow section starts after the piston stroke is complete.

Or having two separate pistons (11 & 12) having a passage of fluid between them.

-a threaded shaft (9) provided on the rod end of the small piston (12) which the mechanical linkage (10) is fastened for application of input force

-another threaded shaft (8) provided on the outer side of the extreme wall or bigger piston (11) on which the reciprocating piston (1) is fastened to exert output force on concrete.

The small piston (12) of the said hydraulic cylinder (7) is typically provided with a stroke-length (x) little more or equal to the stroke-length of the reciprocating piston (t) to also perform the work of overload protection or manual disengagement as well as force multiplication in such a case, however the stroke length is maintained by having: mechanical restriction in such a way that the small area piston (12) never enters in the enlarged hollow section of the cylinder or the bigger piston side.

(iii) Alternatively the small piston (12) is provided with a shorter stroke-length when utilized as only as a force multiplier unit n a hydraulically driven concrete pump.

(IV) A small hydraulic oil tank (15) for the overload protectipn & disengagement function.

(V) A non-return cum antj-cavitation valve (16) for the overload protection & disengagement function.

(Vi) A safety relief valve (13) for the overload protection

(Vii) A ball valve (17) for manual disengagement function

(viii) High pressure hoses between the cylinder & the tan(< for overload protection & disengagement function. (ix) _. Pressure gauge to show the pressure on the fluid.

The above mentioned invention is a huge breakthrough since 1914, as it successfully addresses ail the limitations of the mechanically driven concrete pump and for the first time in the history of concrete, pumps makes the mechanically driven pump as reliable and as forceful as a hydraulically driven concrete pump.

It has a very simple & cost effective design, which multiplies the input force developed by a simple mechanical linkages to many times by using a simple low cost custom designed hydraulic cylinder (7) filled with a static fluid (18) enclosed or confined between two differential areas (11 & 12) on both sides and the multiplication of Force depends upon the ratio of the two areas as per Pascal's principle. Thus this invention removes the very limitation of the mechanically driven pumps and the pressure on concrete can be easily multiplied to any value by using even a very small prime mover. Additionally at the same time, the same device by addition of items (iv) to (ix) not only provides fully automatic overload protection but also enables the operator to manually disengage the pumping operation at will without using a clutch.

The invention therefore provides a very cost-effective but robust & reliable mechanical drive machine to pump concrete, which is having very less capital & operation cost and is useful for the majority of the construction industry.

The custom designed hydraulic cylinder (7) could be single acting or double acting as the rod end of the piston (12) is mechanically coupled wit the mechanical linkages and its stroke and direction of movement completely depends upon the mechanical linkages.

[006] BRIEF DESCRIPTION OF THE DRAWINGS:

1. The Fig. No. 1 on sheet no. 1 shows Prior Art : the J.C. Kooyman mechanically driven concrete pump developed in 1935 without any arrangement or mechanism to increase the reciprocating force.

2. The Fig. No. 2 on sheet no. 2 shows the sectional front view of the best method of performing the said invention along with its separate & independent hydraulic circuit to perform all the three combined functions of force multiplication, overload protection and manual disengagement in a mechanically driven concrete pump. 3. The Fig. No 3 on sheet no. 3 shows the theory in context of the invention which is the Pascal's law.

4. The Fig. no. 4on Sheet No. 4 shows another embodiment (Fig 4A) of the same invention and the invention in isolation (Fig.4 B).

5. The Fig. no 5 on sheet no. 5 shows the invention used in a hydraulically operated twin cylinder concrete pump only for the purpose of force-multiplication.

6. The Fig. no 6 on sheet no. 6 shows only the overload protection & disengagement function in a mechanically driven concrete pump without force multiplication.

*

The rotary valve operating mechanism is not shown in the drawing so as to keep this application only focused on the force multiplier & overload protection cum disengagement device.

[007] DETAILED DISCRETION & WORKING OF THE INVENTION WITH REFERENCE TO THE DRAWINGS:

In accordance with the present application, "A reciprocating piston concrete pump having a Force Multiplier Cum automatic overload protection & disengaging device separate & independent of its drive mechanism" is described with reference to the drawing. Kindly refer to the Fig. no. 2 on sheet no. 2 which describes the best method of performing the said invention.

