US1826416A - Power actuator - Google Patents

Description

Oct. 6, 1931. c. s. BRAGG ET AL POWER ACTUATOR Original Filed Jan. 5, 1925 ATTORNEY Patented Oct. 6, 1931 UNTTED sTATEs PATENT oEFlcE CALEB S. BRAGG ANDVVICTOR W. KLIESRATH, F LONG ISLAND CITY, NEW YORK, AS- SIGNOBS CIJO BBAGG-KLIESRATH CORPORATION, 0F LONG ISLAND CITY, NEW' YORK,

A CORPORATION 0F NEW YORK POWER ACTUATOB vOriginal application filed January 5, 19'2, Serial No. 506. Divided and this application tiled August 80,

192s. serial No. 132,367. Renewed December 1o, 1980.

. Our invention consists in the novel features hereinafter described, reference being had to the accompanying drawings, which illustrate one embodiment ofv the same, se-

@ lected by us for purposes of illustration, and the. said invention is vfully disclosed in the following description and claims.

This application is a division'of. our former application filed January 5,1925, and given l0 Serial No. 506. l

-Our invention relates to a power actuator,

adapt-ed especiall for use in connection with -tautomotive vehic es propelled by an internal 'combustion engine, and most conveniently operated by suctionl from a suction passage of the engine between the throttle valve and the engine cylinder, or cylinders, as for example, by means of a connection with the intake manifold of the engine. In our prior app'li.

0 cation for Letters Patent of the United States filed December 22, 1923, Serial No. 682,346,

we' have disclosed apower actuator of this general type connected with the intake manifold of the internal combustion engine by means of a pipe or passage in which are located an adjustable regulatin valve or other restricting means, a check valve, and a storage space, or tank, and comprising a cylinder, a double acting piston therein, and reversing valve mechanism for' applying differential pressures on, opposite faces of the piston, and said actuator being combined with a' fot lever, or other part to be actuated in suchv manner that the latter can be operated by the actuator under the control of the foot'lever while the operator may add his physical power to the power of the actuator when desired,

s or in case of failure of the actuator, may

positively operate the actuated part by physical power applied to the foot lever, or other operator operated part.

The regulating valve or other restricting device prevents such large volumes of air being drawn into the intake manifold as to be therethrough, so as to stall the engine when idling while the storage space or storage tank provides a large space in which a partial vacuum or Tarification is maintained at all times.

4outer side of the piston being connected with Vtheatmosphere, and the immediate result is li kelyto dilute the explosive charges passingy while the engine is running, by withdrawingA tank, in the suction line extending to the in take manifold exterior to the actuator cylinder, and maintain a condition of partial vacuum or rariiication within the actuator cylinder itself, on both sides of the piston, which is made to supply the necessary storage space.

Thereby w'e obtain a number of important and advantageous results in the construction, installation andoperation of the power' actuator. In the first place, the tank, which is a bulky element, is entirely done away with and the construction is correspondingly simplified and' rendered less expensive. As a partial vacuum is maintained within the actuator cylinder on both sides of the piston therein,

when the device is in normal or inoperative osition, when the reversing valve mechanism 1s moved into a position to effect the operation of the actuator, one end of the cylinder on one side of-'the piston is connected with the intake manifoldor other vacuum roducing means, the other end of the cylin er on the that the atmospheric air rushes into the end of the c linder to which it is admitted, and effects t e operation of the iston in the desired direction and to the desired extent with,-l

out any appreciable quantity of air being actually withdrawn from the cylinder and vadmitted to the intakefmanifold or other sucton isv moved in the opposite direction.

