US2977040A - Pneumatic pressure boosting apparatus - Google Patents

Description

March 28, 1961 D. H. DULEBOHN EI'AL 2,977,040

PNEUMATIC PRESSURE BOOSTING APPARATUS 2 Sheets-Sheet 1 Filed Aug. 9, 1957 March 28, 1961 D. H. DULEBOHN ETAL 2,

PNEUMATIC PRESSURE BOOSTING APPARATUS 5 W1 2 WWO Z m Wi 26 W nu n a .7 2 Z Z w y 5 Filed Aug. 9, 1957 2,977,040 I PNEUMATIC PRESSURE BOOSTING APPARATUS Filed Aug. 9, 1957, Ser. No. 677,271

6 Claims. (Cl. 230-52 This invention relates to pumping mechanisms and more particularly relates to fluid pressure-controlling pumps.

In most manufacturing plants and shops, a supply of air pressure is available. However, the shop line pressure is oftentimes inadequate to operate special equipment. One example of such equipment is a pneumatic die cushion or pressure pad which generally requires a pneumatic pressure substantially higher than line pressure.

An object of the invention is to provide new and improved apparatus of simple and inexpensive construction and operation for controlling and varying shop line pressure over a wide range.

Another object of the invention is the provision of a novel booster pump operated by shop line pressure to controllably regulate output pressure over a range from 30 zero pressure to twice shop line pressure.

Still another object of the invention is the provision in a double acting reciprocating pump mechanism of a new and novel valve control mechanism to operate in response to reciprocation of the pistons and control the delivery and exhaust of air.

A further object of the invention is to provide an improved fiuid pressure boosting pump employing only a single pump-operated control valve for alternately directing a regulated fluid pressure to the separate cylinders for operating the pistons and producing an output pressure substantially equal to the shop line pressure plus the regulated pressure.

A still further object of our invention is to provide in a pneumatic motor and pumping mechanism employing conventional tubing and with pneumatic cylinders, of new and improved means for retaining cylinder-defining end closures in the tubing.

Still another object of the invention is the provision of an improved pneumatic motor and pumping mechanism wherein a portion of the air under pressure supplied to the mechanism is first utilized to do work and subsequently is discharged into the high pressure pump output, thereby causing fullest use to be made of the air supplied so as to increase the operating efiiciency of the mechanism.

These and other objects and advantages of our invention will more fully appear from the following description made in connection with the accompanying drawings wherein like reference characters refer to the same or similar parts throughout the several views and in which:

Fig. 1 is a perspective view of the invention;

-Fig. 2 is a longitudinal section View of the reciprocating motor and pump mechanism and showing the pump-operating valve and actuating mechanism therefor;

Fig. 3 is a detail transverse section view taken on a substantially vertical plane as indicated at '33 in Fig. 2 and having parts broken away for clarity;

Fig. 4 and Fig. 5 are detail diagrammatic views of the valve-operatingmechanism and showing said mechanism in different stages of its operation; and r Fig. 6 is a diagrammatic sketch of the air control mechanism showing the operation of the invention. A

States Patent One form of the present invention is shown in the drawings and is described herein. The invention is'connectible to a shop air line 10 for supplying air to a discharge line or conduit 11 at pressures varying from approximately zero to twice the shop line air pressure. The high pressure discharge conduit 11 may supply the air to any type of apparatus which may require a high pressure, but relatively small flow of air, such as a pneumatic die cushion in a metal-stamping machine. Of course a conventional filter 12 and lubricator 13 may be inserted into the shop line 10.

The mechanism comprising the present invention includes a reciprocating air motor and pump mechanism which is indicated in general by the numeral 14, air supp'lycontrol apparatus, indicated in general by numeral 15, and air reversing valve mechanism 16 which includes the actuating mechanism therefor. The air motor and pump mechanism 14 comprises a length of rigid tubing 17 defining a pair of aligned cylinders 18 and 19 in the opposite ends thereof and in which the pistons 20 and 21 are reciprocably mounted. The pistons 20 and 21 are affixedly interconnected by means of a reciprocable piston rod 22 which extends through openings 23a and 24a in the inner end members 23 and 24 of the cylinders 18 and 19 respectively. Rod 22 is sealed to the end members 23 and 24 by suitable packing or gaskets 23b and 24b. The inner end surfaces of the end members 23 and 24 bear against the supporting structure 25 of the valve mechanism 16 (hereinafter more fully described) and are thereby prevented frommoving inwardly. End members 23 and 24 are sealed at their outer peripheries by O-rings 26 and 27 which are mounted in suitable annular grooves in the external periphery of the end members 23 and 24 and are engaged with the inner surface of the tube 17 in sealing relation.

