WO2013164780A1

WO2013164780A1 - A load truck and a method of offloading a load truck

Info

Publication number: WO2013164780A1
Application number: PCT/IB2013/053466
Authority: WO
Inventors: Tiran Moshe; Doron Moshe
Original assignee: VAN DER WALT LOUIS STEPHANUS
Current assignee: VAN DER WALT LOUIS STEPHANUS
Priority date: 2012-05-02
Filing date: 2013-05-02
Publication date: 2013-11-07
Anticipated expiration: 2014-11-02

Description

A LOAD TRUCK AND A METHOD OF OFFLOADING A LOAD TRUCK

FIELD OF THE INVENTION

This invention relates to load trucks and to methods of offloading load units. More particularly, the invention relates to a load truck for moving loads units laden on pallets or slip sheets and to a method of offloading such a load unit.

BACKGROUND OF THE INVENTION

The use of loads trucks for moving palletised load units for the purpose of transportation and storage is well known. There are a large variety of load trucks which are used to move palletised load units, including low-lift pallet trucks and fork lift trucks.

Pallet trucks may be propelled manually or by a motor. Some pallet trucks and fork lift trucks are operated by a ride-on operator and others by an operator on foot.

A more recently developed method of moving load units for the purpose of transportation and storage is to load them onto slip sheets instead of pallets. Proper moving of load units laden on slip sheets requires specialised load trucks. These include fork lift trucks fitted with so-called push/pull mechanisms for pulling load units onto their forks and for pushing them from the forks, and so-called roller forks. In some such load trucks, the push/pull mechanism includes a travelling push/pull member which is connected to a fixed part by means of a scissor mechanism, which maintains a fixed orientation of the push/pull member, and a hydraulic cylinder assembly acting between components of the scissor mechanism for effecting displacement of the push/pull member. Typically, load trucks used for moving palletized or load sheet laden load units may be classified into low-lift trucks and fork lift trucks. Low-lift trucks provide for only limited lifting of a load unit to clear the ground, whereas fork lift trucks provide for sufficient lifting of a load unit for inter alia stacking purposes. A low-lift truck may be either human propelled or motor propelled. Fork lift trucks typically are motor propelled.

There are motor propelled, ride-on variants of both low-lift trucks and fork lift trucks. Walk-along load trucks, which are operable by a human operator on foot, may be either operator propelled or motor propelled. Operator propelled low-lift trucks, sometimes referred to as hand trucks, typically represent the low cost end of the spectrum of load trucks. One particular load truck with which the Applicant is familiar is disclosed in

WO 201 1/098966.

It is sometimes required to place a load unit laden on a pallet or a slip sheet against an object, for example a front wall of a shipping container or another load unit. Such placement has two main advantages, namely assisting in load stability and optimising space utilization. The Applicant has found that using the load truck of WO 201 1 /098966 according to the method of WO 201 1 /098966, can still result in a gap being left between the load unit and the object against which it was to be placed. This is due to some degree to the inadequacies of the lashing or fastening means used to secure the load truck when the load unit is pushed from the load truck.

It is an object of the invention to provide for a load truck which at least ameliorates the disadvantages of the load truck disclosed in WO 201 1 /09866.

SUMMARY OF THE INVENTION

According to the invention, there is provided a load truck, the load truck includes: a load support structure for a load unit, the structure defining a front end, a rear end and a longitudinal direction, and including at least one retractable ground wheel; and

a load shifting mechanism including:

a fixed member, fixed with respect to the load support structure at a position rearwardly spaced from the front end of the load support structure;

a travelling member defining an upright front face, above the load support structure and transverse to the load support structure, for operatively pushing the load from the load support structure, the travelling member being displaceable in the longitudinal direction between a rearward position, intermediate the fixed member and the front end of the load support structure and remote from the front end, and a forward position proximate the front end of the load support structure; and

an actuation mechanism operable to displace the travelling member between the rearward position and the forward position on the load support structure;

wherein the load support structure includes a bearing surface on an underside thereof for bearing frictionally against the ground or base surface, the ground wheel being displaceable between two positions, namely:

an extended position in which it stands proud of the bearing surface and supports the load support structure allowing displacement thereof; and

a retracted position in which the bearing surface stands proud of the ground wheel, such that the bearing surface frictionally engages the ground or base surface and acts as a friction brake, inhibiting displacement of the load support structure.

