US2403532A

US2403532A - Hydraulic compensating propeller

Info

Publication number: US2403532A
Authority: US
Inventors: Hoover Walter Scott
Original assignee: Individual
Current assignee: Individual
Priority date: 1941-03-14
Filing date: 1941-03-14
Publication date: 1946-07-09
Anticipated expiration: 1963-07-09

Description

July 9, 1-946.

' W; S. HOOVER,

HYDRAULIC COMPENSATING PROPELLER Filed-March 14, 1941 4 Sheets-Sheet 1 INVENTOIR lfer .facoi'flioover ATTORNEY y 9, 1946' w. s. HOOVER 2,403,532

' 7 HYDRAULIC COMPENSATING VPROPELLER- Filed March 14, 1941 4 Sheets-Sheet 2 INVENTOR Wa Her 5:0 #Hoover QW #1 M ATTORNEY July 9, 1946 w. s. HOOVER 2,403,532

I HY DBAULIC COMPENSATING PROPELLER Filed March 14, 1941 4 Sheets-Sheet 3 INVENTOR ATTORN E'Y 1M1?! fer ScofiHoover July 9, 1946.v 'w. s. HOOVER HYDRAULIC COMPENSATING PROPELLER I I Filed March 14, 1941 4 Sheets-Sheet 4 no N 4 (i) INVENTOR WalferScofiHabvefi ATTO RNEY.

. cording to the invention.

Patented July 9, 1946 UNITED STATES PATENT 'OFFICE I HYDRAULIC COMPENSATING PROPELLEB Y Walter Scott Hoover, ltlontreal, Quebec, Canada Application March 14, 1941, Serial No. 333,391

\ 21 Claims. (01. 170-103) This invention relates to improvements in aeronautical propellers and has. particular reference to an improved unitaryconstruction embodying a controllable-pitch aeronautical propeller and control mechanism therefor.

Anobject of the invention resides in the provision of a combined controllable-pitch aeronautical propellerand self-contained control apparatus therefor arranged in a compact unitary ti'cularly pointed out hereinafter or will become apparent as the description proceeds.

In the accompanying drawings, in which like reference numerals are used to designate similar parts throughout, there is illustrated a suitable mechanical embodiment for the purpose of disclosing the invention. The drawings, however, are for the purposeof illustration only and are not to be taken as limiting or restricting the invention since it will be apparent to those skilled in the art that various changes in the illustrated construction may be resorted to without in any way exceeding the scope of the invention.

In the drawings:

Fig. 1 is a longitudinal sectional view through a propeller and control apparatusoonstmcted ac- Fig. 2 is a front-elevational view of the propeller shown in Fig. 1a portion being broken away'on the line 2-2 of Fig. 1 and shown in section to better illustrate the construction of the ontheline HofFig. 3-.

Fig. 6 isa sectional view similar to Figs. 4 and 5takenonthe1ine H ofFig. 3.

Hg. 7 is a sectional view or a portion of a gov- 2 ernor compensating device taken on the line 1-1 of Fig. 1.

Fig. a is an elevational view of another portion struction thereof, and

Fig. 9 is a schematic view illustrating the operation of the governor pitch changing and control apparatus shown in Fig. 1.

Referring to the drawings in detail, and particularly to Fig. 1, the numeral lllgenerally indicates a propeller shaft projecting from an engine nose 12 through an outboard hearing it in a manner well known to the art. Mounted on the pro- Jecting end of the shaft III by suitable means, such a the cones I 6 and I8 and the end nut 20, is a propeller hub, generally indicated at 22. This hub may conveniently be a one piece structure having a shaft surrounding portion 24 and a plurality of blade sockets, one of which is-indicated at 28, within which are rotatably mounted respective propeller blades, as indicated at 28, by means of suitable abutments and thrust bearings in a manner well known to the art. v