The outer heads or end closures 28 and 29 have inner portions which fit tightly against the inner peripheral surface of the tube 17 and are sealed thereto by O-rings 3i) and 31 respectively which are carried in suitable grooves and bear against the inner surface of the tubing 17. The outer end portions 28a and 29a are of reduced diameter ascompared to the inner portions and outwardly facing "annular shoulder surfaces 28b and 29b are defined.

v In'wardly projecting abutment means are provided adjacent the ends of tube 17 to engage the shoulder surfaces 28b and 29b and prevent outward movement of the end closures 28 and 29. In the form shown, such means include resiliently expandable retaining rings 32 and 33 which are seated in: annular grooves 34 and 35 respectively at the opposite ends of tubing 17.

Means are provided for restraining inward movement of the end closures 28 and 29 and for drawing the end closures outwardly to cause the shoulder surfaces to bear firmly against the retaining rings 32 and 33. In the form shown, such means includes annular washers, 36'and 37 which engage the ends of the tubing 17 and which encompass the outer end portions 28a and 29a of the end closures 28 and 29. Such means also include annular, resiliently constrictable retainers 38 and 39 which are seated in annular grooves 44) and 41 in the outer periphery of the end closures 2S and 29 and which bear against the washers 36and 37 to be supported from the eridslof tubing 17. Retainers 38 and 39 have side surfaces 38a and 39a facing outwardly with respect to tubing 17 and which are of conical or flared configuration converging inwardly with respect'to tubing 17. The grooves 40 and 41 also, have similarly flared side surfaces 40a and 41a confrontingthe flared surfaces 38a and 39a of the retainers so as to produce, upon constriction of the retainers 38 and 39, limited outward movement of the end. closures 28 and 29.

The cylinders 18 and 19 a number of air pressure chambers 42, 43, 44 and 45. During operation, in a manner hereinafter described, the air in chambers 44 and 45 is continuously under at least line pressure, and the pressure in these chambers is alternately materially increased to the output or discharge pressure, and the air in chambers 42 and 43 is alternately at substantially atmospheric pressure and at a regulated pressure which may vary from Zero to substantially shop line pressure.

Pistons and 21 are sealed at their external periphery against the tubing 17 by a conventional packing or leather gaskets 46 and 47. The piston rod 22 extends through the pistons 20 and 21 and is secured thereto by means of pins 22a and 22b extending through apertures 22c and 22d respectively in the ends of rod 22. The pins bear against washers 20a and 21a. The pistons 20 and 21 are sealed in relation to the rod 22 by O-rings 48 and 49 which are seated in grooves 22c and 22 in the rod 22, and the O-rings 48 and 49 bear against the inner peripheral surfaces 20b and 21b of pistons 26 and 21. Retaining rings 50 and 51 are secured on the rod 22 and bear against the pistons 20 and 21 for restraining movement of the pistons with respect to the rod.

The air reversing valve mechanism 16 is carried by the tubing 17 centrally between the cylinders 18 and 19, and in the form shown, the tubing 17 is provided with a pair of enlarged and diametrically opposed, substantially rectangular openings 52 and 53 in the upper and lower sides thereof. The valve mechanism supporting structure includes top and bottom mounting plates 54 and 55 which lie across the openings 52 and 53 and are supported on the opposite longitudinally extending edges thereof. Pivot plates 56 underlie the bottom mounting plate 55. Plates 54, 55 and 56 are provided with apertures (not shown) through which bolts 57 extend. The bolts 57 and nuts 57a thereon securely hold the mounting plates 54 and55 and pivot plates 56 on the tubing 17 and provide backing for the inner closure members 23 and 24 of the cylinders.

