US3736078A

US3736078A - Drive control and hold-in arrangement for a rotary actuator

Info

Publication number: US3736078A
Application number: US00158757A
Authority: US
Inventors: R G Read; N L Sikora; K W Verge
Original assignee: Bendix Corp
Current assignee: Bendix Corp
Priority date: 1971-07-01
Filing date: 1971-07-01
Publication date: 1973-05-29
Anticipated expiration: 1990-05-29

Abstract

A rotary actuator of the type in which a ring gear is orbited within a stationary reaction gear and about an output gear, the ring gear driven to so orbit by a torque producing vector which is constantly indexing about the circumference thereof to produce its orbiting motion is disclosed, in which an arrangement is provided for producing a hydraulically generated hold-in vector acting on the ring gear at an angle displaced from the torque producing vector and which also constantly indexes about the circumference thereof in the same manner so that the ring gear is maintained in engagement with the reaction and output gear during its orbiting motion without the use of rotary bearings or cranks. This arrangement also provides for a disengagement of the ring gear from the reaction and output gear in the event a hold-in vector of a certain magnitude is not produced to thus provide a means to controllably discontinue drive through the unit.

Description

United States Patent [191 Read et al. 9

[ 1 May 29, 1973 DRIVE CONTROL AND HOLD-IN ARRANGEMENT FOR A ROTARY ACTUATOR [75] Inventors: Ronald C. Read, Birmingham; Norbert L. Sikora, Southfield; Kenneth W. Verge, Farmington, all of Mich.

[73] Assignee: The Bendix Corporation, Southfield,

Mich.

[22] Filed: July 1, 1971 [21] Appl. No.: l58,757

[52] US. Cl ..418/60, 418/61 [51] Int. Cl ..F0lc 1/02, F03c 3/00, F040 1/02 [58] Field of Search ..4l8/60, 61, 210, 418/212, 213

, [56] References Cited UNITED STATES PATENTS 1,969,651 8/1934 Kretschmer ..4l8/61 3,383,931 5/1968 Patterson ..418/6l 3,389,618 6/1968 McDermott... ..4l8/6l 3,574,489 4/1971 Pierrat ..4l8/6l 3,453,966 7/1969 Eddy ..4l8/6l 3,490,383 1/1970 Parrett... ..418/6l FOREIGN PATENTS OR APPLICATIONS 398,678 9/1933 GreatBritain ..4l8/60 1,026,500 2/1953 France ..4l8/6l Primary Examiner-Carlton R. Croyle Assistant Examiner-John J. Vrabuk A ttorney-John R. Benefiel; Plante, Hartz, Smith & Thompson [57] ABSTRACT A rotary actuator of the type in which a ring gear is orbited within a stationary reaction gear and about an output gear, the ring gear driven to so orbit by a torque producing vector which is constantly indexing about the circumference thereof to produce its orbiting motion is disclosed, in which an arrangement is provided for producing a hydraulically generated hold-in vector acting on the ring gear at an angle displaced from the torque producing vector and which also constantly indexes about the circumference thereof in the same manner so that the ring gear is maintained in engagement with the reaction and output gear during its orbiting motion without the use of rotary bearings or cranks. This arrangement also provides for a disengagement of the ring gear from the reaction and output gear in the event a hold-in vector of a certain magnitude is not produced to thus provide a means to controllably discontinue drive through the unit.

22 Claims, 13 Drawing Figures PATENTED HAYES I975 SHEET 1 [1F 5 INVENTORS RONALD G- READ NORBERT L. SIKORA KENNETH W- VERGE ATTORNEY PATENTEU 3.736.078

SHEET '4 [1F 5 mvsmoRs FIGS RONALD e. READ NORBERT L. s||

KENNETH w. vs

. BY M R 8W ATTORNEY PAIENIEWZ 3,736,078

SHEET 5 OF 5 lNVENTORS RONALD G. READ NORBERT L. SIKQRA KENNETH W. VERGE BY 4;, H

ATTORNEY DRIVE CONTROL AND HOLD-IN ARRANGEMENT FOR A ROTARY ACTUATOR BACKGROUND OF THE INVENTION 1. Field of the Invention This invention concerns rotary actuators and more particularly, rotary actuators of the eccentric rotor type.