A minimum one reciprocating rubber piston (1) is made to reciprocate in the pumping cylinder (2) through a simple crankshaft (3) -not visible in the drawing & connecting rod (4) arrangement wherein the inside dia. of the pumping cylinder is hard chrome plated or induction hardened. An off-centre three way improved rotary gate valve (5) A water-box (6) is provided to hold water for lubrication of the said rubber piston (1 ).

A custom designed hydraulic cylinder (7) is provided wherein cylinder (7) is having a threaded shaft (8) on the left side end of its extreme wall (11) on which the rubber piston (1) is mounted while the rod-side end on is also having a threaded shaft (9) on which the mechanical linkage (10) is connected. However the left side on which the reciprocating piston is mounted is provided with a hollow enlarged section wherein the extreme end wall (11) is of a larger diameter than the small piston (12). On the rod side threading (9) the mechanical linkage (10) is connected. The mechanical linkage (10) connected on the rod end which provides the input force exerted by the mechanical linkage (10). The small hydraulic piston (12) is fitted with high pressure seals not shown in the drawing.

A hydraulic safety pressure relief v/alve (13) is fitted on the piston side port (14) of the hydraulic cylinder (7) and is settable. The piston side port (14) is further connected to the hydraulic tank (15) through a one way non return cum anti-cavitation valve (16). The same delivery line is also connected to the tank through a ball valve (17) with a manual operating lever. Alternatively the ball valve can be actuated by a solenoid.

The rotary gate Valve actuation linkages are not shown as they are not related to the working of overload protection device.

Theory behind the invention:

Pascal's Principle:

Statement : "PRESSURE IS TRANSMITTED UNDIMINISHED IN AN ENCLOSED OR CONFINED STATIC FLUID".

Kindly refer to the Fig. No.3 on sheet no.3 which shows the Pascal's Principle in context with this invention.

The Fig shows a static or confined fluid (18) in a vessel (19). The vessel has a opening through which a stopper (20) is inserted having a cross-sectional area of 5 centimeter square and a force of 10 N is applied on the stopper.

So the area A1= 5 sq. cm & the applied force F1= 10 N

Then the pressure P1 is calculated as: P1= Force divided by area= F1 / A1. So P1= 10 N / 5 sq.cm = 2 N/sq cm

Now pressure is transmitted undiminished in an enclosed or confined static fluid (18) as per Pascal's principle which means that the pressure acting on the other side (11) of the vessel P2 is same as P1 which means 2 N/sq.cm

Let us-assume that the other side (11) of the vessel has a much larger area say 500 sq. cm. Now the resulting force on the opposite side of the vessel can be calculated as : P2= F2 /A2

So F2= P2 X A2= 2 X 500 = 1000 N

Thus the Force is multiplied 100 times.

This invention uses the same principle and accordingly a custom designed hydraulic cylinder is provided having a larger area (11) in a hollow enlarged section on one side and a piston of small cross section (12) connected to the mechanical linkage (10) is used for application of input force as it is mechanically fastened to the threaded shaft (9) . A static fluid (18) is confined or enclosed between the two differential areas. The output force F2 is exerted on the reciprocating piston (1) as the reciprocating piston is mechanically fastened to the threaded shaft (8) on the bigger area side thereby allowing the input force to be multiplied.

Working of the invention: Please refer to the Fig. No 2 on sheet no. 2 which describes the best method of performing the said application.

Step 1. The prime mover is switched ON.

Step 2. The drive is made available to the eccentric crankshaft. The pumping action starts and the rubber piston (1) is made to reciprocate through the crank (3) & connecting rod (4) arrangement.

Step 3. Due to the pumping action, the concrete is pumped through the delivery line and the delivery of concrete starts. If there is no blockage, the pump acts like a normal reciprocating piston pump as the hydraulic oil in the hydraulic cylinder is static and confined or enclosed as it is locked in completely as the non-return valve (16), ball valve (17) & safety relief valve (13) all are in a firmly closed position.

