US2436268A

US2436268A - Fluid pressure compounding system

Info

Publication number: US2436268A
Authority: US
Inventors: Schnell Steve
Original assignee: Wagner Electric Corp
Current assignee: Wagner Electric Corp
Priority date: 1943-07-02
Filing date: 1943-07-02
Publication date: 1948-02-17
Anticipated expiration: 1965-02-17

Description

F KB. I

Feb. 17, 1948.

S. SCHNELL FLUID PRESSURE COMPOUNDING SYSTEM Fileci July 2, 1943 2 Sheds-Sheet 1 INVENTOR S. SGHNELL AT TORNE Patented Feb. 17, 1948 FLUID PRESSURE COMPOUNDING SYSTEM Steve Schnell, Kirkwood, Mo., assignor to Wagner Electric Corporation, St. Louis, Mo., a corporation of Delaware Application July 2', 1943, Serial No. 493,231

, 19 Claims.

My invention relates to a fluid pressure actuating system and more particularly to one in which fluid pressure developed at a source can be directly transmitted to an actuating motor until a predetermined pressure is reached, after which the pressure fluid eifective in the motor will be caused to be greater than that developed at the source.

" is connected by a conduit II with the fluid mo- One of the objects of my invention is to provide improved pressure fluid ratio changing or compounding means for a pressure fluid system of the kind referred to.

Another object of my invention is to provide an improved cut-off valve means and compounding units for association with a pressure fluid system for causing the source of pressure to be cut off from an actuated fluid motor and thereafter the pressure fluid of the source to produce increased pressure effective in the motor.

Other objects of my invention will become ap-- parent from the following description taken in connection with the accompanying drawings in which Figure 1 is a schematic view of a fluid pressure system embodying my invention, with the cut-01f valve mean and the compounding unit thereof being shown in section; and Figures 2 and 3 are sectional views of other compounding units which may be employed in place of the unit shown in Figure 1. I

Referring to the drawings in detail and first to Figure 1, the pressure fluid actuating system in which my invention is embodied is shown, by way of example, as being employed for operating brakes but it is understood that it may be employed, if desired, for operating any device or apparatus. The system showncomprises essentiaily four units, namely, 'a' manually-controlled master cylinder device A, brakes B, a control valve unit C, and a compounding unit D.

The master cylinder device A is of known construction and comprises acylinderl having reciprocable therein a piston 2 connected by a piston rod 3 to a pedal 4. The piston is biased ,to'ietracted position by a spring 5 where it uncovers a porthole '6 for placing the portion of the cylinder ahead of the piston in communication with a reservoir 1. The outlet of the master cylinder device is connected to the central part of the compounding unit D by a conduit 8. This conduit 8 has a branch conduit 9 which is connected to one end of the control valve unit C. The other end of this control valve unit is connected to one end of the compounding unit D by means of a conduit in. The other end of unit D tors I2 for operating the brake assemblies [3.

The control valve unit 0 i embodied in a casing it having a large cylinder l5 and a small cylinder Hi, the latter being connected to conduit 9 previously referred to. Carried by the casing is a member I! provided with a cylinder l8 extending into cylinder [5 and slightly smaller in diameter than cylinder Hi. The outer end of cylinder I8 is closed by a fitting I9 to which conduit I0 is connected, s'a'id'fitting 19 having a passage 20 for placing the conduit in communication with cylinder [8. Cylinder l8 has mount- ,cd therein a piston'2i provided with a hollow extension 22 extending into cylinder 16. Thi extension projects through'a movable piston in the form of a wall 23 at the 'juncture of cylinders 15 and It, said wall'being biased into engagement with the shoulder '24 between said cylinders by means of a coil spring 25 interposed between the'wall and member H which carries cylinder 18. A packing cup 26 is associated with the wall and extension 22 for preventing fluid from flowing past the wall.