2. Description of the Prior Art In many applications of rotary actuators, a relatively high reliability decoupling capability is very desirable, and for such applications, such capability should be possible without compromising the basic simplicity and size of the device. Conventional rotary clutch arrangments add bulk and complexity and comprise reliability so that as a result rotary actuators have not offered the overall simplicity and reliability of linear fluid actuators having this capability. Such clutch arrangements also may introduce power losses as the actuator elements that are not decoupled will continue to be driven by the power source.

In addition, in rotary actuators of the type described in US Pat. No. 3,5 l4,765 the geometry of the gear set and the pressure angle of the gear teeth is such that the reaction of the output gear to the driving torque exerted by the orbiting member normally creates a demeshing force tending to disengage the orbiting member from the output gear with which it is normally engaged. Conventional arrangements support the orbiter on rotary bearings mounted on an eccentric member to withstand the force as well as to provide the driving force required to orbit this element or provide other structural constraints of the motion of the orbiting member.

In the aforementioned patent which discloses a rotary hydraulic force vector to provide the orbital forces, a system of absorbing this reaction on the flanks of the gear teeth spaced on either side of the demeshing vector is utilized.

In the conventional approach, the use of such rotary bearings increases power losses, complicates the design, increases manufacturing and servicing costs, and increases the inertia of the unit.

In the approach disclosed in the references U.S. patent, tooth wear may be a significant drawback in certain high tooth load applications.

Hence, it is an object of the present invention to provide a highly reliable and simple decoupling arrangement for such a gearset which does not involve significant power losses in the decoupled state.

Another primary object is to provide an arrangement for providing a hold-in force to counter the demeshing reaction which does not involve rotary bearings on the orbiting element or excessive reaction tooth loadings on the flanks of the gear teeth.

SUMMARY OF THE INVENTION These and other objects which will become apparent upon a reading of the following specification and claims are accomplished by providing a rotating hold-in vector acting on the orbiter along the eccentricity axis and at an angle to the torque producing vector and rotating about the gear set during orbiting in the same manner as the torque producing vector. In the event the hold-in vector is removed or declines to a certain predetermined minimum, the demeshing forces are allowed to disengage the orbiter from the output gear to thus discontinue drive through the unit.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a view of a specific embodiment of an actuator according to the present invention of a section taken along the longitudinal axis thereof.

FIG. 2 is a paritally sectional view of the actuator shown in FIG. 1.

FIG. 3 is an enlarged view of the section taken along the line 3-3 in FIG. 1.

FIG. 4 is a diagrammatic representation of the torque producing vector produced by the porting arrangement shown in FIG. 3.

FIG. 5 is a view of the section taken along the line 55 in FIG. 1.

FIG. 6 is a view of the section taken along the line 6-6 in FIG. 1. I

FIG. 7 is a view of the section taken along the line 7-7 in FIG. 6.

FIG. 8 is an enlarged view of the section taken along line 88 in FIG. 1.

FIG. 9 is a diagrammatic representation of the holdin vector produced by the porting arrangement shown in FIG. 8.

FIG. 10 is a view of the section taken along the line 10-10 in FIG. 1.

FIG. 11 is a view of the section taken along the line 11l1 in FIG. 1.

FIG. 12 is a view of the section taken along the line l2--12 in FIG. 1.

Fig. 13 is a sectional view of the position of the centering pistons in the decoupled condition of the actuator shown in FIGS. 5 and 10 in the driving condition of the actuator.

