US1872660A

US1872660A - Power actuator

Info

Publication number: US1872660A
Application number: US132365A
Authority: US
Inventors: Caleb S Bragg; Victor W Kliesrath
Original assignee: Bragg Kliesrath Corp
Current assignee: Bragg Kliesrath Corp
Priority date: 1925-01-05
Filing date: 1926-08-30
Publication date: 1932-08-23
Anticipated expiration: 1949-08-23
Also published as: DE518737C; US1826416A; GB260967A; DE549177C; FR609218A; US1801483A; FR631643A; US1848000A; GB245444A

Description

Aug. 23, 1932.

c. s. BRAGG ET AL POWER ACTUATOR Original Filed Jan. 5, 1925 3 Sheets-Sheet l Til QJINIVENTORS BY A:$ORNEY 7 Patented Aug. 23, 1932 UNITED STATES "PATENT OFFICE ems s. BRAGG, or PALM 3mm, INDIANA, ASSIGNORS c ISLAND CITY, NEW YORK, A CORPORATION BEACH, FLORIDA,

TO BRAGG-KLIESRATH CORPORATION, LONG AND vroron w. xmnsmrn, or son'rn OF NEW YORK POWER ACTUATOR Orlghml application fled January l5, application illustrate several embodiments of thesame,

I States filed December 22, 1923 selected by us for purposes of illustration, a

and the said invention is fully disclosed in the following description and claims.

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

Our invention relates to a power actuator,

adapted especially for use in connection with automotive vehicles propelled by an internal combustion engine, and most conveniently operated by suction 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 application for Letters Patent of the United c Serial No. 682,346, issued as Patent No. 1,79%,853, March 24, 1931, wehave disclosed a power 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 regulating valve or other restricting means, a check valve, and a storage space, 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 foot lever, or other operator opera ed part, and with a brake mechanism or other part to be actuated in such 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, or in case of failure of the actuator, may positively operate the actuated part by physical power appliedto the foot lever, or other operator operated part. i

The regulating valve or other restricting device prevents such large volumes of air being drawn into the intake manifold as to be likely to dilute the explosive charges passing therethrough, so as to stall the engine when idling while the storage space or storor tank, and comprising a age tank provides a large space in which a partial vacuum or rarification s maintained .at all times, while the englne is running, by withdrawing the air therefrom in comparatively small quantities, and insures the in- 1925, Serial it'o. 506. Benewed February 15, 1982. Divided and this filed August 30, 1926. Serial No. 132,365.

stantaneous withdrawal of the necessary amount of air from the actuator cylinder when the reversing valve mechanism is moved to open position, to insure the instantaneous and effective operation of the actuator.

According to our invention, we dispense with any extraneous storage space or storage tank in the suction line extending to the intake manifold exterior to the actuator cylinder, and maintain a condition of partial vacuum or rarification within the actuator cylinder itself, on both sides of the piston, which is made to supply the necessary storage space. Thereby we obtain a number 0 important and advantageous results in the construction, installation and operation of the power actuator. In the first place, the tank, which is a bulky element, is entirely done away respondingly simplified and rendered less expensive. As a partial, vacuum is maintaine within the actuator. cylinder on both sides of the piston therein when the device is in normal or inoperative position, when the reversing valve mechanism is moved into a position to'efiect the operation of the actuator,

with and the construction is cor,- Y

one end of the cylinder on one side of the and the immediate result is that the atmospheric air rushes into the end of the cylinder" to which it is admitted, and eflfects the operation of the piston in the desired direction Q and to'the desired extent without any appreciable quantity of air being actually withdrawn from the cylinder and admitted to the intake manifold or other suction means, thereby eliminating the drop in the suction or rarlfication, which would result were the cylinder full of air and this air admitted during the application, of the brakes. The maximum suction isv therefore immediately available. The restricting valve properly adjusted ,,hicles such as automobiles, trucks and motor buses, for example, as when the brake is applied the actuator is operated without any material admission of air to the intake manifold and therefore without any possibility of injuriously affecting the explosive mixture or of stalling the engine, and when the valve mechanism is reversed to effect 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 of the brakes can be gradually withdrawn to the intake manifold, under the control of the regulating valve, so as to prevent interference with the operation of the engine, while securing the effective 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 piston in a direction to release the brakes shall be as rapid as the movement of the piston in the direction to apply the brakes. As a matter of fact, a very slight movement of the piston in the direction to release the brakes would be sutlicient to release them, and for this reason continued application and releasing of the brakes without allowing the piston to come to the at rest position may be elfected with comparatively small amount of air bein 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 would be desirable to have it moved in the opposite direction. Furthermore when the piston comes to the at rest position after an application of the brakes, there is a partial vacuum in the rear of the cylinder. Therefore, the only air to be exhausted is the amount admitted-to the forward end of the cylinder to effect 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 continually keeps at least one end of our cylinder under vacuum, the total amount of air in the cylinder would have to be exhausted after each operation of the brakes.