The load support structure may be in the form of a fork member. In such case, the load support structure may include at least two spaced apart, longitudinally extending support elements. Each support element may be provided with at least one retractable ground wheel and at least one bearing surface. The retractable wheel may be hydraulically displaceable, or it may be mechanically displaceable, e.g. by means of a torsion tube assembly.

The bearing surface may be embodied by a brake member mounted on an underside of the load support structure or an underside of the load support element. The break member may be a brake block of any suitable material, e.g. a metal or a polymeric material such as rubber or plastic. The brake member may be integral with the load support structure or the load support element, e.g. it may extend downwardly from the underside thereof.

In another embodiment, the bearing surface may be integral with the underside of the load support structure or the load support element.

The load shifting mechanism may include a scissor mechanism interconnecting the travelling member and the fixed member. The scissor mechanism may maintain a fixed orientation of the travelling member relative to the support structure.

The actuation mechanism may be a hydraulic cylinder assembly. The hydraulic cylinder assembly may have opposite ends thereof connected to the fixed member and the travelling member respectively, and may be operable to exert opposing forces between the members to displace the travelling member from the rearward position to the forward position on the load support structure.

The hydraulic cylinder assembly may have a central axis disposed in the longitudinal direction of the load support structure. The hydraulic cylinder assembly may be a telescopic cylinder assembly. The hydraulic cylinder assembly may be double acting. In this case, the actuation mechanism is a push/pull mechanism and may be provided with a slip sheet gripping mechanism for gripping a slip sheet for pulling a load unit laden on the slip sheet onto the load support formation.

The load truck may be a low-lift truck, in which the load support structure is adjustable only within a limited height range near ground level. The load truck may be operable by a human operator on foot. It may be propelled by the operator.

It will be appreciated by a person skilled in the art that the load truck of the invention may be of any type essentially as herein envisaged, i.e. a low-lift truck or a fork lift truck, human propelled or motor propelled, and ride-on or walk-along.

According to a second aspect of the invention there is provided a method of offloading a load unit against an object, the method including:

supporting the load unit on a load support structure of a load truck, the load support structure defining a front end, a rear end and a longitudinal direction, and including at least one retractable ground wheel and a bearing surface on an underside of the load support structure for bearing frictionally against the ground or base surface, the ground wheel being displaceable between an extended position in which it stands proud of the bearing surface and supports the load support structure allowing displacement thereof, and a retracted position in which the bearing surface stands proud of the ground wheel, such that the bearing surface frictionally engages the ground or base surface and acts as a friction brake, inhibiting displacement of the load support structure, and a load shifting mechanism operable to push the load unit from the load support structure in a forward direction of the load support structure;

positioning the load truck for offloading the load unit adjacent to the object, with a front end of the load support structure facing the object; and

by operation of the load shifting mechanism, pushing the load unit from the load support structure in the longitudinal direction;

wherein during the pushing of the load unit, the load truck is anchored by retracting the at least one retractable ground wheel to bring the bearing surface into abutment with the ground or base surface, resulting in the load shifting mechanism pushing the load unit into abutment with the object.

The method may include, during at least a last stage of the pushing of the load unit, extending the at least one retractable wheel so as to lift the bearing surface from abutment with the ground or base surface, thereby to allow the load truck to be displaced in a rearward direction relative to the load unit being pushed from the load support structure.

The problem referred to above of a gap being left during offloading is thereby ameliorated by the method of the second aspect of the invention. Advantages include optimisation of space usage and load stability.

The load truck used in the method may be a low-lift truck, in which the load support structure is adjustable only within a limited height range near ground level.

The load truck may be operable by a human operator on foot. It may be propelled by the operator.

It will be appreciated by a person skilled in the art that the method of the invention may be applied to any type of load truck essentially as herein envisaged, i.e. a low-lift truck or a fork lift truck, human propelled or motor propelled, and ride-on or walk-along.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described, by way of example, with reference to the accompanying diagrammatic drawings.