DETAILED DESCRIPTION In the following detailed description, certain specific terminology will be utilized for the sake of clarity and specific embodiments will be described in order to provide a complete understanding of the invention, but it is to be understood that the invention is not so limited and may be practiced in a variety of forms and embodiments.

Referring to the Drawings, and particularly FIG. 1, an actuator 10 according to the present invention is depicted in longitudinal section, which includes an externally toothed output shaft 12 supported at each end by bushings 14 and 16 disposed in front and rear cover plates 18, 20, respectively.

The output shaft 12 which has integral output gear external teeth is driven by a ring gear assembly 22 which includes an internally toothed sleeve 24 eccentrically positioned with respect to the output shaft 12 (See FIGS. 3 and 8) and meshing therewith. I

Fixed to sleeve 24 are a pair of torque producing motor rings 26 and 28 and an intermediate hold-in motor ring 30. The gear and sleeve assembly 22 is orbited about the output shaft 12 axis by means of a pair of fluid motors 32 and 34 described infra in detail acting on the motor rings 26 and 28, while the force required to maintain the internally toothed sleeve 24 in mesh with the externally toothed output shaft 12 against the demeshing forces generated by the tooth pressure angles and the reaction of the load to the torque produced is provided by a'fluid motor 36 also described in detail infra and acting on the hold-in motor ring 30. As discussed supra, such an arrangement is necessary since the assembly 22 is not structurally constrained to move in the orbit about the output shaft 12 axis but rather floats in the plane of its orbital motion in order to eliminate the inertia, friction and expense of bearing, crank or other such arrangments.

Referring to FIG. 3, the torque producing fluid motor 32, which is typical of both motors 32 and 34, is shown in detail, and includes an internally toothed reaction gear 38 which has the same number of internal teeth 40 machined therein as the gear 26 external teeth 42, but which are somewhat larger as shown to accommodate the orbiting movement of the gear 26 within the reaction gear 38 and about the output shaft 12 axis.

A plurality of

fluid actuation chambers

44, 46, 48, 50, 52, 54, 56, 58, and 60 are defined by the interior of the reaction gear 38, the exterior of the gear 26, and the space between a series of sealing vanes 62.

The sealing vanes 62 are retained at one end in sockets 64 beveled at 66 to allow swiveling movement of the vanes and disposed in slots 68 at the other end to allow both swiveling and sliding movement therein. Thus as the gear 26 orbits, the vanes move in and out of the slots and swivel to accommodate the relative movement between the reaction gear 38 and gear 26 while still preventing fluid from passing from one chamber to the other.

The chambers 44-60 are defined axially by a porting plate 70 on one side and a manifold 72 on the other, both of which are sealed to the reaction gear 38 at 74 and 76.

Each chamber of the torque producing motor 32 communicates with a radially extending slot 78 axially relieved into one side of the external gear 26 as shown in FIG. 1 and passing into the space between the teeth 42 to provide a fluid access to each chamber 44-60.

Each chamber 44-60 has an associated supply port 80 and return port 82 with the communication therebetween controlled by the registry of each slot 78 therewith, which is in turn controlled by the relative position of the gear 26 with respect to the porting plate 76.

The supply ports 80 are provided with a source of high pressure fluid via passages 84 which communicate with a supply annulus 86 (FIGS. 1, l2), groove 88 formed in the end plate 90, passage 92 (FIGS. 1, 11) formed by a series of aligned openings in the various plates and gears, groove 94 and recess 96 in manifold 98. Recess 96 is supplied with high pressure fluid via inlet port 100 (FIG. adapted to receive a fitting and high pressure line (not shown) from a source of fluid under pressure (also not shown).

The return ports 82 communicate via passages 102 with a return annulus 104 formed in the end plate 90, in turn communicating with passage 106 formed by aligned openings in the various plates and gears in the same fashion as passage 92.

Passage 106 communicates with groovel08 and recess 110 in manifold 98. Recess 110 in turn passes into outlet port 1 12 which is adapted to receive a fitting and return line (not shown) to the sump (also not shown).