ur invention therefore enables us to simplify and decrease the cost of the apparatus, and at the same time insures the most eflicient operation of the actuator without prejudice to the continuous and eilicient operation of theinternal combustion engine 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 featuresare broadly claimed together with one of the specific embodiments for carrying ourinvention into effect, and

the present application is directed to certain other specific embodiments for carrying the invention into eflect disclosed in our PI'QVl-w ous application above referred to, but not specifically claimed therein, but which are specifically claimed in this application.

Referring to the accompanying drawings,

Fig. 1 represents a diagrammatic View of an installation in which our improved power actuator is connected with the internal combustion engine of an automotive vehiclefor the operation of thebrake mechanism thereof.

Fig. 2 is an enlarged sectional view-illustrating one form of our improved actuator having one embodiment of our present invention therein.

Fig. 3 isan enlarged sectional view of the power actuator shown in Fig. 2, portions being broken away.

Fig. 4 is a partial-sectional view of our improved power actuator showing another modification of our present invention embodied therein.

Fig. 5 is an enlarged sectional view of our power actuator showing still another modi-. fication of our present invention embodied therein.

Fig. 6 is a partial sectional view of a por-' tion of the actuator illustrating a slight mod ification of the construction shown in Fig. 5.

In Fig. 1 of the accompanying drawings, We have shown digrammatically an installation suitable for use in an automotive vehicle in which one of our improved actuators is shown as interposed in the connections be tween afoot lever, 88, and brake mechanism for the vehicle, diagrammatically represented at 70, 71 and 72, indicating a brake drum, brake band and brake lever. The

brake mechanism will be provided withthe usual retracting means, indicated diagrammatically in the drawing, by the spring, 74.

60 represents an internal combustion engine for propelling the vehicle, and provided with an intake manifold, indicated at 61, and communicating with the carburetor, 61?, to which is connected a pipe, 62, between the throttle valve indicated at 61 and the engine cylinders, in which pipe are located preferably an adjustable regulating valve, or restricting valve, 64, a check valve, 65, and a vent valve, 67, normally closed and opening outwardly. The pipe, 62, commuof our improved 1 eating with the reversing valve mechanism.

The sleeve, 320, is connected by a link, 85, with the foot lever, 88, which is provided with the usual retracting spring, 89, and the piston rod, 305, of the actuator is connectedv by a link, 73, with the brake lever, 72.-

In Figs. 2 and 3, we have shown one form actuator embodying our present invention. In this figure, 301, represents the actuator cylinder closed atboth ends by heads, 302, connected by bolts indicated at 302*, in Fig. 1, or otherwise. 303 represents the double acting piston provided with oppositely disposed gaskets, 304. 305

represents a hollow piston rod which extends through a stufiing box, 306, in one end of the cylinder, and is connected at its inner end with the piston, 303. The hub, 310, of the piston is provided with two valve chambers, 311 and 312 respectively, each of which is provided with two valve seats preferably conical and coaxial with the axis of the piston. The valve chamber, 311, is provided with seats, 313 and 314, and the valve chamher, 312, is provided with valve seats, 315 and 316. The piston hub is provided with an outlet chamber or suction chamber indicated at 317, which communicates with each of the valve chambers through the valve seats, 314 and 315. The piston hub is also provided with a higher pressure chamber, 318, in this instance communicating with the atmosphere and with the valve seat, 316, and by a lateral passage, 319, with the valve seat, 313. The valve actuating part, in this instance, a hollow sleeve, 320, passes through a stufiing box, 321, in'the cylinder head at the opposite end of the cylinder from the stuffing box, 306, the said sleeve extending longitudinally through the piston hub and valve chambers, and through the hollow piston rod, 305, and being longitudinally movable to eflect the operation of the reversing valve. The valve s'leeve may be made conveniently in two parts, 320 and 320 if desired, and as herein shown is provided with a pair of oppositely disposed poppet valves in each valve chamber, the said valves being preferably formed 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 in dicated at 340, 341, 342 and 343, the