A 4-way air valve 58 is mounted by bolts and nuts 59 on the top mounting plate 54. The 4-way valve 58 may be of any suitable design, and has a number of ports 60, 61, 62 and 63 on the front and rear sides thereof. The valve 58 has a shiftable control element 64, which in the form shown projects endwise outwardly from the opposite ends of the valve 58 and is reciprocable to different positions as is seen in Figs. 2, 4 and 5. The exact construction of the valve 58 is unimportant to the present invention except to the extent that by shifting of the control element 64, the connections of the ports are changed. In the position of the control element 64 shown in Figs. 2 and 4, communication is provided between ports 60 and 62 and communication is also provided between ports 61 and 63, and as seen in Fig. 5, when the control element 64 is shifted to the other position, communication is provided between ports 60 and 63 and communication is also provided between ports 61 and 62. Valve 58 is oriented longitudinally of piston rod 22 with the control element 64 positioned directly above the rod 22.

Mechanism is provided for operating the valve 58 in response to movement of the pistons 20 and 21 and rod 22 and the mechanism is constructed to move the control element 64 quickly, with a snap-like action, from one position to another when the pistons 20 and 21 reach the ends of their strokes. With the control element 64 in the position shown in Fig. 2, the pistons 26) and 21 and rod 22 will be moved in the direction of arrow A, and when the pistons 20 and 21 very nearly approach head 28 and inner closure member 24 respectively, the control element 64 is quickly moved in the direction of arrow B, after which the port connections of the valve 58 are changed so as to immediately cause reversal of the direction of travel of the pistons 20 and 21 and and pistons 20 and 21 define movement in the direction of arrow C. The valve-01: erating mechanism includes a pair of generally upright and opposed trip arms 65 and 66 which are spaced from each other in a direction longitudinally of the piston rod 22 and which are generally channel-shaped, and open inwardly toward each other. Trip arms 65 and 66 have aligned apertures 65a and 66a slidably receiving the piston rod 22 therethrough. Trip arms 65 and 66 are swingably mounted at their lower ends on pins 67 and 68 which are mounted in depending ears 69 and 70 which are formed integrally of the pivot plates 56. A tension spring 71 interconnects the trip arms 65 and 66 and continuously urges them against the opposite ends of control element 64. Spring 71 is secured to the trip arms 65 and 66 by pins 72 which are mounted in the sidewalls 65b and 66b of the channel-shaped trip arms.

A trip arm actuator 73 comprises an enlarged ring secured on the piston rod 22 by means of E-rings 73a so as to engage the edges of the walls 65b and 66b when the pistons are moved in one direction or the other. It will be noted that the edges of walls 65b and 66]) are rounded at the point of engagement with the actuating ring 73 so as to provide point contact therewith.

The lower ends of the trip arms are bifurcated and insert elements 74 and 75 are mounted in the bifurcated lower ends of the trip arms 65 and 66 respectively, and are secured thereto as by bolts 74a and 75a. The insert elements 74 and 75 have downwardly facing shoulder surfaces 741) and 75b which adapt the insert elements 74 and 75 to operate as latching elements. The insert elements 74- and 75 also have upwardly projecting portions 74c and 75c which define rounded upper camming surfaces 74d and 75d respectively for purposes hereinafter described.

A swingable keeper element 76 is mounted on a pin 77 which extends through and is carried by a pair of spaced and opposed ears 78 which project upwardly from and are formed integrally of the pivot plates 56. The keeper element 76 has a depending shank portion 76a which defines a pair of keeper surfaces 76b which are adapted to engage the surfaces 75b and 74b of the insert elements 74 and 75 in latching or locking relation so as to prevent downward swinging of the insert elements 74 and 75, one at a time, and thereby prevent inward swinging of the upper end of one of the trip arms 65 and 66. The keeper element 76 is also provided with a pair of concave, downwardly facing camming surfaces 76d disposed at the upper end of shank 76a and in overlying, confronting relation with respect camming surfaces 74d and 75d respectively of the insert elements 74 and 75.

