US2031456A - Pump construction - Google Patents

Description

Feb, m, 13%. E. H. BLUNT PUMP CONSTRUCTION Original Filed Feb. 5, 1930 4 Sheets-Sheet Feb, 18, 193. E. H. BLUNT Zflfiflfifi P MP CONSTRUCTION Original Filed Feb. 3, 1950 4 Sheets-Sheet 2 15* 1! EMU Ill 2&3 3,45%

Feb, 18, W36 E. H. BLUNT PUMP CONSTRUCTION Original Filed Feb. 3, 1950 4 Sheets-Sheet 3 Feb w, W36. E. H. BLUNT PUMP CONSTRUCTION Original Filed Feb. 5, 1930 4 Sheets-Sheet Patented Feb. 1 8, 1936 warren srArEs PATENT orrica Application February 3, 1930, Serial No. 425,663

' Renewed January 13, 1934 12 Claims.

My invention relates toimprovements in pumps and particularly to what are commonly termed steam driven direct acting pumps. This application is a continuation in part of my application 5 604,414 filed Dec. 1, 1922, and now Patent 1,745,597 dated Feb. 4, 1930, in which I have claimed a feed water heater but which patent discloses a combination of two steam driven pumps having certain features of construction which may be employed for other purposes than in a feed water heater. 7

One object of the present invention is to provide a pair of steam driven pumps in which the pistons are capable of operating against a greater pressure when moving in one direction than when moving in the opposite direction.

Another object is toprovide a construction of this character in which the two pistons are capable of operating against a greater pressure when moving in one direction than when moving in the opposite direction.

Another object is to provide a construction of this character in which the two pistons although movable simultaneously in opposite directions arrive at the ends of their strokes more quickly when moving in one direction than when moving in the opposite direction so that one piston will usually remain stationary and Wait for the other piston to reach its end of the stroke in the opposite direction. The two pistons are thus synchronized at the start of each stroke although one may arrive at the end of its stroke before the other.

Another object is to provide means for cushioning the pistons at the end of a pumping stroke so as to insure the gradual slowing down of the piston and prevent shock.

In the construction as herein illustrated the pumps are intended to handle liquids and the power is supplied by steam. There are two units each consisting of a, pump cylinder and piston and a steam cylinder and piston. The pistons of each unit are connected by a common piston rod which passes through the adjacent ends of the steam and pump cylinders. The steam is supplied to the steam cylinders through a main valve of conventional type which is controlled by a single auxiliary valve arranged transversely on the top of the steam cylinders. This auxiliary valve is mechanically actuated by tappets connected to the respective steam piston rods.

In the particular structure shown the pump units receive liquid alternately from a common source through intake valves at a suitable pres- 5 sure and these pistons alternately discharge this liquid through common valve passages at substantially the received pressure. The opposite ends of the pump pistons are of greater area and intended to alternately receive liquid from a common source and discharge this liquid alternately through a common port or ports but at a materially greater pressure than the pressure at which the liquid is received. This unequal pressure of discharge at the opposite ends of the pump pistons obviously requires a special valve for supplying steam pressure appropriate for the work to be done.

In this case, for instance, the pump units are arranged with vertical piston rods and the steam pressure employed to force the pistons down may be for instance, 250 pounds to the square inch, whereas the pressure required for lifting the pistons may not exceed pounds per square inch. This difference in pressure may be acquired in various ways, for instance, by use of a reducing valve of conventional type interposed in the passage for the steam to the lower sides of the steam pistons.

Such a construction is admirably adapted to the handling of two different liquids or fluids at the same time with such appropriate volumetric ratio as may be necessary.

One instance of such use is that of my former Patent 1,745,597 where the pump draws in a certain volume of cold water in the upper ends of the pump cylinders and forces that cold water into a feed water heating chamber, while the opposite or lower ends of the pumps receive a larger volume of hot water from the heater vessel and force it into the boiler. In this case the difierence in volume of the cold and hot water is of course made up by the steam which is condensed within the vessel. The upper ends of the pumps will in such case be receiving water under the comparatively low head due to the height of the Water tank of a locomotive and forcing this cold water into the heater vessel against the pressure of what would ordinarily be the exhaust steam used to heat the heater vessel. The lower ends of the pumps will of course be receiving hot water from the heater vessel under the head due to this height above the pump suction valves, whereas the lower ends of the pumps must discharge this heated water against boiler pressure. So far as the present invention is concerned, 50 however, the mechanism might be employed for handling diiferent liquids or liquids containing chemicals to be mixed.