the brake'is applied the actuator is operated without any material admission of air tothe intake manifold, and therefore without any possibility of injuriousl affecting the explosive mixture or of stal ing the engine, and

e when the valve mechanism is reversed to ef- 90 can be gradually Withdrawn to the intake feet the release of the brakes, by operating the piston in the opposite direction, the atmospheric air admitted for the purpose of obtaining the previous application ofthe brakes manifold, under the control of the regulating valve, so'as to prevent interference with the o eration of the engine, while securing the eective release of the brake mechanism. If the motor should stall, due to the admission of this air when the brakes are being released, it would be a matter'of far'less importance than the stalling of the motor when the brakes are being applied. It is not so important that the movement of the iston in a direction to release the brakes' s all be as rapid as the movement of the piston in the direction to ap ly the brakes. As a matter of fact, a very s ight movement of the piston in the directlon to release the brakes would be suiiicient to release them, and for this reason continuedap lication'and releasing of the brakes without a lowing the iston to come to the at rest position may effected with comparatively sm-all amount of air being drawn into the intake manifold, and the piston may be permitted to return to its normal position after an application of the brakes more slowly than it wouldbedesirable to have it moved in the opposite direction. Furthermore, when the piston comes to the at rest positlon after an application of the brakes,

artial vacuum in the rear of the erefore; the -only, air to he exthere is a cylinder.

-hausted is the amount admitted to the forward end of the cylinder to eect the releasing of the brakes, which is considerably less than the total amount of air that could be contained in the cylinder, were it not for our invention, which continuallykeeps at least one-end of our cylinder under vacuum, the total amount'of air inl the cylinder would. have to be exhausted after each operation of the brakes. Y

Our invention therefore enables us to simplify and decrease the cost ofthe apparatus, and at the same time insures the most eicient operation of the actuator without prejudice to the continuous and eicient'operation of the internal combustion engine .cally to anot from the suction passage of which the necessary power or suction for the operation of the actuator is derived.

In our former application above referred to, these features are broadly claimed, together with one of the specific embodiments or carrying our invention into effect, and

the presentapplication is directed specifier specifieembodiment for carrying the inventlon into eiect disclosed in our 'previous application above referred to, but not specifica l claimed therein, but which is specifically c aimed in this application.

Referring to the accompanying drawings Fig. 1 represents a diagrammatic view of an installatronin which ourfimproved ower actuator is connected with themterna combustion engine of an automotive vehicle for the operation of lthe brake mechanismTthere-` Fig. 2 is an enlarged sectional view i1- lustrating one form of'our improved actuator having one embodiment of our present invention therein, a portion ofthe piston rod' and-'valve actuating sleeve being Ibroken away and showing the piston in normal retracted position.

Fig. 3 is a detail sectional view of the termmaLportions ofthe piston rod and valve" actuating sleeve omitted from Fig. 2.

Fig. 4 is a detail sectional view of a portion of the construction shown in Fig. 2.

In Fig. 1 of the accompanying drawin we have shown diagrammatically an instali]- tion suitable for use in-an automotive vehicle in which one of our improved actuators is shown as interposed in the connections between a foot lever, 88, and brake mechanism for the vehicle, diaI ammatica ly represented at 70, 71 and 2, indicating a brake drum, brake band and brake lever. It will be understood that the brake mechanism will be provided with the usual retracting means for restoring it and assisting in restoring the piston of the actuator to the retracted or normal position, said means being indicated diagrammatically in Fig. 1, by the spring, 74. 60 represents an internal combustion enginefor propelling the'vehicle, and provided with an intake manifold, indicated at 61, and communicating with the carburetor, 6l, to which is connected a ipe, 62 between the throttle valve, indicate at 61", and the engine cylinders, in which pi are located preferably an adjustable regu atingvalve, or restricting valve, 64, check valve 65, 'and a vent valve, 67 normally closed, and openin outwardly. The pipe, 62, communicates witg one of our im roved power actuators, the cylinder of which is indica-ted at 701, in Fig..1, the saidl nected to a link, 85, with the foot lever, 88, which is provided with the usual retracting spring, 89, and the piston rod, 205, of the actuator is connected by a link, 7 3,- with the brake lever, 72.