In the drawings:

FIGURE 1 shows a rear three-dimensional view of a load truck, in accordance with the invention, in a first operative configuration thereof;

FIGURE 2 shows a rear three-dimensional view of the load truck of

Figure 1 , in a second operative configuration thereof;

FIGURE 3 shows a side view of the load truck of Figure 1 , in the first operative configuration; shows a side view of the load truck of Figure 1 , in the second operative configuration; and

show respectively side views of the load truck of Figure 1 , in progressively offloading a load unit against an object.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENT

In the drawings, reference numeral 10 generally indicates a load truck, in accordance with the invention. The load truck 10 is a low-lift truck.

With particular reference to Figures 1 and 2, the load truck 10 includes:

a load support structure in the form of a fork 12 including two parallel, spaced apart fork beams 14;

a bogie mounting assembly 1 6 mounted on rear ends of the fork beams 14;

a bogie 18 including a pair of rear wheels 20;

a bearing surface 19 on an underside of each fork beam 14 for bearing frictionally against the ground or base surface;

a retractable front wheel 21 , supporting the respective fork beams 14, the wheels 21 being displaceable by a torsion tube assembly (not shown) between an extended position in which they stand proud of the bearing surfaces 19 and support the fork beams 14 allowing displacement thereof, and a retracted position in which the bearing surfaces 19 stand proud of the wheel 21 , such that the bearing surfaces 19 frictionally engage the ground or base surface and act as a friction brake, inhibiting displacement of the fork beams 12;

a lifting mechanism including a hydraulic jack 22, for lifting and lowering the bearing surfaces 19 by retracting and extending the retractable wheels 20 and 21 ; and

a handle 24.

The fork beams 14 extend in a longitudinal direction of the fork 12. The fork 12 has a front end 13.1 and a rear end 13.2. Each fork beam 14 includes a series of longitudinally spaced load support rollers 15, a bearing surface 19 and a retractable wheel 21 .

The load truck 10 is manually operated and propelled by a human operator on foot. The operator uses the handle 24 for actuating the hydraulic jack 22 for extending and retracting the wheels 21 , thereby lifting and lowering the fork 12. The wheels 21 are typically connected to the handle by a torsion tube assembly within the forks 14 (not shown) which enables the wheels 21 to be retracted and extended by operation of the handle 24 and the hydraulic cylinder 22.

In the embodiment shown, when the handle 24 is lowered, the hydraulic cylinder 22 is actuated and the torsion tube assembly (not shown) acts to extend the retractable wheels 24 so that they stand proud of the bearing surfaces 19, thereby lifting the forks 14 and lifting the bearing surfaces 19 away from frictional abutment with the ground, for example as shown in Figures 6 and 7. When the handle 24 is returned to its upright position, the wheels 21 are retracted as shown in any one of Figures 1 to 4, the forks 14 are lowered and the bearing surfaces 19, which then stand proud of the retractable wheels 21 , are brought into frictional abutment with the ground.

The load truck 10 includes a load shifting mechanism 25 including:

an upright fixed member in the form of a fixed frame 26 mounted on the fork beams 14 just in front of the bogie mounting assembly 16;

an upright travelling member in the form of a travelling frame 28, supported on the respective fork beams 14 by means of the two support wheels 38 which travel on the respective fork beams 14;

a scissor mechanism 30 interconnecting the frames 26 and 28; and an actuator mechanism 27 including:

a longitudinal double acting, telescopic, hydraulic cylinder assembly 32 acting between the fixed frame 26 and the travelling frame 28; and

a power pack 36 for powering the hydraulic cylinder assembly 32 by means of pressurised hydraulic oil. The scissor mechanism 30 provides for displacement of the travelling frame 28 between a rearward position, as shown in Figures 1 , 3 and 5, and a forward position, as shown in Figures 2, 4 and 7. The scissor mechanism 30 maintains the travelling frame 28 parallel to the fixed frame 26 so that an upright front face 29 (see Figure 3) of the travelling frame 28 is maintained upright and transverse relative to the fork 12.