Air pressure is supplied to and discharged from air pressure chamber 42 by means of a flow conduit or pipe 7 79 which is connected at one end by means of a fitting 79a to port 61 of the valve 58. The end closure or head 28 is drilled and tapped at 28c, and the other end of conduit 79 has a fitting 79b threaded into the head 28 to provide flow communication between the conduit 79 and the air pressure chamber 42. Air pressure chamber 43 is connected in flow communication with port 60' of valve 58 by means of a flow conduit 80, which at one end, is connected to the port 60 by means of a fitting 80a. End closure or head 29 is drilled and tapped at 29c, and another fitting 80b is threaded into the head 29 and is connected with the conduit 80 to provide flow communication between the conduit 80 and air pressure chamber 43.

The air supply control apparatus 15 includes a line pressure supply tube or pipe 81, which at one end is connected to the shop air line 10, and which is connected at the other end to the inlets of air pressure chambers 44 and 45 through elbow fittings 82 and 83, check valves 84 and 85 which are arranged to prevent reverse flow or outward flow of fluid from the chambers therethrough, and threaded nipples 86 which are threaded into apertures 87 in the inner end members 23 and .24.

The apertures 87 in the members 23 and 24are generally L shaped, extending generally radially inwardly of the outer periphery and then in a direction parallel to the axis of the cylinder and then into the air pressure chamber. A variable air pressure regulator 88 is mounted on a base plate 89 as by bolts 90 and is connected with the shop air line to receive air therefrom. The base plate 89 has a depending portion 89a which is secured to the top mounting plate 54 as by bolts 89b. Regulator 88 is of a conventional type having a manually operable control lever 88a which, when turned, varies the air pressure at the output of the regulator and holds the output pressure constant regardless of the quantity of air flowing therethrough. The outlet of regulator 88 is connected to a regulated air pressure supply tube or pipe'91 which, at its other end, is connected with the port 62 of valve 58. Each of the supply tubes 81 and 91 have manually operable control valves 92 and 93 connected therein and arranged in tandem with relation to each other and operated by single push-pull control member 94, which, in the form shown, is moved to the left to open the valves 92 and 93 and is moved to the right to close the valves 92 and 93.

The high pressure outlet or discharge pipe 11 is connected through fittings 11a and 11b to check valves 95 and 96 and threaded nipples 97 to the outlets of air pressure chambers 44 and 45 respectively. The nipples 97 are threaded into L-shaped apertures 98 to the inner end members 23 and 24 which are substantially identical in arrangement to the apertures 87. The check valves 95 and 96 are constructed to prevent reverse flow through the outlets, or prevent inward flow from the discharge conduit 11 into the air pressure chambers 44 and 45. The regulated pressure supply tube or pipe91 is connected to the outlet or discharge conduit 11 by means of a check valve 99 which permits flow from the pipe 91 to the outlet conduit 11 but prevents flow in a reverse direction from the conduit II. to the regulated pressure supply tube 91. Of course suitable air pressure feeders 100a and 10% may be provided on the regulator and in the high pressure discharge tube 11 respectively for measuring the regulated air pressure and the discharge pressure.

Operation In the operation of the invention the output or discharge pressure in the conduit 11 may be varied over an extremely large range, that is, from approximately zero p.s.i. to approximately twice the shop line air pressure. Frequently the shop line pressure is approximately 100 p.s.i. and therefore, the air pressure in the output or discharge pipe 11 maybe varied from zero to 200 psi.

When the control valves92 and 93 are closed, the reciprocable air motorand pumping mechanism is inoperative because no air is supplied thereto. Airunder pressure is supplied from the shopline 10 through the regulator 88 through a portion of the regulated .pressure supply pipe.

91, through check valve 99 into the discharge conduit 11 whereinthe air pressure is equal to the air pressure at the output of the regulator 88. In this mode of operation, the air pressure in the discharge conduit 11 may be varied by operation of the regulator 88 from shop line air pressure down to zero p.s.i.

By operating the control knob 94, the air control valves 92 and 93 are simultaneously opened. When this occurs, several things willhappen substantially simultaneously, to wit: air under shop line pressure immediately rushes through the supply tube $11, check valves 84 and 85, air pressure chambers 44 and 45, and check valves 95 and 96 into the air discharge conduit 11, and thereby the pressure in the pipe 11 is immediately brought up to shop line pressure; shop line pressure in the conduit 11 will immediately close check valve 99 to prevent any further flow of air under pressure therethrough, and air under regulated pressure immediately rushes through the supply pipe.91, valve 58 and through one of the conduits 79 or into the corresponding air pressure chamber 42 or 43 to start/the air motor and pumping mechanism 14 into operation.

