US2494839A - Hydraulic steering apparatus - Google Patents

Description

Jam 17 1950 F. E. STEINMEYER 2,494,839

HYDRAULIC STEERING APPARATUS Filed April 5, 1946 4 Sheets-Sheet l 7'0 RESERVOIR T0 RESERVOIR ARM Z2 HORIJON7AL7 PORTS 25a, 260.,24a CLOSED ARM 22 Till? 25a NED CLOCkW/SE, 26a ops/v, 25

CONNECTED TO 24a} flaw Z 25 TURNED counlrskcwckwlss, 25:: ans 26a CONNECTED TO 240,.

T0 RESERVOIR INVENTOR.

8V WMQQV W ATTORNEYS Jan. 17, 1950 STEINMEYER 2,494,839

HYDRAULIQSTEERING APPARATUS Filed April 5, 1946 4 Sheets-Sheet 2 .INVENTOR W6; ywmm ATTORNEYS Jan. 17, 1950 F. E. STEINMEYER 2,494,839

HYDRAULIC STEERING APPARATUS 4 Sheets-Sheet 5 Filed April 5, 1946 INVENTOF2.

7 Wm m AT'i'oRwEvs Jan. 17, 1950 F. E. sTElNMEYER 2,494,339

HYDRAULIC STEERING APPARATUS Filed. April 5, 1946 4 Sheets-Sheet 4 INVENTOR- ATTORNEYS Patented Jan. 17, 1950 UNITED STATES PATENT I OFFICE HYDRAULIC STEERING APPARATUS Frank E. Steinmeyer, Garden City,

to Colombian Bronze Corporation,

N. Y., assignor Freeport,

N. Y a corporation of New York Application April 5, 1946, Serial No. 659,933

Claims.

My invention relates to improved hydraulic apparatus, and particularly to hydraulic steering apparatus. Ihe invention is illustrated particularly in connection with hydraulic steering apparatus for ships. 1

In known apparatus for this type, it is usual to provide a pump of the reciprocating piston type. This pump is actuated by the rotation of the steering shaft and it actuates a follower piston which operates the rudder. In such known apparatus, it is necessary to move the follower piston synchronously with the pump piston or pistons. Any. leakage in the line destroys or lessens this synchronism.

According to my invention, it is not necessary to maintain such synchronism. While the invention is not limited to a pump of the reciprocating piston type or to any type of pump, it is illustrated in connection with this type of pump. Instead of mounting the pump cylinders upon a fixed support as in prior practice, I mount said pump cylinder upon a turnable support which can be turned both clockwise and counter-clockwise, around the axis of rotation of the rotatable steering shaft. Th steering shaft actuates the pump piston or pump pistons by a cam or eccentric or by crank and link connections, or any suitable driving means. The fiow of liquid out of the pump is controlled by means of controlling valvemeans which are fixed to the frame or casing of the apparatus. The position of the rotatable support controls the opening and closing of said controlling valve-means. The turnable support is biased by spring means to a valve-closing position in which said controllingvalve-means are closed, so as to prevent the flow of liquid out of th pump cylinders while said support is in said valve-closing position. While the controlling valve-means are thus closed, the torque which is impressed upon the steering shaft by means of the steering wheel, is also impressed upon said turnable support, by means of the pump pistons and pump cylinders, and the pressure of the operating liquid. l

Hence, when the steering shaft is turned either clockwise or counterclockwisethrough aselected small angle, for example, an angle of 5 or less, the turnable support is initially turnedin unison with the steering shaft through. said selected small angle, until the turning movement of the turnable support opens said controlling valvemeans. The further turning of the suppoi'tis then stopped by a suitable fixed stop. The pump then acts like an ordinary pump which is actuated by the continued rotation of the steering shaft. When the torque on the steering shaft is discontinued and thepressur in the line drops to zero, the turnablesupport is moved back to its valve-closing position. The steering wheel can thus be turned several ievolutionsinase 2 lected direction, in order to turn the rudder in the selected direction through the desired angle. As soon as the turning of the steering wheel is discontinued, the valve-means are closed, by turning the support back to its valve-closing position, thus locking the rudder in its adjusted position, until the steering wheel is again turned.

