US2081946A - Hydraulic engine controlling device - Google Patents

Description

June 1, 1937. E. MARTIN ET AL mnmumc ENGINE commune nnvrcn Filed May 21, 1936 3 Sheets-Sheet l TOR.

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A TfTORNEY June 1, 1937. E. MARTIN er AL 2,083,946 HYDkAULIC ENGINE CONTROLLING DEVICE 'Filed May 21, 1936 3 Sheets-Sheet 5 INVENTOR. .E'rla Marla:

JabnEZnarAm/ar am BY M '9- ATTORNEY Patented June I 1, 1937 2,081,946

UNITED? STATES PATENT OFFICE HYDRAULIC ENGINE CONTROIJJNG DEVICE Eric Martin, West Hartford, and John Elmer I Anderson, Portland, Conn., assignors to United Aircraft Corporation, East Hartford, Conn., a I corporation of Delaware Application my 21, 1936, Serial No. 81,046

' 19 Claims. (01. 60-91) 3 This invention relates to improvements in enas a radial air-cooled internal combustion engine controlling mechanisms, and has particular gine ordinarily. employed for the propulsion of reference to a controlling mechanism for use in airplanes. It is to be understood, however, that a vehicle, such as an airplane, having one or a the device may be applied to various power plants, 5 plurality of engines for controlling the speedof and the particular type of engine illustrated in 5 the engine or engines. no way aflects the scope of the invention. The An object of the invention resides in the proengine drives a controllable pitch propeller, genvision of hydraulic means for manually controlerally indicated at l2, having two or more radialling the engine'speed. ly disposed blades l4 rotatably mounted at their A further object resides in the provision of root or base ends in a hub barrel member I6 10 manually actuatable hydraulic means of the for pitch changing movement about their loncharacter described for controlling the speeds of gitudinal axes. The pitch angle of the blades all of a plurality of engines simultaneously. ll is/controlled by a pair of centrifugally actu- A still further object resides in the provision ated counterweights l8 directly connected tothe of manually actuatable hydraulic means of the respective blades and a hydraulic mechanism 15 character described for synchronizing thespeeds operatively connected to the counterweights. In of the various engines when the device is applied the form of propeller illustrated, the counterto an engine driven vehicle having aplurality of weights, under the action of centrifugal force, n i es tend to turn the blades l4 toward their high pitch Other objects and advantages will'be more. position, and the movable cylinder 22 of the hy- 20 particularly pointed out hereinafter or will bedraulic mechanism is operative to overcome the come apparent as the description proceeds. tendency of the counterweights to move the In the accompanying drawings, in which like blades to high pitch position, and to turn the reference numerals are used to designate similar blades to their low pitch position. The pro- 1 25 parts throughout, there are illustrated three peller has a limiting high pitch andlow pitch 25 slightly modified mechanical embodiments of position, and the pitch controlling mechanism what is now considered to be the preferred form is effective to maintain the blades at any pitch of the idea of the invention. The drawings, angle between these two positions, depending however, are for the purpose of illustration only upon the supply of hydraulic fluid to the hyand are not to be taken aslimiting the invention draulic mechanism 20. 30

