US1773703A - Power actuator - Google Patents

Description

Aug. 19, 1930.. I c; s, BRAGG ET AL POWER ACTUATOR Filed Dec. 4, 1924 2 Sheets-Sheet l OW ATTORNEY Ail 19, 1930. c, BRAGG ET AL 1,773,703

POWER ACTUATOR Filed Dec. 4, 1924 2 Sheets-Sheet 2 INV NTOR qwwll m S ATTORNEY Patented Aug. 19, 1930 v UNITED STATES PATENT OFFICE CALEB s. Blues, on PALM iinncn, rLoainA, Ann vxoron w. KLIESBA'TH, or PORT WASHINGTON, NEW YORK, ASSIGNORS TO IBBAGG-KLIESBATH CORPORATION, OF

LONG ISLAND CITY, NEW YORK, A CORPORATION OF NEW YORK rowan .acruaron Application filed December 4, 1924. Serial m 753,821.

Our invention consists in the novel features hereinafter described, reference being had to the accompanying drawings, which illustrate 1 several'forms in which we have contemplated embodying the invention, selected by us for.

purposes of illustration, and the said invention is fully disclosed in the following description and claims.

. Our invention relates to the type of power actuator disclosed in our former. application for Letters Patent of the United States filed "inder,

1 which is conveniently located in the piston the piston,

itself and includes a movable apparatus operated by an actuating valve sleeve extending through one end of the cylinder, through and usually through a portion of the piston rod which is made hollow for that purpose. These power actuators are advantageously used in connection with internal combustion engines of "automotive vehicles, which engines in their normal operation continually provide differential pressures, to wit,

- a rarefication or low pressure the suction as the low pressure and'pressure fluid as the and t intake manifold of an ordinary multi-cy1inpassalge existing betweenthe throttle valve e engine cylinder, as for example, the

der engine, while pressure fluid is available from the explosion chamber of acylinder or cylinders of the engine. These power actuators can therefore be conveniently operated either by suction or rarefication, as the low pressure, and atmospheric air as the high A pressure,

or by pressurefiuid fromone of the cylinders as the. high pressure and atmospheric air as the low pressure, or by suction high pressure, as set forth in our application above referred to. For many reasons we 'prefer to operate these power actuators by means of suction from the intake manifold as the low pressurein connectionwith atmospheric air as the high pressure.

In the operation of these actuators it is necessarily highly important to prevent leakage in the valve mechanism and cylinder, and

this is particularly important where suction is employed in connection with atmospheric air at fifteen pounds per square inch as leakage produces a material reduction in the available power produced by the actuator. It

is equally important that the valve mecha-' nism shall operate freely, that is to say, with the least possible friction, and it is also important that the piston rod and valve actuating sleeve, which extends througha head,'or heads, of the cylinder, shall be able to work freely without undue friction whilethe cylinder remains sealed against leakage;

Our invention contemplates the provision of improved valve mechanism for this type of actuator provided with means for preventing leakage, and at the same time insuring the freedom of movement of the valves with respect to the piston and'also provides for preventing leakage to or from the cylin der'around the apertures through which the piston rod and. valve actuatingrod or sleeve extend, so that the maximum efiieiency of the apparatus is insured without undue friction. Our invention alsoincludesyielding means for normally holding the valve mechanism in neutral position, to maintain the actuator piston in a balanced condition at any point in the cylinder, which yielding means also serves the function of preventing undue movement of the valve mechanism onaccount 1 of the necessary friction between the mov-' able'parts and the piston 'when the piston 4 moves in'response to the opening movement v of thevalve in either direction.

. Referring to the accompanymgdrawings,

less diagram- Fig. 1 represents amore or inatic view of an installation including; one

of our improved actuators arranged in con-' nection with the intake manifold of an inter nal combustion engineon an automotive vehicle for the actuation of the brake mechanism. Fig. 2 is an improved actuator showing the-reversing enlarged sectionaloview of our.

valve mechanism and 'the means for effecting a tight joint between the cylinder heads and the piston rod and valve actuating rod or sleeve and the yielding device interposed between the valve actuating'mechanism and the piston.