valves

341 and 342 being suction valves, and the valves, 340 and 343 being air inlet valves.

The valves are yieldingly held in engage-' ment with their seats, preferably by a yielding cushioning device. interposed between the pairs of valves, and indicated at 350. The actuating sleeve is provided with suitpipe having a flexible able means for opening one valve of each pair when the sleeve is moved in either direction. In this instance, the sleeve is shown provided with a collar, 322,1ocated between the suction valves, 341 and 342, and adapted to operate either of the said valves. and the sleeve is also provided with collars, 331 and 332, mounted on the valve sleeve outside of the air inlet valves, '340 and 343 respectively, for operating said valves. Communication between the suction pipe, 62, and the suction chamber, 317, is effected in this instance? through the hollow valve sleeve, which is provided with a fitting, 326, at its outer end, to which the pipe, 62, is connected, and lateral passages, 324, are formed in the collar,

322, to connect the interior of the sleeve with "the suction chamber. 4

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 ofthe United States, filed November 22, 1924, and given Serial No. 751,481.

In the form of our invention illustrated in Figs. 2 and 3, the central collar 322, in the vacuum chamber, 317, which actuates the suction valve, is so located with respect to a stop, in this instance formed by a shoulder, 326, on the fitting, 326, which engages the adjustable follower, 321*, of the stuffing box, 321, when the parts are in normal or ofi position, that when the piston is arrested by the engagement of its hub with the opposite end of the cylinder, the valve actuating sleeve, 320, will hold the suction valve, 342, slightly off its seat, as shown in Figs. 2 and 3, thereby placing the cylinder in rear of the piston in communication with the suction chamber through a port or ports, 335, which connect the valve seat, 315, with that portion of the cylinder. The other suction valve, 341, being seated, the ports, 334, which connect its valve seat, 314, with the forward portion of the cylinder are closed. In order to insure the evacuation of the portion of the cylinder on the other side of the piston, the main body of the piston is in this instance provided with an aperture or passage therethrough indicated at 342 having a valve seat, 342", at the end adjacent to the forward face of the piston, to receive a valve, 342, normally held in closed position by a spring, 342 engaging the valve stem, 342. The valve stem, 342, projects from the rear face of the piston (to the right in Figs. 2 and 3) sufficiently to engage a fixed portion of the cylinder, as the the piston, and as the valve, 342, is cracked the air introduced into the cylinder on the forward side of the piston to insure its retraction, or return to normal position, will be exhausted as soon as the piston comes to rest, thus maintaining partial vacuum at all times within the cylinder on both sides of the piston when the parts are at rest and the engine is in operation.

It follows from this construction that as 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. If now it is de sired to apply the brakes, the foot lever is actuated to move the sleeve, 320, in the direc-' tion of the arrow in Fig. 2, thereby permitting the suction valve, 342, to close, and subsequentl opening the suction valve, 341, and