ln Fig. 2 we have shown one form of our improved actuator embodying our present invention. In this figure, 701, represents the actuator cylinder closed at both ends by heads, 702, connected by bolts, indicated at 702, in Fig. 1, or otherwise. 703 represents the double acting piston provided with oppositely disposed gaskets, 704. 705 represents a -hollow piston rod which extends through a stufiing box, 706, in one end of the cylinder, and is connected at its inner end with the piston, 703. The hub, 710, of the piston is rovided with two valve chambers, 11 and 12 respectively, each of which is provided with two 4valve seats preferably conical and coaxial with the axis of the piston. The valve chamber, 711, is provided with seats, 713 and 714, and the valve chamher, 712, is provided with valve seats, 715 and 716. The piston hub is provided with an outlet chamber, or suction chamber, indicated at 717, which communicates with each of the valve chambers through the valve seats, 714 and 715. Arl'he piston hub is also provided with a higher pressure chamber, 718, in this instance communicating with the atmosphere and with the valve seat, 716, and by a lateral passage, 719, with the valve seat, 713. The

Iii?

'valve actuating part, in this instance, the sleeve, 720, passes through a stufiing box, 721, in the cylinder head at the opposlte end of 'the cylinder from the stufiin box, 706, the

,said sleeve extending lon itu inall through the piston hub and va ve cham ers, and through the hollow piston rod, 705, and being iongitudinally movable to eiiect the operation of the reversing valves. The valve sleeve may. be made conveniently in two parts, 720 and 720, if desired, and as herein shown, is provided with a pair of oppositely disposed poppet valves in each valve cham- 'fer, the said valves being preferably ormed of molded rubber and frictionally engaging 'the sleeve, so that the sleeve may move through the valve while forming an air-tight joint therewith. The valves are indicated at 740, 741, 742 and 743, the valves, 741 and 742 hein suction valves, and the valves, 744) and 743 eing air inlet valves. The valves are -1 yieldingly held in engagement with their seats, preferably by an elastic cushioning device interposed between the palrs-.of valves, and indicated at 750. The actuatlng sleeve is provided with suitable means for opening one valve of'each pair when the sleeve is moved in either direction. 1n this instance sleeve is shown provided with a fixed collar, 722, located adjacent to the suction valve, 741, and a collar, 722g, which is movable longitudinally of the sleeve, 720, by

lmeans of connecting red, 744, extendin through the hollow sleeve, 7 20, and connecte at its forward end to an actuating part adapted to be brou ht into operation when the parts have reac ed their normal or retracted positions as illustrated in Fig. 2. The valve sleeve is also provided with collars, 731 and 732, for operating the .air inlet valves.

Communication between the suction pipe, 62, and the suction chamber, 717, is effected in this instance through the hollow valve sleeve, which is provided with a fitting, 726, at its outer end, to which the pipe, 62, is connected. The fixed collar 722, is so located with respect to a stop carried by the sleeve, 7 20, in this instance provided by the engagement between the inner end of the fitting or collar, 726, and the adjustable collar, 721, of the adjacent stufiing box, that when the piston returns to its normal or retracted position, as shown in Fig. 2, the sleeve will e arrested in such osition that the fixed collar, 722, will slig tly unseat the valve, 741, permitting communication between the vacuum chamber, 717, of the cylinder on the forward side of the piston through the port or passa e,'734. The movable collar, 722, is capab e of being moved longitudinally with respect to the valve actuating sleeve by meansof a connecting rod, 744, extending through the hollow sleeve, 720, connected to the collar, 722l at its inner end, and connected at its forward or outer end to an actuating part, adapted to be brought into operation when the parts have reached their normal or retracted position. In this instance we have shown the vacuum pipe, 62, connected to the sleeve by a fitting, indicated at 7,45, having a ball terminal, 746, secured in a spherical socket in the stop collar, 726, of the valve actuating sleeve, so as to permit the fitting, 745, to have a slightly rocking movement longitudinally of the sleeve, 720. On this fitting, 745,'is located an adjustable collar, 747, which ma be in the form of a nut engaging a threa ed portion on the exterior of the fitting, 745, and provided with a stop pin, 748, which engages a part of thecylinder, in this instance the valve, 7 21, of t e stufiing box, 7 21,`so as to rock the fitting, 745, in the direction of the arrow, Fig. 2, when the valve sleevel is restored to its` retracted or normal position, b the retracting spring of the foot pedal. n this instance the forward end of the connecting rod, 744, is screwed into the ball, 746, in such manner that the rocking movement imparted to the fitting, 745, will move the collar section, 722, in a direction toward the valve, 742 far enough to slightly unseat the valve, and thus establish communication between the vacuum chamber, 717, and that portion of the cylinder in rear of the piston. When the valve actuating sleeve is moved forward' to actuate the brake mechanism, the opening ofthe valve, 73,- will effect a compression of the cushioning device, 750, and close the valve, 742, restoring the movable collar section, 7 22, and connected parts, as the projection, 7 48 is released.