The piston remains on the extreme right side of the hydraulic cylinder as there is no pressure on the rod side as it is connected to the tank (15) without any restriction. Since the fluid (18) is confined in the cylinder (7) and an input force F1 is applied by the mechanical linkage (10), pressure is created in the confined liquid which is the same everywhere as per Pascal's law.

Therefore the force acting on the larger area (11) of the cylinder is automatically multiplied and the same force acts on the reciprocating piston (1) as the reciprocating piston (1) is mechanically coupled with the larger area(11). So if there is any resistance in the pumping pipeline, the force is multiplied as soon as the pressure rises in the confined liquid.

Step 4: However, if there is a sudden blockage in the delivery line, the reverse pressure on the piston of the hydraulic cylinder (7) rises. Once this pressure rises beyond the preset pressure of the safety relief valve (13), the relief valve operates & the oil is drained out to the hydraulic tank (15). In this situation, the rubber piston (1) remains where it is due to back pressure in the pipeline and the hydraulic piston (12) is pushed forward without any pressure as the oil is directed to the tank (15) by the relief valve (13). Thus the pressure is released and the mechanical linkage (10) & the prime mover are protected. During the return stroke, the anti-cavitation cum non return valve (16) sucks oil from the hydraulic tank (15) and the small hydraulic piston (12) comes back to the extreme rod end position. The same cycle is repeated in next stroke if the overload remains. It is important to note here that a locking arrangement at the end of the reverse stroke of the rubber piston (1) is provided at the end of the travel of the reciprocating piston (1); so as to enable the mechanical linkage (10) to pull back only the small area piston (12). Such locking arrangement is not shown in the fig. This is in order to avoid the entry of the rubber piston (1) into the water-box (6) due to back pressure of concrete in the pipeline and to allow the small piston to create lower pressure in the hydraulic cylinder (7) so as to allow oil passage from the anti-cavitation valve (16) during its reverse stroke.

Step 5: As soon as the overload is gone, and the pressure comes down the relief pressure of the safety valve (13), the linear force is again transmitted to the piston (1). This linear force is again multiplied and is applied on the material under pumping. This all happens automatically without any human intervention.

Step 6: The operator can however disengage the pump manually anytime at will by simply operating the ball valve lever thereby allowing the hydraulic oil to go to the tank. The small hydraulic piston (12) reciprocates & the power is not transmitted to the reciprocating rubber piston(1) and therefore the pumping piston (1) is disengaged from the mechanical linkages

Thus the said invention acts as a Force multiplier as well as a overload protection & disengaging device as was required since long time in a concrete pump having a reciprocating piston driven through mechanical linkages. The value of the safety hydraulic pressure can be easily calculated by calculating the safe concrete pressure.

Thus considering our earlier example of the concrete pump having a prime-mover of 19KW can now develop theoretically any amount of force which can develop any amount of pressure on concrete without increasing the power of the prime-mover.

Let us for example assume that this very pump is now fitted with a custom designed cylinder acting as a force multiplier Cum Overloading Device Cum dis-engaging device as disclosed is the Fig. 2 on sheet no. 2 which is the best method of performing this invention and the said device is provided with:

1. A larger area (11) having 150 mm diameter & hence a cross-sectional area of 28. 26 sq. inches;

2. A small area piston (12) having 50 mm diameter & hence a cross-sectional area of 3.14 sq. inches.

3. A static fluid (18) is closed or confined between these two differential areas.

4. The small area piston (12) is provided with a stroke-length (x) of say 185 mm wherein the stroke-length of the reciprocating piston is 180mm due to a 90 mm off-set crank.

Now, the maximum reciprocating force developed on the reciprocating piston (1) by the said engine & the said off-set crank-connecting rod mechanism is approx. 15106 Pound as previously calculated on sheet no. 5.

Now this force (F1) of 15106 pounds is acting on the small area piston (12) having a cross-sectional area creates a pressure of 4810.82 PSI on the static enclosed fluid (18).