Fig. 1 shows a part sectional and part side elevation of. a combined or twin unit pump with the necessary valves and conduits and also one type of steam operating mechanism.

Fig. 2 is a side elevation of the right hand pump shown in Fig. 1 partly in section on the plane of the line 22.

Fig. 3 is a sectional view of the combined stuffing box and water cushioning device of Fig. 1, showing details of preferred construction.

Figs. 4 to 19, inclusive, show details of a modification of the steam valve control of Figs. 1 and 2.

Fig. 4 is a section of an auxiliary synchronizing steam valve taken on the plane of the line 4-4 of Fig. 11.

' Fig. 5 is a section taken on the plane of the line 5 of Fig. 11.

Fig. 6 is a section taken on the plane of the line 6 of Figs. 15 and 16.

Fig. '7 is a section through the synchronizing valve taken on the plane of the line 7 of Figs. 15 and 16.

Fig. 8 shows a top plan view of a pair of steam cylinders with the preferred form of steam valves parts being shown in section.

Fig. 9 is a side elevation, partly sectioned, of thesame steam cylinders and shows the mounting of the regulating synchronizing valve 15 on top.

Fig. 10 is a horizontal sectional view on the plane of line IO-Hl in Fig. 9 and plan of the preferred type of synchronizing valve in the first position of its pumping cycle.

Fig. 11 is a vertical sectional elevation of the same valve in the same position as in Fig. 10, a section being taken on the plane of the line llll of Fig. 8,

Fig. 12 is a vertical sectional elevation of the left hand tappet-rod valve, on the plane of the line |2-I2 of Fig. 8.

Fig. 13 is a sectional plan showing the synchronizing valve in its second position.

Fig. 14 is a sectional plan of this valve in its third position.

Fig. 15 is a sectional plan of the same valve in its fourth position.

Fig. 16 is a sectional elevation of the valve in the same position.

Fig. 17 is a sectional plan of the synchronizing valve in its fifth position.

Fig. 18 is a sectional plan View of this valve in its last or sixth position.

Fig. 19 is a left end view of same valve on the line l9- l9'of Fig. 10.

In the form shown in Fig. 1 the pump cylinders 1 and 2 are arranged side by side and are provided with pistons 3 and 4 having piston rods 5 and 6 respectively. These piston rods may have sleeves such as 5a and 6a. The pump cylinders are provided with an upper head 1 and a lower head 1'. The upper ends of the pump cylinders are provided with a supply pipe 8 and suction valves 9 between the supply pipe and the chamber l which connects the upper ends of the two cylinders. Each pump cylinder is provided with a discharge valve H which is preferably of the multiple beat type and controls the discharge of liquid through the conduit l2, for instance, to a spray head of a feed water heater connected to the outlet l3 as set forth in my Patent Fig. 2 shows the two chambers l0 and IDA and the discharge valve I l and I IA for the two pumps. Valve HA discharges through pipe [4 which is connected to conduit l2.

The lower end of the pump has an intake or supply pipe 15 discharging into the chamber IS. The right hand pump cylinder is provided with intake or suction valves 11 and the left hand cylinder is provided with suction valves 23. The lower ends of the cylinders are provided with outlet passages 24 leading to chambers 20 and 20A on opposite sides which are connected by a passage 25. The chambers 20 and 20A may be provided with separate cover plates 26.

Valves l9 control the discharge of water from the lower ends of the pump cylinders to the chambers 20 and 20A and the discharge members 2| and 22. Portions of the pump cylinder head 1 extend downwardly in the form of flanges 21 forming stuffing boxes for the piston rods and providing cushioning means which will be described hereinafter.