Other objects and advantages of my invention are disclosed in the annexed description and drawings.

Fig. 1 is a diagrammatic top plan View, partially in horizontal section. Th pump which is illustrated is a two-cylinder pump. Fig. 2 is a rear vertical elevation of a commercial embodiment, the representationof the rear vertical cover of the casing having been omitted.

Fig. 3 is a top plan view of Fig. 2, partially in horizontal section, taken below the top wall of the casing.

Fig. 4 is a vertical longitudinal section through the line 4-4 of Fi 2.

The principle of the invention will be explained with reference to Fig. l.

Eccentric 2 is fixed to the horizontal, rotatable steering shaft I, so that eccentric 2 and shaft I are turned in unison. Shaft I has a central axis of rotation 43. The eccentric 2 is the usual cylindrical disc, and it has a horizontal central axis 44. Fig. 1 shows the turnable support 18 in the position in which the controlling valve-means are closed. In Fig. 1, the axis 44 of eccentric 2 is located vertically above axis 43 of steering shaft I. For convenience, the vertical line 415 and the horizontal line 42 are designated respectively as the major axis and the minor axis of the eccentric 2. The horizontal line 42 intersects the axis 44 of eccentric 2.

In Fig. 1, the pump cylinders 5 and 6 and the pump pistons 3 and 4 are horizontally disposed. Said pump pistons 3 and 4 have outer and planar walls of circular contour, which abut the periph ery of eccentric 2 at two horizontal lines which are perpendicular to the plane of Fig. 1, and which are defined by the ends of line 42. The horizontal line 4|, which intersects the axis 43 of shaft I, is coincident with the common lateral axis of cylinders 5 and 6, and pistons 3 and 4. The pistons 3 and 4 are biased towards eccentric 2, so that said pistons always abut the cylindrical periphery of eccentric 2 when the pumping action takes place, by means of compression springs which are located in the cylinders 5 and 5.

The turnable support [8 is yieldingly maintained in its position of Fig. 1, by suitable springmeans such as 32-32 shown in Fig. 2.

Pump cylinders 5 and 6 have flexible outlet pipes l and 8 which are connected to manifold l6, and flexible inlet or suction pipes I l and 12, which are connected to a reservoir for the oil or other operating liquid.

Between the cylinders 5, 6 and manifold I6, the flexible outlet pipes 1 and 8 are provided with outlet check-valves which are located in casings 9 and Ill, so that the liquid can flow only outwardly through outlet pipes I and 8. These casings 9 and I are fixed to the frame or casing of the apparatus.

Between the cylinders and 6 and the reservoir, the flexible inlet pipes I I and 'l2 are provided with inlet check-valves in casings H and 19, so that liquid can flow only inwardly in said pipes I! and I2. These casings I 4 and I5 are also fixed to the frame or casing of the apparatus.

These check-valves are conventional and are not shown. The manifold I6 is also fixed to the drarne or casing of the apparatus.

The controlling valve' means are located in a casing *I 'I, which is fixed to the frame or casing of the apparatus. Thesecontrolling valve-means can be, for example, an Electrol valve which is fully described in U. S. Patent No. 2,349,069 granted'May 1944. For this reason, the controlling valve-means are not illustrated.

Manifold I6 connected toaiport of easing I I by a pipe I6a, The control valves in casing H are of the non-leak .poppet type.

Respectiveoutlet pipes 25a'n'd 26 are'conne'cted to respective ports 25a and 26a of casing II. Another pipe 24 is connected at one end thereof to "a port 24a of casing 1 1, and at its other end to the same reservoir to which the inlet pipes I I and 1 2 are connected.

The poppet valves in v'alve='casing H are actuated and controlled by shaft 23, to which arm 22 is fixed. I

When the turnable support I8 and arm 22 are Ehorizont'al, al1 thevalves inc'asing I? are closed, so that no liquid can flow through pipes Mia, 25, 2 1,26. The cas'ing I'I is always filled with-liquid.