As per Pascal's law therefore the same pressure of 4810.82 PSI acts on the larger area (11) having a cross-sectional area of 28.26 sq. inches. Therefore the Force acting on larger area F2 can be calculated as 135953.77 Pounds. Thus original force of 15106 Pounds has been multiplied almost 9 times. Hence the maximum piston face pressure can be calculated by dividing the force F2 by the cross-sectional area of the reciprocating piston (1) which is 40.69 sq. inches at around 3341.2 PSI instead of the original 371.24 PSI. Further the safety relief valve (13) can be pre-set at a value little lower than 4810.82 PSI so as to allow the oil to flow to the tank so as to limit the pressure in the static fluid (18) and to in turn limit the force F1 and therefore the torque on the crank. Thus in case of any overload the mechanical linkages and the prime mover are protected by operation of safety valve (13) and it limits the torque below the pre-set value without using a torque limiter. Most importantly the overload protection is fully automatic and without any human intervention and is related to the pressure on concrete as well as the torque on the crank.

Further the ball valve (17) can be anytime operated by the operator so as to disengage the pumping action. This is because the stroke length of small area piston (12) in this example is maintained at 185 mm whereas the stroke-length of the reciprocating piston (1) ίβ 180 mm due to the crank off-set distance of 90 mm. Therefore once the ball valve (17) is operated the fluid (18) is no longer static and is allowed to and fro to the hydraulic tan(< (15) and only the small piston (12) reciprocates and the reciprocating piston (1) does not due to the back pressure in the pipeline and the frictional force in the pumping cylinder. Therefore the pumping action can be disengaged without using a clutch.

Thus this example makes it very clear that this invention enables to increase the reciprocating force to theoretically any limit without increasing the prime mover power. In turn the force on the reciprocating piston creates a pressure on the concrete in the pipeline. However this invention does not violate the energy conservation law as the force is multiplied only when there is resistance in the pipeline.

Thus the above example proves beyond doubt that due to this Invention, a small concrete pump having a small size prime mover can develop a huge amount of pressure on concrete which was not at ail possible in any of the mechanically driven concrete pumps developed since 1914 till date and also enables to have 100% reliable overload protection & smooth manual disengagement of mechanical linkages & prime mover.

FIG. No. 4 on Sheet No. 4 :

The Fig. No.4 on sheet no. 4 discloses another embodiment of the said hydraulic cylinder (7). The Fig 4 A discloses the hydraulic cylinder (7) made up of two pistons ( 11 & 12) having differential areas and a open passage of fluid between them and the force F1 applied on the small area piston is multiplied due to the difference in areas of both the two pistons. The bigger area piston is provided a threaded shaft (8) on which the reciprocating piston (1) is mounted and the smaller piston (12) is also provided a threading shaft (9) its rod end which is mechanically fastened to the mechanical linkage (10) for application of input force. The fluid between the two pistons (18) is a static fluid enclosed or confined between the two pistons.

The Fig. 4B discloses the hydraulic cylinder as described earlier having a hollow enlarged section with the extreme end wall (11) having a bigger area of cross-section than the small piston (12). The bigger area wall (11) is provided with a threading on outer side (8) on which the reciprocating piston (1) is mounted. The piston side end is also provided threading (9) for mechanical attachment of the mechanical linkage (10).

Both embodiments work in similar fashion and the small piston (12) is provided with a stroke-length 'x' as shown in the Fig 4A & 4 B.

The stroke-length "x" is of high importance as it plays a major role especially in the overload protection and the disengagement function.

When the invention is used for achieving the combined functions of force multiplication, overload protection and manual disengagement, the stroke length "x" has to be little more than or exactly equal to the stroke length of the reciprocating piston or double the offset distance of the crank.

However when the invention is used only for force multiplication, a shorter stroke-length can be maintained so as to make the unit compact so as to be accommodated even in a hydraulically operated twin cylinder concrete pump.