the air inlet valve, 343; This connects the cylinder forward of the piston with the suction chamber, 317, and admits atmospheric air in rear of the piston, moving the piston forward in a direction to apply the .brakes, but no appreciable amount of air will be drawn into the intake manifold through the pipe, 62, as the portion of the cylinder forward of the piston is already exhausted. The forward movement of the piston will follow any extent of the forward movement of the brake lever, 88, and when the movement of the brakelever stops,-the piston will continue to move forwardly until the suction valves, 341, and air inlet valve, 343., closed, so as to hold the piston and brakes as applied. Where continued applications of the brakes are desired, a slight release of the foot lever producing a slight rearward movement of the valve sleeve will open the suction valve, 342, without opening the air inlet valve 340 and connect the cylinder in rear of the piston with the suction passage, 317 thus withdrawing portions of the air admitted for the piston stroke and producing a partial or entire equalization of pressures on opposite sides of the piston, which will instantly permit the brakes to relieve themselves, under the action of their retracting means, as the spring, 74, and slightly retract the piston. A slight forward moyement of the pedal lever will again admit air in rear of the piston, and'connect the cylinder forward of the piston with the suction chamber, and a number of successive applications of the brake can be made without admitting material quantities of air into the intake manifold. When the foot lever, 88, is released, the retracting spring, 83, will move the valve sleeve, 320, in a direction opposite that indicated by the arrow in Fig. 2, and the suction valve, 341, will be forced to its seat by the cushioning device, and the reversed movement of the sleeve, 320, under the action of the retracting spring, 89, of the foot lever, will en the suction valve, 342, connecting the cy 'nder in rear of the piston with the suction chamber, and the air inlet valve, 340, will be opened admitting atmospheric air to the cylinder forward of the iston through the opening, 333, controlled y said valve, thus returning the piston to normal osition, illustrated in Figs. 2 and 3, the piston being arrested by engagement with the end of the cylinder, and the valve actuating sleeve being arrested by the engagement of the shoulder, 326, with the follower, 321", and the auxiliary valve, 342, being opened by the engagement of its stem with the head of the cylinder. The suction chamber, 317, will therefore be in communication with the cylinder in rear of the piston by reason of the unseated position of the valve 342, and will also be connected with the cyhnder forward of the piston by the auxiliary passage, 342, equalizing the pressures on opposlte sides of the piston, and the air previously admitted, to effect the reverse movement of the piston, will be exhausted from the cylinder producing rarification on both sides of the piston. -The exhaustion of air fromthe cylinder, therefore, only takes place during and after the return stroke of the piston, and the air exhausted from the cylinder is de livered gradually to the intake manifold by properly regulating the restricting valve, 64, in the pipe, 62, 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 first movement of the piston rearwardly will relieve the pressure of the brakes, and it'is not important that the piston should move rearwardly as uickly as it moves forwardly to apply the rakes.

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 feedin of too small an amount of hydrocarbon uel, and the piston is left submerged in vacuum and ready 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, sothat after the cylinder is subjected to the greatest amount of suction, the condition of rarification so produced will remain, and as the brakes are usually operated at intervals, the greatest possible rarificationwill ordinarily exist in the cylinder of the actuator at all times, ready to effective apply the brakes in the manner before described.

We prefer to connect the valve actuating sleeve, 320320=, with the piston by means providing for a limited amount of lost motion, sufficient to permit the operation of the valves, so that after this lost motion ist-aken up, the physical power of the operator can be directly applied to the piston and the brake mechanism connected therewith, to

442. The recess, 442*, is

motion permitting the movement instance, as shown in Fig.

enable the operator to add his physical force to that of the actuator, or to operate the brakes by his physical force 'alone if the power should fail for any reason, the lost of the valves in any case, and serving when power fails to vent the cylinder. In the present 2, the section, 320 of the valve sleeve is provided with arecessed portion, 320*, and a collar, 320, and a piston rod, 305 is in this instance provided with, set screws, 305 extending into said recess (or recesses) 320', so that when the sleeve is moved forward by the foot lever to; apply the brakes, and the piston has followed, applying the brakes to the full capacity of the actuator,,the operator may be pushing the foot lever, 88, further forward until the rear edge of the recess, 320*, engages the screws, 305 apply his physical force to the piston and brake mechanism in addition to the power of the actuator. It also follows from this construction that the operator, should the power of the actuator fail, may apply the brakes directly by his physical power, the first forward movement of the valve actuating sleeveiwill set the valves so as to vent the cylinder forward of the piston and admit air in the rear of thepiston, to permit this movement. On the release of the foot lever, the retracting spring, 89, will shift the valve sleeve rearwardly, so as to vent the cylinder (in case of failure of power), and the forward end of the recess, 320", will engage the set screws and move the piston rearwardly to release the brakes and restore the parts to or position.