When ar'm 22 is turned olocl'cwise from its hori- 'z'ontal position to a lownw "aroly inclined position through an angle of less than 90, liquid is f-ree to enter valve-casing 11 "through pipe Ito, and to pass out of valve-"ca's'i-ng '-I'I only through :pipe 26. Insuch position of arm 22, liquid which enters valve-casing I7 through pipe 25 can flow only through pipe 24 to the reservoir.

'When arm 22 is turned counterclockwise through an a'ngle of "less 'than 90 to an upwardly inclined position, liquid can enter valve-casing 17 through pipe IGa, "pass out through pipe 25, and the liquid which enters casing H through pipe '2 to the reservoir.

Arm 2-2 -'is turnabl-y connected by pivo't pin 21 toalink'lal, 'which is' turnably connected by pivot pin 28 to the 'turnalole sii port -18.

Pipes 25 and 26 are connected to respective ports -21 and aaor a-=fixea cylinder 29. The follower piston'30 is recipro'cated between ports 21 and 28. This follower "piston '30 'actuates the rudder by conventional *means, which are not shown. The cylinder 29 isfmade of sufficient volume between ports 27 and 28, so that "it requircs a plurality 'of'coinplete revolutions of the steering shaft I, to move "the follower piston 38 from one extreme position thereof to its other extreme position.

To 'explain the "operatioh of the device, it is assumed thatthe's'teering shaf t l is turned clockwise, When the parts are in the respective posrtions of Fig. 1.

When eccentric 2 is'turned clockwise, it urges piston 4 inwardly in its' c'ylinde'rfi, thus producing pressure upon the incompressible liquid in outlet pipe 8, manifold I6 and pipe 16a. This liquid cannot enter casing II, because all its valves are then closed. This liquid cannot flow reversely in pipe I, because of the check-valve in casing 9. The piston '4 is thus, in effect, locked to eccentric 2. 'The eccentric 2 'thus exerts a clockwise torque upon support I 8, so that its turns clockwise in unison with eccentric 2. When support I8 is thus turned, the shaft 23 is turned clockwise by arm '22 and link I 9.

There may be afslight play between the parts. As "soon a's arm 22 is thus turned clockwise through a small angle, liquid can fiow out of cylinder 6 through pipe 8 through manifold I6, pipe 16a, casing I'I, pipe 26, but not through pipes 25 and 24. Pressure is thus exerted upon the follower piston 30, to move it towards :port 21, thus turning the-rudder in the selected direction. The liquid which is thus pumped out of cylinder :6, must therefore be pumped against the load pressure which is required to actuate the follower piston ilfl. -The force which is exerted by eccentric '2 against piston 4, is =-applied along a line which 'is above axis 43-, until eccentric 2 has been turned substantially 90 "from its position of Fig. 1,

Hence the eccentric 2 will apply a clockwise torque upon-support I8,1untileccentric2 has been turned substantially 90 from 'its position of Fig. 1, making allowance for the small angle in which support I 8-is tur'nedin unison withsnaft I.

The turning inovement of support I8 around the axis 43st shaft 1 is stopped by a suitable fixed stop, when support I8 has-"been turned from its position of Fig. 4 through a selected 'angle. For example, this selected nngle may be 5 01 less.

when 's'liaft "and ec n'tric 2 'arethus turned clockwise from their positions of Fig. 1, the eccentric 2 will f'or'ce piston l inwardly ina pumping stroke in its cylinder is, until the "line 15 or eccentric 2 is on line II, while holding "sup ort I8 turned clockwise "from its position of Fig. 1, a ainst the aforesaid stop. While piston 4 is thus moved in its pressure or pumping stroke, the piston 3 is mov d outwardly by its compression'spr'in'g in its cylinder '5 in a suction stroke. I When eccentric '2 is turned clockwise through I "from said position in which line 45 is on line H, to a positionin which line 45 is again on line II, the piston '3 is moved inwardly in its cylinder --5 in a respective pressure or .pumping stroke, and piston 4 is moved outwardly by its compression spring in cylinder 6 ins respective suction .--stroke, while the clockwise torque is maintained uponsupport I8.

Further clockwise "rotation of eccentric -2 'during the next quarter revolution, back to the position -of Fig. 1, 'causes outward movement of piston 3 and inward movement of pisto'n 4.