The Fig. no. 5 on sheet no. 5 discloses the invention used in a hydraulically operated twin cylinder concrete pump, The hydraulic cylinder (7) having a static fluid (18) which is confined and enclosed in the hollow enlarged section due to the small piston (12) on which the input force is applied by means of hydraulic cylinders (23) and (24) wherein the hydraulic cylinders (23) and (24) are operated by fluid (22) which is displaced by the hydraulic pump used in the drive mechanism of the concrete pump. Therefore the fluids (18) and (22) are completely separate and independent and there is no relation with each other as the custom designed hydraulic cylinder (7) is essentially an "add on" unit completely separate & independent in its function from the drive mechanism.

When the invention is used only for force multiplication, it may or may not use all the safety components such as the safety valve, ball valve, non return valve and hydraulic tank, etc. In such a case it is also provided with a shorter stroke-length (x) so as to make it highly compact in order to easily accommodate between the reciprocating piston (1) & the mechanical linkage (10).

Novelty of the Invention:

First of all, a simple device based on Pascal's law enables to over-come all three serious problems associated with mechanically driven pumps. It needs to be specifically mentioned that the mechanical drive pumps have lost their significance due to these very limitations which are overcome by using a simple device for the first time since 1914. It is also well known that "Pascal's Law" is into existence for such a long time, makes the invention a very important invention as it overcomes the all three serious limitations by using Pascal's law in a dynamic mechanical system, without using a hydraulic pump.

Further the said simple device is mechanically accommodated between the reciprocating piston and the mechanical linkages, wherein the device comes into picture automatically only when there is a resistance in the pipeline. Further this device is completely different than any other manifestation of Pascal's law as the device works dynamically & automatically with respect to the repetitive force applied by the mechanical linkages and the pressure developed in the closed or confined liquid is dynamically used for transmission of power with and without using the actual displacement of the said pistons. This is because of the fact that the small piston is mechanically a separate entity compared to the hollow enlarged section and the force applied on the small piston is transmitted only though the confined liquid to the reciprocating piston, thereby enabling force multiplication. The displacement of larger area side happens only when the pipeline is completely jammed but which is very little and hence the law of energy conservation is not violated.

Further the said device enables the end user to mechanically dis-engage the pumping action simply by operating the ball valve. Thus the pumping action can be dis-engaged at will without using a clutch between the prime mover & the reciprocating piston.

Additionally the said device protects the mechanical linkages and the prime mover when the concrete pressure rises beyond the unsafe limit and the torque on the mechanical linkage goes above the calculated torque. This is easily achieved by using a simple safety relief valve (13) which can be pre-set depending upon the conversion ratio between the pressure developed in the confined fluid and the concrete pressure developed in the pipeline and the torque on the mechanical linkages. This feature makes the mechanically driven pump 100% reliable on all the three counts for the first time since 1914.

1. Force Multiplication of a mechanically driven pump without using a hydraulic pump: In the Entire history of concrete pumps since 1914, there has been no such arrangement in any of the mechanically driven concrete pumps wherein the mechanically applied force is increased multifold irrespective of the output without using a hydraulic pump.

The invention does use a very simple way for multiplying the reciprocating force based on Pascal's law. However the techno-commercial implication of this invention is very huge as the mechanical pumps have become obsolete due to low concrete pressures developed due to low reciprocating forces.

Further this invention has a far reaching effect wherein the force multiplier Cum overload protection & disengagement device design so is simple & cost effective and can be mechanically easily accommodated due to its threaded design in any reciprocating motion including those having hydraulic drives so as to multiply the reciprocating force & the said device is completely independent of the drive system.

2. 100% reliable fully automatic overload protection: such a overload protection system is not there in any of the prior arts of any of the mechanically driven reciprocating concrete pumps developed over the last several decades since 1914 all over the world. The overload protection system disclosed by this invention is 100% reliable and completely avoids any damage to the mechanical linkages & the diesel engine. Further the overload protection system is fully automatic and works without any human intervention and completely safeguards the mechanical linkages and the prime mover from sudden as well as gradual overloads.

