US2464283A

US2464283A - Hydraulic apparatus

Info

Publication number: US2464283A
Application number: US545700A
Authority: US
Inventors: Cecil E Adams
Original assignee: Denison Engineering Co
Current assignee: Denison Engineering Co
Priority date: 1944-07-19
Filing date: 1944-07-19
Publication date: 1949-03-15
Anticipated expiration: 1966-03-15

Description

March 15, 1949. ADAAS 2,464,283

HYDRAULIC APPARATUS Filed July 19, 1944 4 Sheets-Sheet 1 INVENTOR a'iczl g EiAdam 5 Wan/u Al 5'? A'ITORNE 4 Sheets-Sheet 2 Filed July 19, 1944 FIG. 3.

a 4 Mi Z 7% in r v m .m. WA

ENTOR aMML/V fiJJMM 9f ATTORNEY 67WWU 66 March 15, 1949. c, ADAMs 2,464,283

HYDRAULIC APPARATUS Filed July 19, 1944 4 Sheets-Sheet I5 J32 J04 32-- K d v v 13 101 al 36 3,6

J33 Y m 107 :zoa

F I 4;. 4 Fl 6 .9. INVENTOR CecLl IZAdams BY 9/244 712' JO/mad A1TORNEY March 15, 1949.

filed July 19, 1944 FIG.7

c. E. ADAMS 2,464,283

HYDRAULIC APPARATUS 4 Sheets-Sheet 4 FIG-l0- FIGJB.

INVENTOR Cec ilEAdam s ATTORNEY Patented Mar. 15, 1949 HYDRAULIC APPARATUS Cecil E. Adams, Columbus, Ohio, assignor to The Denison Engineering Ohio, a corporation of Ohio Application July 19, 1944, Serial No. 545,700

The present invention relates to fluid pressure systems employing a fluid pressure operated power unit which drives machine tools such as Dresses,

drills, milling machines, etc., and also'relates tofluid control mechanism for governing the speed of operation of the power unit.

One of the objects of the present invention is to provide a fluid pressure system including a source of fluid pressure, such as a pump, a fluid operated power unit and a control mechanism for controlling the fluid pressure on the unit so as to operate the unit at a selected predetermined fixed rate or rates of speed.

Another object of the present invention is to provide a fluid pressure system in which the fluid pressure on the power unit is varied or maintained to compensate for variation in resistance encountered by the power unit in the work being done and to restrain the speed of the power unit in the event that extraneous force tends to permit or cause an undesirable increase in rate of speed of operation of the power unit.

In carrying out the foregoing objects, it is a further object of the present invention to utilize variation in pressure in the system, caused by the conditions imposed upon the power unit, to

regulate the speed of operation of the power unit.

More specifically, it is an object of the present invention to utilize the change in pressure of the fluid being discharged from the power unit, which change in pressure is effected by the work imposed upon the power unit, to effect a change of fluid pressure delivered to the power unit whereby the powcr unit operates at a selected rate or rates or speed.

A further object of the present invention is to provide for selectively adjusting the pressure at which the fluid is applied to the power unit.

Another object of the present invention is to automatically vary the fluid pressure to the power unit to cause the same to operate at a constant speed regardless of the work load imposed upon the power unit.

A further object of the present invention is to provide valve mechanism which is responsive to the rate of flow of fluid being discharged from the power unit to control the fluid pressure to the power unit to carry out the foregoing objects.

A still further object of the present invention is to provide a simple fluid pressure responsive flow control mechanism wherein conventional parts of a directional flow control valve form the main body and the major parts of the mechanism.

Still another object of the present invention is Company, Columbus,

20 Claims. (Cl. 121-45) to provide a simple fluid pressure flow control mechanism which is operable in one position for obtaining the maximum speed of operation 01" the power unit and operable in another position for causing the power unit to operate at a slower speed, said mechanism being capable of manipulation so as to instantly obtain the change of speed.

A further object of the present invention is to incorporate the simple'fiuid pressure flow control mechanism in a single unit.

More specifically, it is a further object of the present invention to provide for varying the pressure of the fluid delivered to the power unit by diverting or by-passing part ofthe fluid being pumped and to control the volume of fluid bypassed in response to the volume of fluid being I discharged from the power unit.