During the pressure or pumping sm-lake of piston :3, liquid is :puinped out of cylinder 5 through its flexible outletspi e I, through manifold 1e, .Ipipe- 1e21, eas ing I 1, and to pipe 26, but nottnrough pipes-'2E- a'nd1'24. The follower 'piston 30isthus 'fuitheractuated towards port-21.

Hence the steering shaft "I can'be turnedclock"- wise throughseveral complete revolutions, to -recipro'ca-te the m'ppistons and "4 in alternate pressure and'suc t'lo strdkes, while supplying liquid under "pressure through pipe 26, to "actuate the follower piston 31'! "in the "same selected direction.

The same operation *is secured when the steering sha'ft I 'i's 'tu'r'ned counterclockwise, in which case the support I8 is held tilted "counterclockwise through the selected angle, until the support l8 abuts another stop.

When the rotation of shaft l is stopped, the pressure of the liquid in the respective power line drops to zero.

As an example, it is assumed that the clockwise rotation of the shaft is stopped, when the major axis 45 is in the vertical position of Fig. 1. At this time, the support I8 is slightly tilted clockwise from its horizontal position, preferably through a maximum angle of or less. Immediately prior to the time that transverse line 45 of eccentric 2 again reaches its position of Fig. 1, piston 3 is moving outwardly in its cylinder 5 and is approximately midway in its suction stroke; piston 4 is moving inwardly in cylinder 6 and is approximately midway in its pumping stroke; support I8 is tilted clockwise from its position of Fig. 1, through the aforesaid small angle, and follower piston 30 is moving forwardly towards port 21. At this time, the piston 4 contacts the eccentric 2, along a lateral horizontal line which is in the plane of line 42. The momentum of piston 4 and of the liquid which is then subjected to pressure by piston 4, will move piston 4 slightly away from eccentric 2, when line 45 resumes its position of Fig. l, and the momentum of piston 3 and the liquid in its suction line will force piston 3 against eccentric 2 at the level of line 42. This will relieve the counterclockwise torque on support I8, so that its spring means, such as the springs 32--32 shown in Fig. 2, will return said support It to its normal horizontal position of Fig. 1, thus closing the valves in casing l1, and locking the rudder in its adjusted position.

When the shaft I is turned counterclockwise, each pumping stroke of each piston 3 and 4 will force liquid out of casing through pipe 25, but not through pipes 24 and 26.

When the follower piston 30 is moved towards front port 21, the liquid which is in front of piston 3|] is forced through pipe 25, and such liquid is by-passed in casing I! through pipe 24 to the reservoir. Similarly, the liquid which flows through pipe 26 to casing I! when piston 30 is moved rearwardly, is by-passed through pipe 24 to the reservoir.

If the eccentric 2 is replaced by other driving means for the pump, there is sufiicient play in such driving means, or sufficient play in the control valves, to turn the support It through the required small angle to horizontal position, when the actuation of shaft is stopped. I

As shown in Fig. 3, the practical embodiment of Figs. 2-4 has two eccentrics 2 and 2a. The eccentric 2 operates the pump pistons 3 and 4, and eccentric 2a operates pistons 3a and 4a. The operation is the same as in the embodiment of Fig. 1. These pump pistons have bearing plates B adjacent the eccentrics 2 and 2a.

Fig. 3 shows one of the compression springs S, which urges the respective pump piston outwardly in its respective cylinder in a respective suction stroke against the periphery of the respective eccentric.

The parts are located in a casing 3|, which has a removable cover 3|a. This casing 3| is filled with oil or other liquid, up to the level of the line L in Fig. 2.

The support I8 is a frame which is turnable around bearings which are coaxial with the axis of shaft I.

Fig. 2 shows two tension springs 32. Each tension spring 32 has a long U-shaped end 33 which i .slidably embraces a respective plate of support l8. Thus, if the support I8 is turned clockwise from its horizontal position of Fig. 2, the left spring 32 will be extended to exert its tension, and the support I8 will slide relative to the slideend 33 of the right spring 32, thus creating a counter torque which biases support l8 back to its horizontal position.