Instead of locating the additional valve in the piston itself, it may be located irij'the head of the cylinder and opened by the piston when it returns to its normal position to establish a communication between the two ends of the cylinder on opposite sides of the piston. Such a construction is illustrated in'Fig. 4, in which the corresponding parts are given the same numerals as those in Figs. 2-and 3, with the addition of 100, to avoid unnecessary description. In this instance the valve, 442, is held off its seat when the parts are in'normal position, in'the same manner as indicated and previously des ribed with reference to Figs. 2 and 3. In thi s instance the head, 402, of the cylinder is provided with passages indicated at 442*, communicating with a recess, 442, and controlled by a valve, 442, the stem. 442", of wh ch projects into the interior of'the cylinder far enoughto be struck by the hub of the piston when it returns to its normal or retracted position, so as to open the valve, connected by a indicated at 442 with the by-pass or pipe,

the cylinder, thepipe being opposite end of "conveniently carried through one-of the hollow bolts, 402 connecting the heads of the cylinder. The efiect of this construction will be, as before described, to place both ends of the cylinder onopposite sides of the piston in communication with the vacuum chamber, 417, when the parts return to and are in normal, or retractedposition, so as to maintain a partial vacuum within the cylinder on both sides of the piston at all times.

In Fig. 5, we have shown a further modification of the invention, in which the desired results are accomplished without interfering with the normal operation of the valve mechanism, that is to say, in which all four of the valves of the reversing valve mechanism are permitted to firmly seat when the parts are in normal position. In this figure, the similar parts to those previously described, are given the same reference numerals as in Figs. 2 and 3, with the addition of 200, toavoid unnecessary description, an will be identical with those previously described with reference to Figs. 2-and 3. In this instance the head, 502, of the cylinder, is provided with a passage, or passages, 542, communicating with a recess, 542, in which is located a valve seat, 542, engaged by a movable valve, 542, which valve'during the application of the brakes closes communication between the recess, 542, and the interior of the cylinder on both sides of the piston.

dss

The valve is operated by a ring, 542, prothe opening of the valve, 542. The valve seat 542, is connected by a flexible pipe, or

tube, 542 with the suction pipe, 562, independent of its connections with the reversing valve mechanism, through the hollow valve sleeve 520, and the valve seat, 542, is also connected by a pipe, 542 with the cylinder on the forward si'deof the piston in the same manner as illustrated in Fig. 4. From this construction it will be noted that when the piston moves forward the valve is seated by its frictional engagement with the piston rod, and may be maintained on its seat by a light spring, 542. en the piston returns to its normal position,moving to the right in Fig.5, the hub of the piston will engage the pins, 542, and open the valve, 542 thereby establishing communication between the auxiliary exhaust pipe, 542, and both ends of the cylinder, exhausting the air from the cylinder on the forward side of the also maintaining the partial vacuum 1n the cylinder at the rear of the piston, produced in returning the piston to its normal position. In Fig. 6, wehave shown another'slight modification ofthe device "illustrated in Fig. 5, Fig. 6, being a partial sectional view in which the parts illustrated in Figs..2 and 300 added. 11 th's figure the auxiliary valve,

tobe

piston, and p instead of being located centrally ofvthe cylinder head, practically within the stuffing box, as illustrated in Fig. 5, is located in a separate fitting, indicated at 644, pro 'vided with a threaded portion, 445, which is screwedv into an aperture in the head, 602, of the cylinder. This fitting is provided with a passage, 642, communicating with the interior of the cylinder and controlled by an auxiliary valve, 642, normally held seated by spring, 642", secured in position by a suitable cap, 642, and the fitting is also provided with a threaded aperture to receive a flexible suction pipe, 642, communicating with the main suction pipe, as described with reference to Fig. 5, and the fitting is also provided with a pipe, 642, which communicates with the other end of the cylinder on the opposite side of the piston. The auxiliary valve, 642 is provided with a valve stem, 642, which projects into the cylinder in position to be engaged bythe piston when the latter returns to its normal position, so as to open the valveandi establish communication between the vacuum pipe or suc- ,tion pipe leading to the manifold of the en gine, and both ends of the cylinder, and thereby maintaining a partial vacuum within the cylinder on both sides of the piston in exactly the same manner as previously described, with reference to Fig. 5.