Each blade has attached to its end within the hub structure a pitch changing gear, a indicated at 20, which gears or gear structures are rotated by a common master gear 32, mounted to rotate about the axis 01' the shaft 10. The gear 22 may be driven by a suitable motor such as the gear type oil motor, generally indicated at 34., which is secured to the front end of the hub 22 within an enclosing spinner 36 and connected to the gear 32 through a suitable reduction gear train, generally indicatedat 38. While agear type oil motor has been illustrated for the purpose of disclosing the invention. it is to be understood that various other types of oil motors, such as vane or piston type motors, may be utilized without in any way exceeding the scope or the invention. Y

Where a hydraulic motor, such as the gear ty e oil motor 24, is utilized, suitable governor and valvevmeans are provided to control the operation 01' the motor in its pitch changing action in a manner such that the propeller pitch will-be adjusted to compensate any tendency of the en-.

gine speed to vary from a selected rate to thereby maintain the speed of the propeller driving engine substantially constant at a selected value at which the; speed responsive governor is set.

. Such means may conveniently comprise a plurallty of annular members, as indicated at 48, 42 and 44 and a plurality of centrifugally actuated flyballs as indicated at 48, surrounding an annular extension 48 provided on the shaft sur-' rounding portion 24 of the'hub 22 between the blade sockets and the adjacent portion of the ennose. 'fiie member 48 is particularly illustrated in Figs. 3, 4, 5 and 6 andcomprises a generally cylindrical member having at one end a shallow internal flange 88 provided with splines 82 which engage with splines 84 on the end portion of the hub extension 48 to provide a driving connection between the hub portion and the member 48 which will constrain the member 48 to rotate with the hub but will permit axial sliding movements of the member 48 relative to the hub portion upon which it is mounted. The member 48 is also provided intermediate its length with an external annular extension 86 and with three spaced internal grooves or channels 88, 88 and 82. The member 58 is provided with a pair of diametrically opposed transverse slots 84 and 88 within which are disposed radially slidable vanes 88 and I8 respectively. Adjacent to the vane 88 the portion 88 is provided with a radial aperture 12 which leads from the periphery of this portion to the channel 88 disposed immediately within the portion 88 and within which aperture there is disposed a ball check valve I4 arranged to permit passage of fluid from the periphery of the member 88 into the groove '88 but to block any flow of fluid from the groove 88 to the periphery of the member 88. Adjacent to the vane 18 is a similar aperture I8 diametrically opposed to the aperture 12 and containing a check valve 18 which also operates to permit'flow of fluid from the periphery of the portion 88 into the channel 88 and to block any flow of fluid from the channel 88 to the periphery of the portion 88. On the opposite side of the vane 88 from the aperture I2 the portion 88 is provided with a peripherial groove 88 which opens to the periphery'of the portion 88 and extends a short circumferential distance from the vane 88 on the side thereof opposite the aperture I2 and is connected by channels 82 with the internal groove 88 and by similar channels 84 with the internal groove 82.,

A jacent to the vane 18 and diametrically opposite the depression 88 there is disposed a similar depression 88 in the periphery of the portion 88 connected at its bottom by channels 88, similar to the channels 82, with the annular groove or channel 88 and with channels, not illustrated but similar to the channels 84, with the annular groove or channel 82. The annular member 42 which overlies the right hand portion of themember 48, as viewed in Fig. 1, is provided with an end flange 88 which overlaps the adjacent end of the member48 and with an annular radial enlargement 82 "at its opposite end which enlargement overlies the portion 88 of the member 48. Referring to Fig. 3, it will be observed that the interior surface of the enlargement 82 is somewhat elliptical in form to provide, semi-circumferential spaces 84 and '88 between the interior surface of this enlargement and the adjacent peripheral surface of the circular portion 88 of the member 48. The annular member 44 has at its end adjacent the member 42 an external annular flange 88 which closes that side of "the annular space within which the portion 88 rotates and has'at its opposite end an internal 82, to operate the pitch changing motor 34.