In the commercial embodiment of Figs. 2-4, one end-portion of support I8 is turnably connected by a pivot'pin 20 to a link 35, which is turnably connected by a pivot pin 31 to a lever 60, which is turnably connected to fixed casing 3| by a pivot pin 34. Lever 6B is turnably connected by pivot pin 36 to the link l9, which is normally horizontal in the commercial embodiment, in which the arm 22 is normally vertical. The normally horizontal link I9 is connected by a pivot pin or ball-joint 2| to the normally vertical arm 22.

The cylinders 3 and 3a have respective outlet pipes and la and respective inlet pipes H and Ila. The check-valve for pipes I and la are located respectively in casings 9 and 9a. The check-valves for the inlet pipes H and Ila are located respectively in casings l4 and Ma.

Fig. 4| shows only a part of pipe lfia. This pipe |6a is connected to port |6b of manifold It. The outlet check-valve casings such as 9 and 9a, are connected directly to manifold It, by means of suitable alined ports.

Pipe 25 is connected to a coupling 25a which is fixed to the bottom wall of casing 3|, and pipe 26 is connected to a similar coupling 26a. These couplings are also respectively connected to the respective ports 21 and 28 of the cylinder 29.

Since the parts which are not shown in Figs. 2 and 4 are duplicates of the illustrated parts of Fig. 1, the construction is clear.

As an example, when shaft is turned clockwise as viewed in Fig. 2, the support |8 is turned initially clockwise in unison with shaft I, thus tensing the left spring 32, while the support l3 slides relative to the U-end 33 of the right spring 32. This provides a reverse or counterclockwise torque upon support I8. The lever 60 is thus turned counterclockwise by link 35, thus actuating link I!) to turn shaft 23 clockwise, until the lower end-portion of lever 60 abuts the wall of casing 3|. Since the casing 3| is filled with oil below the line L, the blow of lever 63 against the wall of easing 3| will be cushioned, thus eliminating objectionable noise and vibration. The lever 63 thus acts as a stop for support |8, so that it remains tilted in clockwise position at a small angle, While the clockwise rotation of shaft is continued.

When the shaft is turned counterclockwise, the right spring 32 is tensed, and the support I8 slides relative to the U-end 33 of the left spring 32. Link 35 is now raised to turn lever 63 clockwise, thus turning shaft 23 counterclockwise. The

upper end-portion of lever 60 then abuts the wall of casing 3|, thus providing the necessary stop. In Fig. 2, the axes of the pivot pins 3'! and 34 are in the same horizontal line.

I thus use a single lever 60 for operating the shaft 23 and to function as a stop.

As shown in Fig. 4, the top of casing 3| has a vent cap C, so that the internal pressure of casing 3| is always equal to external atmospheric pressure.

I have described a preferred embodiment of my invention, but numerous changes and omissions and additions can be made without departing faaicnsee .r'e'cipro'cated between thep'orts i2?! :and 328, represent any kind :of servo motor'whichis operated we rby the discharge of liquid zfrom a pressure pump -:of any type, which :is v.operatively connected to shaft l. The invention alsoiappliesfzoapparatus in which the shaft l is rotate'd'ina single selected direction.

The apparatus can "be used for :steering -ve- FhiCIBS in addition to'steering ships.

'In the specific embodiment disclosed, the

f'pump-operating means 2 also move the support Hi from its normal position :in'Fig. .1 to a posi- 131011 in which said support 15B also holds the controlling valve-means in casing 17, in respective open and closed positions, but the invention is not limited to this dual function of said pumpoperatin means.

While I have illustrated a pressure hydraulic pump, the invention is not limited thereto, and it is not necessarily :limited to the use of anydraulic system, because the operating fluid may be air or a gas, in-any type of power transmission H The cylinder '29 and piston 3 0 exemplify "a reversible servo-motor which may be of any type and which has respective ports, as exemplified by ports 2! and 28, through'which the operating fluid can enter said servo-motor and pass out of v said servo-motor. The direction of movement of said servo-motor depends upon the direction of movement of the operating fluid in said servomotor between said ports. The controlling valvemeans are adapted to connectieither of :said ports to said pump. Thesecontrolling valve-means are connected in any manner to the shaft, so that when the shaft is turned :inone direction, one of said ports remains connected 'to said pump, and when the shaft is turned in the reverse direction, the other port remains connected to said .pump, While the shaft is turned through any desired angle. Optionally, said controlling valvemeans are biased so as to close both said ports when the shaft is stationary.