The piston 21 is provided at its forward end with a valve element 21 for engagement with a valve seat 28 surrounding passage 20 in fitting 19. This valve element is biased to seated position by a spring ZQpositioned in extension 22 and interposed between piston 2| and the end of cylinder IS. A passage 30 through piston 2| connects the portion of cylinder I8 ahead of the piston with the hollow extension 22 so that fluid under pressure entering cylinder l6 through conduit 9 may also be effective in cylinder i8 ahead of piston 21. A packing cup 3| is associated with piston 2i for preventing leakage past the piston. In order to limit the unseating movement of piston 2|, extension 22 carries an an nular flange 32 for engaging the movable wall 23. By means of this flange wall 23 can act to move the piston and re-seat the valve element under certain conditions.

The compounding device D i embodied in an' elongated casing 33 provided with

cylinders

34 and 35 on opposite sides of a partition 36, said cylinders being shown of like diameters but they may be difierent. The outer end of cylinder 34 is connected by a fitting 31 to conduit H leading to the fluid motors of the brake assemblies and the outer end of cylinder 35 is connected by a fltting 38 to conduit [0 coming from the control valve unit 0. The cylinder .34 has mounted therein a piston 39 provided with a packing cup 40 and cylinder 35 has mounted therein a piston 4| provided with a packing cup 42. Piston 4| is connected to piston 39 by a rod 43 which extends through partition 36. Both pistons 39 and 42 are biased to normally retracted positions by a spring 44 interposed between piston 4| and partition 36, said retracted positions being determined by a shoulder 45.--which is; eugagedby pis' ion 39. The'i'nner-end of'cylinder'34 at the-rear" of piston 39 is connected to the previously referred to conduit 8 coming from the master cylnioveItiie'ofpiston Z'of theimaster cylinder -W'ith force acting-on the fluid in cylinder 34, it will have a pressure twice that of the pressure fluid being developed by the master inder device and in order that fluid; may by-pass.

piston 39 when it is in retracted position, said piston is provided with a centrai =passage'-46 through which piston rod 43 extends. This piston rod at the rear of piston 39 carries a valve element 41 for cooperation with the rear'of thepiston to.

prevent flow of fluid through passage 46. In order to seal the piston rod and prevent any flow of fluid from cylinder 34-to cylinder 35, a packing element 48 surrounds-the'piston rod-at the partition 36- In order thatthe flow of fluid from conduit It to cylinder 35 may be restricted but only when iston 4| is in its normally retracted position,

said piston carries a pin 49 provided with a spherical end for reception in passage 50 of" fitting 38 to which conduit Hi'isconnected. Thus it is seen that this passage t'nl'will be restricted by the spherical end of the rod until piston 41' has moved such' distance inwardly'in'cylinder 35 as to remove the end' from passage 50.

Referring now to the operation of'my' improved system, all the conduits; the master cylinder device, control valve unit A. compounding unit D, and the fluid motorslz'are'filled'i with a suitable liquid. The parts" of the various units will 'be in the positions shown when the system is inoperative. Under' such conditions the piston 2| in the control valve unit C will be positioned so that the valve element 21' engages seat 28 to prevent any flow of fluid through the control valve unit. The valve element 41 carried by piston rod 43 in the compounding unit will be openso that fluid may flow through passage 46 in piston 39.

If the brake pedal should be operated to cause piston 2 of the-master cylinder device to develop pressure fluid, this fluid under pressure will be transmitted through passage 46 in piston 39 throu h cylinder 34 and conduit II to the fluid motors l2 of the brake assemblies to apply the brakes. The pressure fluid in the fluid motors l2 will be the same as that developed by the master cylinder device.