Still more specifically, it is an object of the present invention to provide for restricting the flow of fluid from the power unit and utilizin variation in pressure of the fluid being discharged from the power unit for operating valve mechanism which controls the quantity of fluid delivered to the power unit.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings wherein preferred forms of embodiments of the invention are clearly shown.

In the drawings:

Fig. 1 is a diagrammatic view of a hydraulic system embodying the principles of the present invention;

Fig. 2 is a vertical longitudinal sectional view taken through a flow controlling mechanism forming part of the hydraulic system illustrated in Fig. 1, the'flow controlling device being illustrated in one position of operation;

Fig. 3 is a similar view showing the flow controlling mechanism in another position of operation;

Fig. 4 is also a similar view showing the device in a third position of operation;

Figs. 5 and 6 are detail horizontal sectional views taken on the planes indicated by the lines 5-5- and 6-6, respectively of Fig. 2;

Fig. 7 is a vertical longitudinal sectional view taken through a modified form of control mechanism showing the same in condition to cause thepower unit to remain at rest in an initial or starting position;

Fig. 8 is a similar view showing, the control mechanism in condition to cause the power unit to perform a working stroke;

Fig. 9 is a similar view showing the mechanism conditioned to return the piston of the power unit to initial or starting position; and

Fig. 10 is a fragmentary vertical sectional view taken through the lower portion of the control mechanism showing the same in condition to cause the power unit to operate at an accelerated rate.

The present invention is capable of use with various types of fluid and is herein defined as a hydraulic system. Referring more particularly to the drawings, the numeral 26 designates the entire hydraulic system shown in Fig. 1. This system includes a motor driven pump 2|, a reservoir 22 from which the pump draws hydraulic fluid, a power unit 23 which is suppliedwith fluid by the pump 2|, and a control mechanism 24 which controls the flow of hydraulic fluid from the pump to the power unit and from the latter to the reservoir 22.

In the present instance, the power unit 23 includes a cylinder 25, a piston 26 disposed for sliding movement in the cylinder and a ram 21 connected with the piston and projecting through the lower end of the cylinder. This ram 21 is utilized to perform any useful work such as stamping, pressing or operating parts in a machine.

The control mechanism 24 includes a body 26 having a longitudinally extending chamber 29 formed therein. This chamber 29 includes a plurality of annularly shaped ports 36, 3|, 32, 33 and 34 spaced longitudinally of the body 26. Port 36 functions as an inlet port and is connected by a conduit 35 with the pump 2| to receive hydraulic fluid under pressure. Ports 3| and 32, which constitute work ports are connected ,by

conduits

36 and 31, respectively, with the opposite ends of the chamber of cylinder 25 of the power unit.

Ports

33 and 34 are outlet ports, communicating with the reservoir 22 by one or more pipes 38. A barrel member 46 slides within chamber 29 to control communication between certain of the ports 36 to 34, inclusive, through the chamber 29. As shown in'Figs. 2 and 3, this barrel member 46 has a plurality of longitudinally spaced annular grooves 4|, 42, 43 and 44 which may be selectively employed to establish communication between sets of adjacent ports 36 to 34, inclusive.

When the barrel 46 is in the position shown in Fig. 2, the groove 44 connects port 32 with port 34. Since port 32 is connected with the upper end of the cylinder 25 through the pipe 31, this end of the cylinder will then be in direct communication with the reservoir 22 through port 32, groove 44 and conduit 38. At the same time, the groove 43 in barrel 46 is in position to establish communication between the ports 36 and 3|. At this time, fluid under pressure will flow from the pump 2| through the conduit 35, ports 36 and 3| and conduit 36 to the lower end of the cylinder 25. This inflowing fluid will force the piston 26 upwardly since the fluid above the piston 26 can escape from the cylinder 25. As the piston 26 and ram 21 approach the limit of upward movement, a fork 45 secured to the ram and surrounding a shipper rod 46, will engage a collar 41 on the rod 46 and move the rod 4|; and barrel 46 upwardly against the action of spring 41A. Spring 41A surrounds the lower end of barrel member 46 and engages the body 28 and spring cup 48. When the barrel 46 has moved to the position shown in Fig. 4, fluid flow from the pump 2| to the lower end of cylinder 25 will be interrupted causing the ram 21 and piston 26 to come to rest.