The ports by which pipes 25, 24, '26 are respectively connected to casing H, are respectively designated as 25a, 2504,2611. The leg-end adjacent Fig". 1 sufiiciently designates the operation of the controlling valve-means in "casing ll, since the I same are well-known per se.

I claim: 1. Hydraulic apparatus which comprisesarotatable shaft, a pump operatively connected to said shaft by pump-operating'means and opera'ted -:by the'rotation of saidshaft to discharge liquid from said pump, a servo-motor connected :to said pump by connectin -pipe-means,:said servo-motor being operated by the liquid which is discharged from said pump through said pipe- 7 means, movable controlling valve-.means located in said pipe means between :said pump'andsaid s61V0mOtOl, said controlling valve-rneans being movable to a closing position to prevent'theflow of liquid through said pipesmeans from said pump to said servo-motor, said controlling valve- :means being also movable to :an open position to permit said now of .liquid, said pump being .ifixed to a .rnovable support, said support being connected to said controlling valve-means byconnecting means to operate said controlling valvemeans to either of said positions, said support being biased by biasing means to a :normal :posi- "tion in which said support holds said controlling valve-means in :said closing position, said shaft rotatable shaft, a pump operatively connected to .said :shaft by pump-operating means and operrated :by the rotation of said shaft in either direction to discharge liquid from :said pump, :a servo-motor which has two sides and Which is operable in two opposite directions, said servo- :motor being oonnectedto said pump by connect- :ing :pipe means "which :are connected to the two opposite sides of .said servo motor, said servom'otor being operated by the liquid which is discharged from said pump through said pipemeans, movable controlling valve-means located finisaid pipe-means between said pump and said servo-motor, said controlling valve-means be- :ingmovable :to respective closing and opening positions to respectively prevent and permit the flowof liquid from said pump to said servo-motor and to direct the flow of said liquid into either of 'the two sides of said servo-motor, thereby controlling the direction of operation thereof, said pump being fixed to a support which is turnable :around the axis of said shaft, stop-means for 3 niiting the turning movement of said support in respective opposed directions, said support be- Ling connected to said controlling valve-means by connecting means to operate said controlling valve-means to either of said positions, said turnable support being biased by biasing means to a normal position in which said support holds said controlling valve-means in said closing position, 'said pump-operating means being constructed and operative to turn said support in unison with said shaft until -'ie turning movement of said support is stopped by said stopmeans, said pump-operating means being constructed and operative to continue to operate said pump upon continued rotation of said shaft after said turning movement of said support has been stopped, said support holding said controlling valve-means open in a respective selected opening position and directing the'flow of liquid into a selected side of the servo-mo'torto operate said servo-motor 'by said pump in a selected direction by the continued rotation of said shaft when said support abuts said stop-means, the pipe-means which are connected to a respective end-of said servo-motor temporarily acting as an inlet for said servo-motor when it .is operated in one direction and temporarily acting as an outlet for said servo-motor when it .isoperate'd in the opposed direction, said controlling valvemeans being connected through an openport to an exhaust for said servo-motor and connecting to said exhaust the pip -means which are tempiston-axis which intersects and is lateral to the shaft-axis, said shaft and said eccentric bein located between said pistons, each said cylinder having an inlet pipe which is connected through an inlet check-valve to a reservoir, each said cylinder having an outlet pipe which is connected through an outlet check-valve to a casing in which controlling valve-means are located, said controlling valve-means being operated by a valve-shaft, said valve-shaft being connected to said turnable support, a servo-motor which comprises a servo-cylinder which has longitudinally spaced ports and a servo-piston which is slidable in said servo-cylinder between said ports, a first servo-pipe which connects said casin to one of said ports, a second servo-pipe which connects said casing to the other of said ports, a third pipe connected at one end to said casing and connected at its other end to said reservoir, said controlling valve means being movable (a) to a. position in which said casing is closed; (1)) to respective positions in each of which liquid can enter said casing through a selected outlet-pipe and liquid can flow out of said casing through a selected servo-pipe and liquid can enter said casing through the other servo-pipe to be lay-passed to said reservoir through said third pipe; said support being biased by biasing means to a normal position in which it holds said controlling valve-means in said position (a); said support holding said controlling valve-means in said position (b) when said support abuts said stopmeans.