When the pressure fluid developed by the master cylinder device is'such that the pressure present in cylinder IBand acting on .piston 2| is great enough to move piston 2| to the left against the bias of spring 29 and opposing pressure fluid acting on the piston, valve-element 21 will be un-' seated. Thisplaces conduit 8'in communication with conduit I0 and permits pressure fluid from the source to be effective onpiston 4| of the compounding device. The valve unit C may be constructed so that valve element 21 is unseated' at any desired pressure. For the purposes of this description it is assumed as one hundred pounds per square inch. The pressure fluid acting on piston 4| causes it to be moved to the left, as viewed in Figure 1. This causes the closing of passage 46 in piston 39- by' the engagement of valve element 41 with the rear; of the piston 39. Communication-is now out oifbetween conduits cylinder deviceandsince this fluid under pressure acts in the fluid'motors I2, the brakes will be appii'edby' a; pressure twice that of the master c'y'liirderdevelopfedpressure fluid. Thus it is seen that wheir'thecon'ipounding unit D comes into operation. after the pressure developed by the master cylinder device reaches a predetermined value, the master cylinder developed pressure will be compounded and will continue to be compounded lo'ng as-themaster cylinder device continues torbe'op'eratedto'develop pressure beyond the predeterminedivaiue at which the compounding imit; conresv-intoi'operation. With the compounding unitinoperationthe brakes may be appliedwith: amanual force; which would be half that or the-'forceiwhich would: be required if the master cylinder device were directly connected to: thefluidmotors' I12 at'all times.

When-therpressurezfluid being developed by the mastercylinderzdevice reaches such a value as to move the movable wall 25 and. piston 2| to the right. valve element 2'1 'wi1l' be re-seated, thereby cuttingoif any-additional flow of fluid through i conduit ||l=to cylinden 35s The pressure fluid at which valve element- =is re-seated will be determinedebythestrengthot spring l5 and the relationship of the area of. cylinder It with respect to cylinder" I58: and-also the strength of spring-29 which tends to re-seat the valve element. For the purpose-of this description the pressure at. which thevalve element re-seats is assumed-to beseven-hundredand fifty pounds per square inch-.. When valve. element 27 is reseated, both pistons 4| and- 39 will no longer be moved and no-morefluid pressure will be developeclv in v the fluid.- motors l2.

With-.the. valve element 21- re-seated when the pressure fluid developed by the-master cylinder device. reaches seven hundred and fifty pounds per square: inch,. then the maximum pressure fl'uid which can be built up in fluid motors 12 will be fifteenhundred pounds per square inch. Before any more pressure fluid can be developed in the fluid-motors, it will be necessary to develop-sucha high: pressure by the master cylinder device. thatpiston. 3.9 could be moved away from valve element-41 to re-open passage 46. However, this would not be likely since sufiicient manual force could not be. applied to the pedal by the operator to bring about the required master cylinderdeve'lo'ped pressure to move piston 39 against the fifteen hundred pounds per square inch pressure ahead of the piston Thus it is seen thattlie contfol valve unit is not only so designed to bring about the functioning of the compounding. unit D when a predetermined pressure is developed. by the master cylinder device. but it also functions to limit the amount of pressure fluid which maybe developed in the fluid motors I2 by manual eifort. If valve element 2'! were not re-closed' at a predetermined pressure, it might be possible to develop as high as one thousandor'twelve hundred pounds per 7 square inch'bythe master cylinder device and gr, with-the functioning ofthecompounding unit such pressure would result in two thousand or twenty-four hundred pounds per square inch pressure in-the fluid motors. Such high pressures are notnecessary and may cause failure of the system. Y

Whenthe pressure fluid developed by the master cylinder device is released, the parts of the units C and D will return to the positions shown in Figure 1.. If the valve element 21 has been re-close'd due to a high pressure fluid developed by the master cylinder device, this valve will first become re-opened as the developed pressure fluid is lowered and when it reaches the assumed value of one hundred pounds per square inch, it will become re-closed. During the time that valve element 21 is open, the pressure fluid in cylinder 34, together with spring 44, will return the pistons to .their normally retracted positions. When piston 39 engages shoulder 45, the fluid pressure in cylinder 34 and the action of spring 44 will unseat valve element 41 and permit the.

pressure fluid in the fluid motors to be totally .released.

In the event the pedal should be operated suddenly, resulting in the development of more than one hundred pounds per square inch and the opening of the control valve unit C prior to the of operation of the master cylinder, the com-.

pounding unit will come into operation at. the time desired. The restricting action at passage 50 will be removed after initial movement of piston 4|.