It will be noted that in all the forms of apparatus herein shown, for. the purpose of illustrating various embodiments of our invention, all of which are capable of use in the general installation illustrated in Fig. 1, a vacuum is continuously maintained in the actuator cylinder on both sidesof the piston when it is in its normal position and the engine is in operation, so that the cylinder itself acts as a storage space, and no ,additional tank or other extraneous storage space is required. In all of these forms of our invention, there is no storage tank and 4 after the engine is started the air in the actuator cylinder and the piping leading to the intake manifoldor other suction passage of the engine is exhausted, when the apparatus is in itsmost eifective and operative condition, a partial vacuum existing in the cylinder on bothsides of the piston.

The check valve, 65, shown in Fig. 1, and interposed in the suction pipe, insures the exhaustion of the cylinder on both sides of the piston to the greatest extent permitted at any time by the operation ofthe engine by the manipulation of the throttle valve, while the vent valve, 67*, shown in Fig. 1, provides for the venting of the cylinder should the motor stop, or the suction fail at any time, and should it become necessary for the operator to apply the brakes by physical power.

What we claim and desire to secure by Letters Patent is of suction, means acting on said valves when the piston is in retracted position for connecting the fportion of the cylinder on one side only 0 the piston with said suction means,.said actuator being provided with an auxiliary passage for connecting said portion of the cylinder with the portion of the cylinder on the opposite side of the piston, when the piston is in retracted position.

2. In a power actuator, the combination of a cylinder closed at both ends, a double acting piston in said cylinder, reversing valve mechanism includin a suction chamber, passages connecting sai chamber with the cylinder on both sides of the piston, an air inlet, passages connectin said air inlet with the cylinder on both si es of the piston, and controlling valves for said passages, means for connecting said suction chamber with a source of suction, means acting on said valves when the piston is brought to retracted position .for connecting the portion of the cylinder on one side only of the piston with said suct on means, said actuator being provided with valve controlled means for connecting said portion of the cylinder with the portion of the cylinder on the opposite side of the piston, when the piston is in off position.

3. In a power actuator, the combination of a cylinder closed at both ends, a double acting piston in said cylinder, reversing valve mechanism including a suction chamber, passages connecting said chamber with the cylinder on both sides of the piston, an air inlet, passages connecting said inlet with the cyliner on both sides of the piston, and con-,

trolling valves for said passages, means fol connecting sa1d suction chamber with a source of suction, means acting on said valves when opposite side of the pistomand an auxiliary valve for said passage carried by the piston and constructed to be opened when the piston is moved to its ofl or retracted position.

of a cylinder closed at both ends, a double acting piston in said cylinder, reversing valve mechanism includin a suction chamber, passages connecting sai chamber with the cylinder on both sides of. the piston, an air inlet,

4. In a power actuator, the combination o cylinder on both sides of the piston,

25. ed position,

passages connectin' said inlet with the cylinder on both sides the piston, suction valves and inlet valves for said passages, means for holding and the other seated when the piston is in retracted or off position, to connect the suction chamber with the cylinder on one side of the piston only, said actuator being provided with means for connecting the said portion of the cylinder with the portion of the cylinder on the other side of the piston, when the piston is in retracted position. 7

5. In a power actuator, the combination of a cylinder closed at both ends, a double acting piston in said cylinder, reversing valve mechanism includin a suction chamber, passagesconnecting sai chamber with the cylin der on both sides of the piston, an air inlet, passages connecting said air inlet with the suction valves and inlet valves for said passages, means for normally holding said valves seated, means for holding one of said suction valves unseated when the iston is in retractto connect the portion of the cylinder on one side of the piston with the suction chamber, said actuator being provided with an auxiliary passage for connecting said portion of the cylinder with the portion of the cylinder on the opposite side,

of a cylinder maintained in open condition when the said suction valve is unseated, and the piston is in its off or retracted position.