cured together against relative rotation at their abutting surface and both members are normally held as a unit against rotation by a. gear 88 drivingly mounted on an axle I88 secured in bearings in a casing, generally indicated at I82, and meshingwith teeth I84 provided on the exterior of the member 42.

f With this arrangement, when the propeller shaft I8 is rotating, the member 48 will be rotated relative to the surrounding

members

42 and 44 and fluid will be drawn into the portions of the

annular spaces

84 and 98 on the sides of the vanes 88 and 18 on which the respective intake depressions 88 and 88 are located and will be expelled by the vanes 88 and I8 through the apertures 12 and 18 into the middle or pressure channel 88. The intake wil1 be from one of the end channels 88 or 82 depending upon the position of the member 48 on the hub extension 48 as will be presently explained. This construction provides a fluid pump which will maintain fluid under pressure in the middle channel 88 and will intake fluid from one of the endchannels 58' or If desired, a pressure relief valve may be placed between the channel 88 and the intake side of the pump preferably adjacent the intake depressions, to limit the maximum pump pressure and prevent breakage. The gear 88 is connected with a suitable motor 89, through suitable means, such as the gear train I88, so that, when the shaft I8 is not rotating the pump can be operated independently to furnish fluid under pressure for changing the pitch of the propeller and particularly for feathering or unfeathering the propeller in the event it is desired to accomplish either of these operations with the engine stopped.

The governor flyballs 48 are mounted on respective axles, one of which is indicated at I I8, the ends of which are received in respective apertured lugs, as indicated at I I2, provided on a ring I I4 which surrounds the hub extension 48 at its end adjacent tothe blade sockets and these flyballs are provided with bell crank arms carrying respective contact members, which may conveniently be in the form of small anti-friction bearings, as indicated at H8, which bear against a thrust washer ll8 disposed against the end of the member 42. With this arrangement, whenever the flyballs 48 swing'outwardly incident to an increase in propeller speed the unit comprising the

members

48, 42 and 44 will be moved to the left, as viewed in Fig. 1. .The action of centrifugal force on the flyballs 48 tending to move the above-mentioned unit to the left is opposed by a governor speeder spring I28 disposed within a flanged bushing I22 the end flange of which bears against the external flange 84 of the member 44, the oppositrend of the speeder spring bearing against the interior of the end flange I24 of a nut I28 screw threaded into the end of the cover member I21 which cover member is rigidly secured to the engine nose l2 and encloses the govprising the

members

48, 42 and 44 and the nut flange 88 which overlaps the adjacent end of the member 48. The

members

42 and 44 are se- I28 whichin-turn encloses the speeder spring I28. If desired, suitable means may be provided in the engine nose I2 for rotating the nut I28 to chanse the loading on the speeder spring I20 and thereby adjust the speed setting of the governor. No particular means have been illustrated since it would be obvious to utilize some well known device such as a worm and gear. mechanism or spur gear device for accomplishing this function. Preferably an oil seal I 28 is provided between the right hand end of the cover member I21 and a shoulder provided on the hub 22 between the extension 48 and the blade sockets in order that lubricant for the governor and valve mechanism may be retained in the cover member against leakage.

The hub extension 48 is provided with a pair of external grooves I30'and I32 which are spaced to lie between the groove 60 and the groove 58 and between the groove 60 and the groove 62, respectively; when the member 40 is in its center or neutral position. The groove I30 is connected through a suitable channel I34 with a manifold I36 leading to one side of the various oil motor elements, as indicated at I38, I40 and I42, and the groove I32 is connected by a similar channel I44 with a manifold I46 leading to theopposite side of the oil motor elements. Both channels I34 and I44 are. connected through respective check valves I48 and I50 with an oil reservoir I52 within the hub space surrounding the reduction gear unit 38.