the scope of which is to be measured entirely by The fiuid is supplied to the hydraulic mechathe scope of the appended claims. nism 20 through the bore 24 of the tubular pro- In the accompanying.- drawings, peller shaft 26 and through the hollow piston 28 Figurel is a partly schematic sectional view of upon which the cylinder 22 is reciprocably a hydraulicengine speed control mechanism conmounted, and is controlled by the action of a 35 structed according to the idea of thisinvention speedgcontrolling governor, generally indicated applied to an engine having a speed governor at 30., and particularly illustrated in Fig. 2. and a governor controlled controllable pitch pro- The governor 30 is of the centrifugally actupeller; v ated type, and has a pair of flyweights 32 mount- Fig. 2 is a partly schematic sectional view 0! a ed upon a rotatable tubular shaft 34 driven by 40 hydraulic speed regulatingmechanism similar H the engine through a suitable gear drive 36. to Fig- 1 except that it is adapted for applica- These flyweights 32 are operatively connected tion to a plurality of engines, the mechanism bewith a longitudinally movable valve member 38 mg shown as applied to engines each having a which controls a pair of ports 40 and 42 through '45'speed governor and driving a governor con-trolled which the hydraulic fluid is supplied to and controllable pitch propeller; drained from the hydraulic propeller controlling Fig. 3 is a schematic illustration of a fourmechanism 20, the fluid being supplied to the engine airplane illustrating how the device of governor through a s 'table' conduit -44 from a the invention could be applied to a multi-engine source of pressure, such as a pump (not illusvehicle; and 'trated).. A similar conduit 45 leads from the 50 Fig. 4 is a partly schematic sectional view governor to the interior of the hollow propellersimilar to Fig. 2 showing a somewhat modified 26 throughs table 011- collector rings 41. The form of engine speed controlling mechanism. action of the flyweights 32 is opposed by an ad- Reterring to the drawings in detail, the nujustable coil spring 46 in such manner that a meral- "I generally indicates a power plant, such change of tension of the spring or any force ex- 55 erted upon the flyweights, in addition to the force exerted by the spring, will tend to change the action of the governor and vary the speed of the engine by changing the pitch angle of the propeller blades l4. With one definite setting of the spring 46, the action of the flyweights 32 will hold the valve 38 in a neutral position whenever the engine is operating at a certain definite speed, and will thus maintain the pitch of the propeller blades such that the propeller absorbs the entire power output of the engine at the speed specified. If the speed of the engine varies from the speed consistent with the setting of the governor spring, the flyweights 32 will move in or out and adjust the valve 38 to either supply additional fluid to the hydraulic mechanism 28 to decrease the pitch of the propeller blades in case the engine speed goes down, or to drain some of the fluid out of the hydraulic mechanism and increase the pitch of the propeller blades in case the speed of the engine goes up and, by such adjustment of the back to the speed for which the governor spring is set. As stated above, any change in the tension of the governor spring will change the speed at which the governor tends to maintain the speed of the engine constant. Thus the speed of a single engine, or the speeds of the individual engines of a multi-motored vehicle, can be changed or adjusted. by varying the tension or loading upon the spring of the respective engine governor.

In the particular trated in Figure 1, above t form of the invention illusthe governor 38 is provided,

flyweights 32 and the spring 46, with a cylindrical extension 48 within w ch is a reciprocable pisf ton 50. The piston 58 has a lapped fit with the interior of the cylinder 48 or with a cylindrical bushing 52 disposed in the cylinder to provide an oil-tight fit between the sides of the piston and cooperating wall of the cylinder or bushing. The piston 58 is mounted or integrally formed upon the upper end of a stem 54, the lower end of which forms an abutment 56 for the upper end of the governor spring 46 so that movements of the piston 58 up and down in the cylinder 48 will alter the load on the spring 46 and thus vary the action of the centrifugal governor 30. A tubular member 58 leads from the space between the closed upper end of the cylinder 48 and ad- ,iacent surface of the piston 58 to ahydraulic cylinder, generally indicated'at 60. The hydraulic cylinder 60 is preferably a relatively small cupshaped member mounted upon the instrument board 62 of the airplane, or other vehicle, and is supplied with a manually actuatable knob 64 screw threadedand looked upon the sleeve member .66 into which is screw threaded the end of a stem 68 which is secured at its opposite end to a piston. 10 movable in the cylinder and having an oil-tight fit with the interior cylinder walls to change the volume of the space between the lower end of the piston and the lower closed end of the cylinder. Manual rotation of the knob 64 by screwing the stem 68 in and out moves the piston 18 to provide the change in volume and consequent change in pressure ofthe hydraulic fluid within the cylinder 60, the cylinder 48, and the tubular connection 58 to change the loading upon the governor spring 46. The sleeve 66 is v provided, \m'thin the cover 12 on the cylinder 60, with an outwardly extending flange 14 which underlies ,a. recessed portion of the cover 72 and takes the thrust of the piston upon the screw propeller, bring the engine threaded stem 68. The stem 68 may be restrained against rotation by suitable means, such as the washer !6, locked between the cover 12 and the upper end of the cylinder. 60 surrounding the stem 68 and provided with a tongue extending into a longitudinal groove 18 provided in the stem.

A fluid pressure gauge, generally indicated at 80, may be mounted upon the instrument board 62 and connected with the conduit 58 by suitable means, such as the branch conduit 82, to indicate, by means of the hand 83, the pressure exerted-by the piston 10 upon the fluid in the system. Preferably, this pressure gauge is provided with indicia 84 which are calibrated directly in units of engine speed, such as revolutions per minute.