A front end of the hydraulic cylinder assembly 32 is connected to a centre of the travelling frame 28 whereas a rear end of the hydraulic cylinder assembly 32 is connected to the fixed frame 26. More particularly, a rear portion of the hydraulic cylinder assembly 32 passes through a centre of the fixed frame 26 and is connected thereto by means of two opposite brackets 34 projecting rearwardly from the fixed frame 26, with a dowel pin 35 releasably interconnecting a rear end of the hydraulic cylinder assembly 32 and the brackets 34.

By operation of the power pack 36, the hydraulic cylinder assembly 32 is selectively extended or contracted, thereby displacing the travelling frame 28 forwardly or rearwardly, respectively.

The load truck 10 may be used in the configuration shown in Figure 1 , with the travelling frame 28 in its rearward position, for moving a palletized load unit in conventional fashion. Alternatively, the load truck 10 may be used for moving a load unit laden on a slip sheet. For this purpose, the load shifting mechanism 25 may be provided with a slip gripping mechanism (not shown) along a bottom edge 37 (see Figure 3) of the travelling frame 28. Such a slip gripping mechanism may be essentially conventional and therefore does not require illustration or description herein.

With reference now to Figures 5 to 7 of the drawings, a method of offloading a load unit, in accordance with the second aspect of the invention, will now be described. It is sometimes required to place a load unit laden on a slip sheet against an object, for example a front wall of a shipping container or another such load unit. Such placement has two main advantages, namely assisting in load stability and optimising space utilization. In practice, the Applicant has found that using the load truck of WO 201 1 /098966 according to the method of WO 201 1/098966, can still result in a gap being left between the load unit and the object against which it was to be placed. This is due to some degree to the lashing or fastening means used to secure the load truck when the load unit is pushed from the load truck. The method of the second aspect of the invention aims to address this problem.

In Figure 5, a load unit (or simply a load) 40 has been laden on a slip sheet 42 and supported on the fork 12 of the load truck 10. The load truck 10, with the load unit 40 thereon, has been pushed into a shipping container 44, which has a floor 46 and an end wall 48, into the position shown in which the front end 13.1 of the fork 12 is positioned at a short distance from the end wall 48, e.g. at a distance approximately one third to one half the length of the load unit 40 from the end wall 48. The handle 24 is placed in the upright position thereby retracting the retractable wheels 21 and placing the bearing surfaces 19 in frictional abutment with the floor 46. In this position, the bearing surfaces 19 act as frictional brakes thereby inhibiting the load truck 10 from being displaced, i.e. the weight of the load 40 on the forks 14 and the bearing surfaces 19 on the floor 46 prevents the load truck 10 from being moved.

In Figure 6, by operating the power pack 36 (see Figure 5), the hydraulic cylinder assembly 32 has been partially extended, causing forward displacement of the travelling frame 28. The travelling frame 28, with its face 29 bearing against the load unit 40, has pushed the load unit 40 and slip sheet 42 into a position in which they abut against the end wall 48 and are predominantly supported on the fork 12. No gap has been left between the load unit 40 and the wall 48, as the Applicant has found often happens in practice, e.g. with conventional load-shifting trucks. With the load unit 40 in abutment with the end wall 48, the handle 24 is lowered, causing the retractable wheels 21 to be extended, i.e. to stand proud of the bearing surfaces 19, thereby to lift the bearing surfaces 19 from frictional abutment with the floor 46. The load truck 10 is then displaceable, i.e. the forks 14 are supported by the wheels 21 and not the bearing surfaces 19. In Figure 7, by operating the power pack 36 (see Figure 5), the hydraulic cylinder assembly 32 has been completely extended. The load unit 40 and the slip sheet 42 which were flush against the wall (Figure 6) have, by acting against the travelling frame 28, displaced the load truck 10 rearwardly with respect to the load unit 40 into a position in which the load unit is entirely supported on the floor 46 in front of the fork 12.