Fig. 3 is an enlarged sectional view of the the valve mechanism and the piston.

the power cylinder of our improve sleeve, 5, being provided within a Fig. 7 is a detail view similar to Fig. 3, showing a slightly modified form of the reversing valve mechanism.

Fig. 8 is a detail perspective view of one of the valve members illustrated in Fig. 7.

Fig. 9 is a similar view of a metallic-"elastic reinforcing device for the valve illustrated inFig. 8. V

Fig. 10 is a similar view showing another modification of the reversing valve.

Referring tothe drawings, 1, re resents power actuator, the ends of which are closed by the front and rear heads, respectively indicated at, 2, and 3, secured to the cylinder in any desired manner, as by bolts, 4, see Fig. 1. The

forward head, 2, of the cylinder, is provided with a guiding sleeve, 5, having a packing recess therein, through which the valve actuating sleeve, 9, extends, the said uiding ushing with a packing sleeve, 6, formed preferably of rubber and provided with an annular outwardly extending flange, 7, en aging the in-,

l ner end of the stuifing box an held in position by a follower, 8, which is threaded into thestufiing box and engages the flange, 7, of the acking sleeve, the interior diameter of the ollower being slightly greater than the exterior diameter of the packing sleeve, so that when a partial vacuum is formed within the adjacent portion of the cylinder, any tendency of the atmospheric air to leak into the cylinder will bring the air pressure on the outer side of the packing sleeve, 6, and tend to hold it more tightly in en agement with the valve actuating sleeve, 9. ithin the cylinder, 1, is a double acting piston, indicated at 10, provided with annular gaskets, 11, 11,

. extending in opposite directions. The piston,

10. is provided with a tubular piston rod, 12, which extends through aguidingsleeve, 13, in the opposite head, 3, of the cylinder provided with a shifting box, and a similar packing sleeve, 14, preferably of rubber, surrounds the hollow piston rod and is provided with a flange 15, engaging the inner end. of the stufling box, the packin sleeve being held'in position by a threaded ollower, 16, engaging the flange, 15, and having its inner well out of contact with the packing sleeve, 14, and forming a recess surrounding the same so that anytendency to leak at this end of the cylinder will press the packing more firmly around the piston rod, and thus prevent leakage. We have found that these packing sleeves, 6 and 14, if made of molded rubber or other suitable material, are very eflicient in preventing leakage, while at the same time they permit a movable part to slide readily throu h them. The hub of the piston, 10, is provide with an axially disposed recess, 10 in which the re-.

versing valve mechanism is located, and the end of the hub is provided with an orifice into which the hollow piston rod, 12, is screwed, and in which it is held from rotation by set screws, 12.

The valve actuating sleeve, or rod, 9, extends through the valve recess, 10", of the hollow piston and through a portion of the hollow piston rod 12, and carries the movable parts of the reversing valve mechanism, which are located within the valve recess, 10.

For convenience of assembling the parts, the

valve actuating sleeve, orrod, is preferably formed in two parts, 9, and 9, connected as hereinafter described,but separated one from the other, the actuating part being preferably made hollow in order to connect the valve mechanism with the source of diiferential pressures employed. Within the valve recess, 10, of the piston is located a collar, 17, which is conveniently formed separately from the sleeve sections, 9 and 9, and is provided with oppositely extending externally threaded portions 18 and 19, the part, 18, screwing into the sleeve section, 9, and the part, 19, screwing into the sleeve section, 9. The collar, 17 is of slightly less diameter than the interior of the valve recess, 10, in the piston, thus forming an annular chamber, indicated at 20, which is placed in communication with the interior of the sleeve section, 9, by means of radial passages, 21, in the collar, 17, communicating with a longitudinal passage, 22, in the threaded projection, 18. The threaded projection, 19, is impervious and separates the sleeve sections, 9 and 9. On opposite sides of the collar, 17 we provide annular valves, 23, extending in opposite directions therefrom, adapted to. slidingly engage the inner surface of the valve recess, 10, in the piston, and preferably formed of molded rubber or other elastic material, and each provided at the end adjacent to the collar with an inwardly extending flange portion, 24, one of said valves being illustrated in detail in Fig. 4. The valves, 23, are held in position by collars, 25,25, on opposite sides of the collar, 17 the collar, 25, in this instance being engaged bya shoulder on the sleeve section, 9, so as to clamp the flange, 24, of the annular valve, 23, against the collar, 17, while the collar, 26, is in this instance placed on the sleeve section, 9, and held in position, as hereinafter described. The collars, 25, 26, have their,exterior peripheries of less diameter than the interior di imeter of the valves, 23, so that any leakage of the higher pressure fluid (in this case atmospheric air) into the interior will tend to collect within the valves, 23, and will therefore tend'to expand said valves against the inner wall of the valve recess, 10*, and maintain the air tight connection between said valves and the piston hub. We may rely upon the natural elasticity of the material (in this instance molded rubber or other suitable material) of which the elastic valves, 23, are