With this arrangement, when the governor flyballs 46 swing outwardly in response to an inreduce its speed. If the engine and propeller speed falls below the speed for which the governor is set, the speeder spring I20 will force the pump and valve unit to the right as viewed in F v r ing the decreased centrifugal force acting on the flyballs 46, and will connect the pressure groove 60 with the groove I32 thereby supplying oil through the channel I44 and manifold I46 to the oil motor 34, to operate the motor to move the propeller blades in a pitch decreasing direction, to thereby reduce'the load on the engine and permitits speed to increase. Whenever the groove 60 is connected with the groove I 30 the pump will intake through the channel I 44 from the manifold I46 and. from the reservoir I52 through the check valve I50 in case it becomes necessary to supply make up oil to the pump and an arrangement, while fully operative, i not always as stable and sensitive as might be desired and it is among the objects of this invention to provide stabilizing means for such a governorpropeller combination to render the control of the propeller by the governor more accurate and sensitive and to avoid the tendency of the governor the propeller hub and having a skirt portion I58 surrounding the end of the propeller shaft within the shaft bore of the propeller hub and a thick cylindrical end portion I60 having a diameter smaller than the skirt portion I58 and having a central aperture therethrough substantially coaxialwith the axis of the shaft I0. Within the cylindrical portion I60 there are provided a substantiall centrall disposed annular groove I62 of substantially rectangular cross-section, an annular chamber I64 and a pair of annular fluid manifolds I66 and I68. The groove I62 is divided into two substantially equal portions by a pair of diametrically opposed integral vanes I10 and I12. An annular member I14 surrounds the groove I62 and is also provided with a pair of diametrically opposed internal radial vanes I16 and I18 which cooperate with the vanes I10 and I12 to divide the groove I62 into four separate chambers. For

convenience in assembly the member I14 is diais secured to the cylindrical extension I80 in such motor system. and similarly, when the groove a manner that whenever the gear 32 is rotated to change the pitch of the propeller the member I14 will be rotated relative to the member I54 to change the dimensions of the chambers between the vanes I10, I12, I16 and I18.

Adjacent to the hydraulic device I54 the hub is provided with a cylindrical bore I84 within which is disposed a piston E86 mounted on a shaft I88 which extends through a passage in the hub to a connection with the end flange I90 of a sleeve member I32 disposed between the member 40 and the hub extension 48 and particularly illustrated in Fig, 8. This sleeve member is slidable on the hub extension 48 and is provided with two rows of apertures, as indicated at I34 and I96, spaced apart the same distance as the grooves I30 and I32 in the hub extension. The manifold 66 in the member I56 is connected with the chambers between the vanes I16 and I10 and the vane I18 and I12 and with the left hand end of the cylinder bore I84 through suitable channels as indicated at I80, 200 and 202 while the manifold I68 is connected with the chambers between the vanes I12 and I16 and I18 and I10 and with the right hand end of the cylinder bore I84 through suitable channels as indicated at 204 and 206.

The operation of the compensating mechanism is schematically illustrated in Fig. 9 in which the blade turning motor 34 has been shown as a vane type motor rather than a gear motor, as shown in Fig. 1, for the sake of simplicity in the illustration. If we assume that the governor flyballs 46 have moved outwardly in response to an increase in speed and have consequently connected the annular pressure chamber 60 with the annular channel I30, hydraulic fluid under pressure will then be supplied through the channel I34 to the inder a 7 motor 34, to the spaces between the motor vanes 288 and 2I8, and between the vanes 2I2 and 2. Now, since the vanes 2| 8 and 2 connected to the inner member 2I8 are relatively fixed, the vanes 288 and M2 will be rotated in a clockwise direction as viewed in Fig. 9, to turn the propeller blades 28 toward a higher pitch condition. As the motor device 34 turns the gear 32 through a suitable reduction gear, such as is indicated at 38 in Fig. 1, the portion I14 of the hydraulic mechanism I54 will also be rotated in a clockwise direction carrying the vane I18 towards the vane I12 and the vane I18 toward the vane I18. This will cause hydraulic pressure to be exerted on the line I88 leading to the right hand end of the cyl- I84. The chambers between the abovementioned vanes are, however, also connected with the annular reservoir I84 through channels 2I8 and 228 and the adjustable restricted orifice 222. If the speed increase is relativel small so that the groove I88 is connected with the pressure chamber 88 by a restricted amount such that the movement of the motor 34 and hydraulic device I54 will produce a fiow through the channel 2I8 within the capacity of the orifice 222, oil will be transferred between the opposed chambers of the device I54 and the reservoir I84 but will not move a the piston I88 which will be maintained in its centered position, as illustrated by the centering