Similar arrangements are provided in end plate 20, porting plate 114, and gear 28 so that the chambers associated with torque motors 34 are placed in communication with the source and the sump in the same man ner.

The

ports

80 and 82 and the slots 78 are so placed that as the gear 26 orbits about the axis of the output gear 12, the slots 78 come into registry successively with the supply ports 80 and then the exhaust ports 82 as a result of the circumferential or angular relative displacement between the porting plate allowed by the clearance between the external teeth 42 and internal teeth 40. Hence, at any given position, the chambers on one side of the eccentricity axis are pressurized and those on the other side are connected to the low pressure region. For example, in the position shown,

chambers

58, 60, 44 and 46 are pressurized since the slots 78 are uncovering all the supply ports of these chambers.

Chambers

50, 52, 54, and 56 are depressurized since the slots 78 are at least paritally uncovering these ports as shown. The net result is a fluid force (shown schematically in FIG. 4) acting on the gear 26 (and the rest of the assembly 22) in the direction so as to cause it to move about the axis of the gear 12 as indicated in FIG. 3. As the gear 26 moves, the slots successively uncover and cover supply and

exhaust ports

80 and 82 due to the shifting circumferential or angular relative position of the porting plate 70 and gear 26 so that an orbiting movement of the gear 26 axis about the axis of the output gear 12 results which movement will drive the output gear 12 by virtue of its meshing engagement of sleeve 24 secured to gear 26.

Ring 28 is similarly driven by fluid motor 34 so as to move in synchronism therewith and add to the torque produced by the ring 26. This arrangement produces an axial force balance within the unit to eliminate tipping of the ring gear assembly 22 which could be caused by a couple set up between a single torque motor and hold-in motor.

As this general type of actuator is now known in the art and is disclosed in US. Pat. No. 3,516,765, assigned to the assignee of the present application, a detailed analysis of the ratios obtained and other characteristics thereof is not here included for the sake of simplicity.

The torque exerted by the assembly 22 and the reaction of the load coupled to the output gear 12 will createa demeshing force as a component produced by the particular pressure angle of the teeth of the output gear 12 and sleeve 24 as discussed infra.

As discussed supra, in order to maintain the sleeve 24 in engagement with the output shaft as well as to provide an advantageous method of discontinuing drive through the unit 10, the actuator according to the present invention includes a separate fluid motor 36 acting on hold-in ring 30.

Ring 30 also fixed to sleeve 24 has external gear teeth 116 formed thereon and is disposed within a reaction gear 118 having the same number of internal teeth 120 formed therein, but of a larger size as with the torque gears 26 and 28 so as to allow orbiting movement of gear 30 within the gear 118 without rotation thereof.

It is noted that the geared relationship between ring 30 and reaction gear 118 may be eliminated, since the reaction forces may be completely absorbed by the reaction gears of the torque motors 32, 34.

The fluid motor 36 includes a plurality of

actuation chambers

122, 124, 126, 128, 130, 132, 134, 136, and 138 (FIG. 8) which are defined by the spaces between reaction gear 118 and hold-in gear 30 subdivided by a plurality of sealing vanes 140, retained in sockets 142 in hold-in gear 30 and slots 144 in the reaction gear 1 18 so as to prevent fluid from passing therebetween during orbiting movement of the hold-in gear 30. The chambers 122-138 are defined axially by porting plate 146 and cover plate 148 sealed to the reaction gear 118 at 150 and 152.

Communication with the chambers 122-138 is controlled by a series of generally U-shaped slots 154 recessed into the face of hold-in gear 30 and opening into the relieved area 156 (FIG. 1) on the external teeth 116. The slots 154 come into and out of registry with a radially offset series of supply and return ports 158 and 160 circumferentially spaced on a center line aligned with the output gear axis as the reaction gear 30 orbits as a result of the resulting relative radial or inand-out movement between the center line of the parts in porting plate 146 and hold-in gear. Thus, at any position such as that shown in FIG. 8, a portion of the chambers 122-138 are pressurized and the remainder are depressurized.