4. Hydraulic steering apparatus comprising a steering shaft, an eccentric mounted on said shaft, a pair of cylinders on diametrically opposite sides of said eccentric, fluid in said cylinders, a pair of pistons in said cylinders in operative engagement with said eccentric whereby rotation of the steering shaft and of the eccentric mounted thereon causes reciprocating movement of the pistons, said piston cylinders being mounted on a pivotable support whose pivot coincides with the longitudinal axis of the steering shaft, stop members which limit the pivotal movement or said pivotally mounted support, tension means connected to said pivotally mounted support and normally urging said support into a neutral position, the torque action of said steering shaft upon said pivotal support through the pistons which the eccentric on said shaft engages being such as to cause pivotal movement of the pivotal support against the action of the tension means and in the direction in which the steering shaft is turned, such pivotal movement ceasing when the pivotal support engages a stop member, further turning movement of the steering shaft causing axial movement of the pistons without affecting the angular position of the pivotal support, a valve, fluid in said valve, pipelines connecting the two cylinders with said valve, a fluid operated servo-motor which has two sides and which is operable in opposite directions, pipelines connecting said valve to the two sides of said servo-motor and valve controlling means connected to said pivotal support whereby pivotal movement of said support operates said valve and opens and closes the pipelines to the respective sides of the servo-motor, whereby the servo-motor is caused to operate in one direction when the flow of liquid under pressure is admitted by the valve into one side of said servo-motor and whereby the servo-motor is caused to operate in the opposite direction when the flow of liquid is directed into the opposite side thereof by said valve, each pipeline operating temporarily as an inlet for said servo-motor when it is operated in one direction and operating temporarily as an outlet for said servo-motor when it is operated in the opposite direction, an exhaust for said servo-motor, said valve being actuated to connect the pipeline which is temporarily acting as an outlet to said exhaust when said pivot support engages a stop member.

5. Hydraulic steering apparatus comprising a steering column, a rotatable support mounted on said steering column, said support being co-axial with said steering column, tensioning means connected to said rotatable support and tending to hold said support in neutral position, stop members adjacent said support which limit the angular movement of said support, a pair of diametrically opposed cylinders mounted on said support, pistons and liquid under pressure in said cylinders, and an eccentric fixedly mounted on said steering column and operatively engaging said pistons, whereby rotary movement of said steering column provides a torque action upon the support through said eccentric, said pistons and said liquid under pressure, causing pivotal movement of said support in the direction of rotation of said steering column against the action of the tension means connected thereto, said pivotal movement of the support ending when the support is brought into contact with one of the stop members, further rotary movement of the steering column causing actuation of said pistons in their respective cylinders, pipelines connected to said cylinders, a valve connected to said pipelines, a source of liquid under pressure connected to said valve, additional pipelines connected to said valve and a fluid operated servo-motor connected to said additional pipelines, said servo-motor being operable in two opposite directions and having two sides to receive said liquid under pressure through said additional pipelines, said valve being connected with a controlling member which is operatively connected to the rotatable support, whereby angular movement of said support in response to rotation of the steering column causes the valve to open and close to direct the flow of liquid under pressure through the additional pipelines into either side of the servo-motor, thereby causing said servo-motor to operate in a selected direction, each pipeline operating temporarily as an inlet for said servo-motor when it is operated in one direction and operating temporarily as an outlet for said servo-motor when it is operated in the opposite direction, an exhaust for said servo-motor, said valve being actuated to connect the pipeline which is temporarily acting as an outlet to said exhaust when said pivot support engages a stop member.

FRANK E. STEINMEYER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 564,265 Wiking July 21, 1896 2,236,467 Clench Mar. 25, 1941 FOREIGN PATENTS Number Country Date 360,458 Great Britain Nov. 2, 1931

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