From the above description it will be observed that the action of the governor 30, and consequently the speed of the engine l0, may be controlled by the operator of the vehicle upon which the engine is mounted by suitably controlling the manually adjustable knob 64 and thereby changing the pressure acting upon the piston 50 of the governor 30.

Since many power driven vehicles, and particularly large airplanes, are driven by a plurality of engines (usually from two to four) it is necessary in these cases that suitable means be provided for controlling all of the engines, and such control mechanism should desirably be arranged so that all of the plurality of engines may be controlled together, or each engine may be controlled separately. Obviously, such a control for a plurality of engines could be arranged by providing each engine-with a hydraulic control arrangement, as illustrated in Fig. 1 and described above, arranging all of the manually actuatable elements on the instrument board of the vehicle in convenient reach of the operator. If desired, these various manually controllable elements could obviously be connected together by suitable means, such as gearing or belting, so that they would all be'operated simultaneously upon the operation of one of them, or upon the operation of a master control element, so that the various engines could be controlled either in unison or separately. A combined and individual control can also be provided by connecting all of the governors, or other speed controlling elements of the engine, with a common fiuid reservoir and providing means for manually adjusting the pressure'in such a reservoir.

mounted upon the instrument board 62 of the airplane, or other vehicle, and is. supplied with a manually actuable knob 98 screw threaded and looked upon a sleeve member 92 into which is screw threaded the end of a stem 94 which is secured at its opposite end to a piston 96 movable in the cylindrical reservoir to change the volume' of the fluid space between the piston and the closed end of the cylindrical reservoir. Manual rotation of the knob 98 by screwing the stem 94 in and out moves the piston 96 to provide the change in volume and consequent change in .the

Such a construction is particularly illustrated in Fig. 2 and in a slightly modified pressure of the hydraulic fluid within the reservoir, the governor cylinders 48, and the tubular connections 88. The sleeve 92 is provided, within the cover 98 on the cylinder reservoir 88, with an outwardly extending flange I which takes the thrust of the piston upon the screw threaded stem 94. If desired, a dial member I02 may'be secured to the sleeve 92 and provided at itsouter edge with indicia I04 which cooperate'with similar indicia I06 provided on the edge of the cover 98 to indicate .the speed and revolutions per minute of the engines for any particular 'setting of the knob 90. Fluid maybe supplied to the reservoir'80 through a suitable fllling spout,

' nism illustrated in Fig. 1.

' speed at which the flyweights -the valve 38 in its neutral position,

' can be attained as indicated at I08, normally closed by a plug H0. A pressure indicating gauge II2 may be connected with the fluid pressure in the system, and this gauge may be calibrated directly in engine speed units, such as revolutionsper minute. If the calibrated gauge is used, the indicating dial I02 may be omitted, as its purpose will be served by the indicia on the pressure gauge. The piston 96 in the cylinder 88 may be provided with a suitable oil, seal, as indicated at H4, and the piston 50 .in the governor cylinder 48 may be either a lapped piston or maybe provided with an oil seal IIG. If an oil seal is used on the piston 50', it may be found desirable to use a coiled compression spring, as indicated at II8, to relieve the governor from the effects of any friction produced between surface of the cylinder 48.

Obviously, the operation of the mechanism illustrated in Fig. 2 so far described is substantially the same as the operation of the mecha- As the piston 98 is ad justed by turning the hand knob 90, the pressure acting upon the governor pistons 50' is changed, thereby changing the loading on the governor springs 46, which in turn changes the governor 32 actto maintain v in which it prevents .the flow of hydraulic fluid to and away from the propeller control mechanism 20.

With a control mechanism as illustrated in Fig. 2, a synchronizing action upon the engines if the various engine governors 30 are calibrated to react within permissible limits of each other, since the hydraulic control mechanism will place the same loading upon the spring of each of the governors. With this arrangement, if one engine tends to vary its speed with respectyto the other engine, the resultant change in the governor connected to the engine tending to change its speed will cause a variation in the pressure in the hydraulic system, which will result in a tendency of the other engines to change their speeds-to matchthe speed of the particular engine. However, as the governors of the other engines will also'afiect the pressure in the system, the result will be that the governor for the to change its speed will'be adjusted to bring that engine back into synchronism with the speeds of the other engines before the speeds of the other engines have varied a substantial amount from the selected rate. pressure upon .the governorslof all the engines, a condition of synchronized engine speed can be readily maintained with. properly calibrated engine governors.