"formed, to hold them .at all times in contact with the inner wall of therecess, 10*, but in order to assist the natural elasticity of the material of which the valves are made, we prefer to employ in connection with each, an elastic spreader, 27, of generally cylindrical forin and serrated longitudinally so as to produce a plurality of spring fingers, 28, adapted to fit within each of the valves, 23, the said spreader being provided with an inwardly extending flange, 29, at its inner end which fits against the flange, 24, at the end of the valve, and is clamped between said flange 24, and the retaining collars, 25, 26, respectively, as clearly indicated in Fig. 3. The spring iin gers, 28, of the spreaders, are bent outwardly and exert an outward pressure at alltimes on the cylindrical portions of the surrounding annular valves, 23, to hold them in contact with the inner face of the valve recess, 10

. 'as' will be readily understood. The piston interior of the valve sleeve section,

hub is provided with one or more radial outlet ports, 30, communicating with the cylinder on one side of the piston, and one or moresimilar outlet ports, 31, communicating with the cylinder on the other side of the piston, which ports are normall closed respectively by the valves, 23, 23, ust described when the valve mechanism is in its neutral position, as indicated in Figs. 2 and 3, but it will be noted that by shifting the valve actuating device, 99, in one direction or the other, the

20, communicating with the 9, may be moved into registration with the passage,or passages, and as in practice the interior of sleeve section, 9, is connected with the intake manifold of the engine, as hereinafter described, the effect will be to exhaust the air from the cylinder on'one or other side of the piston.

The reversing valve mechanism also in eludes means for admitting a higher pressure fluid. as atmospheric air, for example, to the end of the cylinder on the opposite face of the piston from the end thereof from which the air is being exhausted. In the present inannular passage,

. stance this is accomplishedby the following 30, or thepassage, or passages, 31,

7 ways.

means. The outer end of the hollow piston rod, 12, is provided with an inlet aperture, 32, through which atmospheric air (or other higher pressure fluid relied upon) may be admitted to the interior of the piston rod, and valve sleeve section, 9 ton is provided with an inlet port, 33, coni municating with the interior of the cylinder on one side of the piston, and a similar inlet port, 34, communicating by a longitudinal passage, 35, in the hub with the cylinder on the opposite side of the piston. Both of these ports are normally held closed by means of a valve, 23 constructed identically like the valves, 23, hereinbefore described, and specifically illustrated in Figs. 4 and 5, and provided with the interior spreader, 27 clamped in position by means of a collar, 36, on the sleeve section, 9. Forconvenience of assembly, in the present instance, we have shown the sleeve section, 9', provided with a shoulder,.37, to engage the collar, 36, and the collar, 26, is provided with an annular projecting portion, 38, against which the collar, 36, clamps the inwardly extending flanges, 29 of the spreader, 27 and flange, 24 of the valve, 23, the parts being assembled on the sleeve section, 9, and screwed upon the extension, 19, of the collar, 17, so as to simultaneously clamp the collars, 26 and 36, upon their respective valves and spreaders, but We do not limit ourselves to this construction. An annular inlet passage, 39, is provided around the extension, 38, of the collar, 26, which communicates with the interior of the sleeve section, 9*, by suitable apertures, 40,