7 Initially, the air pressures in the inner air pressure chambers 44 and 45 are identical and therefore the forces exerted against the pistons 20 and 21 are identical and therefore the effect of the air pressures in chambers 44 and 45 offset each other.

In Fig. 6, the valve 5 8 is shown in'such a condition that air under regulated pressure is supplied into the conduit 79 and into the air pressure chamber 42. The air pres-sure chamber 43 is open to the atmosphere through the conduit 80, valve 58 and exhaust port 63 (which in the diagrammatic sketches 4, 5 and 6 is shown with a short nipple 63a thereon so as to be visible). Under these conditions, air in the pressure chambers 42 and 45 urge the pistons to the left causing the air pressure in chamber 44 to increase. The air under shop line pressure in chamber 45 and the air under regulated pressure in the chamber 42 have the capability of moving the pistons 20 and 21 to the left until the air pressure in chamber 44 equals the arithmetic total of the shop line air pressure and the regulated air pressure. Because the regulated pressure in chamber 42 may be varied from zero to shop line air pressure by regulator 88, the pressure in chamber 44 .may be varied from shop line pressure to substantially twice shop line pressure. When the pressure in chamber 44 equals the sum of the pressures in chambers 42 and 45, the pistons 20 and 21 will stop.

It will be remembered however that as the'pistons 2t and 21 started to move, the air pressure in thehigh pressure discharge conduit 11 was only shop line pressure, and as soon as the air pressure in chamber 44 exceeds shop line pressure, the check valve will open and air will be discharged from the chamber 44. Because :the pressure in chamber 44 isrelieved, the piston 20 will again start to build up the pressure, whereupon check valve will open again and the pressure in the discharge conduit 11 will gradually rise. It should be understood that as the pistons 29 and 21 move to the left, air under shop line pressure continues to flow into the air pressure chamber 45 and when air under regulated pressure continues to flow into the chamber 42. The force against the pistons 20 and 21 is thereby maintained substantially constant.

As the pistons 20 and 21 approach their left hand limit of movement, substantially all of the air from the chamber 44 has been driven into the discharge conduit 11, and no additional air has come into the chamber 44 because the pressure therein exceeds, at least slightly, the shop line pressure and the check valve 84 therefore remains closed. When the pistons 20 and 21 reach their limit of left hand movement, the valve 58 is-operatcdso as to reverse the connections to the air pressure chambers 42 and 43, cansing the air in the chamber'42 to be exhausted to the atmosphere and also causing application of air under regullated pressure to the chamber 43.

When this occurs, the pressures in chambers 44 and 45 are approximately equal to shop line pressure, and the application of regulated air pressure into chamber 43 and the exhausting of air from chamber 42 tothe atmosphere causes the pistons 20 and 21 to mo-veto the right. The air pressure in chamber 45 is now-increasing and as the air pressure in the chamber 45 exceeds the'pressure in discharge conduit 11 the check valve 96 is opened to allow discharge of some of the air into the conduit 11. Only shopline pressure is'applied into chamber 44 as that'chamber enlarges, due to movement of the piston, and therefore check valve 95 remains closed.

In the manner described, the air-motor and pumping mechanism 14 will continue to operate until the air pressure in the discharge conduit 11 equals the arithmetic total of the shop line air pressure plus the regulated air pressure. When this occurs, equal forces urge-the pistons in opposite directions and the pistons will stop. .In actual operation, the pistons 20 and 21 will reciprocate rapidly as the pressure is being built up in the conduit 11, and as the pressure in the conduit 11 approaches the sum of the shop line pressure plus the regulated pressure, the speed of operation of the pistons 20 and 21 is materially decreased.