In Figure 2 there is disclosed a modified compounding unit D which can be employed in place of the'compounding unit D described in connection with Figure 1. In this unit D there is provided a casing 5| having stepped

cylinders

52 and 53. Within cylinder 52 is positioned a piston member 54 having stepped

cylinders

55 and 55. The forward end of this member 54 carries a head 51 in cylinder 52 which is smaller than cylinder 5!. The portion of cylinder 52 ahead of head 51 is connected at one side to.

conduit 8 coming from the master cylinder de vice as shown in Figure 1. The outer end of cylinder 52 is closed by a fitting plug 58 which is provided with a central outlet passage 59 to which conduit l I is connected, said conduit being the one connected to the fluid motors of the. This fitting carber 54 by way of a passage 6| through the head.

51.

Cylinders

55 and 56 have reciprocable therein integrally connected

pistons

52 and 63.

A spring 54 biases these pistons to retracted po-' sition against a stop ring 65 carried by the rear end of the cylindrical member 54. The rear end:

of casing 51 having cylinder 53 is closed by a plug 66 to which conduit l0 coming from the control valve unit. 0 is connected. The piston member 54 carries a packingcup 61 for sealing it with cylinder 53. The head 51 and pistons 52 1 and 63 also have packing

cups

58, 69, and 10 to seal them with the cylinders in which they re-.

ciprocate. In order that the space between the piston member 54 and cylinder 53, together with the space between pistons 62 and 63, maybe maintained at atmospheric pressure, casing 51 is provided with a passage 1i and the piston member 54 with a passage 12.

Referring to the operation of the modified compound unit D, the parts thereof will be in the positions shown in Figure 2 when the system is not being operated. When the pressure fluid is initially developed by the master cylinder device and forced into conduit 8, it will be directly transmitted to conduit H and the fluid motors of the brake assemblies since head 51 will not be seated against seat 60. When the pressure developed by the master cylinder device reaches a predetermined pressure assumed as one hundred pounds per square inch, it will cause opening of valve element 21 of the control valve unit C (Figure 1) and pressure fluid will be forced through conduit in and act on piston 53 and the end of the piston member 54. This pressure is suflicient, due to the proportioning of the parts.

to move piston member 54 to the left to cause head 51 to engage seat 60 and cut ofi communication between conduits 8 and H. Movement of piston member 54 to close the valve will result from pressure acting on the end of the mem-' left and cause piston 62 to develop pressure fluidand transmit it through conduit H to the brake- When head 51 seats on seat 60, it will be held seated as the arrangement is such fluid motors.

that the force acting on the rear end of piston member 54, plus the force of spring 54, is greaterthan the pressure fluid from the master cylinderacting on head 51 tending to unseat the head The pressure fluid acting on the end wall 56' of cylinder 56 also tends to aid in holding head 51:

seated.

Since piston 63 is larger than piston 52, there willbe a compounding action and, as a result thereof, the pressure fluid efl'ective in the fluid motor will be greater than the pressure fluid be ing developed by the master cylinder device. Ifthe ratio of the areas of pistons 63 and 62 is twoto one, the pressure fluid effective in the fluidmotors will be approximately twice that developed in the master cylinder device.

If the pressure-fluid developed by the master cylinder device should exceed the value of seven hundred and fifty pounds per square inch, conduit in will be cut off from the master cylinder device by the closing of the control valve unit 0 in the manner already described and, therefore, no additional pressure fluid will be transmitted to the fluid motors.