and the sleeve section, 9 is also provided with a plurality of apertures, 41, which communicate with the inner end of the valve chamber, 10 in the piston hub. When the valve mechanism is in its neutral position, the elastic cylindrical valve, 23 closes both the outlet ports, 33 and 34, but it will be seen that if the valve mechanism is moved in one direction, or the other, either the port, 33, or the port, 34, will be uncovered for the purpose of admitting higher pressure fluid,

as atmospheric air, for example, to the cylinder on the side thereof opposite the portion of the cylinder from which the air is being exhausted by the opening of one or other of the outlet ports, 30-31.

It will be noted that the valve actuating sleeve, 9, 9 has a certain amount of lost motion with respect to the piston and we prefer that this lost motion shall be positively limited. This may beaccomplished in many In the present instance we have shown the set screws, 12', provided with extensions, 12", extending into longitudinal slots, 42,v in the sleeve section. 9*, for the purpose of positively limiting the extent of movement of the valve actuating sleeve and piston with respect to eachother. We also prefer to provide yielding means for normally maintaining the valve mechanism in its neutral position With respect to the piston, thus holding the piston normally in balanced position. To this end we have illustrated in Figs. 2 and 6, one means for accomplishing this result, which consists of a coil. spring, 43, having its end rigidly secured to spiders, 44, one of which is secured to sleeve section, 9 and the other of which is secured to the inner end of a plug, 45, engaging the end of the hollow piston rod, 12, which is conveniently provided with a. perforated car, 46, for facilitating the attachment of the piston rod to the part to be actuated, said plug being provided with an aperture communicating with the inlet aperture, 32, before referred to. This construction interposes a yielding member, to wit, the spring, 43, between the sleeve, 9, and 9, and the piston adapted to normally hold the valve mechanism in its neutral position, and to restore it to neutral position after the spring has been either compressed or expanded by a relative movement of the actuating sleeve with respect to the piston in one direction or the other. This spring also performs another function which is hereinafter pointed out.

We will now briefly described the operation of the power actuator constructed as hereinbefore set forth. Fig. 1 of the drawing represents, diagrammatically, one form of installation which is conveniently employed. In this figure, 50, represents an internal combustion engine of any usual or preferred constrnction, and, 51, represents a portion of the suction passage between the throttle valve and cylinders, as for example in this instance, the intake manifold. 52, re resents a suction pipe extending from the intake manifold to a storage tank or space, indicated at 53, said pipe being provided preferably with an adj ustable regulating valve, 54, and check valve, 55, as set forth in our prior application above referred to, the storage tank, 53, being connected by a flexible pipe, 56, of larger diameter than the pipe, 52, with the interior of the sleeve section, 9. In this instance the sleeve section, 9, as shown in Fig. 2, is preferably provided witha plug, 47, on its outer end having a perforated lug or ear, 48, for attaching purposes, said plug being provided with an outlet aperture, 49, communicating by a longitudinal passage, 49, with the interior of the sleeve section, 9, and the pipe, 56, from the suction storage tank will be conveniently connected to the outlet aperture, 49. As indicated in Fig. 1, the actuator is intended to operate the brake mechanism of an automotive vehicle, and is shown in this instance connected directly in the linkage between the operator operated part, or foot pedal, indicated at 57, and the brake mechanism, inclicated diagrammatically at 58, which is one of the ways in whichwe contemplate employing the improved actuator. In this instance the piston rod, 12, is connected by a link, 59, with the brake mechanism, 58, so as to positively apply and release the brakes by the move ment of the actuator piston. The foot level 57, is provided with the usual retracting spring, 60, and is connected by a link, 61, with the valve actuating sleeve, 9, 9.