The specific details of the poppet valve mechanism herein shown and described form no part of our present invention, as the same is disclosed and claimed in our former application for Letters Patent of the United cylin `742, effecting Van equalization'of States, filed November 22, 1924, and given Serial No. 751,481.

lt follows from this construction thatas soon as the engine is started, the suction produced in the-intake manifold will exhaust the air from the cylinder of the actuator on both sides of the piston, and maintain the piston submerged in vacuum when retracted. If it is desired to apply the brakes, the foot lever is actuated to move the sleeve, 720., in

the direction of the arrow, Fig. 2, permitting the suction valve, 742, to close, and further opening the suction valve, 741, and opening the air inlet valve, 7 43.V This continues the action of the cylinder forward of the piston with the suction chamber, 717, and -admits atmospheric air in rear of the piston, moving the piston forward in a direction to yapply the brakes, but no appreciable amount of air will be `drawn into the intake manifold throu h' the pipe, 62, as that portion of the (ger is already exhausted. The forward movement of the piston will follow any extent of 4the forward movement of the brake lever, 88, and when the brake lever stops, the piston will continue to move forward until the air inlet valve, 743 closes, `so as to hold the piston and brakes. Where 4continued applications of the brakes are desired, a slight release ofthe foot lever will open the suction valve, 742, producing 'a partialor entire equalization of pressures on o posite sides of the piston, which will permit the brakes to relieve themselves and sli htly retract 'the-A piston under the action o the retracting means for the brake mechanism indicated at 74 in Fig. 1. A slight forward movement of the pedal lever `will again close the suction valve, 742, and open the valve, 743, admitting air in rear of the piston/anda number of successive applications of the brakes can be made without admitting material quantities of air into the intake manifold. When the 'foot is removed from the foot'lever, 88, the lever will be moved rearwardly by its retracting spring, opening the suction valve, ressures within the cylinder on both'sides o the piston and permitting the brakes to relieve themselves, and the" further reversemovement of the sleeve, 7 20, will close the 'suction valve, 741, and open the air inlet valve, 740, admitting atmospheric air to the cylinder forward of'the piston through the opening,

733, controlled by said valve, thus returning the piston to normal position. The piston will be arrested by engagement of its hub with the end of the cylinder. The valve yactuating sleeve will be arrested by the engagement of the collar, 726with the valve, 721, this opening the suction valve, 741, closing the air inlet valve, 740, and holding the suction valve, 7 41, in open position. At the same time the engagement of\the pin, 7 48, with the follower or other stationary part of the Y cylinder, will effect the opening of the suction valve, 742. When, as before stated, the parts come to rest, the suction chamber, 717, will, therefore, be in communication with the cyl inder on both sides of the piston and will vexhaust the air previously admitted to effeet the reverse movement of the piston, leaving it again submerged in vacuum. The exhaustion of air from the cylinder therefore only takes place duringand after the return stroke of the piston, and this air is delivered graduallyto the intake manifoldby the restricting valve, 64,*so that the operation of the engine will not be interfered with, and the eduction of the air 'may be retarded as much as desired, as the firrt movement of the piston rearwardly will relieve the pressure of the brakes,I and it is not important that the piston should move rearwardly as quickly as it moves 'forwardly to apply the brakes.