When the pressure fluid developed by the master cylinder device is released, the parts of the compounding unit D will return to their positions shown in Figure 2. When piston 63 abuts against stop ring 65, the forces which become operative on the piston member 54 will cause head 51 to be unseated from seat 60 and 'pressure fluid will be released from the fluid amazes:

substituted for thecompounding unit D of the system shown in Figure 1. This unit- D comprises a cylinder 13 open at both ends. plug 14 closes one end and a fitting plug vl closes the other end. The plug 14 is provided with an integral cylinder 76 which extends into cylinder 13 and is concentric therewith to form an annular chamber 11. Positioned within the annular chamber is an annular piston 18 having an extension 19. Secured to extension 19 is a piston 80 which is positioned in the cylindrical extension 15. The forward end of extension 19 forms a piston 8| which is positioned in a cylinder 82 carried by the fitting plug 15.

Cylinder 82 communicates through a passage 83 with conduit leading to the fluid motors of the brake. The cylinder 16 communicates by a passage 84 in plug 14 with conduit 8 coming from the master cylinder device. Fitting 14 also hasa passage 85 to which conduit I8 is connected tocommunicate with the annular chamber 11.

A passage 86 extends through piston 88, extension 79, and piston 8| for placing conduit 8 directly in communication with cylinder 82 and conduit II. This passage is formed with a valve seat 81 which has cooperating therewith a valve element 88 acted upon by a spring 89 to bias it toward seated position. The valve element 88 is carried by a stem 98 extending through passage 86- and projecting slightly beyond piston 80 when valve element 88 is seated. The pistons are biased by a spring 9| to a retracted position where piston 88 engages the fitting plug 14. This positioning of piston 80 results in relative movement between it and valve stem 90, thereby causing valve element 88 to be unseated. The

pistons

78,88, and 8| are provided with suitable packing cups 92, 93, and 94 to prevent leakage. of fluid.

The parts of the compounding unit will be as as shown in Figure 3 when the system is inoperative. When pressure fluid is initially developed by the master cylinder device, the fluid from conduit 8 will flow through passage 86 to conduit II and the fluid motors since valve element 88 is open. When the master cylinder device develops the assumed one hundred pounds per square inch pressure to cause opening of the control valve unit C, fluid under pressure will flow through conduit l8 and become effective on the annular piston 78. This will result in all the pistons being moved forwardly and the automatic closing of valve element 88. When this valve element is closed, pressure fluid from the master cylinder will act on both pistons 18 and 88 and cause piston 8| to develop pressure. Since piston 8| has an area smaller than the combined areas of the annular piston 18 and piston 80, there will be a compounding action which will result in greater pressure fluid being developed in the brake fluid motors than that developed by the master cylinder device. If the total area of pistons 18 and 88 is twice that of piston 8!, the ratio betwwen the pressure fluid in the fluid motors and that developed by the master cylinder device will be approximately two to one.

' When the pressure fiuid developed by the master cylinder device is released, the parts will return to the positions shown in Figure 3. Pistons l8 and 88 will be returned by the action of the pressure fluid in the fluid motors acting on piston 8|, together with the action of spring 9|. When piston 80 is returned to its retracted position, valve stem 98 will engage fitting plug M A fittin and thereby cause openlngofv valve-element '88 to.- release all the pressure, fluid tnthe fluid motors to. the master cylinder device The action of the control valve unit 0 in pre vent-ing excessive pressure from being developed in the fluid motors is the same as previously described.

Being aware of the possibility of modifications; in the particular structure herein described without departing from the fundamental principlesiof; my invention, I do not intend that its scope be: limited except as set forth by the appended claims? Having fully described my invention, what I claim as new and desire tosecure by Letters Pat ent of the United States is:

1. In a pressure fluid system, a manually-operated source of pressure fluid; a fluid motor to be actuated; conduit means between said source and said motor; valve means associated with said conduit means for cutting off communication from said source to said motor which comprises a cylinder, two spaced pistons therein, a rod con-- nected between said pistons and said valve associated with said rod, said pistons movable relatively to each other until said valve is closed;

means comprising conduit means and other valve means independent of said first valve means for connecting the pressure fluid operated means to the source when the pressure from the source is at a predetermined value to thereby cause closing of said first valve means; means in said other valve operable by an increased pressure from said source to place said pressure fluid effective in said motor under increased pressure, said increased pressure being a multiple of the pressure pro-'- duced by said source; and means in said other valve operable by pressure fluid derived from said source to reclose said other valve when the pressure developed by said source exceeds a value higher than said predetermined value to thereby cause said manually-operated source to become effective on said fluid motor.