Referring now to Figs. 2 and 3, in which the valve mechanism is shown in neutral position, if the foot lever is moved forwardly, the valve sleeve will be actuated to the extent permitted by the limited lost motion between the sleeve and the piston, thereby moving the valve sleeve in the direction of the arrow, a, in Fig. 2. The effect of this movement is to 'bring the annular suction space, 20, in communication with the outlet port, or ports, 30, and communicating with the cylinder forward of the piston and at the same time to uncover the inlet port, 33, communicating with the cylinder in rear of the piston. Air is immediatel exhausted from the forward end of the cyfinder and atmospheric air enters the rear portion of the cylinder, causing an immediate forward movement of the piston and applying the brake mechanism.

As soon as the forward movement of the foot lever stops the movement of the piston will cause it to catch up with the valve mech-' anism and restore the latter to the neutral position, in which the yielding device or spring, 43, will assist. Upon the release of the foot pedal the valve mechanism will be moved in the direction of the arrow, b, in Fig. 2, by the retracting spring 60, of the foot lever thereby bringing the annular suction chamber, 20, 9f the valve mechanism into communication with the outlet port, or ports, 31, and simultaneously uncovering the inlet port 34, thus exhausting air from the cylinder in rear of the piston and admitting atmospheric air to the cylinder forward of the piston and effecting a rearward movement of the piston to release the brakes, the parts coming into neutral position as soon as the return no movement of the pedal is halted, or completed, in which case the hub of the piston engages the rear head, 3, of the cylinder, the valve sleeve having previously been arrested by the engagement of the plug, 47, with the follower, 8, of the stuffing box, which also serves as an adjustable stop for the valve sleeve.

When the pedal is actuated in either direction to move the valves with respect to the piston, as the piston begins to move, the frictional resistance between the piston and the valve would naturally tend to produce a further forward movement of the valve mechanism which might produce a greater movement by the actuator than was desired, unless the operator applies varying pressures to the foot lever to his inconvenience. The spring, 43, performs an important function in this connection for the reason that when the valve 1 0 mechanism is moved, this spring is either compressed or expanded, and in either case, as the piston begins to move in the same direction as that in which the valve sleeve hasjust been moved, the expansion or compression of the spring will produce a retarding effect on the valve mechanism and sleeve which counteracts the tendency ofthe friction between the piston and valve mechanism and obviates any tendency to move the valve mechanism further than it has been positively moved by the foot of the operator. The retractingspring, 60, is sufficiently powerful to effect the rearward movement of the valve sleeve on the release of the foot lever.

The limitation of the extent of lost mo tion between the valve actuating mechanism and the piston also performs an important function. For example, if the actuating mechanism for any reason does not apply the brakes with sufficient force, the operator can,

by exerting his physical pressure on the foot g lever and moving the valve actuating sleeve to the limit of lost motion, actually apply his own physical force to the piston and through the pistonto the brake mechanism or other part to be actuated in addition to that applied by the actuator itself. Further, should the power (in this instance suction) fail for any reason, the operator can directly actuate the piston and the connected brake mechanism or other parts to be actuated by his own physical power, by simply pressing on the foot lever sufficiently to take up the lost motion between the valve actuating sleeve, 9, 9 and the piston, and continuing to exert pressure on the foot lever, thereby positively moving the piston forward and applying the brake mechanism. The return movement of the foot lever under the action of the retracting spring will likewise restore the piston and brake mechanism to normal condition. The movements of the valves in such cases serving to vent the cylinder so that the actuator offers no resistance beyond the'friction of the gaskets.

It will be understood that the cylindrical valve members, 23 and 23", as well as the cylindrical packing sleeves, 6 and 14:, are formed of flexible material such as rubber, leather or the like, and preferably of elastic material such as molded rubber. These devices are preferably made of such a size that when placed in position, they will be slightly compressed in the case of the valve, or expanded in the case of the packing sleeves, so as to fit snugl against the surfaces with which they make air tight connection. e may rely entirely upon the elasticity of the material, as in the case of molded rubber, although this'elasticity may be supplemented by the elastic metallic spreaders which have been described. Yhere leather is employed, obviously the metallic Spreaders will be neces-' sary in order, to supply the necessary elasticity and hold the leather valves (or packmg sleeves) firmly against the surfaces with which they are to make an air tight contact. in the case of the packing sleeves, the elastic metallic device will have its fingers bent inwardly to compress the packing sleeves upon the enclosed parts if the material of' the connection therewith, they do 'not, as a matter of fact, offer any great amount of frictional resistance, and are, therefore specially advantageous in preventing leakage while facilitating the easy operation of the apparatus, also eliminating dust and grit, without scratching or cutting the frictionally en-' aged parts.