Supply ports 158 communicate with passages 162 (FIGS. 1, 8) in porting plate 146 which in turn communicates with a supply annulus 164 (FIGS. 1 and 6) which is supplied with fluid under pressure via passage 166 opening into inlet port 168 (FIGS. 2, 5) adapted to receive a fitting and high pressureline (not shown) to a source of fluid under pressure (also not shown).

The return ports 160 are connected to the return via passages 170 in porting plate 146 which open into a return annulus 172 in manifold 72 (FIGS. 1, 6) which in turn is connected via passage 174 (FIGS. 2, 5) to outlet port 176 adapted to receive a fitting and return line to the sump (not shown).

The U-shaped slots and the supply and return ports 158 and 160 are positioned so that as the hold-in gear 30 is orbited about the axis of the output gear 12 the in-and-out movement causes a progressive covering and uncovering of the supply and return ports 158 and 160 such that a fluid pressure is applied to the hold-in gear 30 by means of the fluid actuation chambers 122-138 in the direction along the eccentricity axis, tending to hold the sleeve 24 and output gear 12 in mesh as indicated in FIG. 9. As the reaction gear 30 orbits the progressive covering and uncovering of the ports 158 and 160 causes the line of action of this fluid force to constantly shift so that as the meshing point changes, the force generated is always directed so as to hold these gears in mesh.

In the position shown in FIG. 8,

chambers

132, 134, 136, and 138 are pressurized, while

chambers

122, 124, 126, 128, and 130 are depressurized to produce the hold-in force indicated in FIG. 9. As the gear orbits from the position shown, the next successive supply ports 158 of chamber 122 is uncovered while the trailing return port 160 of chamber 132 is covered and so on through the orbiting movement of the hold-in gear 30.

As can be appreciated by a comparison of FIGS. 3 and 8, the use of a porting arrangement that relies on the angular or circumferential relative displacement of the radial slots and ports to produce the successive pressurization of chambers for one of the torque producing fluid motors and the radial or in-and-out relative displacment of the circumferential slots and ports to produce the successive pressurization of chambers of the hold-in fluid motor is very advantageous, since the extreme displacements of each of these motions lags the other by 90 as the assembly 22 orbits about the output gear 12 axis. Thus the optimum arrangement of a pure torque producing vector and a pure hold-in vector which would be at right angles to each other as shown in FIGS. 4 and 9, is inherently capable of being produced by this porting arrangment. Furthermore, the full relative motion of the orbiting gears and the stationary plate is available to perform the porting function to thereby maximize the usable port sizes and minimize fluid losses therethrough.

It can also be appreciated from this description that purely fluid pressure forces are used in maintaining these gears in mesh, and that drive through the unit can be shut down very simply by discontinuing the supply of fluid to the hold-in fluid motor 36, as the demeshing forces will immediately tend to cause the assembly 22 including the internally toothed sleeve 24 attached

gears

26, 28, and 30 to move so as to be centered with respect to the reaction gears as well as the outer gear 12. This produces a decoupling of the output gear 12 from the sleeve 24 as shown in FIG. 13 as well as blocking of all the ports of the fluid motors 32, 34 and 36 to discontinue orbiting movement thereof. In this mode the output shaft 12 can be freely rotated without backdriving any gearing or motor members.

In order to insure accurate centering and secure positioning of the assembly 22 which in the decoupled state would be completely free-floating, two sets of centering pistons (three per set) are provided as shown in FIGS. 5, l0, and 13 in

manifolds

72 and 98.

The first set includes three

pistons

178, 180, 182, slidably disposed in stepped

bores

184, 186, and 188 in manifold member 72, and retained therein by means of

plugs

190, 192, and 194. Compression springs 196, 198, 200 bias the

respective pistons

178, 180, 182 inwardly toward the sleeve 24.