The withdrawal of the air may, therefore, be distributed over a great or,less period of time, according to the adjustment of the valve, 64, so as to avoid the undue dilution of the explosive charges or the feeding of too small an amount of hydrocarbon fuel, and the piston is left submerged in vacuum and readyl for immediate and effective operation to apply the brakes at any moment. As the degree of suction in the suction passages of the engine varies from time to time, we interpose the check valve, 65, in the pipe, 62,-so that after the cylinder is subjected to the greatest amount of suction, the condition of rarifcation so produced will remain, and as the brakes are usuall operated at intervals, the greatest possi le rariication will ordinarily exist in the cylinder of the actuator at all times, ready to effectively a ply the brakes in the manner before descri ed. We prefer to connect the valve actuating sleeve, 720, 720, with the piston by `means providing for a limited amount of lost inetion, sufficient to permit the operation of the valves, so that after this lost motion is taken up, the physical power of the operate.1 can be directly applied to the piston and the brake mechanism connected therewith, tov en able the ofperator to add his'physical force i to that o the actuator,or tooperate the brakes by his physical force alone if the power should fail for any reason, the lost motion. permitting 'the 4movement'. of the valves in any case, and serving when power lll@ fails to vent the cylinder. In. the present instance, as shown in Fig. 3, the section, 720, of the valve sleeve is provided with a recessed portion, 720", and a collar, 720C, and a piston rod, 705, is in this instance provided ywith set screws, 705, extending into said recess (or recesses) 720", so that when the sleeve is moved forward bylthe foot lever to apply the brakes, and the piston has followed applying the brakes to the full capacit o the actuator, the oy erator may, by pu 'ing the foot lever, 88, urther` forward until the rear edge of'the rece, 720", will appl his physical force to the piston and there y to the brake mechanism, in addition to the power of the actuator. It also follows from this construction that, should the power of the actuator fail for any reason, the operator may a ply his physical force to the iston and bra e mechanism to apply the bra es, the first forward movement o the valve actuating sleeve, to take up the lost motion, movin the valves into position to vent the cylinder forward of the piston and admit air in rear of the piston to permit this movement. In like manner, when the foot lever V is released, the retracting spring will move it rearwardly and shift-the valve actuati sleeve so as to vent the cylinder y(in case o failure of power) and the forward end of the recel-SS,A 720D. v

It ,will be noted that a vacuum is continuously' maintained in the actuator cylinder on both sides of the piston when it is in nor- Inal position, so that the cylinder itself acts as a storage space and no additional tank or other extra'- neous stora e space is required. As we have termed it, t e piston is normally maintained Submergedin vacuum. y

What we claim-and desire to secure by Letters Patent is v 1. In a power actuator, the combination of a cylinder closed at both ends, a double acting piston in said cylinder, reversing valve mechanism, means for connecting saldi-'eversing valve mechanism with' sources of high and low fluid pressure, a longtudinall movable valve operating partprovided wit valve engaging devices fixed in relation thereto, for

operating certainof said-valves, an o rator operated part connected with said va v e o erating part, a retractin spring operative y connected withv said va' ve operating part, means for arresting said valve o rating part when the piston is in retracte position, in position to hold one of said valves o n to connect the cylinder on one side of t e pis-v ton with the low pressure source, means carried o 'n said valve actuating part and, Inovable independently with respect to said valve actuating' part for operatively engaging another of said valves, and means for arresting said independently movable valve engaging means part when the piston is 1n normal reacting movable part carried by andthe engine is in operation,

tracted osition to eect the opening of said other va ve and place the cylinder on the opposite side of the piston in connection with the low pressure source. v I