At this time, the proximate ends of grooves 43 and 44 will register with port 32 permitting fluid to flow from port 36 to port 32 and then to port 34 from which it will flow directly to the reservoir 22. When the control valve mechanism is disposed in the position shown in Fig. 4, the piston 26 and the ram 21 are retained in the elevated position.

When it is desired to operate the ram, a control lever 49, connected with the barrel 46 by the shipper rod 46, is operated to move the barrel 46 upwardly to the position shown in Fig. 3. In this position, the groove 43 connects

chambers

30 and 32 so that fluid under pressure will flow from the pump 2| to the upper end of the cylinder 25. This incoming fluid will exert a downward pressure on the piston 26 causing it and the ram 21 to move downwardly. The fluid in the cylinder 25 below the piston then is forced through the conduit 36 to the chamber 3|. This fluid must have an outlet in order to permit the descent of the piston 26 and therefore the outer surface of the barrel 46 has a plurality of longitudinally extend ing grooves 5| which provide limited communication between the port 3| and the port 33 when the barrel is in the position shown in Fig. 3. Since the grooves 5| are limited in size and since the piston is moving downwardly, the fluid in cylinder 25 below piston 26, in conduit 36 and port 3| will be under pressure.

This pressure is utilized to control the rate of descent of the piston 26 and ram 21. To attain this,- the barrel 46 is provided with an internal cylindrical chamber 52 and a plurality of

lateral ports

53, 54, 55 and 56 which are spaced longitudinally of the barrel for reasons to be set forth hereafter. A spool 51 is disposed for sliding movement in the chamber 52. This spool is provided with an annular groove 58 intermediate spool heads 66 and -6|. A projection 62 extends from the head 6| and the bottom end thereof is arranged to engage the bottom wall of the chamber 52 and serves as a stop to limit the downward movement of the spool in the chamber 52. The spool 51 is urged downwardly to its lowermost position by a coil spring 63 arranged in the barrel 46 between the head 66 of spool 51 and a plug 64 slidably received by the upper end portion of the chamber 52. The uppermost longitudinal position of this plug is determined by an adjusting cap 65'threadedly received by the upper end of the barrel 46; the cap 65 is maintained in its adjusted position by a jam nut 66. The upper threaded end of the barrel 46 also receives a stop nut 61 which limits the downward movement of the barrel in the cylinder 29. Ports 53 interconnect port 42 with the lower part of the chamber 52 so that when the barrel 46 is in the position shown in Fig. 3, the ports 53 will establish communication between the port 3| and the lower part of the cylinder 52 in the barrel. Thus, when fluid is under pressure in the port 3|, as previously described, this pressure will exist also inthe chamber 52 below the head 6| of the spool. The size of the grooves 5| are computed with respect to the capacity of the system so that they properly impede the flow of fluid therethrough. This fluid pressure will exert an upward for: causing the spool to move upwardly in OPPOSltlui'i to the force of spring 63. The port 56 provides a relief for the fluid in the upper end of the chamber 52 permitting the fluid to flow into the groove and port 34 from which it will flow to the reservoir 22.

When the 'spool 51 moves upwardly, the head 8 portion 30 thereof uncovers port 55 which port is then in registration with the port 34 and the groove 53 of the spool will establish communication between the port 54 and port 55, port 54 being formed in the barrel 40 at the groove 43. Due to this location of the port 54, some of the fluid flowing from port 30 to port 32 .and the upper end of cylinder 25, will be by-passed through port 54, groove 53 and port 55 to port 34 which communicates with the reservoir 22. The amount of fluid by-passed will depend upon the fluid pressure in the port 3|. Thus, if this pressure increases, more force will be applied to the spool to move it in opposition to the spring 33 and the head 30 will uncover a greater portion of the ports 55. As more fluid is by-passed through

ports

54 and 34, less fluid will be directed to the upper end of the piston 26 and the downward speed of the piston will consequently be decreased. When the piston 23 reaches the limit of its downward movement, fluid flow from the lower end of cylinder 25 will cease and pressure in port 3| will fall; the spring 63 will then return the spool 51 to its lowest position where port 55 will be blocked by spool head 60.