"No other known design of any mechanically driven concrete pump discloses such an arrangement wherein the diesel engine driving the pump mechanically, is protected automatically by hydraulically disengaging the engine in case there is even a sudden shock load and at the same time increase the reciprocating force to multiple times of the force applied by mechanical linkages." 3. Manual disengagement of the pumping action of a mechanical drive without using a clutch: Presently available mechanically driven concrete pumps are provided with a clutch to engage or disengage the pumping action. No presently available mechanically driven pump can be disengaged from the prime mover without using a clutch. "This is a very novel feature and eliminates the otherwise essential clutch assembly from the mechanically driven concrete pump". And also results in reduction of capital as well as maintenance cost.

4. Pre-setting of hydraulic pressure in a mechanical drive: This is unheard of in the entire history of mechanically driven concrete pumps as it has introduced a concept pre-setting of safety pressure so as to avoid the damages to mechanical linkages & prime mover. "In earlier versions, the only option is to use a torque limiter. However the torque limiter is always related to the crank torque and cannot be associated with the concrete pressure as in this case".

5. Clear demarcation of forces:

"For the first time in the history of concrete pumps whether mechanical or hydraulic, the reciprocating forces are clearly demarcated due to this particular invention.

To elaborate, the reciprocating force developed by the reciprocating piston (1) which is inside the pumping cylinder is much larger than the input reciprocating force developed by the mechanical linkages (10) outside the pumping cylinder. In layman terms it means that the pumping force is very high after the force multiplier cum overload protection & disengaging device but low before the same. This means that lower torques can also generate very high reciprocating force which cannot act backwards inflicting damages on the linkages & prime mover.

[008] TECHNOLOGICAL ADVANTAGES & ECONOMIC SIGNIFICANCE: As mentjoned above a single low cost device can perform the following important things:

1. Multiply the reciprocating force without increasing power of prime mover

2. Multiply the input force irrespective of output

3. Act as a overload protection 4. Act as a normal disengaging device and enables the operator to disengage the pump from the prime-mover & mechanical linkages and successfully eliminates the clutch assembly.

5. Clearly demarcates between the input & output reciprocating forces and prevents the very high reciprocating force in the pumping cylinder to act backwards on the mechanical linkages & prime mover.

6. Works as a separate add on unit without any relation with the drive mechanism of the concrete pump.

The above Six very important advantages are so revolutionary and so against the conventional design that the entire concrete pump history since 1914 can be rewritten.

This invention develops very high concrete pressure at the lowest power irrespective of the output which means that the big costly hvdraulically driven pumps may no longer reguired And very high pressure concrete pumps can be made available at a very affordable price due to this invention.

Further since a small concrete pump having a small power prime mover can also be effectively used for high rise concrete pumping. Apart from the cost benefit, the diesel consumption can be brought down as the force can be multiplied many tjmes without using a bigger size prime mover and only when there is a restriction.

Further this invention can also be used in valve actuators so as to ensure higher forces and bring great reliability to the equipment.

Claims

WE CLAIM:

1. In accordance with the present invention, "A reciprocating piston concrete pump having a Force Multiplier Cum automatic overload protection & disengaging device separate from its drive mechanism" is disclosed wherein the invention is an improved concrete pump which typically & essentially consists of the followings.

a. A reciprocating piston concrete pump wherein the reciprocating piston -1 is made to reciprocate by using mechanical linkages or alternatively by using hydraulic pump drive mechanism.

b. A hydraulic force multiplier cum overload protection & disengaging device which independently works on Pascal's principle, mechanically installed between the reciprocating piston -1 & the mechanical linkage -10 wherein the hydraulic force multiplier cum overload protection and disengaging device is an "add on" unit completely separate & independent in its function from the pump's drive mechanism and is typically & essentially made up off:

(i) A custom designed hydraulic cylinder -7 having:

-a confined or enclosed static fluid filled-18 enclosed or confined between two differential areas -11 & 12 and the two differential areas are typically obtained by

-having a hollow enlarged but closed section on one side with the extreme wall -11 having a larger cross-sectional area than the small piston -12, wherein the hollow section starts after the piston stroke is complete.

Or having two separate pistons -11 & 12 having a passage of fluid between them.