6. In a power actuator, the combination closed at both ends, a double acting piston in said cylinder, reversing valve mechanism including a suction chamber, passages connecting said chamber with the cylinder on both sides of the piston, an air inlet, passages connecting said air inlet with the cylinder on both sides of the piston, suction valves and inlet valves for said passages, 'means for holding one of said suction valves unseated, to connect said suction chamber with the cylinder on one side of the piston when the piston is in retracted position, said actuator being provided with a passage independent of the passages controlled by the suction and inlet valves for connecting said portion of the cylinder with the portion of the cylinder on the other side of the piston, an auxiliary valve for said passage, and means brought into operation when the piston is in its retracted position, for opening said auxiliary valve.

7 In a power actuator, the combination of a cylinder closed at both ends, a double acting piston in said cylinder, reversing valve mechanism including a suction chamber, passages connecting said chamber with the cylinder on both sides of the inlet passages connecting said inlet with the cylinder on both sides of thepiston, suction valves and inlet valves for said passages, means for holding one of said suction valves one of said suction valves unseated piston, an air retracted position,

unseated, to connect said suction chamber with the cylinder on one side of the piston when the piston is in retracted position, said actuator being provided with a passage.in-

dependent of the passages controlled by the reversing valves for connecting said portion of the cylinder with the portion of the cylinderon the other side of the piston, an auxiliary valve for said passage, said auxiliary valve being constructed to be opened bysaid cylinder when the piston comes to 7 rest in its retracted or off position.

8, In a power actuator, the combination of a cylinder closed at both ends, a double acting piston in said cylinder, reversing valve mechanism in said piston, means for connecting said reversing valve mechanism with a source of suction and and operator operated means for said reversing valve mechanism, means acting on 'the' valve mechanism for connecting the cylinder on one side of the piston wlth the source of suction when the piston is in retracted or 0 position, said actuator being provided with a passage for connecting the said portion of the cylinder with the portion of the cylinder on the opposite side of the piston, when the piston is in retracted position. 9. In a power actuator, the combinationoif a cylinder closed at both ends, a double actingpiston in said cylinder, reversing valve mechanism in said piston, means for connecting said reversing valve a source of suction and with the atmosphere, and operator operated means for said re-- versing valve mechanism, the valve mechanism for connecting the cylinder on one side of the piston with the source of suction, when the piston is inretracted or 0E position, said actuator being provided with a passage for connecting the said porniechanism with with the atmosphere,

means acting on tion of the cylinder with the portion of the cylinder on the opposite side of the piston, an auxiliary valve for controlling said passage, and means for opening said auxiliary her and suction passages extending therefrom to the'cylinder on both sides ofthe piston, an air inlet passage, and passages for connecting said air inlet with the cylinder on both sides of the piston,

air inlet passages, yielding means normally holding said valves seated, and a vacuum producing means connected with said vacuum chamber, of means forholding one of said suction valves and inlet vvalves for controlling said suction and suction valves'unseated when the piston is in the piston being provided therethrough, maintained in with a passage r to'connect the portions of the 1 open condition both sides of the piston, suction valves and inlet valves for controlling said suction and air inlet passages, yielding means normal- 1y holding said valves seated, and a vacuum producing means connected with said vacuum chamber of means for'holding one of said suction valves unseated when the piston is in retracted position, the piston being provided with a passage therethrough, for connecting the portions of the cylinder on opposite sides of the piston, an auxiliary valve for controlling said passage, and means for opening said auxiliary valve when the piston is in retracted position.

12. In a power actuator, automotive vehicles provided with an internal combustion engine havinga suction passage, the combination with a cylinder closed at both ends, a double acting piston in said cylinder connected to the part to be operated, reversing valve mechanism including a suction chamber, passages connecting said chamber with the cylinder on both sides of the piston, and air inlet'passages connecting said inlet with the cylinder on both sides of the piston, controlling-valves for said passages, yielding means for normally holding said controlling valves seated, ofasuction pipe for connecting said suction chamber -with'the suction passage-of the engine, means for holding one of said 'valves unseated when the piston is in retracted position to connect the portion of the cylinder on one side of the piston with the suction chamber, said actuator being provided with an auxiliary passage for connecting the portions offlthe cylinder on opposite sides of the piston, an auxiliary valve for controlling said auxiliary passage, means for seating the auxiliary valve, means for opening the auxiliary valve when the piston is in retracted position, and an operator operated part for actuating said reversing valve mechanlsm. I x a k 13. In a power actuator, automotive vehicles provided with an internal combustion engine having a suction passage, the combination with a cylinder closed atboth ends, a double acting piston in said cylinder connected with'the part to be actuated, reversing valve mechanism including a suction chamber,'passages connecting said chamber with the cylinder on both sides of the piston, and air inlet passages connecting said inlet with the cylinder on both sides ofthe piston,