The power unit 23 may be utilized to exert a holding or clamping force by maintaining the control lever 40 depressed to place the barrel 40 in the position shown in Fig. 3. At this time fluid pressure in conduit 35,

port

30 and 32, conduit 31 and the upper end of cylinder 25 will increase until a maximum pressure, determined by a relief valve 10 has been reached. This maximum pressure will be applied to the upper end of piston 25 to exert maximum downward force on the ram 21. When this condition occurs, the full pressure and volume of fluid delivered by the pump 2| may be used in operating other mechanisms which might be disposed in the fluid circuit. After the piston and rain have reached the limit of their downward movement and have been retained there for the desired time, the lever '49 may be released to permit spring 41A to return the barrel 40 to the position shown in Fig. 2, wherein

ports

32 and 34 are connected to vent the upper end of cylinder 25 to the reservoir 22. Ports 30 and 3| will also be connected to supply fluid under pressure to the lower end of cylinder 25 to cause the ram and piston to raise toward the initial or starting position. As the latter position is approached, the fork 45 will engage collar 41 and move barrel 40 to the position shown in Fig. 4, at which time the lower end of cylinder 25 will be blocked from the pump 2| and reservoir 22.

Ports

30, 32 and 34 will be connected to divert fluid from the pump 2| to the reservoir 22 and the power unit will cease to operate.

The control mechanism above described permits the use of fluid discharged from a power unit to control the flow of fluid under pressure to the unit to effect its operation in a desired manner. The speed of movement of the ram may be varied by adjusting the cap 05 so that the tension of the spring 33 on the spool 51 can be varied to vary the pressure at which the fluid is by-passed. Thus the volume of fluid directed to the power unit can be varied to secure the speed desired; if it is desired, the tension of the spring 63 can be so adjusted as to prevent movement of the spool 51 to the position where the fluid normally flowing from the high pressure chamber or port to the power unit will be by-passed, thus, preventing this by-passing and providing for full flow of fluid to the power unit.

Desirable control can be secured by another means shown in Figs. '7 to 10, wherein a modifled form of control has been. disclosed. In this modified form of control mechanism, the barrel is provided with ports instead of external grooves and communication between the inlet, outlet and work ports occurs through the interior of the barrel. These ports are designed to register with the

ports

30 and 34, inclusive, and the spool mechanism is arranged to connectcertain ports to produce the desired action. Normally, the ram 21 and piston 23 of the'power unit are at rest in an elevated or starting position and under this condition the modified valve mechanism occupies the position shown in Fig; 7 wherein the fluid pressure from the pump 2| is sent directly to the reservoir and some fluid is trapped in the lower end of cylinder 25 by blocking port When the power unit is to be operated, the control lever 49 is actuated to move the valve mechanism to the position shown in. Fig. 8, wherein barrel I40 will be arranged to establish communication between an angularly extending passage I05 adjacent the lower end of the barrel, and port I3I. Passage I06 terminates in a longitudinally extending bore I01, formed in. the barrel I40 and connected at its lower end with a transversely extending passage I08. When the barrel is in its elevated position, shown in Fig. 8, this lateral passage I08 registers with outlet port I33 which is connected by suitable conduits with the reservoir 22. In this latter position of the barrel, the lower end of the power unit will be in communication with reservoir 22 through chamber I3I, passage I06, bore I01,- passage I03 and port I33. The upper end of the power cylinder will then be in communication with the source of fluid pressure 2| through conduit 35, port I30, port IOI, groove I54 in. the spool, port I04 and port I32, which port I32 is connected to the upper end of the power cylinder by conduit 31.