As, under some circumstances, it may be found desirable, in the ease of a multi-engined vehicle, to remove one of the engines from the action ofthe combined engine control means, provision this seal and the inner v I28, the plunger I42is the line 88 leading particular engine tending Thus, by maintaining an equal I 3 has been made for connecting and disconnecting each engine separately with the common reservoir 88. A mechanism suitable for this purpose may include a valve block I20 mounted in the instrument .board 62 in convenient reach of the operator of the vehicle. This block I20 is provided for each engine with one aperture I24 within which is slidably mounted a valve' stem I28 having a port or reduced portion the adjacent ends of the conduits 88 when the valve is in the ,open position illustrated in Fig. 2. Each valve is controlled by a handle or knob I30 and a latch member I32. The latch member may ,be provided with catches I34 and I38 located at the open and closed position of the valve, and is desirably spring pressed in a direction to maintain the latch member in engagement with the edge of a plate I38 secured to'the top of the valve stem, the function of this latch member being to releasably hold the valve in either its open or closed position. The valve may be moved upon release of the latch member. I32 from its open gtO its closed position, or vice versa, by means of the hand knob' I30 which is secured to, or made integrally with, the plate I38. The valve block I20 is provided wit a second aperture I40 for each engine within which is disposed a plunger I42 spring urged downwardly by means of a coiled spring I44 disposed between a shoulder on the plunger and the under surface oi. the top of a gland nut I46. A screw I48 is screw threaded into the top of the plunger I42 and extends upwardly through an aperture in the plate I38 to contact with the underside of an abutment I50 provided on the stem of the hand knob I30. When the knob I30 is pulled outwardly, or upwardly as illustrated in Fig. 1, to close the valve also moved upwardly by contact of the screw head withthe plate I I38. and-draws the hydraulic fluid out of the upper 88 between "the cylinder and valve to relieve the pressure of the hydraulic fluid upon the piston 50'. The purpose of this arrangement for relieving the pressure in the cylinder of the governor is to permit the propeller to go immediately into its high pitch position, in case the engine is cut oif because of engine or propeller failure, or to render the governor subject to separate manual control in the event it is cut out of the common control mechanism for that purpose. If desired, a suitable individual engine control, such as is illustrated in Fig. 1, may also be connected into to each of the engine governors in order to provide manual control for each engine at times when combined or unitary engine control is not desirable.

In the form of the invention illustrated in Fig. 4, thegeneral arrangement of parts is similar to that illustrated in Fig. 2, the main difference being that instead of having a governor spring in each governor, a single spring is provided between the screw threaded stem and the piston disposed within the cylindrical reservoir. Referring par- :ticularly toFig. 4, the governor 30 is provided with a rotatable stem geared to the engine, and an axiallymovable valve similar to that illustrated in connection with the governor 30 in Figs. 1 and 2. In the governor illustrated in Fig. 4, the flyweights I52 have been illustrated as adjustable so that the governors can be more accurately calibrated. In this construction, the cylinder 48 is similarto the cylinder 48 of the governor illustrated in Fig. 1 and receives a lapped piston I54 directly connected with a slidable valve I58, and

I28 in line with end of the cylinder and the tubular connection a tubular conductor 88 leads from the top of the cylinder 48 through-the cut-out valve I20 which is similar in all respects to that illustrated in Fig. 2 and described above. From this cut-out valve, the conductor leads to the interior of a cylindrical reservoir I58 mounted on the instrument board 62. The reservoir I58 is provided interiorly thereof with a reciprocable piston I60, and is closed by a cover member I62, the conduits 88, 88a, 88b, and 880 being led into the closed bottom I 64 of the cylinderand opening into the space between the closed bottom and the adjacent end of the piston an upwardly extending annular boss I66 provided interiorly thereofwith screw threads into which is threaded a manually rotatable stem I 68 provided with a manually actuatable knob I10. The lower end of the stem I68 is pivotally mounted in an abutment plate I12 which is slidably, but nonrotatably, received in a cavity I" provided in the inner portion of the boss I66. A coiled compres sion spring I76 is interposed between the abutment I12 and the top of the piston I68. From this description, it will be observed that the spring I16 serves to maintain a selected degree of pressure upon the fluid within the reservoir I58, which pressure is transmitted to the pistons I54 of the various governors and controls the action of the flyweights so that all of the governors acting against the same pressure will have the same effect and maintain their respective engines at a constant common speed determined by the tension imposed on the spring I16 by the manually adjustable stem I68. The action of the mechanism illustrated in Fig. 4 in maintaining the various engines at the same common speed is substantially the same as that described in connection with Fig. 2.