springs

224 and 228, since it has been found thatfor such small and relatively slow pitch changes the governor does not need to be compensated. However, if the governor acts strongly incident to a rapid change in speed so that the flowfrom the device I54 cannot be accommodated by the orifice 222 the piston I88 will be moved to the left, as viewed in Figs. 1 and 9, and will move the sleeve I82 to the left following the similar movements of the member 48. This movement of the sleeve following the member "will maintain a certain degree of restriction between the presure chamber 88 and the channel I38 which restriction will gradually increase as the propeller blades approach the pitch condition necessary to restore the engine and propeller to the selected speed and the sleeve I82 will be in position to substantially block the flow of fiuid from the pressure, chamber to the channel I88 when the propeller has reached the proper pitch setting although the engine speed is still above the selected speed. As the speed of the engine and propeller slows down and the governor returns to its neutral position; the sleeve I82 will maintain the connection between the pressure chamber 88 and the groove I38 blocked so that no further change in the propeller pitch will take place during the movement of the member" back to its centered position in which it obstructs this connection. As the member 40 moves back toward its center position under the influence of the speeder spring I28 the sleeve I82 will follow as the fluid bleeds out of the right hand end of the cylinder I84 through the device I54 and through the restriction 222 to the reservoir I84 and. under the influence of the centering

springs

224 and 228 will also reach a centered or neutral position about the same time that thesmember 48 reaches its centered position leaving the propeller pitch at the correct angle to maintain theselected speed and the'goverx )r' in condition to act to change the pitch in case the speed again varies.

The propeller blades are. preferably locked in the adjusted pitch position against turning under the eifect of centrifugal or aerodynamic forces by r 1,668,971, issued May 8, 1928, to Ernest G. Mc- Cauley for Screw mechanism for adjustable and reversible pitch propellers, and particularly illustrated in Figs. 1 and 2 of this application. IAS shown this lock includes the cam member 228 rotatable within the relatively fixed sleeve member 238 and held against rotation relative to the sleeve member by the locking balls 282 as long as the motor 34 is not exerting a pitch changing effort, the balls being releasable by the element 284 and lost motion connection 238 whenever the motor acts to change the propeller pitch. \Application of power by the motor 34 will, because of the lost motion connection, first turn the gear 238 on the shaft 248 thereby moving the element 284 which is keyed fast to gear 288. 'This will unlock one ball 232 and permit the shaft 248 with its attached mm 228 to be freely rotated. As soon as the pump gear 238 takes up the lost motion in connection 288, the motor will drive the shaft 248 and through the gear train 38 change the propeller pitch. If, however, the propeller attempts to drive the motor the cam 228 driven bythe shaft 248 will catch up with and will be locked by one of the balls 232.

If the speed of the propeller should be below thatifor which the governor is set, the governor spring would act to move the member 48 to the right as viewed in Fig. 9 andactuate the motor 84 to decrease the pitch angle of the propeller. This movement of the motor 34 will cause a movement of the hydraulic device I58 which would apply hydraulic pressure through the line I88 to the left hand end of the cylinder I84 to move the sleeve I82 toward the right to followthe similar movements of the member 48 and the compensating action would be the same as that described above in connection with a; speed increase above the governor setting. After the proper pitch angle has been attained and 'the member 48 moves back to its centered position the sleeve I82 would follow this movement toward the left as viewed in Fig. 9 as the fiuid was bled from the left hand end of the piston I84 through the adjustable restricted orifice 242 to the reservoir I84. Thus, the propeller would asain be left at the proper pitch position to maintain the selected speed and the governorwould be brought back to its neutral position and in condition to act to change the propeller pitch in case the speed again varies in either direction from the selected value.