A casting 28 forms a bridge resting upon the head I and in turn supporting the plate 3| which forms the lower heads of the steam cylinders 29 and 38. Stufiing boxes 32 guide the piston rods through the lower heads of the steam cylinders. Steam piston 33 is secured on the upper end of the piston rod and is loosely connected to a tappet-rod 34 in a well known manner. A button 35 on the lower end of the tappet-rod is adapted to engage a plate 36 on the top of the piston 33. Enlargement 36A on the upper part of the tappet-rod is also adapted to engage the plate 36. Piston 33a is secured to piston rod 6 and travels in the steam cylinder 30. The upper ends of the steam cylinders are provided with a plate 31a which provides the usual heads for the steam cylinders.

A steam actuated main valve 8|, contained in a casing 38, supplies the operating steam to the top of one steam cylinder and to the bottom of the other cylinder simultaneously, and vice versa. This valve is similar to that used by locomotive air compressors and is shown in vertical section (Figs. 1 and 2) and in horizontal section (Fig. 8). A steam port 85, within casing 38, connects by a passage 85a, to the top of steam cylinder 29 and also through a pressure reducing valve similar to 44 of Fig. 2, it connects with conduit 45 and the bottom of cylinder 30.

The main valve for controlling the admission and exhaust of steam is of a conventional type as shown in my Patent 1,745,597. One form is shown in Figs. 1 and 2 and at the right of Fig. 8, although the latter figure shows a modification of other details. The valve receptacle 3B is secured on one side of steam cylinder 29. This has a valve seat 38a which supports a slide valve 8|. This slide valve is connected to a stem 83 which has pistons 82 and 84 of unequal areas on opposite ends as shown in Figs. 2 and 8.

Steam is admitted to the valve chamber from pipe 4|. If desired, a steam throttling device or governor 42, of conventional type may be interposed and connected by pipe 43 to a pressure regulating supply (not shown).

A valve housing 44 and pipe 45 provide a conduit for connecting the main valve chamber with the lower end of the cylinder 29. This conduit contains a reducing valve 46 mounted on a stem 41. This may be adjusted by the nut 48 to regulate the permissible closing of the valve. The stem is guided in a spider 49.

This permissible closing regulates the live steam pressure to the bottom of each main piston but the valve 46 is free to rise, allowing a rapid escape of the exhaust steam whenever the down stroke of the pump has been reversed.

The steam port 85 (Fig. 8) connects through passage 85w to the top of the right hand steam cylinder 29. The passage 85b is an extension from port '85 to the bottom of the left hand steam cylinder 30 through a pressure reducing valve similar to that shown in Fig. 2 and above described.

Port 86 is connected to the bottom'of the steam cylinder 29 past the reducing valve 44 and the pipe 45 above described. Port 86 (shown in Fig 8) is also connected through conduit 86a. to the top of the left hand steam cylinder, in the :usual manner.

Port 81 allows exhaust through pipe 81a and alternately connects with ports 85 and 86 in the usual manner. The space between the two pistons 82 and 84 is filled with live steam so that on account of the greater area of the piston 82 the tendency of the live steam pressure is to force the valve'carry ing pistons to the left or in the direction of piston 82.

The admission and exhaust of steam to and from the main valve above described may be accomplished in various ways, for instance, as shown and described in my Patent 1,745,591 Such a valve shifting mechanism is shown diagrammatically in Fig. '1 where an auxiliary valve is mounted on the top of the steam cylinder head and has two parts, 31 and 31a, moved back and forth transversely by tappet-rods 34 and 34'. These tappet-rods have pins 34a and 3417 on their upper ends which extend into inclined or offset slots 40a and 48 respectively, which are formed as a part of the valve members We and 31, so that the valve members are reciprocated horizontally by the vertical movement of the tap-. pet-rods.

Details of such valve mechanism in a modified form will be described hereinafter in connection with Figs. 4 to 7 and 8 to 19 respectively.

The operation of the mechanism thus far de scribed is as follows:

Live steam is admitted through the pipe to the main valve in the casing 38 and passes through port 85 and passage 85a; to the spaces above the piston 33. This forces the steam piston 33 downwardly and with it the pump piston pressure through a reducing valve such as illustrated in Fig. '2 (but not shown in connection with the left hand cylinder). The rising piston 330. at the upper end of its stroke forces the tappet 34" upwardly so that its pin 34'!) sliding in the slot 48 moves the valve 31 to the left. When these twovalves are set as just described an auxiliary steam passage 88 to the main valve leading to the left hand side of the piston 82 as viewed in Fig. 2 is opened and live steam then forces the piston 8-2 and valve member '8] to the right as viewed in Fig. 2 so as to close the port 85 and shut off the steam to the upper end of the piston 33 and the lower end of the piston 3311.. As the piston 33 risesit of course lifts the pump piston 4 and draws liquid through the conduit 15 into the chamber 16 and past the valves 23 into the space beneath the piston '4.