As stated in connection with the description of Fig. 2, the change in the action of one governor will result in variation of the pressure of the hydraulic fluid, which pressure change will first react upon thegovernors of the other engines to slightly change their speed, and will then react upon the governors of'all the engines to bring the engine speeds back into synchronism.

While there have been illustrated and described three slightly modified arrangements of what is now considered to be the preferred form of the idea of 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 engine comprising,

of parts may be resorted to as come within the scope of the sub-joined claims.

Having now described the invention so that others skilled in the art may clearly understand the same, what it is desired to secure by Letters Patent is as follows:

What is claimed is:

1. In combination with a vehicle engine having an engine speed controlling'governor thereon, means for manually controlling the speed of said an expansible chamber device in said governor, a manually operable expansible chamber device carried by the vehicle upon which said engine is mounted, and hydraulic conduit means'connecting said two expansible chamber devices.

2. In combination with an airplane engine driving a controllable pitch aeronautical propeller, and a governor for controlling the speed of said engine by changing the pitch of said propeller, means for manually adjusting said gov ernor comprising, a piston and cylinder device on I 68. The cover I62 isprovided with said governor, a second piston and cylinder device, manually operable means for adjusting the volume of said second piston and cylinder device, and hydraulic conduit means connecting said two cylinders.

3. In combination with an airplane engine driving a controllable pitch aeronautical propeller and a governor for controlling the speed of said engine by changing the pitch of said propeller, a plurality of fiyweights in said governor, a spring for opposing centrifugal action of said flyweights, and means governor comprising, a cylinder on said governor, a piston in said cylinder operatively connected with said governor spring to alter the loading thereon, a second cylinder, a piston in said second cylinder, a manually operable screw adjustment means for moving the piston in said second cylinder, and hydraulic conduit means connecting the cylinder on said governor with the cylinder containing said manually movable piston.

4. In combination with an airplane engine driving a controllable pitch aeronautical propeller and a governor for controlling the speed of said engine by changing the pitch of said propeller, a plurality of fiyweights in said governor, a spring for opposing centrifugal action of said flyweights, and means for manually adjusting said governor comprising, a cylinder on said governor, a piston in said cylinder operatively connected with said governor spring to alter the loading thereon, a second cylinder, a piston in said second cylinder, manually operable means for moving the piston in said second cylinder, hydraulic, conduit means connecting the cylinder on said governor with the cylinder containing said manually movable piston, and a pressure gauge connected with said hydraulic conduit for indicating the pressure in the hydraulic system.

5. In combination with an airplane engine driving a controllable pitch aeronautical propeller and a governor for controlling the speed of said engine by changing the pitch of said propeller, a plurality of flyweights in said governor, a spring for opposing centrifugal action of said flyweights, and means for manually adjusting sald for manually adjusting said means connecting the cylinder on said governor with the cylinder containing said manually movable piston, a pressure gauge connected with said hydraulic conduit for indicating the pressure in the hydraulic system, and indicia on said pressure gauge reading directly in units of engine speed.

6. In combination with a plurality of jointly operating engines each provided with a speed controlling device, hydraulic means comprising a common pressure reservoir hydraulically connected with the speed controlling device of each engine for maintaining the operating speeds of all of said engines at a common rate.

'7. In combination with operating engines each provided with a speed controlling device, hydraulic means comprising a manually adjustable expansiblechamber reservoir hydraulically connected with each of said speed controlling devices for maintaining the operating speed of all of said engines at a common rate and manually selecting such rate.

a 8. In combination with a plurality of jointly a plurality of jointly ally operable .trolling device, hydraulic means comprising a common pressure reservoir hydraulically con nected with the speed controlling devices of said engines for maintaining the operating speed oi all of said engines at a common rate, and manumeans for independently disconnecting any of said engines from said reservoir.

9. In combination with a plurality of jointly operating engines 'each having a centrifugally actuated speed governor, hydraulic means comprising a common pressure reservoir'hydraulically connected with each of said governors for controlling said governors to maintain said engines at a common operating speed.