It will be obvious that variations may be made in the form of our improved valve sleeves without departing from the spirit of our invention. For example, in Fig. 7 we have illustrated a modified form of valve mechanism in which one of the elastic valves,

123", forming the valve for the outlet ports,

130, is carried by the piston, while the ports themselves are provided in a collar, 125, carried by the sleeve section, 109, the other outlet port, or ports, 131. being formed in tlie piston hub and controlled by a valve 123 constructed as previously described and carried by the sleeve section, 109*. In this case the valve member. 123*. is provided with an outwardly projecting flange, 124, as indicated in Fig. 8, and in connection therewith we employ a metallic elastic compressing device,

127, provided with spring fingers, 128, bent so as to exert an inward pressure on the sleeve, 123", the said metallic device being provided with an outwardly extending flange, 129, as shown in Fig. 9, to engage the flange, 124, of the valve. These parts, as shown in Fig. 7, are located in an annular recess in the piston surrounding the collar, 125. of the valve sleeve, and are clamped in position by means of retaining rings, 162, held in place by screws, 163, the inner surface of the rings, 162, being out of contact with the spring fingers, 128, and forming an annular space, so that any pressure accumulated between the said ring and the valve sleeve. 123 will tend to press the sleeve more tightly upon the collar, 125. In Fig.

7 we have also shown the valve sleeve member, 109", provided with p 'formed in one -connection with each of said flanges as indicated at 127. and being clamped against the opposite faces of the flange, 124, by collars, 136, on the sleeve section, 109". The other parts illustrated in Fig. 7 correspond with those previously described with reference to Figs, 2 and 3, and are indicated by the same reference numerals with the addition of 100 to each.

The operation of the valve mechanism shown in Fig. 7 is substantially the same as that of the mechanism illustrated in Figs. 2 and 3. When the actuating sleeve, 109, 109*, is moved in the direction of the arrow, a, in Fig. 7, the outlet ports, 130, will be moved out from under the valve, 123", so as to communicate with the cylinder forward of the piston While the valve member, 123, will uncover the inlet port, 133, and admit air at atmospheric pressure through the port, 133, to the other end of the cylinder. When the valve sleeve is moved in the direction of the arrow, 6, in Fig. 7, the annular suction space, indicated at 120, will be brought into communication with the outlet port, 131, to exhaust air from the cylinder in rear of the piston. while the inlet passage,

139, will be brought into communication with the inlet port, 134, and through the passage, 135, will admit atmospheric air into the cylinder on the other side of the piston.

In Fig. 10 we have shown still another modification of our invention, in which all of the valve members are carried by the piston in a manner similar to that indicated in the case of the valve, 123, in Fig. 7. In Fig. 10 we have shown the valve sleeve, 209, as piece and provided centrally with a transverse partition or plug, indicated at 219, to separate the suction passage from the air inletpassage, the said valve sleeve being provided forward of the partition (to the left in Fig. 10) with a plurality of outlet ports, 221, and with similar inlet ports, 240, on the other side of the partition. The piston hub is provided with three elastic valve members, 223, 223 "and 223, of the type shown in Fig. 8, having cylindrical portions surrounding the sleeve 209, and outwardly projecting annular flanges, 224, each of said valve members being provided with a compressing device similar to that shown in Fig. 9, indicated at 227, and provided with an outwardly extending flange, 229. The flanges, 229 and 224., of the valves and compressing devices are clamped between the rear end of the recess inthe piston hub, and a follower, 262, screwed into the opposite end of the hub, suitable spacing collars, 226 and 236, being interposed for the purpose of fixing the relative positions of the valve members. The inlet and outlet ports in the hub are provided as follows.