Referring now to Figs. 2, 4 and in regard to the valve-operating mechanism, the control element 64 of valve 58 is initially in its left hand position, and the regulated air pressure, supply tube 91 is connected through valve 58 to the conduit 80 and air pressure chamber 43, and the air pressure chamber 42 is open to atmospheric air through how conduit 79 and the exhaust port nipple 63a. Pressure in chamber 45 is increasing and discharging into the conduit 11. As seen in Fig. 2, the actuator 73 is approximately midway between the trip arms 65 and 66. As the piston rod 22 moves in the direction of arrow A, the actuator engages the trip arm 65 in the manner shown in Fig. 4. The latching or insert element 75 of trip arm 66 is engaged at the surface 75b by the coop-erating surface 76b of the keeper element 76 and the trip arm 66 is restrained from moving in a clockwise direction. As the actuator 73 engages the trip arm 65, the upper end of the trip arm 65 is swung in a clockwise direction and away from the end of the control element 64. Of course as the trip arm 65 begins to swing, the tension exerted by spring 71 on trip arm 66 is increased. The camming surface 740 of the insert element 74 swings upwardly toward the camming surface 76d of the keeper element 76 and engages the camming surface, causing the keeper eiement76 to commence swinging in a counterclockwise direction so as to move the shank portion 76a away from the lower end of trip arm 66 and to remove the surface 76b from the shoulder surface 75b. Actuator 73 continues to swing the trip arm 65, and as this swinging continues, the keeper element continues to swing in a counterclockwise direction and finally, trip arm 66 is released and the tension exerted on the trip arm 66 by spring 71 causes the trip arm 66 to quickly swing in a clockwise direction with a snap action so as to instantaneously shift the control element 64 of the valve 58 and cause reversal of the air connections therethrough. As the shoulder surface 75b of the insert or latch element 75 releases from the keeper element 76, the surface 76b of the keeper element slips under the corresponding surface 74b of the other latching or insert element 74 on the trip arm 65 so as to latch the trip arm 65 and prevent counterclockwise movement thereof.

Immediately upon shifting of the control element 64 to the right, the flow conduit 80 is opened to atmospheric pressure through the valve 58 to permit exhausting of the air pressure chamber 43, and substantially simultaneously, the regulated air pressure is applied to the flow conduit 79 and into the air pressure chamber 42. The pistons and 21 and piston rod 22 immediately commence movement in the direction of arrow C.

The valve-operating mechanism operate in a similar manner as the pistons 20 and 21 reach their left hand limit of travel. The trip arm 66 will be swung outwardly away from the control element 64 in a counterclockwise direction, and will operate against the keeper element '76 to release the trip arm 65 which snaps the control element 64 to the left to thereby operate valve 59 and reverse the air connections therethrough. Similarly as before, the trip arm 66 is latched in its new position.

it will be seen that we have provided new and improved apparatus for varying shop air line pressure over an extremely wide range, from approximately Zero psi. to twice the shop line pressure by merely operating a single control to admit or preclude entrance of air into the air motor and pumping mechanism and by varying the air pressure reducing regulator.

It will further be apparent that we have provided a novel valve operating mechanism for quickly shifting the control element for the air reversing valve so as to reverse the air connections to certain air pressure chambers of the air motor and pumping mechanism in response to movement of the air driven pistons substantial- 1y into their limits of movement. 1

It should also be apparent that we have provided a novel air motor and pumping mechanism which is designed to increase air pressure from the shop line pressure up to approximately twice shop line pressure, and which causes the pressure at the discharge to substantially immediately build up to shop line pressure so as to minimize the lag from the time of commencing operation of the pumping mechanism to the time at which pressure at the discharge equals twice the shop line pressure.

It should also be obvious that we have provided a novel and improved cylinder construction for reciprocating air motor and pumping apparatus so as to facilitate cheap and inexpensive enclosing of the ends of the cylinders.

It will, of course, be understood that various changes may be made in the form, detail, arrangement and proportion of the parts without departing from the scope of my invention which consists of the matter described herein and set forth in the appended claims.