-a threaded shaft -9 provided on the rod end of the small piston -12 which the mechanical linkage -10 is fastened for application of input force

-another threaded shaft -8 provided on the outer side of the extreme wall or bigger piston -11 on which the reciprocating piston -1 is fastened to exert output force on concrete. (ii) The small piston -12 of the said hydraulic cylinder -7 is typically provided with a stroke-length -x little more or equal to the stroke-length of the reciprocating piston -1 to also perform the work of overload protection or manual disengagement as well as force multiplication in such a case, however the stroke length is maintained by having mechanical restriction in such a way that the small area piston -12 never enters in the enlarged hollow section of the cylinder or the bigger piston side.

(iii) Alternatively the small piston -12 is provided with a shorter stroke-length (x) for using as only a force multiplier unit in a hydraulically driven concrete pump.

(iv) A small hydraulic oil tank -15 for the overload protection & disengagement function.

(v) A non-return cum anti-cavitation valve -16 for the overload protection & disengagement function.

(vi) A safety relief valve -13 for the overload protection

(vii) A ball valve -17 for manual disengagement function

(viii) High pressure hoses between the cylinder & the tank for overload protection & disengagement function.

(ix) Pressure gauge to show the pressure on the fluid.

2. "A reciprocating piston concrete pump having a Force Multiplier Cum automatic overload protection & disengaging device separate from its drive mechanism" as described in claim 1, wherein the invention is a mechanically or hydraulically driven reciprocating piston concrete pump provided with a separate & independent custom designed hydraulic cylinder -7 having a static fluid -18 confined or enclosed between two differential areas -11 & 12 and the said hydraulic cylinder -7 is mechanically accommodated between the reciprocating rubber piston -1 and the mechanical linkage -10 which is applying reciprocating force.

3. "A reciprocating piston concrete pump having a Force Multiplier Cum automatic overload protection & disengaging device separate from its drive mechanism" as described in claim 1, wherein the said invention is a concrete pump having a mechanically driven reciprocating piston-1 and the mechanical linkages -10 & the prime mover are automatically protected by using a hydraulic cylinder -7 installed between the reciprocating piston -1 & the mechanical linkages -10 wherein the said hydraulic cylinder -7 is provided with differential areas -11 & 12 on both sides and a closed or confined static fluid-18 between them where the differential areas are obtained either by means of a hollow enlarged section having an extreme wall -11 with a larger cross-sectional area than the hydraulic piston -12 or alternatively by having two different diameter pistons -11 & 12 with a passage of fluid between them where the reciprocating piston -1 is mechanically coupled to the larger diameter piston -11 $ the mechanical linkages -10 are mechanically coupled with rod end of the smaller diameter piston -12.

4. "A reciprocating piston concrete pump having a Force Multiplier Cum automatic overload protection & disengaging device separate from its drive mechanism" as described in claim 1, wherein the said invention is a concrete pump having minimum one reciprocating piston -1 installed on a custom designed hydraulic cylinder -7 wherein the hydraulic cylinder -7 has a static fluid -18 enclosed or confined between two differential areas -11 & 12 and each differential area side is provided with a threaded portion -8 & 9 in order to be accommodated between the reciprocating piston -1 & the mechanical linkage - 10.

5. "A reciprocating piston concrete pump having a Force Multiplier Cum automatic overload protection & disengaging device separate from its drive mechanism" as described in claim 1, is a concrete pump typically having an additional hydraulic cylinder -7 mechanically installed between the reciprocating piston -1 and the mechanical linkage 10 wherein the said hydraulic cylinder -7 contains a static fluid enclosed or confined between two areas -11 & 12.

6. "A reciprocating piston concrete pump having a Force Multiplier Cum automatic overload protection & disengaging device separate from its drive mechanism" as described in claim 1, is a concrete pump typically dri en through hydraulic drive having an additional hydraulic cylinder -7 mechanically installed between the reciprocating piston -1 and the mechanical linkage -10 wherein the said hydraulic cylinder -7 contains a static fluid -18 enclosed or confined between two areas -11 & 12 and the mechanical linkage-10 typically means a rod end or piston end of the hydraulic cylinder used to hydrauljcally operate the reciprocating piston -1.