While a suitable mechanical embodiment has been hereinabove described and illustrated in the accompanying drawings for the purpose of disclosing the invention, it is to be understood that the invention is not limited to the particular construction so illustrated and described, but that such changes in the size, shape and arrangement of the various parts may be resorted to as come within the scope of the'sub-ioined claims.

Having now described the invention so that others skilled in the art may clearly understand I the some, what it is desired to secure by Letters a suitable locking device such as the well known lock disclosed in United States Patent Number 15 said hub and rotatable therewith, and a relatively Patent is as follows:

1. In a hydro-controllable Propeller, a hub, a plurality of blades carried by said hub and mounted for pitch changing movements. a fluid motor operatively connected with said blades for changing the pitch thereof, a fiuid pumpcarried by said hub for supplying pressure fluid to said motor, connections from both sides of said motor to said pump, and means for varying said connection to control the operation of said motor, said pump including a rotor membersurrounding one end of non-rotatable member surrounding said rotor member, said rotor member and said hub end having 'grooves constituting intake and outlet channels for said pump said rotor member and said hub end being relatively movable to control said intake and outlet channels.

2. A fluid pump for a hydro-controllable propeller having a blade carrying hub structure comprising, a portion encircling one end of said hub structure and provided with an annular external ring rotatable with said hub structure, a relatively fixed annular portionsurrounding said rotatable portion and having an annular groove receiving said ring, said groove being non-circular in shape to provide pump chambers between the periphery of said ring and the bottom of said groove, intake and outlet ports in said ring, a vane carried by said ring between each adjacent intake and outlet port, and annular grooves in the interiorof said rotatable portion connected one with said outlet ports and two, located one on each side of said outlet port connected groove, with said intake ports.

3. Pitch control means for a hydro-controllable propeller having a blade carrying hub structure comprising, a pitch changing fluid motor, a pump rotor carried by and rotatable with said hub structure, a pump casing surrounding said rotor and held against rotation, grooves in the interior of said rotor constituting a pressure channel and a pair of intake channels, a pair of grooves in said hub, separate means connecting one of said hub grooves with one side of said motor and the other hub groove with the other side of said motor, and speed responsive means operative to connect said pressure channel with either of said hub grooves to connect either side of said motor with the pump outlet while connecting the alternative side with the pump intake through the other hub groove and an intake channel to operate said motor in'either direction depending upon the speed change demand of said speed responsive means.

4. Pitch control means for a hydro-=controllable propeller having a blade carrying hub structure comprising, a pitch changing fluid motor, a pump rotor carried by and rotatable with said hub structure, a pump casing surrounding said rotor and held against rotation, grooves in the interior 10 able .portion for regulating the propeller speed by moving said common portion. v

I 6. Pitch control means for a hydro-controllable. propeller having a blade carrying hub of said rotor structure constituting a pressure channel and a pair of alternatively operative intake channels for said pump, a pair of grooves in said hub structure, separate means connecting one of said hub grooves with one side of said motor and the other hub groove with the other side of said motor, a governor mechanism carried by said hub structure, and a connection between said governor mechanism and said pump rotor for shifting said rotor axially of said hub structure to connect said pressure channel with either of said hub grooves to connect either side or said motor with said pump outlet and the alternative side with said pump intake by connecting one intake channel with the other hub groove to thereby operate said motor in response to the speed change demands of said governor.