230 represents a recess in. the hub adjacent to the v alve, 223", which forms one of the outlet ports. 231 is a passage through the hub and through a portion of the spacing collar, 226, which forms the other outlet port, and also in this instance performs the additional function of an inlet port communicating with the cylinder in rear of the piston, that is to say on the right as shown in Fig. 10. The other inlet port is indicated at 234, in registration with an aperture in the spacing collar, 236, and communicating by the passage, 235, with the cylinder on the forward side of the piston. The other parts illustrated in Fig. 10 correspond with those heretofore described with refer ence to Figs. 2 and 3, and have been given the same reference numerals. with 200 added.

In this construction illustrated in Fig. 10, the operation of the apparatus will be sub stantially the same as heretofore described. When the parts are in the normal position indicated in Fig. 10, the inlet ports, 221, and the outlet ports, 24-0, of the valve sleeve, 209, are both closed by the sleeve valves, 223 and 223, respectively. If, now, the valve sleeve, 209, is moved to the left in the direction of the arrow, a, in Fig. 10, the outlet ports, 221, leading to the suction, will be carried out from under the valve, 223, and Will'establish communication through the annular reeess, 230. with the cylinder forward of the piston (at the left in Fig. 10), while the inlet ports, 24-0, will pass from under the valve, 223, and into communication with the port, 231, so as to admit atmospheric air under pressure to the cylinder in rear of the piston (to the right in Fig. 10). When the valves are in normal position, if the sleeve, 209. is moved in the direction of the arrow, Z), in Fig. 10, that is to say to the right-in that figure, the outlet ports, 221, leading to suction will be brought into communication with the passage, 231, and exhaust the air from the cylinder in rear of the piston (to the right in Fig. 10) and the inlet ports, 240, communicating with the atmosphere will be ,brought into communication with the inlet port, 234, and inlet passage, 235, and admit air to the cylinder on Y the other side of the piston (to the left inports adapted to be brought into communication with the cylinder on opposite sides of the piston by movementof the valve member, said valve member being provided with cy-' lindrical coaxial portions, said portions of the valve member and the inner cylindrical face of the valve chamber being provided. the one with annular yielding sealing portions for closing the ports in the other of said parts when the valve member is in normal or neutral position, said sealing per-- tions being each connected to one of said parts at one edge and being parallel to butseparated from the adjacent cylindrical'surface of the part to which it is connected to form an annular recess adapted to communicate with the source of higher pressure and hold said sealing member in sealing engagement with the cylindrical surface of the other part, a valve actuating sleeve connected with the valve member and provided with a suction passage communicating with the suction ports of the valve member, means for connecting the air inlet port of the valve member at all times with the atmosphere,

an operator operated part connected with the valve member for operating the same, and means acting to normally hold the valve mechanism in position to seal the ports in the valve chamber against higher or lower pressure.

2. In a power actuator, the combination with a cylinder closed at both ends and a double acting piston operating therein, of controlling valve mechanism for the actuator comprising a cylindrical valve chamber within the piston coaxial therewith and provided with suction and air inlet ports communicating with the cylinder on opposite In testimony whereof we at'fix our signatures.

CALEB S. BRAGG. VICTOR W KLIESRATH.

sides of the piston, a coaxial valve member within said valve chamber movable longitudinally thereof and provided with suction and air inlet ports adaptedto be brought into communication with the cylinder on opposite sides of the piston by movement of the valve member. said valve member being provided with cylindrical coaxial portions, said portions of the valve member and the inner cylindrical face of the valve chamber being provided the one with annular yielding sealing portions for closing the ports in the other of said parts when the valve member is in normal or neutral position, said sealing portions being each connected to one of said parts at one edge and being parallel to but separated from the adjacent cylindrical surface of the part to which it is connected to form an annular recess adapted to communicate with'the source of higher pressure and hold said sealing member in sealing engagement with the cylindrical surface 01 the other part, a valve actuating sleeve connected with the valve member and provided with a suction passage communicating with the suction ports of the valve member, means for connecting the air inlet port of the valve member at all times with the atmosphere, an

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