At this time, fluid under pressure will flow from the power source to the upper end of the power unit and the fluid from the lower end of this unit will be exhausted to the reservoir. A needle valve H0 is received by the bore I0'Ifor controlling the movement of the piston. in the power unit. By adjusting this needle valve, the rate of flow between passages I05 and I08 may be controlled. By restricting the communication, pressure will be generated in port I3I,

which pressure will be transmitted by port I42 to the interior of the barrel I 40 below the spool I53. This pressure urges the spool upwardly against the action of spring I58. If the pressure is great enough, the spool will move upwardly until. the head I 55 at the upper end reaches a position wherein groove I54 communicates with port I05. At this time, some of the fluid under pressure will divert back to the reservoir and by-pass'the power unit. Due to this diversion of fluid, the speed of movement of the piston and ram will be decreased. The degree of reduction in speed may be determined by controlling the rate of communication between passages I06 and I 08, through manipulation of valve IIO. If the needle valve H0 is adjusted to reduce the effective size of the outlet from the power unit, the pressure required to effect a by-pass of fluid will be built up quickly, thus causing the power unit to operate at a slower rate than it will operate when. the size of the outlet is larger and the required pressure is built up more slowly. Valve H is operated by means of a knob III connected with the upper end of the valve stem II2, projecting from the upper end of the barrel. Suitable packing is employed around the stem II2 to prevent the escape of fluid.

After the ram has completed its working stroke and it is desired to return the ram to the starting position, the control lever is released to permit spring 41A to return the barrel I40 to the position shown in Fig. 9. At this time, the barrel I40 is at its lowermost position in the body I24, when so positioned, ports I03 and I04 in the barrel will be in communication with the port I30 and the spool I53 will be in the position wherein the groove I54 thereof bridges the ports ml and I03 and port I04. The port IN is in registration at this time with port I3I which is connected with the lower end of cylinder 25. At this time also, another port I05in' the barrel I40 will register with port I32 which is connected with the upper end of the cylinder 25 and another set of ports I02 in the barrel I40 will register with the outlet port I34. When these ports are so positioned, fluid under pressure will flow from port I30 through ports I03 and I04, groove I54 and port IOI to port I3I from-which it will flow to the lower end of the power cylinder 25. This fluid will move the piston 20 upwardly causing the fluid in the cylinder 25 above the piston 22 which opens automatically to return fluid from conduit 35 to the tank when the pressure exceeds the highest pressure desirable in the system.

The invention herein defined and disclosed permits using the conventional elements in parts of the well known directional control valves, the modifications consisting principally in the redesign of the barrel and the parts carried therein. Thus, a conventional direction valve has been changed in a facile manner to an automatically operated flow control valve.

While the forms of embodiments of the present invention as herein disclosed constitute preferred forms, it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow.

I claim: Q

l.A control valve comprising a casing with a plurality of ports included therein, said ports including inlet, outlet and work ports;'. a member disposed for movement in said casing, said movable member having flow conducting means to selectively connect said work ports with said inlet and outlet ports, said movable member having a passage connecting said flow conducting means; and valve means in said passage and cooperating with said movable member for controlling fluid fiow through the passage therein,

to flow to the port I32 from which it will flow through port I05 into the interior of the barrel I'40and thence, through port I02 to port I34 and to the reservoir 22.

In both forms of the invention shown, the positions of the spools to by-pass fluid-under pressure is dependent upon the pressurezcreated by the exhaust or return flow of fluid from the power unit. Thus, if the return flow is decreased due to a retarding of the-ram or piston,'less fluid *will be by-passed and therefore increased fluid pressure will be applied to the power unit to maintain the speed of the ram. The control of the speed of the ram is entirely automatic, variations therein being secured in the manner heretofore pointed out.

The modified form shown in Figs. '7, 8, 9, and 10 is provided with a. two speed feature whereby the power unit or ram may be operated at two speeds during its working stroke. To secure this feature, the barrel I40 is provided adjacent its lower end with an external groove, I60 which may be used to establish substantially unrestricted communication between ports I3I and I33 by stopping the barrel at the position shown in Fig. 10. When the barrel is so positioned, fluid will flow from the power unit to the reservoir 22 without building back pressure. The by-passing mecha? nism will not function and the necessary volume of fluid, to effect full speed operation of the power unit, will be directed thereto. By elevating barrel I40 to the position shown in Fig. 8, return flow of fluid to the reservoirwill be restricted and pressure to operate the by-passing of flow of fluid being discharged from the power unit.