5. Pitch control means for a hydro-controllable propeller having a. blade carrying hub structure comprising, a. hub carried fluid motor for changing the pitch ofsaid blades, a hub carried pump for supplyingpressure fluid to said .motor, a valve combined with said Dump and having at least one movable portion common with said pump for controlling the application 01 said fluid to said motor and a speed controlstructure comprising, a hub carried fluid motor for changing the pitch of said blades, a1hub I carried pump for supplying pressure fluid to said motor, one portion of said pump forming a portion of a valve, said valve portion being movable,

for controlling the application of said fluid to said motor, propeller speed regulating means connected with said movable valve portion and including a governor for actuating said valve portion and a hub carried supply of fluid.

7. Pitch control means for a hydro-controllable propeller having a blade carrying hub structure comprising, a hub-carried fluid motor for changing the pitch of'said blades, a hub carried pump for supplying pressure fluid to said motor, a hub carried governor for controlling the application of said fluid to said motor; and a hub carried governor compensator having a central position but movable, by changes in propeller pitch, temporarily away from said central posin t te porarily change the governor setting and retard the pitch changing action of said governor as the propeller pitch approaches a condition consistent with the speed change demands of said governor means, independent of propeller pitch, restoring said compensator to said central position.

8. Pitch control means for a hydro-controllable propeller having a blade carrying hub structure comprising, a fluid motor for changing the pitch of said blades, a fluid pump for supplying pressure fluid to said motor, a reversing valve between said pump and said motor having a preselected closed position, a governor for operating lable propeller having a blade carrying hub structure comprising, a fluid motor for changing the pitch of said blades, 9. fluid pump for supplying pressure fluid to said motor, a reversing Y valve between said pump and said motor, a governor for operating said valve, and a governor compensator for changing the closed position of said valve in a direction to follow up the valve operating movements of said governor, said govemor compensator comprising a fluid displacement device movable in proportion to the pitch changing movements of said blades and a fluid motor operated by said displacement device for shifting the closed position of said valve.

10. In combination, a reversible fluid motor, a pump for supplying pressure fluid to said motor, a two part reversing valve between said pump and said motor having a predetermined closed position, a governor for moving one part of said valve relative to the other part to control the operation of said motor, and a governor compensator comprising a perforated sleeve between the two parts of said valve and means operated by movement of said motor for moving said sleeve to shift the closed position of said valve proportional to the rate and extent of the movements of said motor and means independent of said motor for gradually restoring said compensator sleeve to said predetermined closed position of said valve.

11. In combination, a reversible fluid motor, a pump for supplying pressure fluid to said motor. a two part reversing valve between said pump and said motor, a governor for moving one part of said valve relative to the other part to control the operation 01' said motor, and a governor compensator comprisin a perforated sleeve between the two parts of said valve, a fluid displacement device operated by said motor, an expansible chamber device operated by the fluid displaced by said fluid displacement device and operatively connected with said sleeve for moving said sleeve to shift the closed position of said valve in proportion to the movements of said motor, resilient centering means associated with saidexpansible chamber device for returning said sleeve to its neutral position, and a fluid bleed for gradually relieving fluid pressure opposing the operation oi said centering means.

12. In combination, a reversible fluid motor, a pump for supplying pressure fluid to said motor, a two part reversing valve between said pump and said motor, a governor for moving one part of said valve relative to the other part to control the operation of said motor, and a governor com- .12 pressure opposing the action of said centering means.

14. In a structure including a support and a propeller rotatable with respect to said support, a pump having'a rotor, at driving connection between said propeller and said rotor, a pump casing enclosing said rotor, a connection between said casing and saidsupport comprising power supply means connected with said support and a power transmitting connection between said power supplying means and said casing, said power transmitting connection and said power supply means preventing rotation of said casing relative to said support when said propeller is rotating and said power supply means is deenergized and serving to rotate said casing relative to said rotor and said propeller when said p'ropeller is not rotating and said power supply pensator comprising, a perforated sleeve between the two parts of said valve, a fluid displacement device operated by said motor, an. expansible chamber deviceoperated by the fluid displaced by said fluid displacement device and operatively connected. with said sleeve for moving said sleeve to shift the closed position oi. said valve in proportion to the movements of said motor, resilient centering means associated with said expansible chamber device for returning said sleeve to its neutral position, a fluid bleed for gradually relieving fluid pressure opposing'the operation of said centering means, and a reservoir for carrying a supply of fluid for said displacement device.