10. In combination with a plurality of jointly operating engines each having a spring controlled centrliugally actuated speed governor, hydraulic means comprising a common pressure reservoir hydraulically connected to each governor to transmit the pressure in said reservoir to the governor springs, to control said governors to maintain said engines at a common operating speed.

11. In combination with a plurality of jointly operating engines each having a centrifugally actuated governor provided with a spring, a piston and cylinder on each governor for changing the loading of said spring, hydraulic means comprising a common variable volumepressure reservoir hydraulicallyconnected with each of said governor cylinders, and means for manually varying the volume of said reservoir.

12. In combination with a plurality of jointly operating engines each having a centrifugally actuated speed governor provided with a piston and cylinder device for controlling the operation of the governor, hydraulic means comprising a common variable volume reservoir hydraulically connected with the piston and cylinder device of each governor, 'a spring for controlling the pressure of the hydraulic fluidin said reservoir, and manually operable means ior varying the loading on said spring.

13. In an airplane having a plurality of engines each driving a controllable pitch propeller,

setting, all the engines a centriiugally actuated speed governor on each engine for controlling the pitch of the respective propeller to maintain the speed of the engine constant, at a rate consistent with the governor means for synchronizing the speeds of comprising, a piston and cylinder device on each governor for controlling the setting thereoi, and a common pressure reservoir hydraulically connected with the piston and cylinder device oi each governor for maintaining the settings Mall of said governors the same,

being matched to maintain the at the same speed when the exerted on all the governor said governors respective engines same pressure is pistons.

14.'In an airplane having a plurality of engines each driving a controllable pitch propeller, a centrifugally actuated speed governor on each engine for controlling the pitch oi the respective propeller to maintain the speed of the engine constant at a rate consistent with the governor setting, means for synchronizing the speeds of all the engines comprising, a piston and cylinder device on each governor for controlling the setting thereoi, and a common pressure reservoir the piston and cylinder device of each'governor for maintaining the settings of all of said governors the same,

and cylinderdevice of each governor for setting, means for synchronizing the speeds of all the engines comprising, a piston and cylinder device on each governor for controlling the setting thereof, and a common pressure reservoir hydraulically connected with the piston and cylinder device of each governor for maintaining the settings of all of said governors the same, and manually operable means for disconnecting any of said governors from said reservoir.

16. In an' airplane having a plurality of engines each driving a controllable pitch propeller, a centrifugally actuated speed governor on each engine for controlling the pitch of the respective propeller to maintain the speed of the engine constant at a rate consistent with the governor setting, means for synchronizing the speeds of all the engines comprising, a piston and cylinder device on each governor for controlling the setting thereof, and a common pressure reservoir hydraulically connected with the piston maintaining the settings of all of said governors .the same, and manually operable connecting any of said governors from said reservoir, and means operatively associated with said manually operable means for relieving the pressure of the hydraulic fluid in the piston and cylinder device of a disconnected governor to allow the respective propeller to go to its high pitch condition or render said governor subject to independent manual control.

1'7. In combination with a mechanism operably connected with a controllable pitch propeller and a governor for controlling the speed of said mechanism by changingthe pitch of said propeller, means for adjusting said governor means for dis-v comprising, an expansible chamber device on rality of flyweights, a spring for opposing centrifugal action of said flywheights, and means for manually adjusting the force of said spring comprising an expansible chamber device operatively connected with said governor spring to alter the loading thereon and thereby change the governed speed, means for operating said expansible chamber device in both directions, said last named means comprising a control device and hydraulic conduit means connecting said expansible chamber device and said control device.

19. In combination with a prime mover having a speed controlling governor constructed and arranged to control the speed of said prime mover, means for adjusting said governor to vary the controlled speed, said governor and said by centrifugal force, and means for manually adurging said device in one direction, and means justing the force of said spring, said last named for introducing hydraulic fluid to said expansible means comprising an expansible chamber device chamber device for urging said device in the operatively connected with said governor spring other direction, and means vfor controlling the to alter the loading thereon and thereby change flow of hydraulic fluid to and from said expan- 5 the governed speed, means for operating said sible chamber device.

expansible chamber device in two directions, said ERLE MARTIN. last named means comprising resilient means JOHN ELMER ANDERSON.

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