Preferably, a relief valve 10 is interposed be said valve means being actuated by fluid pressure obtaining in a work port when connected with an outlet port. I

2. A control valve comprising a casing having a chamber and a plurality of ports spaced longitudinally thereof, said ports including inlet, outlet and work ports; a plunger disposed for movement in said chamber, said plunger having spacedv external recesses and being movable to selectively connect said work with said inlet and outlet ports, said plunger having an internal passage connecting said recesses; means for restricting fluid flow between a work port and an outlet to increase fluid pressure in the former;

and valve means in said passage and cooperative.

with said plunger to control fluid flow through the passage therein, said valve means being actuated by fluid pressure obtaining in the work port from which the flow of fluid is restricted.

3. In a hydraulic system of the type having a source of fluid under pressure and a power cylinder; means for controlling the flow of fluid to and from said power cylinder comprising a body having a chamber and a plurality of inlet and spaced longitudinally thereof; means disposed for longitudinal movementin said chamber to control communication between certain of said ports, said means having a hollow member with grooves shaped and disposed to connect certain ports in saidbody in predetermined positions of movement of said member, said member being provided with spaced openings to establish communication between the interior and the exterior thereof; communication between certain ports being restricted when said hollow member is in a predetermined position whereby a pressure will be built up in one of the ports; and valve means disposed for movement in said member, said valve means being responsive to the pressure built up in said port to control communication through said member between said openings. 4. Ahydraulic system comprising in combination, a source of fluid under pressure; a power cylinder; means for automatically controlling the operation of said power cylinder, said means including a body having a chamber and a plurality accuse of ports ispaced longitudinally thereof; means connecting one of said ports with said fluid pressure source, a port on either side of said flrst port serving as outlet ports; means connecting a port between said first port and either outlet port with the ends of said power cylinder; a barrel in the chamber in said body, said barrel having external recesses which alternately connect each cylinder port with the pressure and outlet ports upon reciprocation of said barrel in said chamber, said barrel having an internal recess and longitudinally spaced openings in the side wall establishing communication between the interior and exterior of said barrel; and a fluid pressure responsive valve mechanism in said recess for controlling communication between certain of said openings, when said barrel is in a predetermined position, said valve mechanism being actuated by the pressure obtaining in the cylinder port connected with an outlet when said barrel is in said predetermined position.

5. Flow control mechanism for hydraulic systems comprising, in combination, a casing having a chamber and inlet, outlet and work ports communicable with the chamber;-. valve means disposed in said chamber for movement between two extreme positions, said means serving to connect said inlet port with a predetermined work port and an outlet with a second work port when in one extreme position of movement and to reverse the inlet, outlet and work port connections in the other extreme position of movement; means for restricting fluid flow between said predetermined work port and outlet port to increase fluid pressure in said predetermined work port when said first mentioned means is in the second position; a second valve means carried by saidflrst valve means and responsibe to fluid pressure in said predetermined work port to connect the second work port with an outlet; said first mentioned means providing substantially unrestricted communication between said predetermined Work port and an outlet when said means is in a stage of movement between said extreme positions whereby no pressure will be built up in said predetermined work port and said second-mentioned valve will prevent communication between the other work port and an outlet.

6. Flow control mechanism comprising, in combination, means having inlet, outlet and work ports; flow-directing means for alternately connecting said work ports with said inlet and outlet ports; means for restricting fluid flow between a predetermined work port and an outlet port whereby fluid pressure will be developed in said predetermined work port; and means in said flow-directing means responsive to said fluid pressure to connect said inlet port with an outlet port while the inlet is connected with a second work port.

7. Flow control mechanism comprising, in combination, means having inlet, outlet and work ports; flow-directing means for alternately connecting said work ports with said inlet and outlet ports; means for restricting fluid flow between a predetermined work port and an outlet port whereby fluid pressure will be developed in said predetermined work port; means for adjusting said restricting means to vary the fluid pressure developed in said predetermined work port, and means within said flow-directing means responsive to said fluid pressure to connect said inlet port with an outlet port while theinlet is connected with a second work port.

8. Flow control mechanism comprising, in combination, a casing having a chamber and spaced inlet, workand outlet ports communicable with the chamber; a barrel member slidably disposed in said chamber, said barrel having a chamber and a plurality of lateral ports to connect the barrel chamber with the ports in said casing; spool means disposed for sliding movement in the chamber in said barrel member to control communication between certain lateral ports; means tending to urge said spool member toward a position to connect predetermined lateral ports in said barrel member; and means for restricting communication between a predetermined work port and an outlet port to increase fluid pressure in said work port, said pressure being transmitted through lateral ports in said barrel member to said spool to move the same in opposition to said urging means whereby communication will be established between said predetermined and other lateral ports.