What is claimed is:

l. A pump for increasing shop line air pressure and the like, comprising a pair of double ended, interconnecting cylinders having reciprocable pistons therein, a rigid interconnection between said pistons producing simultaneous movement thereof, said cylinders and pistons defining a first pair of pressure chambers having air therein tending to move the pistons in a first direction, and said cylinders and pistons defining a second pair of pressure chambers having air therein tending to move the pistons in a second direction opposite to said first direction, one chamberof each of said pairs of chambers having inlets connected with a source of air pressure and having outlets connected with a high pressure discharge conduit, check valve means at said inlets and outlets preventing reverse flow therethrough, the other chamber of each pair of chambers having a flow conduit connected thereto for alternately supplying and discharging air, a pressure-reducing means connected with the source of air pressure and supplying air at regulated pressure, and valve means connecting, alternately, said flow conduits one at a time with the pressure reducing means to receive air at regulated pressure therefrom and also connecting alternately, the conduits one at a time to atmospheric air for exhausting the corresponding chamber, and said valve being operable to alternate the connections of said flow conduits, whereby said valve means may be operated at the end of the piston strokes to cause air to be discharged at said outlets at a pressure substantially exceeding shop line pressure.

2. A pump for increasing shop line air pressure and the like, comprising a pair of double ended interconnected cylinders having reciprocable pistons therein, a rigid .interconnection between said pistons producing simultaneous movement thereof, said cylinders and pistons defining a first pair of pressure chambers having air therein tending to move the pistons in a first direction, and said cylinders and pistons also defining a second pair of pressure chambers having air therein tending to move the pistons in a second direction opposite to said first direction, one chamber of each of said pairs of chambers having inlets connected with a source of air pressure and having outlets connected with a high pressure discharge conduit, check valve means at said inlets and outlets preventing reverse flow therethrough, the other chamber of each of the pairs of chambers having a flow conduit connected thereto for alternately supplying and discharging air, a variable pressure regulator connected with the source of air pressure and supplying air at regulated pressure, operable valve means connecting, alternately, said flow conduits one at a time with the pressure regulator and also connecting alternately, the

conduits one at-a time to atmospheric air for exhausting the corresponding chamber, and mechanism operating said valve means at the ends of the strokes of the pistons tojalternate the conduit connections, whereby pressure at the discharge conduit may be varied upwardly in excess of shop line pressure.

3. Apparatus for varyingair pressure over a wide range below and above shop line pressure, comprising a discharge conduit, a pair of double ended interconnected cylindershaving reciprocable pistons therein, a rigid interconnection between said pistons producing simultaneous movement thereof, said cylinders and pistons'defining a first pair of pressure chambers having airtherein tending to move the pistons in a first direction, and said cylinders and pistons defining a second pair of pressure chambers having air therein tending to move the pistons in a second direction opposite to said first direction, one chamber of each of said pairs of chambers having outlets connected with said discharge conduit and having inlets, check valve means at said inlets and said outlets preventing reverse flow therethrough, the other chamber of each pair of chambers having a flow conduit connected thereto for alternately supplying and discharging air, a line pressure supply tube connected to said inlets and being connected to the source of shop line pressure, and said line pressure supply tube having a control valve therein for obstructing air flow, a variable pressure regulator connected with the source and supplying air at regulated pressure, a regulated pressure supply tube connected with the regulator and receiving air therefrom and including a control valve for obstructing air flow through the tube, operable valve means connecting, alternately, said flow conduits one at a time with the regulated pressure supply tube and also connecting alternately, the conduits one at a time to atmospheric air for exhausting a corresponding chamber, mechanism operating said valve means at the ends of the strokes of the pistons for alternating the connections of said conduits, and a flow connection from the regulator to said discharge conduit and including a check valve preventing flow from the discharge conduit to the regulator, whereby the pressure in the discharge conduit may be varied from substantially zero to substantially twice shop line pressure.

4. A reciprocating motor to be operated by air under pressure and the like, comprising cylinder means, piston means in the cylinder means and including a piston rod, said piston means and cylinder means defining a pair of pressure chambers arranged with respect to the piston means whereby air applied in the chambers tends to urge the piston means and piston rod in opposite directions, valve means in communication with said chambers and connecting, alternately, the chambers with a source of air under pressure and also alternately opening the chambers to atmospheric air for exhausting air, said valve means including a shiftable control element for changing the connections of the chambers, supporting structure carrying the valve means adjacent the piston rod, a pair of trip arms on the supporting structure adjacent the piston rod and spaced from each other in a direction longitudinally of the rod, said trip arms engaging the control element and urging the same in difierent directions, spring means bearing against said trip arms and urging the arms toward the control element causing each arm to tend to move the control element, a movable keeper element on the supporting structure adjacent said trip arms, each of the trip arms having a latching element adjacent said keeper element and said keeper element being shiftable out of and into locking relation with said latching elements one at a time to render the corresponding trip arm inoperative and allow operation of the other trip arm, an actuator on the piston rod between the trip arms and being engageable with the operative trip arm for moving the same away from the control element, said trip arms and said keeper element also having camming means moving the keeper element, in response to movement of the operative-arm, out of locking engagement with the latching element of the inoperative trip arm, and also moving the trip element into locking engagement with the operative trip arm, whereby when released, the inoperative trip arm is rendered operative and is moved by the spring means to operate the control element of the valve means and cause changing of the connections to the chambers and thereby cause the piston means and rod to reverse direction.