7. "A reciprocating piston concrete pump having a Force Multiplier Cum automatic overload protection & disengaging device separate from its drive mechanism" as described in claim 1, consists of a concrete pump typically driven through hydraulic drive having an additional hydraulic cylinder -7 mechanically installed between the reciprocating piston -1 and the mechanical linkage -10 wherein the said hydraulic cylinder -7 contains a static fluid-18 enclosed or confined between two areas -11 & 12 and the mechanical linkage - 10 typically means the driving end of the hydraulic cylinder used to hydraullcally operate the reciprocating piston -1 and the said cylinder -7 is separate and independent of its drive mechanism.

8. "A reciprocating piston concrete pump having a Force Multiplier Cum automatic overload protection & disengaging device separate from its drive mechanism" as described in claim 1, typically consists of a concrete pump having an additional hydraulic cylinder -7 mechanically installed between the reciprocating piston -1 and the mechanical linkage -10 wherein the said hydraulic cylinder -7 contains a static fluid -18 enclosed or confined between two areas -11 & 12 and a ball valve -17 is provided so as to manually disengage the pump action by allowing the fluid -18 a passage to the hydraulic tank -15.

9. "A reciprocating piston concrete pump having a Force Multiplier Cum automatic overload protection & disengaging device separate from its drive mechanism" as described in claim 1, consists of a concrete pump having an additional hydraulic cylinder -7 mechanically installed between the reciprocating piston -1 and the mechanical linkage -10 wherein the said hydraulic cylinder -7 contains a static fluid -18 enclosed or confined between two areas -11 & 12 and a safety relief valve -13 is provided in order to relieve the pressure on the confined fluid -18 in case the pressure crosses the preset limit of the said relief valve -13.

10. "A reciprocating piston concrete pump having a Force Multiplier Cum automatic overload protection & disengaging device separate from its drive mechanism" as described in claim 1, wherein the said invention is a mechanically driven concrete pump which typically & essentially consists of an additional hydraulic cylinder -7 mechanically installed between the reciprocating piston -1 and the mechanical linkages -10 wherein the said cylinder -1 is alternatively a single acting cylinder having a static fluid -18 enclosed or confined between two areas -11 & 12.

11. "A reciprocating piston concrete pump having a Force Multiplier Qum automatic overload protection & disengaging device separate from its drive mechanism" as described in claim 1, wherein the said invention is a mechanically driven concrete pump which typically & essentially consists of an additional hydraulic cylinder -7 mechanically installed between the reciprocating piston -1 and the mechanical linkages -10 wherein the said reciprocating piston - 1 is made to reciprocate by using mechanical means including but not limiting to a crank & a connecting rod.

12. "A reciprocating piston concrete pump having a Force Multiplier Cum automatic overload protection & disengaging device separate from its drive mechanism" as described in claim 1, wherein the said invention is a mechanically driven concrete pump which typically & essentially consists of an additional hydraulic cylinder -7 mechanically installed between the reciprocating piston -1 and the mechanical linkages -10 wherein the piston -12 of the said cylinder -7 is provided with a stroke length -x more than or equal to the stroke- length of the reciprocating piston -1.

13. "A reciprocating piston concrete pump having a Force Multiplier Cum automatic overload protection & disengaging device separate from its drive mechanism" as described in claim 1, wherein the said invention is a hydraulically driven concrete pump which typically & essentially consists of an additional hydraulic cylinder -7 mechanically installed between the reciprocating piston -1 and the hydraulic cylinder driving the reciprocating piston -1 wherein the said cylinder is provided with a shorter stroke-length x than the stroke of the reciprocating piston and the said cylinder is used only as a force-multiplier.

14. "A reciprocating piston concrete pump having a Force Multiplier Cum automatic overload protection & disengaging device separate from its drive mechanism" as described in claim 1, wherein the said invention is typically a mechanically driven concrete pump which typically & essentially consists of an additional hydraulic cylinder -7 mechanically installed between the reciprocating piston -1 having a confined or enclosed fluid -18 between two areas -1 1 & 12 and is alternatively provided with a pressure sensor in order to operate an electromagnetic clutch to disengage the prime mover if the pressure crosses a pre-set limit.