9. Flow control mechanism comprising, in combination, a casing having a chamber and spaced inlet, work and outlet ports communicable with the chamber; a barrel member disposed in said chamber, said barrel member having an internal chamber and a plurality of lateral ports and being movable in said casing chamber to register the lateral with certain of said inlet, outlet and work ports in predetermined positions of said barrel member; spool means slidably disposed in the chamber of the barrel member to control communication between certain lateral ports therein; means tending to urge said spool toward a. position to connect a lateral port registering with said inlet port and a second lateral port registering with a work port when said barrel member is in one position in said casing, said first and second lateral ports registering with a second work and the inlet port, respectively in a second position of movement of said barrel; means operative when said barrel member is in said second position to establish restricted communication between the first work port and an outlet port whereby a fluid pressure will be generated in said first work port, said pressure being transmitted through a lateral port in said barrel member to said spool to move the same in opposition to said urging means and connect said first and second lateral ports with a third lateral port registering with an outlet port.

10. Flow control mechanism comprising, in

combination, means forming inlet, outlet and Work ports; valve means for connecting a predetermined work port with said inlet and another work port with an outlet, said means being adjustable to reverse said connections; means operable when said connections are reversed to also connect said inlet with an outlet whereby a portion of the flow from said inlet will be bypassed through the outlet; and means carried by and movable relative to said valve means and responsive to the pressure of the fluid flowing from said predetermined work port to an outlet for varying the volume of fluid by-passed.

11, Flow control mechanism for hydraulic apparatus comprising, in combination, a casing having a. chamber and inlet, outlet and work ports communicable with the chamber; means in said chamber operative in one position to establish communication between a predetermined work port and said inlet and between a, second work port and an outlet, said means being movable to a second position to connect said second work port with said inlet and establish substantially unrestricted communication between said predesheds es termined work port and an outlet; additional means operative when said first-mentioned means is moved in the same direction to a third position beyond said second position to restrict communication between said predetermined work port and an outlet whereby a, pressure will be built up in said work port; and means responsive to said pressure to simultaneously connect the inlet, an outlet, and said second work port.

12. Flow control mechanism comprising, in combination, a body having a bore with inlet, cylinder and outlet ports spacedlongitudinally thereof; a plunger having an internal chamber movably disposed in said bore, said plunger having ports spaced longitudinally thereof and registering with certain of said'ports in said body in diflerent positions of longitudinal movement of said plunger to alternately connect said cylinder ports with said inlet and outlet ports; a spool valve supported for movement within said plunger chamber; means tending to urge said spool valve toward a position to prevent communication between a cylinder port and an outlet port when said plunger is in a certain position, said plunger having a port to establish communication between a second cylinder port and the chamber when said plunger is in said certain position; means establishing a regulable fluid flow between said-second cylinder port and an outlet port when said plunger is in said certain position,

said means serving to build up a pressure in said second port which pressure is transmitted to the chamber in said plunger to move said spool valve in opposition to said urging means; and means formed with said plunger and operative when the'latter is in another position to cause fluid flowing from said second cylinder port to exhaust to by-passsaid flow establishing means.

13. A flow control valve comprising, in combination, a four-way valve having an inlet, an outlet, a pair of work ports and a spool for selectively connecting either of said work ports with said inlet and the other with said outlet; means for restricting fluid flow from a selected work port to said outlet to cause a fluid pressure to be built up in said work port when the other work port is receiving fluid from said inlet; a valve controlled passage in said spool for connecting the inlet, the outlet and the other work port; and, a

valve in said passage, said valve being exposed and responsive to the fluid pressure in said selected work port to control fluid flow through said passage.

14. In a flow control valve of the type having a casing with inlet, outlet and a, pair of work ports and a spool adjustable in said casing to selectively connect either of said work ports with said inlet and the other with said outlet; means for limiting the rate of fluid flow from a selected work port to said outlet to build up a fluid pressure in the selected work port when the other work port is receiving fluid from said inlet; and a valve in said spool actuated by the fluid pressure in the selected work port to direct to said outlet a portion of the fluid flowing from said inlet to the other work port.