2. In a pressure fluid system, amanually-operated source of pressure fluid; a fluid motor to be actuated; conduit means between said source and said motor; valve means associated with said con-' duict means for cutting ofi communication from said source to said motor which comprises a'cylinder and two operatively associated pistonstherein, said valve associated with one of said pistons; other valve means for connecting the pressure fluid operated means with said source when the pressure from said source is at a predetermined value to thereby cause the closing of said first mentioned valve means by moving one of said pistons relatively to the other piston; means in said other valve operable by an increased pressure from said source to place said pressure fluid efiective in said motor under increased pressure, said increased pressure being a multiple of the pressure produced by said source; and means in said other valve operable by the increased pressure fluid derived from said source to re-close said valve whenthe pressure developed by said source exceeds a value which is higher than said first predetermined value.

3. In a pressure fluid system, a manually-controlled source of pressure fluid, a fluid motor to be actuated. conduit means between the source and motor, valve means associated with said cond'uit means for cutting off communication from the source to the motor, pressure fluid operated means for closing said valve means, conduit means between the source and said pressure fluid .5 operated means, normally closed valve means for said last named conduit'means, means for opening the last named valve means by a predetermined fluid pressure from the source, means for applying force to the fluid under pressure in the motor by the pressure fluid operated means after the first valve means is closed, and means for reclosing the last named valve means by fluid pressure from the source when it reaches a second predetermined value.

4. In a pressure fluid system, a manually-controlled source of pressure fluid, a fluid motor to be actuated, conduit means between the source and motor, valve means associated with said conduit means for cutting ofi communication from the source to the motor, pressure fluid operated means for closing said valve means, conduit means between the source and said pressure fluid operated means, normally closed valve means for said last named conduit means, means for opening the last named valve means by predetermined fluid pres--' sure from the source, means for applying force to the fluid under pressure in the motor by the pressure fluid operated means after'the first valve means is closed, and means independent of the second valve means for restricting the flow of fluid under pressure to the pressure fluid operated means during its operation to close the first named valve means.

5. In a pressure fluid system, a manually-controlled source of pressure fluid, a fluid motor to be actuated, conduit means between the source and motor, valve means associated with the conduit means for cutting off communication between the source and motor, a second fluid motor for controlling the closing of the valve'means, means including valve means for connecting the last named fluid motor with the source but only when the pressure from the source reaches a predetermined value, a third fluid motor independent of the second motor for applying pressure to the" fluid efiective in the first motor, and means for causing the third fluid motor and the'second' fluid motor to be simultaneously operated by pressure fluid from the source after the closing of the first valve means to thereby cause greater fluid pres sure to be effective in the first motor than that from the source.

6. In a pressure fluid system, a manually-controlled source of pressure fluid, a fluid motor to be actuated, a cylinder, a piston therein provided with a passage therethrough, conduit means for connecting the source with said piston passage, other conduit means for connecting the cylinder ahead of the piston with the fluid motor, valve means for closing the piston passage, pressure fluid operated means for closing the valve means .i

and for applying pressure to the piston, conduit means for connecting said pressure fluid operated means with the source, a normally closed valve for said last named conduit means, means. for opening said last named valve when the fluid pressure -'f rom the source reaches'a' predetermined value, and means for applying pressure fluid from said source directly to the first named piston when the valve'means is closed, sai'dlast 10 fluid motor, a movable valve element for closing the-piston passage, a fluid motor for closing the valve means and applying pressure to the =piston when the valve element is closed, and

other valve means operable independently of movement of said valve element for connecting the second fluid motor to the source when the fluid pressure therefrom reaches a predetermined value.