2. In a ower actuator, the combination of a cylin er closed at both ends, a double piston in said cylinder, reversin valve mechanism, means for connectin said reversing valve mechanism with a so ce of suction and with the atmosphere, a longitudinally extending valve actuatin part movable with the pistonl and exten mg through apertures in said valves, and rovlded with means for opening a suction va ve, and an air inlet valve when moved in either direction including a fixed collar attached to said valve actuating part fo'r engagin one of the suction valves, and a movable co lar on said valve actuati part and movable with respect thereto or engaging the other suction valve, means for arresting said sleeve in position tohold one of said suction valves open when the piston is in normal retracted position, a

said va'lve actuatin part and movable with respect thereto, and operatively connected with said movable collar, a retracting spring operatively connected with said valve actuating part, and means for effecting a relative movement of said movable part with respect to the valve actuating part when the piston is in retracted position to open the other of said suction valves, and maintain the piston vsubmerged .in vacuum when retracted.

3. In va power actuator, the combination of a" cylinder closed at both ends, a double acting piston in said cylinder, reversing valve mechanism located in the hub of the piston, and comprising suction and inlet valves, means for connecting the suction valves with a source of suction, means for connectin the air inlet valves with the atmosphere, ylelding means for normallyseatin said suction and inlet valves, a longitudina ly extending valve actuating sleeve through apertures in said parts and provided with means for opening -a suction -valve and an air inlet valve' when moved in either direction, said means including a fixed collar attached to said valve actuating part adjacent to one suction valve and a movable collar carried by said valve actuating part and movable longitudinally thereon and located adjacent to the other suctionvalve,l means for arresting said sleeve in position to hold the suction valve adjacent to said'A stationary collar in partially open position, a" movable part carried by said sleeve, and movable relatively with respect thereto, a connection from said movable part extending longitudinally-'of said sleeve to said movable collar, a `retracting ring operatively connected with saidy va ve l actuating part, and means for effecting a relative movement of said movable part and said movable collar with respect to the sleeve for positively opening the other suction valve when the piston is in normal retracted position, to maintain the piston submerged in vacuum when retracted.

4. In' a power actuator, the combination of a cylinder closed at both ends, a double acting piston in said cylinder, reversing valve mechanism located in the hub of the piston, and comprising suction and inlet valves, means for connecting the suction valves with a source of suction, means for connecting the air inlet valves with the atmosphere, a longitudinally extending valve -actuating sleeve through apertures in said parts and provided With means for opening a suction valve and an air inlet valve when moved in either direction, said means including a fixed collar attached to said valve actuating part adjacent to one suction valve and a movable collar carried by said valve actuating part and movable longitudinally thereon, and located adjacent to the other. suction valve, means for arresting said sleeve in position to hold the suction valve adjacent to said stationary collar in artially open position, a movable part carrie by said sleeve, projecting laterally thenefrom and movable relatively with respect to the sleeve, a connection between said movable part and said movable collar extending longitudinally through said sleeve a retracting spring operatively connected with the valve actuating part and means for effecting a movement of said movable part and said movable collar with respect to said sleeve, when the piston is in normal retracted position for positively opening the other of said Suction valves, to maintain the piston submerged in vacuum when retracted.

5. In apower actuator, the combination of a cylinder closed at both ends, a double acting piston in said cylinder. reversing valve mechanism located in the hub of the piston, and comprising two pairs of oppositely disposed coaxial valves, each pair including a suction valve and an air inlet valve ,yielding means interposed between the valve of each pair for seating the same, means for connectmg the suction valves with a source of suction, means for connecting the air inlet valves with the atmosphere, a valve actuating part extending longitudinally through one end of the cylinder through said valves and provided with means for opening a suction valve and an airA inlet valve when moved in either direction, including a fixed collar at.

tached to said valve actuating part adjacent to one suction valve and a movable collar carried by said valve actuating part, and movable longitudinally thereon, and located adjacent to 'the other suction valve, an operator operated part connected with said valve actuating part, a retracting spring operatively connected with said valve actuating part, a stop'carried by the valve actuating part for engaging a part connected with the cylinder, when the piston is in normal retracted position, to enable said xed collar to hold its adjacent suction valve in open position, a movable part carried by said valve' actuating part and movable with respect therel" to, connections between said movable part and said movable collar, said movable part being provided with a portion adapted to engage a part connected with the cylinder' when the piston is in retracted position for with the cylinder 'on both sides of the piston,

valves for controlling said suction and air inlet passages, and yielding means normally tending to seat all of said valves, vacuum producing means connected with said vacuum chamber, a longitudinally extending valve actuating sleeve, extending through apertures in said valves and provided with means for opening one of the suction valves and one of the air inlet valves, when moved in either direction including a collar section fixed to said sleeve, and a movable collar section located between said suction valves, a