13. Pitch control means for a hydro-controllable propeller having a blade carrying hub structure, a pitch changing fluid motor, a pump rotor carried by and rotatable with said hub structure, a pump casing surrounding said rotor and held against rotation, grooves in the interior oi'said rotor constituting a pressure channel and v a pair oi. alternatively operative intake channels for said pump, a pair of grooves in said hub structure, separate means connecting one of said hub rooves with one side of said motor and the other hub groove with the other side of said motor, a governor carried by said hub structure, and a connection between said governor and said pumprotor for shifting said rotor axially of said hub I structure to 'connect said pressure channel with either 01' said hub grooves to connect either side of said motor with said pump outlet and the alternative side with said pump intake by connecting one oi said intake channels with the other hub groove to. thereby operate said motor in either direction in response to the speed change demands of said governor and a governor compensator comprising, a perforated sleeve disposed means is energized.

" 15. In a controllable-pitch propeller having hydraulically operated pitch changing means, an hydraulic pump having two relatively movable portions comprising one portion rotatable with said propeller and relative to another portion for supplying fluid under -pressure to said pitch hydraulically-operated pitch-changing means, an I hydraulic pump having two relatively movable portions comprising one portion rotatable with said propeller and relative to another portion for supplying fluid under pressure to said pitchclianging means during operation of said propeller, said other portion being rotatable relative to said propeller and said one portion for supplying fluid under pressure to said pitch-changing means while said propeller is' stationary and means includingan electric motor for holding said other portion stationary while the propeller is rotating and for rotating said other portion while said propeller is stationary.

1'7. In a controllable pitch propeller having hydraulically-operated pitch-changing means, an hydraulic pump having two relatively movable portions comprising one portion rotatable with said propeller and relative to another portion for supplying fluid under pressure to said pitchchanging means during operation of said propeller, saidother portion being rotatable relative to said propeller and said one portion for supplying fluid under pressure to said pitch-changing tionary while the propeller is rotating and enerassociated with said expansible chamber device for returning said sleeve to its neutral position,

gizable for rotating said other portion while said. propeller isstationary. 18; A combined pump and governor comprising, a rotatable shaft, a rotary pump surrounding said shaft and having a rotor rotatable with said shaft and a stationary casing surrounding said rotor, passages in said shaft and rotor arranged to form fluid connections between said shaft and said pump, p ed responsive means associated with said shaft operably connected with said pump for moving said casing and rotor relative to said shaft to change the relative relation of the and a fluid bleed for gradually relieving fluid 'Il passages insaid shaft and rotor to control the output or said pump in accordance with the speed of said speed responsive device.

19. A combined pump and governor, comprising, a pump having a rotor and a casing, a member rotatable with said rotor, valve ports in said rotor connected with the intake and outlet of said pump, valve ports in said member positioned to cooperate with the rotor valve ports, speed responsive means associated with said pump and said member, means connecting said speed responsive means and said pump for moving said pump rotor relative to said member to control the output of said pump by controlling the-relative position of said valve ports.

20. In a hydro-controllable propeller, a hub, a

, motor, a cut-oil valve between said pump and motor, a governor for operating said .valve, a

governor compensator for operating said valve plurality oi. blades carried by said hub and- 21. In a hydro-controllable propeller, a hub, a

plurality of blades carried by said hub and mounted for pitch changing movements, afluid motor operatively connected with said blades for changing the pitch thereof, a fluid pum'p carried by said hub for supplying pressure fluid to said motor, a cut-off valve between said pijimp and motor, a governor ioroperating said valve and a overnor compensator including means operative in response to the velocity of pitch change movement of the blades for shifting the position of said valve.

WALTER SCOT! HOOVER.