controlling valves for said passages, yielding means for normally holding said controlling valves seated, of a suction pipe for connecting said suction chamber with the suction passage of the engine, means for ho1ding one of said valves unseated when the piston is in retracted position, to connect the portion of the cylinder on one side of the piston with the suction chamber, said piston being provided with an auxiliary passage therethrough connecting the portions of the cylinder on opposite sides of the piston, an auxiliary valve for controlling said passage, yielding means for seating said auxiliary valve, means for opening said auxiliary when the piston is brought to retracted position, and

an operator operated part for actuating said a higher pressure fluid on one side of the piston to 15. I motive vehicles provided with an internal combustion engine having a throttle controlled suction passage, the combination with produce a power stroke thereof.

a part to be actuated, an actuator for said,

part including a cylinder and a piston movable th'erein, passages for conveying motive fluid to and from said cylinder to actuate said piston, and an auxiliary passage adapted to connect both ends of said cylinder to suction for equalizing pressure on both sides of the n vacuum brake mechanism for autopiston when the piston is brought to retracted position.

16. In vacuum brake mechanism for automotive vehicles provided with an internal combustion engine having a throttle controlled suction passage,'the combination with a part to be actuated, an actuator for said part including a cylinder and a piston movable therein, a suction pipe connecting said cylinder and said source of suction, a high pressure inlet, passages connecting said suction pipe and said higher pressure inlet to said cylinder, and an auxiliary passage connecting the portions of the cylinder to suction on both sides of the piston when the piston is brought to retracted position.

17. In vacuum brake mechanism for automotive vehicles provided with an internal combustion engine having a throttle controlled suction passage, the combination with a part tobe actuated, an actuator for said part lncluding a cylinder and a piston inovable therein, a suction pipe connecting said cylinder and said source of suction, a hig pressure inlet, passages connecting said suction pipe and said higher pressure inlet to 5 said cylinder, and an auxiliary passage through said piston connectin the portions or the cylinder on to suction oth sides of the piston when the piston is brought to retracted position.

10 18. In vacuum brake mechanism for automotive vehicles provided with an internal combustion engine having a throttle controlled suction passage, the combination with a part to be actuated, an actuator for said 15 part including a cylinder and a. piston movable therein, a suction pipe connecting said cylinder and said source of suction, a high pressure inlet, passages connecting said suction pipe and said higher pressure inlet to ac said cylinder, an auxiliary passage connecting the ortions of the cylinder on both sides of the piston, and a valve opening communication through said auxiliary passage when the piston is brought to retracted position. 19. In vacuum brake mechanism for automotive vehicles provided with an internal combustion engine having a throttle controlled suction passage, the combination with a part to be actuated, an actuator for said so partincliuding a cylinder and a piston movable therein, passages leading to and from said cylinder for conveying motive fluid to opposite sides of the piston to actuate the same, valves for controlling said passages 85 an auxiliary passage connecting both ends 0 the cylinder to equalize pressures on opposite sides of the piston, and a separate valve for controlling-said auxiliary passage 20.- In a power actuator, the combination so of acylinder closed at both ends, a double acting piston in said cylinder, reversing valve mechanism including a suction chamber, passages connecting said suction chamber with the cylinder on both sides of the piston, an air inlet, passages connecting said inlet with the cylinder on both sides of the piston, and controlling valves for said passages, means for connecting said suction chamber with a v source of suction, means operable when the so piston is in retracted position for connecting the portion of the cylinder on one side of thepisto'n only with said suction means, and an auxiliary means for connecting suction to said portion of the cylinder with the cylinder 55 on the opposite side of the piston when the piston i s*brought to retracted position In testimony whereof we afix our signatures CALEB S. BRAGGP VICTOR W. IESRATHv