' retracting spring operatively connected with said valve actuating part, a movable part on said sleeve adapted to engagea part connected with the cylinder for arresting said sleeve in position to cause the stationary lcollar section to hold its adjacent suction valve partially opened, and a connection between said movable part and said movable collar section for positively opening the other. of said suction valves when the parts are in retracted or normal position, to maintain the piston submerged in vacuum. V

7 In an automotive vehicle provided with an internal combustion engine having a suction passage, the combination with power actuator comprising among its members a cylinder closed at both ends, a piston in said cylinder, reversing valve mechanism in the piston, including a suction chamber. passages connecting it with the cylinder on both sides of the piston, air linlet passages connected with the cylinder on both sides vof the piston, suction and air inlet valves controlling said passages, and yielding means normally tending to seat said valves, of means for connecting the said sucton chamber with the suction passage of the engine, a valve actuating part provided with means for opening said valves ICO the longitudinal movement of the valve actuating part, so disposed as to effect the opening o't' one inlet valve and one suction valve when the valve actuating part is moved in either direction with respect to the piston, 'the .valve opening means for said suction valves being movable with respect to each other, a. retracting spring operatively connected with said valve actuating part, means called into action when the piston is in normal retracted yposition to arrest the valve actuating part,and shift said suction valve opening means with respect to each other to maintain both suction valves in open position, and maintain the piston submerged in vacuum, an operator operated part connected with the valve actuating part, and means for I connecting the piston with a part to be actuated.

8. In an automotive vehicle provided with-l an internal combustion engine having a suction passage and brake mechanism for the vehicle, the combination with a power actuator comprising among its members a cylinder closed at each end, a piston in said cylinder, reversing valve mechanism located in the piston, including a suction chamber, passages connecting,r itwith the cylinder on both sides of theppiston, air inlet 'passages connected with the cylinders on both sides of the piston, suction and air inlet valves controliing said passages, and yielding means normally tending to sea-t said valves, of means for connecting the .said suction chamber with the suction passage of the engine, a valve liftnating part extending through said valvesy and to the exterior of the cylinder, and provided with means for opening one of said suction valves and one of said inlet valves when moved in either direction, including. a tixed part on said valve actuating part for engaging one suction valve, anda part movable with respect to the valve actuatingpart and carried thereby forV engaging the other suction-valve, means for arresting the valve actuating part in position to hold one suc-- tion valve open by said fixed openingmeans when the piston is in retracted position, a retracting spring operatively connected with the valve actuating part, andV means for 'shifting said movable opening means to .effect the opening of the other suction valve when 'the plston 1s 1n normal retracted posltion, to

connect the portions' of the cylinder on both sides of the piston with each o'ther and with the suction passage of the engine, and maintain the piston submerged in vacuum when in retracted position, .an operator operated part connected with said valve actuating part, and means for connecting the piston with the brake mechanism.

9. In an automotive vehicle provided with an internal combustion engine having a suotion passage and brake mechanism for the vehicle, the combination with a power actunormally tending to seat said valves, of means for connecting the said suction chamber with the suction passage of the engine, a valve actuating part extending through said valves and to the exterior of the cylinder, and provided with means for opening one of said suctionv valves and one of said inlet valves when moved in either direction, including a fixed part on said valve actuating part for engaging one suction valve, and a part movable with respect to the valve actuating part and carried thereby for engaging the other suction valve, a@ retracting spring operatively connected with the valve actuating part, means for arresting'the valve actuating part in position to hold one suction valve open by said fixed opening means when the piston is in normal retracted position, lto connect the portions of the cylinder'on both sides of the pistowith each other and with the suction passa e of the engine, and maintain the piston sumerged in vacuum whenpin retracted position, an o erator operated partconnected .with said valve actuating part, means for connecting the piston with the brake mechanism, and neans including a provision for lost motion for connecting the valve actuating part with the piston.