8. In apressure fluid system, a manually-controlled source of fluid pressure, a fluid motor to be actuated, a cylinder, a piston therein provided with a passage therethrough, conduit means for connecting the source to the cylinder on one side of the piston, conduit means for connecting the cylinder on the opposite side of the piston to the fluid motor, a valve element for closing the piston passage, a fluid motor for closing the .valve 1 means and applying pressure to the piston when the valve is closed, other valve means for con- 'necting the second fluid motor to the source when the the fluid pressure therefrom reaches a pre determined value, and means for closing said or the piston, conduit means for connecting the cylinder on the opposite side of the piston to the fluid motor, a valve element for closing the piston passage', a fluid motor independent of the piston and cylinder for closing the valve element and applying pressure to the piston when the valve element is closed, conduit means between the source and the second fluid motor, a normally closed valve means for said last named conduit means, and means for opening said last named'valve means by a predetermined fluid pressure from the source.

10. '-In a pressure fluid system, a manually-controlled source of pressure fluid, a fluid motor to be actuated, a cylinder, a piston therein provided a with a passage therethrough, conduit means for connecting the source to the cylinder on one side of 'the piston, conduit means for connecting the I cylinder on the opposite side of the piston to the fluid motor, a valve element for closing the piston passage, a second cylinder aligned with the first piston when the valve element is in closed posi- -'tion, and means comprising other valve means for connecting the second cylinder to the source when the pressure fluid therefrom reaches a predetermined value to thereby cause the piston in -the second cylinder to close the valve element and the two pistons to be moved in unison to develop pressure in the first cylinder.

11. In a pressure fluid system, a manually-controlled source of pressure fluid, a fluid motor to .be actuated, a cylinder, a piston therein providedwith a passage therethrough, conduit means for connecting the source to the cylinder on one side of the piston, conduit means for connectving the cylinder on the opposite side of the piston to the fluid motor, a valve element for closing the piston passage, a second cylinder aligned with the first cylinder, a piston in said second cylinder,

a piston rod connecting the last named piston for restricting thetrate of flowof fluid tothe;sec-- ond cylinder but only prior to the substantial movement of the piston therein.

12. In a pressure fluid system, a manuallycontrolled source of pressure, afluid-motorrto be actuated, two cylinders, conduit: means for connecting one cylinder to the source, conduit-means for connecting the other cylinder to the fluid motor, connected pistons in the cylinders, a passage through the pistons, normally open valve means for controlling said passage, a cylinder surrounding the cylinder connected to the source and provided with an annular chamber, an annular piston positioned in the annular chamber and connected to the other piston, means for controlling the closing of the valve means: by-

movement of the annular piston. conduit: means for connecting the nnular chamber to the source of pressure fluid, normally closed valve means in said last named conduit means, and means; for opening said last named valve means when .fluld pressure from the source reaches a predetermined value.

13. In a pressure fluid system, a manuallycontrolled source of pressure fluid, a fluidmotor to be actuated, conduit means betWeen-the source and the motor, valve means associated with the conduit means for cutting oil communication between the source and motor and comprising a normally open valve element, a cylinder, 8, piston in the cylinder connected to the valve element and provided with stepped cylinders, intercomnected piston in said stepped cylinders, means for connecting'the smaller cylinder-oi? said stepped cylinders to the conduit means at a point between the motor and the valve means, conduit means for connecting the first named cylinder and the larger cylinder of said stepped cylinders with the source of pressure, a normally closed valve means for said last named conduit means, and means for opening said last named valve means when the fluid pressure from the source reaches a predetermined value to thereby apply pressure to the piston connected with the valve element and the larger of the interconnected pistons to close the first valve means and subsequently cause the smaller of the interconnected pistons to apply pressure to the fluid in the fluid motor.