When the valve port 85 is closed the valve port 8B is opened and live steam passes through passsage 88a, Fig. 8, to the top of the left hand piston in cylinder 30 and at the same time through the reducing valve 56 shown in Fig. 2 to the bottom of the right hand steam cylinder 29 thus reversingthe action of the steam pistons and pumps as above described. As the pump piston 3, Fig. 1, rises the water above it is forced out into the chamber I and through valve H to the discharge conduits I2, 13. At the same time the pump piston '4 is being forced downwardly by steam piston 83a and the water below the left hand pump piston is forced upwardly through pas- .sages 24 and I8 and valves I9 into chamber '20 and thence out through passages 2 I, 22. It will be seen that the effective area of the lower face of each of the pumping pistons is greater than the area of the upper face so that on the down stroke of each piston a greater volume of water is handled than on the up stroke. The difference in volume can be determined by using such cross sectional area of piston rod (or sleeve) as would produce the necessary difierence in volume.

The use of reducing valves 44 above described provides a materially less steam pressure for the up stroke of "the steam pistons and of course a correspondingly reduced steam consumption. As the pressure against which the pump pistons discharge on the up strokes is much less than the pressure against which the pumps discharge on the down strokes, the up stroke can be made at a higher velocity and consequently a piston may reach the upper end of its stroke before the companion piston reaches the lower end of its stroke and vice versa. Each piston, however, must remain at the end of its stroke until the other piston has arrived at the end of its stroke before steam is admitted to start the next stroke.

In Fig. 3 I have shown the preferred form of construction of pump cylinder stuffing box and piston. The cylinder 2 is provided with a bushing 60 forming the inner wall in which the piston 4 slides. This bushing is provided with passages 24 leading to the conduit 15. The lower end of the piston has a flange 58 provided with passages 58a so that as the flange gradually closes the passages 24, airwhich may be trapped beneath the piston can escape. The head 1 carries a depending flange 51a having passages 56a, and the piston 4 has a flange 4a adapted to pass beyond the flange 510. at the upper end of the stroke. Liquid trapped between the piston and the flange 51a escapes slowly through the passages 56a, thus producing a cushioning action and permitting the piston to move at high speed throughout practically its entire stroke, inasmuch as the end of the stroke is cushioned gradually.

In case a sleeve 6a is to be employed on the piston rod 6, a stufling 'box may be provided having a screw cap 52 with an inner flange 53 adapted to bear on a split gland 54, these parts being secured together. Difierent sizes of glands may be provided to fit different sizes of sleeves. A split filler 55, adapted to different sized sleeves is used to retain the packing.

In Figs. 4 to 19, inclusive, I have shown a special form of auxiliary valve mechanism for controlling the action of the steam pistons and the connected pump pistons so that each pump piston can move upwardly at a somewhat faster rate than downwardly and yet ensure the simultaneous starting of both pistons. The pistons 33a: and 33y in Figs. 8 and 9 happen to be of different diameters but this is immaterial.

For the purpose above mentioned, I interpose a secondary steam controlling valve, hereafter called a modified synchronizing valve in the casing 15 which is preferably mounted on the upper steam cylinder head, as shown in Figs. 8 and 9. Its horizontal travel is essentially the same as that of the valves 31 and 31a of Fig. 1.

The valve casing 15 contains two horizontally movable piston valves with a central valve body between. The right hand valve 16 is moved by an outer piston 11 which is steam-operated and connected to 16 by stem 11.

This valve 16 is attached to the cylindrical central valve 18 which covers and uncovers a number of small steam ports I00, I02, I04, I05, I06 and I01. Further to the left the valve 19, similarly operated by a steam piston 80 to which it is attached, is free to move horizontally with respect to valve 18.