5. A reciprocating motor to be operated by' air and the like under pressure, comprising cylinder means, piston means in the cylinder means and including a piston rod, said piston means and cylinder means'defining a pair of pressure chambers arranged with respect to the piston means whereby air applied in the chambers tends to urge the piston means and piston rod in opposite directions, valve means in communication with said chambers, and connecting, alternately, the chambers with a source of air under pressure, and also alternately opening the chambers to atmospheric air for exhausting the air from the chamber, said valve means including a shiftable control element for changing the connections of the chambers, supporting structure carrying the valve means adjacent the piston rod, a pair of trip arms on the supporting structure adjacent the piston rod and spaced from each other in a direction longitudinally of the rod, said trip arms engaging the control element and urging the same in diflerent directions, spring means bearing against said trip arms and urging the arms toward the control element causing each arm to tend to move the control element, a keeper element swingably mounted on the support structure between the trip arms and swingable toward and away from each of the trip arms, each of the trip arms having a latching element adjacent said keeper element, and said keeper element being shiftable out of and into locking relation with said latching element one at a time to render the corresponding trip arm inoperative andallow operation of the other trip arm, said trip arms and said keeper element also having camming means swinging the keeper element, in response to movement of the operative arm, out of locking engagement with the latching element of the inoperative trip arm, and also swinging the trip element into locking engagement with the operative trip arm, whereby the inoperative trip arm, when released, is" rendered operative and is moved by the spring means to operate the control element of the valve means and cause changing of the connections to the chambers and thereby cause the piston means and rod to reverse direction.

6. A reciprocating motor to be operated by fluid pressure, comprising cylinder means, piston means in the cylinder means and including a piston rod, said piston means and cylinder means defining a pair of pressure chambers arranged with respect to the piston means whereby fluid applied in the chambers tends to urge the piston means and piston rod in opposite directions, valve means 1n communication with said chambers and connecting, alternately, the chambers with the source of fluid under pressure and also alternately opening the chambers for exhausting the fluid, said valve means including a shiftable control element for changing the connections of the chambers, supporting structure carrying the valve means ad acent the piston rod, a pair of trip arms swingably mounted on the support structure adjacent the piston rod and spaced from each other in a direction longitudinally of the rod, said trip arms engaging the control element and urging the same in dilferent directions, spring means bearing against said trip arms and urging the arms toward the control element causing each arm to tend to move the control element, a movable keeper element on the supporting structure adjacent said trip arms, each of the trip arms having a latching element adjacent said keeper element and said keeper element being shiftable out of and into locking relation with said latching elements one at a time to render the corresponding trip arm inoperative and allow operation of the trip arm, an actuator on the piston rod between the trip arms and being engageable with the operative trip arm for moving the same away from the control element, said trip arms and said keeper element also having camming means moving the keeper element, in response to movement of the operative arm, out of locking engagement with the latching element of the inoperative trip arm, and also moving the trip element into locking engagement with the operative trip arm, whereby when released, the inoperative trip arm is rendered operative and is moved by the spring means to operate the control element of the valve means and cause changing of the References Cited in the file of this patent UNITED STATES PATENTS 516,410 Steitz Mar. 13, 1894 756,903 Spencer et a1. Apr. 12, 1904 2,293,076 Ponting Aug. 18, 1942 2,336,446 Tucker et a1. Dec. 7, 1943 2,650,868 Waldron Sept. 1, 1953 2,717,186 Campbell Sept. 6, 1955 2,866,415 Montelius Dec. 30, 1958

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