15. A flow control valve comprising, in combination, a body having a bore and an inlet, an outlet and first and second work ports communicating therewith; a pair of members disposed for movement in unison and relative movement in said bore, said members cooperating in different positions of movement in unison to direct fluid from said inlet to one or the other of said work ports and'from the other work port to said outlet;

- 12 and'means for limiting fluid flow from the flrst work port to the outlet to create a back pressure in said work port during the admission of fluid from said inlet to the second work P one f said members being responsive to the back pressure to direct some 01 the fluid from said inlet directly to said outlet.

16. In a hydraulic system, a source of fluid pressure; a fluid motor; means for controlling the operation of said motor comprising a four-way valve between said source and said motor, said valve having a casing with inlet, motor and exhaust ports; a pair of telescoping members disposed for movement in said casing said members cooperating to direct fluid from said source to said motor and from the latter to exhaust; means yieldably maintaining said members in a pre determined relation; and, means for applying fluid pressure to said members to cause relative movement thereof in opposition to said "maintaining means to establish controlled communication between said inlet and exhaust ports.

1'7. In a hydraulic system, a source of fluid pressure; a reversible fluid motor; means for controlling the operation of said motor comprising a four-way valve having a casing with an inlet connected with said pressure source, work ports connected with said motor, and exhaust ports; a twopart spool with flow-directing passages for controlling fluid flow through said casing, said parts being movable in unison in said casing to reverse the operation of said motor, and relatively movable by bypass fluid from said source through certain passages to'exhaust to control the speed of said motor.

18. In a hydraulic system, a source of fluid pressure; a reversible fluid motor; means for controlling the operation of said motor comprising a four-way valve having a casing with an inlet connected with said pressure source, work ports connected with said motor, and exhaust ports; a two-part spool with flow-directing passages for controlling flu'id flow through said casing, said parts being movable in unison in said casing to alternately connect said work ports with said inlet and exhaust ports to reverse the operation of said motor and relatively movable to bypass fluid from said source through certain of said passages to exhaust to control the speed of said motor; and means for introducing fluid pressure between said parts to efl'ect relative movement thereoir 19. In a hydraulic system, a source of fluid pressure; a reversible fluid motor; means for controlling the operation of said motor comprising a four-way valv having a casing with an inlet connected withe said pressure source, work ports connected with said motor, and exhaust. ports; a two-part spool with flow-directing passages for controlling fluid flow through said casing, said parts being movable in unison to alternately connect said work ports with said inlet and exhaust ports to effect forward and reverse operation of said motor and relatively movable to bypass fluid from said source through certain of said passages to exhaust to control the speed of said motor; rr'ieans for introducing fluid pressure between said parts to effect relative movement thereof; and means effective upon movement of said parts to a predetermined position during forward operation of said motor for rendering said fluid pressure introducing means inoperative.

20. In a hydraulic system, a source of pressure: a reversible fluid motor; means for con- 13 trolling the operation of said motor comprising a casing having an inlet connected with said pressure source, Work ports connected with said motor, and exhaust ports; valve means movably supported in said casing said valve means having a hollow ported body and a spool movably disposed in said body; means tending to retain said spool in a predetermined position; means for moving said valve means to efiect forward and reverse operation of said motor; restricting means operative when said motor is operating in one direction to resist exhaust flow from said motor to create back pressure; means for applying such back pressure to said spool to move the same in opposition to said retaining means to a position establishing controlled communication between said inlet and exhaust ports, and means for selectively rendering said restricting means inoperative during operation of said motor in one direction.

CECIL E. ADAMS.

REFERENCES CITED The following references are of record in the file of this patent:

Certificate of Correction Patent No. 2,464,283. March 15, 1949.

CECIL E. ADAMS It is hereby certified that errors appear in the printed specification of the above numbered patent requiring correction as follows:

Column 9, line 38, claim 5, for responsibe read responsive; column 12, line 33, claim 17, for the words by bypass read to bypass;

and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Ofiice.

Signed and sealed this 28th day of June, A. D. 1949.

THOMAS F. MURPHY,

Assistant Uommz'm'oner of Patents.