These outer valves shift horizontally whenever their associated tappets 90 and 9| rise, and operate the respective valves within the casings 90A and 9IA, thus reversing their travel when the tappet-rods fall. This gives four possible combinations of pistons positions for the passing of small amounts of steam through the center valve 18 and the ports I00, I02, I04, I05, I06 and I01, though only two combinations of pistons are formed and required should the two pistons stop simultaneously.

I meet these conditions by rotating the center valve 18 during the cycle, and so opening two extra ports whenever needed.

The main steam valve has already been described in connection with the operation of the form shown in Figs. 1 and 2, although it is a conventional structure and is generally familiar to those skilled in the art.

Starting with Fig. 8, it will be seen that the passage 88 connects port 88a of the main steam valve chamber with port I04 in the auxiliary or synchronizing valve 15. Port I04 is connected to port I by passage 15:1: in the wall of the valve casing 15.

Live steam passage 89 supplies steam direct to the casings of valves 90a and 9Ia. Passage 89 is also connected to posts H4 and H by passages 4.1: and II5ac. Passage 89 is also connected to ports I06 and I01 by passages I06:v and I01zc. Passage I00x is shown in Fig. '7 and passage I011: in Fig. 5.

Valve casing 9Ia (Fig. 8) is connected to port I I3 by passage H2 and valve casing 90a is similarly connected to port III by passage IIO.

Ports I02 and I05 at times exhaust through passage I03 to the atmosphere.

Valve casing 9Ia has an exhaust passage II6 to the atmosphere (Fig. 12) and valve casing 90a has a similar exhaust passage (not shown). Interior valves 90B and 9IB, operated by their respective tappet rods, are of slide valve construction and each alternately allows live steam to pass to the outer ends of the auxiliary valve 15, and later escape to the atmosphere.

Passage 88 is connected to port 58a in the main valve casing 38 so that exhaust from 08 to the atmosphere, will relieve pressure on the outer face of piston 82 and cause the attached valve member 8| to travel towards 58A, due to the unbalanced steam pressure on the unequal inner areas of pistons 82 and 84, Fig. 8.

Tappet-rods 90 and 9I moving their respective slide valves 903 (Fig. 9) and 9IB (Fig. 12) in the usual manner admit or release steam to and from the outer ends of the pistons 11 and 80 through passages H0 and H2 as shown in the cylinder head. Live steam pressure is always maintained between piston 11 and valve 16. With live steam supplied to the outer faces of 11, the unequal piston areas keep the two at the left, as shown in Figs. and 11, but :0 when steam is exhausted through III and valve 903, the pistons shift, as in Fig. 5.

In Figs. 15 and 16 a complete assembly of the parts within the synchronizing valve casing 15 is shown. For instance, with the rod 9| pulling down the side valve 9IB, Fig. 12, live steam supplied to recess 89A by passage 89, flows through H2 and port II3, driving piston 80 to the right, as in Fig. 10.

When rod 90 lifts valve 9IB, the port to H2 is protected from the live steam, and connects by an interior passage of 9IB with the outlet port of I I6, allowing steam to escape through port I I3 to the atmosphere, the piston 80 shifting to the left, as in Fig. 15. Piston 11 may have two split packing rings I I1. Valve 16 may have similar packing rings, as is customary. Central valve 10 has two outer portions with broad split rings I I8 and two narrow split rings I I9 on the inner portion of the valve, while between them is located the steam slot II8a. The casing 15 may have removable bushings or linings such as I20 and I2I. In the upper part of bushing I20 there are located steam balance ports I 2I, at times diametrically opposite the-ports, I03, I01, I04, I06. A steam passage I23 through rotating valve 18 connects I22 at times with circumferential slot IOI, as shown in Figs. 5, 7, 11, etc.

The left valve 19, shown specifically in Fig. 15, has a hollow extension 92 with a curved slot 93 in which travels a pin 94 attached to a stem 95 which is firmly attached to the central valve 18 by a nut 96 (Fig. 17).

Within the slot 93 is shown a double row of arrows and small circles 91 that show the relative direction and travel of pin 94 and the possible locations where the pin would stop for each of the six possible positions as herein defined.