10. In an automotive vehicle rovided with an internal combustion engine aving a suc'- tion passage and brake mechanism for thc vehicle, the-combination with a power actuator comprising among its members a cylinder closed at each end, a piston in said cylinder, reversinA valve mechanism located in the piston, inclu ing a suction chamber, passages connecting it with the cylinder on both sides of the piston. air inlet passages connected with the cylinders on both sides of the piston,

suction and air inlet valves controlling said passages, and yielding means normally tending to seat said valves. of means for connecting the said suction chamber with the suction passage of the engine, a valve actuating part extending through said' valves and to the exterior'o'f the cylinder, and provided with means for opening said valves including collars fix'ed thereto for engaging one suction valvev and the inlet valves, and a. collar movable with respect -to the valve actuating part for opening the other suction valve, means for arresting said valve actuating part, in position to hold one of said suction valves in open position by a fixed collar, when the piston is in retracted position, a retracting spring operatively connected with the valve actuating part, a movable device connected withl the valve actuating part for engaging a part connected with the cylinders when the piston is in normal retracted position, and a connection from said movable part to the said movable collar for opening the other suction valve when' the piston is in retracted osition, to connectA the portions of the cyllnder on both sides of the piston witheach other and with the suction passage of the engine, and maintain the piston submerged `in vacuum when in retracted position, an operator operated part connected with said valve actuating part, and means for connecting the piston with the' brake mechanism. i v

11. In a power actuator, a c linder, a piston movable thereinconnecte to a part to be actuated, valve mechanism for controlling differentials of pressure to opposite sides of said piston including a valve operating member and valves movable with and wlth respect to said member, an element carried by said valve operating member, means for limiting the movement of said member to hold one of the low pressure valves in open position when the piston is in normal retracted position, and a second element shiftable with respect to the first element, together with means for shifting saidsecond Velement to open the other low pressure valve and there.

byi connect both sides of the piston with lo pressure.

12. In a power actuator, a cylinder, a piston movable therein connected to a part to be actuated, valve mechanism for controlling dilerentials of pressure' to opposite sides of ysaid piston including a valve operating member and valves movable with and with respect to said member, an element connected to move with said valve operatlng member, vmeans to limit the movement of said valve operating member so as to hold'one of" the low pressure valves open when the piston is in normal retracted'position, and a second element movable on the valve operating member and engaging with the-other low renssure valve to openthe same when the plston is retracted, together with means for operycc ating said second member.

'13. In a power actuator, a cylinder, a piston movable therein connected with a part to be actuated, valve mechanism for 'controlling differentials of pressureto opposite sides-of said piston including a valve operating meniber, and high and low pressure valves movable with and with'v respect to'said member, valve engaging elements on said member, means for arresting said valve operating member to hold one -of said low pressure valves in open position iwhen the piston is in n ormal retracted position, and means for relatively separat-ingsaid elements to open the other low pressure valve when the plston is retracted.

. 14. In a por. er actuator, a cylinder, a pis-- :hanane tive separationv of thelow pressure valves to open the same and connect the cylinder on both sides of the'piston with the source of low pressure.

15. In a power actuator, a cylinder, a pis-` ton movable therein, inlet and outlet passages for conveying motive fluid to and from said cylinder to actuate said piston, valves for said passages, actuating collars for said valves, means for arresting one of said collars `in posltion to hold one of the .outletvalves in open position when the piston is in normal retracted position, and means Aadapted to move said actuating collars relatively to each other to unseat the other of said outlet valves when the piston is in retracted position, to

connect both ends of said cylinder with said outlet passage.

. In testimony whereof we tures.

CALEB S. BRAGG. VICTOR W. KIJESRATH.

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