14. In a fluid pressure system, a manuallycontrolled source of fluid pressure, 'a fluid motor to be actuated, a casing provided with a cylinder, conduit means for connecting one end of the casing with a source of fluid pressure, conduit means including an outlet port for connecting the same end of the casing with the fluid motor. a valve seat surrounding the outlet port, a piston mounted in the cylinder of the casing and provided with a valve element engaging the valve seat and cutting off communication between the conduit means, said piston being provided with stepped cylinders the smaller of which is in communication at all times with the outlet port, interconnected-pistons in said stepped cylinders, a, spring for biasing all of said pistons to inoperative positions wherein the valve element is unseated, conduit means for connecting the cylinder of the casing and i *12 larger cylinder orcthestepped; cylinders with the source-ofifluid pressure-so-thatthepistons-therein may :be;-acted upon by-fiuid pressure, normally closed valve meansassociatedwiththe last named conduit, means, and means for-opening-said valve means whenv the fluid pressure from the source reaches a, predetermined value; to thereby operate the piston in the cylinder of the casing and the pistons in the stepped: cylinders to seat the valve element-and actuate'the fluid motor with greaterfluid pressure than that from the source.

15. In a. pressure fluid system, a manuallyoperated source ofpressure fluid; a fluid motor to be actuated: conduit means between said source and said motor; valve means associated with said conduit means for'cutting oft communication from saidsource to said motor; pressure fluid operated means for closing said valve means which comprises two cylinder and piston means therein movable relatively to said cylinder and one of said pistons engageable with said valve to cut off communication between said source and .mined valuega second piston acted upon by pressure fluid from said source, means operatively connecting said second piston to apply force to said flrst piston to move it in a valve element closing direction but only when said valve is open, and a spring acting on said second piston to oppose its movement by pressure fluid.

16. In a pressure fluid system, a master cylinder, a fluid motor to be actuated thereby, a first cylinder,-a piston therein, conduit means connecting said master cylinder and said motor including a passage. through said piston, a valve for closing said piston passage, a second cylinder coaxially disposed with respect to said first cylinder, a second piston in said second cylinder, means connecting said valve and said second piston, said second piston moving said first piston after said valve is closed, andmeans for applying pressure fluid to said second piston from said master cylinder after a predetermined pressure has been developed in said first cylinder including a valve operable when the pressure developed by said master-cylinder is higher than said predetermined pressure, said higher pressure developed by said master cylinder applied to both pistons to compound the pressure in said motor.

17. In a pressure fluid system, a source of pressure, a fluidmotor to be operated thereby, a

.ilrst cylinder, a piston therein having a passage @231 said pressure vfluid from said source acting 13 on both or said pistons after said valve has been closed in order to compound the pressure within said motor;

18. In a pressure fluid system, a master cyan der, a brake cylinder, a compounding device.

conduit means connecting said master cylinder and said brake cylinder, a first piston in' said compoundin device having a passageway therethrough included in said conduit means, a valve to close saidpassageway, a second piston in said compounding device, means connecting said valve and said second piston, said valve closable after-,1

a predetermined-pressure has been. developed in said brake cylinderglmeans to control the admission ofjpre'ssure fluid againstsaid second piston including-a valve and a piston responsive to a pressure higher than said predetermined pres-i sure in'orderto open said valve. and means to 14 ond piston, a control means, a second valve in said control means, a piston device associated with said second Valve operable by pressure fluid developed by said master cylinder above a. predetermined pressure to thereby move said second piston to close said first valve and cause said master cylinder to apply pressure to both of.

said pistons in order to compound the pressure fluid insaid-motor, and means to reclose said second 'valve after said higher pressure exceeds a higher and-diirei'entpredetermined value.

' RliFBENGES crrnn 13 file vfolloylring, reierences are of record in the file of this patent:

reclose said second valve alter a predetermined f compounded pressure has been developed in said motor. H

19. Ina pressure fluid system, a master cylinder, a fluid motor to be actuated thereby, a conipoundin'g device having a first-and second c'ylin-.

der therein, a piston in eachof said cylinders, conduit means includingapassage' in one of said pistonsto connect said master'cylinder with said motor, a valve for said passage in said first pm ton, meansconnecting said1valve-and said sec-- I -s'ra'rns PATENTS vikers Apr. so, 1946