Valve 19 has a key or lug 98 (see Fig. 4) traveling in a slot 99 in the valve casing, thus preventing 19 from revolving. Central valve 13 and the attached rod 95 are free to rotate and also to slide horizontally, being forced to rotate by the pin bearing against the curved walls of the groove 93.

In a complete pumping cycle of two pumping units having opposing strokes I have six possible combinations or positions of the two pump pistons, as to which one first finished the stroke. They are here named in their natural order, as the first, second, third, fourth, fifth and sixth positions.

The first and fourth positions are the operating ones while the others are intermediate. For instance the interior valves of 15 might jump from the first directly to the fourth position and immediately reverse the main steam valve 38. Or they might go from first to second with no results, or from first to third and no reversal would occur. A like condition occurs between the fourth and fifth and sixth positions.

In the first position as shown in Figs. 10 and 11, 4 and 5, any steam contained in passage 88 follows the arrows through 151: to port I00, slot IOI in the valve 18, then to port I 02, and escape passage I03, to the atmosphere, all the other ports under valve 18 being then closed.

Valve 18' having shut off the live steam supply to passage 88 and allowed the escape of steam from port 58a,,Fig. 8, so that the unbalanced pressure of steam on the opposite side of piston 82 moves slide valve 8I to the left as shown. This opens port and admits high pressure steam on the top of piston 33m and reduced pressure steam underneath piston 33y. The right hand piston 33:1: therefore descends and the left hand piston rises. Should the rising left hand piston 33y be the first to end its stroke, its tappet 9I will raise slide valve 9IB, cutting off the live steam supply from chamber 09A to passage H2, and thereby exhausting steam through port I I3, passage I I2, and valve 9 I B, into passage I I 8 to the atmosphere (Figs. 10 and 12). Unbalanced pressure between 19 and 80 causes them to shift to the left, forming the second position, Fig. 13. Valve I8 does not shift, slot IOI remains as before, passage 88 is open to the atmosphere and the main steam valve 81 keeps. its position, as shown in the first position.

Should the falling right hand piston 33:1: end its stroke first, the tappet draws down valve 903, allowing steam to escape through port III, passage I I0 and slide valve 903 to the atmosphere.

This is the third position (Fig. 14), wherein valve I9 remains at the right but steam escaping through. port I I, allows valves I8 and central valve 18; to shift to the right; the slot IOI now registers with ports I04 and I05, the latter connecting with passage I03 and the steam from 88 escaping to the air and the main valve 81 remaining as in the first position.

But when the left piston 33y reaches the top and the right piston 33a: reaches the bottom, either at the same time or otherwise, then position four is reached and the slide valves 9IB and 90B are shifted to allow steam to escape from the outer faces of pistons 80 and 8|, causing them to move apart, as shown in Figs. 15 and 16. During the subsequent positions five or six (Figs. 17 and 18), the synchronizing valve 15 will allow live steam to pass from 89 to 88 and by its unbalanced pressure on piston 82 will shift main valve 8'! to the right. This will shut off live steam from the top of 33a: and the bottom of 3311 and apply it to the bottom of 330a and the top of 3311 etc. reversing the pumps until the cycle is completed, when the main steam valve 8| will be returned to the position, as shown in Figs. 10, 11, as shown in the first position explanation.

'In the fourth position (Figs. 15, 16 and '7), though the valve I8, is forced to the right as in Fig. 14, valve 19 in being forced to the left, has rotated valve I8 by means of pin 94, so that port (Fig. 7) is closed and the slot IOI now connects port I04 with port I06. Live steam from the passage 89 (Fig. '7) now follows the dotted arrows through passage I06x, port I06, slot IOI, port I04 under passage 151: into passage 88, and this steam presses against the outer face of piston 82, Fig. 8, moving main slide valve 8| to the right or towards piston head 38 thereby admitting live steam to main port 88 with high pressure steam delivered to the top of piston 33y, reduced pressure to the bottom of piston 3350 thereby reversing the pumping operation as required. The left piston is now on the down stroke and the right piston 33a: is on the up stroke.