The Applicants submit that the configuration of the load shifting mechanism 25, the retractable wheels 21 and the bearing surfaces 19, and particularly the use of the retractable wheels 21 and the bearing surfaces 19 in conjunction with the hydraulic cylinder assembly 32 acting longitudinally between the travelling frame 28 and the fixed frame 26 in accordance with the invention, surprisingly provides an efficient, economical, and practical load shifting arrangement which ameliorates the problems associated with the load trucks and methods of the prior art.

Differently stated, while the load shifting mechanism 25 without the braking provided by the bearing surface 19 can be useful for shifting a load 40, the reactive force of the weight of the load 40 can result in inadvertent displacement of the load truck 10. A bearing surface 19 with no load-shifting abilities may be unnecessary. Thus, the Applicants believe that the combination of a load shifting mechanism 25 and the bearing surface 19 functioning as a braking mechanism provides a synergy which leads to the advantages mentioned.

Although the load truck 10 in the above example is a walk-along, human propelled, low-lift truck, it must be appreciated that different embodiments of a load truck, in accordance with the invention, may be of any type essentially as herein envisaged, i.e. a low-lift truck or a fork lift truck, human propelled or motor propelled, and ride-on or walk-along. So, for example, the retractable wheels 21 , the bearing surfaces 19 and the load shifting mechanism 25 may alternatively be provided on a motor propelled fork lift truck.

Claims

A load truck, the load truck including:

a load support structure for a load unit, the structure defining a front end, a rear end and a longitudinal direction, and including at least one retractable ground wheel; and

a load shifting mechanism including:

a travelling member defining an upright front face, above the load support structure and transverse to the load support structure, for operatively pushing the load unit from the load support structure, the travelling member being displaceable in the longitudinal direction between a rearward position, intermediate the fixed member and the front end of the load support structure and remote from the front end, and a forward position proximate the front end of the load support structure; and an actuation mechanism operable to displace the travelling member between the rearward position and the forward position on the load support structure;

2. The load truck of claim 1 , wherein the load support structure is in the form of a fork member comprising at least two spaced apart, longitudinally extending support elements.

3. The load truck of claim 2, wherein each support element is provided with at least one retractable ground wheel and at least one bearing surface.

4. The load truck of claim 3, wherein the retractable wheel is mechanically displaceable by means of a torsion tube assembly.

5. The load truck of any of claims 1 to 4 inclusive, wherein the bearing surface is embodied by a brake member mounted on an underside of the load support structure or an underside of the load support element.

6. The load truck of any of claims 1 to 4 inclusive, wherein the brake member is integral with the load support structure or the load support element.

7. The load truck of any of the preceding claims, wherein the load shifting mechanism includes a scissor mechanism interconnecting the travelling member and the fixed member which maintains a fixed orientation of the travelling member relative to the support structure.

8. The load truck of any of the preceding claims, wherein the actuation mechanism is a hydraulic cylinder assembly which has opposite ends thereof connected to the fixed member and the travelling member respectively and is operable to exert opposing forces between the members to displace the travelling member from the rearward position to the forward position on the load support structure.

9. The load truck of any of the preceding claims, wherein the load truck is a low-lift truck, in which the load support structure is adjustable only within a limited height range near ground level.

10. The load truck of any of the preceding claims, wherein the load truck is operable by a human operator on foot.

1 1 . The load truck of claim 10, wherein the load truck is propelled by the operator.

12. A method of offloading a load unit against an object, the method including:

by operation of the load shifting mechanism, pushing the load unit from the load support structure in the longitudinal direction; wherein during the pushing of the load unit, the load truck is anchored by retracting the at least one retractable ground wheel to bring the bearing surface into abutment with the ground or base surface, resulting in the load shifting mechanism pushing the load unit into abutment with the object.

13. The method of claim 12, which includes, during at least a last stage of the pushing of the load unit, extending the at least one retractable wheel so as to lift the bearing surface from abutment with the ground or base surface, thereby to allow the load truck to be displaced in a rearward direction relative to the load unit being pushed from the load support structure.

The method of claim 12 or claim 13, wherein the load truck is a load truck as claimed in any of claims 9 to 1 1 inclusive.