In the fifth position (Fig. 17) the central valve 18 is moved to the left but does not rotate from the fourth position determination, as is shown.

by right piston 33:0 first arriving at the top of its stroke and the tappet 90 shifts the slide valve 903, that admits live steam to the outer face of piston 11. Slot IOI, however, in travelling .to the left has registered with ports I01 and. I00, similarly to its previous registry over I06 and I04 of Fig. 7, thereby permitting live steam to follow the arrows from passage 89, through passage 7 I0'Ir, port I01, slot IOI, port I00, passage 15a:

and back through passage 88 to the face of piston 82, keeping themain steam valve 8f as described in its fourth position.

In the sixth and final position (Fig. 18) which may occur right after that of the fourth position, the left hand piston 33y has first arrived at the bottom and the tappet 9| shifts the sliding valve 9IB, causing live steam to flow into passage, H0 and port I I3 and moving piston 80 and pin 94 to the right. As. will be seen the pin does not rotate and the center valve I8 remains as in the fourth position. The slot I M registers over ports I06 and I04, live steam still following the direction of the dottedv arrows through ports, slot and passage 88 back to the piston 83 and. keeps the main valve in the samev position. Though the left piston 80 has shifted to the right, there has occurred no rotation to prevent the center valve I8 from registering. over the proper ports.

This completes thepum-ping cycle, as the next piston movement would bring everything back to the starting point, as shown in. the beginning. These six positions will be the same whether the inner valves 16 and I9 are shifted by steam or by mechanical means, such as the tappet rod and slotted hole device of Fig. 1.

It will be again noted that in Fig. 10 (first position) the main steam valve 8| remains at the left or towards piston 82, while in Fig. 15 (fourth position) it is shifted to the right. In each case both pistons have completed their strokes, an ideal condition.

' Should the second position intervene, nothing happens until the lagging piston finishes and merges into the fourth position, causing an immediate reversal.

Also should the third position occur in place of the second position, nothing happens until the other lagging piston finishes and also merges into the fourth position and. causes a reversal.

The fifth or sixth positions are likewise intermediate between the fourth position and the following first position, and areas ineffective as the preceding second and third positions.

' I claim:-

1. The combination of two double-acting steam driven pumps having steam cylinders with a common steam supply and pump cylinders having common low pressure inlet valves and common low pressure outlet valves at corresponding ends of the pump cylinders, common high pressure inlet valves and common high pressure outlet valves in the opposite ends of the pump cylinders, each steam cylinder and each pump cylinder having a piston, a single piston rod connecting one steam piston with a pump piston and a single piston rod connecting the other pump piston with the other steam piston, said piston rods being operable independently of each other and being movable simultaneously in; opposite directions, said piston rods being movable toward the steam piston ends at a higher rate of speed than in the opposite direction, and means for supplying materially greater steam pressure to each steam piston when moving toward its pump cylinder than when moving in the opposite direction whereby each pump piston pumps effectively against much greater pressure when moving in one direction than when moving in the opposite direction.

2. The combination of a pair of pump cylinders, each having separate inlet and outlet passages, a double acting piston in each cylinder, a steam cylinder with a piston connected to each pump piston, a single auxiliary steam valve on top of said steam cylinders and movable transversely thereon, a tappet-rod operated by each steam piston, each steam valve having an angular slot and said tappet-rods having pins engaging the said slots to mechanically actuate said steam valves, a main steam valve controlled by the auxiliary steam valve and controlling the admission and exhaust of steam to and from said cylinders and a reducing valve interposed between the main valve and one end of each steam cylinder so as to provide for a material difierence in pumping pressure at the opposite ends of the pump cylinders.

3. A pump having two cylinders with separate inlet and outlet passages and double-acting pump pistons movable simultaneously in opposite directions and at different speeds independently of each other, a steam driven piston for operating each pump piston, means for supplying a. greater pressure to the steam pistons when moving in one direction from that applied when moving in the other direction so as to enable each pump piston to pump against a greater pressure when moving in one direction than when moving in the opposite direction, valve mechanism for controlling the admission and exhaust of steamso that each piston will arrive at one end of its stroke before the other piston arrives at the opposite end of its stroke and vice versa.

4. The combination of two double-acting pumps, each having a cylinder with an inlet valve and an outlet valve at each end, a piston in each cylinder having a piston rod extending outside the upper end of the cylinder, each pump piston having a greater effective area on the lower face than on the upper face, a steam cylinder on top of each pump, valve mechanism and connections for controlling the admission and exhaust of steam to and from both steam cylinders, a piston in each steam cylinder having a piston rod connected to a pump piston rod, said steam pistons being movable independently, means of connection between the steam piston rods and said valve mechanism and. reducing valves for supplying steam at a less pressure for the up strokes of the pistons than for the down strokes so as to provide greater pumping pressure on the down strokes of the pump pistons than on the up strokes.

5. A duplex pump construction comprising two pump cylinders each having separate inlet and outlet passages and a double-acting pump piston, steam cylinders with pistons connected to the respective pump pistons, said steam pistons being movable alternately independently of each other in opposite directions and means for applying materially greater unit pressure on one side of each steam piston than on its other side so that each pump piston pumps effectively against greater pressure in one direction than the other.

6. A duplex pump construction comprising two pump cylinders each having separate inlet and outlet passages and a double acting pump piston, steam cylinders with pistons connected to the respective pump pistons, said steam pistons being movable alternately independently of each other in opposite directions, and means for applying materially greater unit pressure on one side of each steam piston then on its other side so that each pump piston pumps effectively against greater pressure in one direction than in the other, each piston being provided with cushioning means, said cushioning means comprising a head for the pump cylinder provided with a cushioning recess at one end of the cylinder, said head having an inwardly projecting flange, the piston rod passing through said head and the piston in the cylinder being connected to said rod and having a flange adapted to coact with the flange on the head so as to trap liquid within the cylinder recess.

7. A construction as set forth in claim. 6 in which the head flange is provided with passages to allow for the escape of the trapped liquid.

8. A construction as set forth in claim 6 in which the flange of the piston surrounds the outside of the flange on the head at the completion of the pumping stroke.

9. A construction as set forth in claim 5 provided with cushioning means for each pump piston, said cushioning means comprising a series of outlet passages at one end of the pump cylinder, a flange on the piston reciprocable in the cylinder and adapted to at least partially close said passages at the end of the pumping stroke, said flange having passages to permit the escape of air through the outer passages in the cylinder at the end of the stroke.

10. A double-liquid pump construction comprising two pump cylinders each having its own separate inlet and outlet valves and a pump piston, a steam cylinder with a piston and rod for each pump piston, each steam piston and its connected pump piston being movable independently of the other steam piston and its pump piston, means for causing each of said steam pistons and connected pump pistons to start simultaneously, and cushioning means for at least one end of each pump piston comprising a series of outlet passages at one end of the pump cylinder, a flange on the piston reciprocable in the cylinder and adapted to at least partially close said passages at the end of the pumping stroke, said flange having passages communicating with the outlet passages to permit the escape of air through the outlet passages in the cylinder at the end of the stroke.

11. A double liquid pump construction comprising two pump cylinders each having its own separate inlet and outlet valves and a pump piston, a steam cylinder with a piston and rod for each pump piston, each steam piston and its connected pump piston being movable independently of the other steam piston and its pump piston, means for causing said steam pistons and their connected pump piston to start simultaneously and cushioning means for at least one end of each pump piston comprising a head for the pump cylinder provided with a cushioning recess at one end of the cylinder, said head having an inwardly projecting flange, and an outwardly projecting flange for supporting a stufling box, the piston rod passing through said head and stufling box and the piston in the cylinder being connected to said rod and having a peripheral flange adapted to 'coact with the inner flange on the head so as to trap liquid within the cylinder recess, the flange of the pump piston surrounding the outside of the inner flange of the head at the completion of the pumping stroke.

12. A pump comprising a cylinder having a head at one end with a cushioning recess therein, said head having an inwardly projecting flange, a piston rod passing through said head, a piston within the cylinder connected to said rod and having a flange adapted to coact with the flange on the head and to trap liquid within the cylinder, the head flange having a restricted passage to allow escape of trapped liquid, cushioning means at the other end of the cylinder, said means comprising a series of outlet passages in the cylinder wall, a flange on the piston reciprocable in the cylinder and adapted to at least partially close said passages at the end of the pumping stroke, said flange having passages to permit the escape of air through the outer passages in the cylinder wall at the end of the stroke.

EDMUND H. BLUNT.

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