Annular chambers

202, 204, and 206 are connected to the supply for the hold-in fluid motor 36 via

passages

208, 210, 212 (FIGS. 6 and 7) communicating with the supply annulus 164 so that whenever fluid under sufficient pressure is supplied to the hold-in fluid motor 36, the pressure supplied thereby to

chambers

202, 204, and 206 causes the pistons to be retracted against the bias of compression springs 196, 198, 200 to the position shown in FIG. 5.

The second set of pistons includes three

pistons

214, 216, and 218 disposed in

bores

220, 222, 224 formed in manifold 98 and retained therein by means of

plugs

226, 228, and 230. Compression springs 232, 234, and 236 bias the

respective pistons

214, 216, 218 inwardly toward the sleeve 24.

Annular chambers

238, 240, 242 formed by steps in the

bores

220, 222, 224 are provided with the hold-in motor 36 supply pressure by means of passages (not shown) similar to

passages

208, 210, 212 communicating with annular groove 244 (FIGS. 1, l1). Annular groove 244 communicates with the hold-in fluid motor supply annulus 164 by means of passage 246 (FIGS. 6, 7), bore 248 in porting plate 146, passage 250 in reaction gear 118, bore 252 in porting plate 148,- and groove 254 (FIGS. 7, 11) in manifold 98.

Thus, in the same fashion as the first piston set, as long as fluid under sufficient pressure is supplied to the hold-in fluid motor 36,

pistons

214, 216, and 218 are able to overcome the spring force acting thereon and are held in the position shown in FIG. 10.

Whenever the pressure declines sufficiently to allow the compression springs 234, 236, and 238 to overcome the force created thereby, the pistons will move to seat on

shoulders

256, 258, 260 formed in the

bores

222, 224, and 228, respectively.

In this position, each piston of both sets contacts the sleeve 24 and causes it to be centered with respect to the axis of the output gear 12 as shown in FIG. 13 to effectively decouple the unit from the driven load.

It is noted that this decoupling is fail-safe as a loss of pressure due to ruptured lines or other malfunction will automatically cause this centering action due to the demeshing forces and the action of the compression springs.

It is also noted that, as the fluid pressure is used in a static sense, only negligible flow requirements are needed, and hence the hold-in system does not expend any significant power either in the coupled or decoupled state.

It can be appreciated that this coupling arrangement also allows the sleeve assembly to be unsupported by bearings and hence substantially reduces the inertia and frictional losses of the unit, as well as its cost while increasing its reliability.

While a specific embodiment has been described, the invention is not to be so limited and many variations are of course possible within the scope of the present invention.

What is claimed is:

1. An actuator comprising:

at least one reaction member having a reaction surface;

an orbiting member floating with respect to said reaction surface of said reaction member;

orbiting means selectively causing said orbiting member to orbit in engagement with said reaction member reaction surface;

an output member and means producing rotation of said output member in response to said orbiting movement of said orbiting member including a geared engagement therebetween;

hold-in means separate from said orbiting means producing a force acting on said orbiting member so as to maintain said geared engagement thereof with said output member during said orbiting of said orbiting member, whereby said floating orbiting member may be maintained in geared engagement against forces tending to produce disengagement thereof.

2. The actuator of claim 1 wherein said hold-in means includes a fluid motor and means supplying fluid under pressure thereto producing said force on said orbiting member.

3. The actuator of claim 2 wherein said orbiting means includes at least one fluid motor separate from said hold-in means fluid motor.

4. The actuator of claim 1 further including centering means positioning said orbiting member concentrically with respect to said reaction member and said output member whenever said hold-in force is less than a predetermined magnitude.

5. The actuator of claim 4 wherein said centering means includes at least one fluid operated device which is biased to tend to produce said centering action on said orbiting member but which bias is overcome by said fluid under pressure supplied to said hold-in fluid motor if of a predetermined magnitude.

6. The actuator of claim 5 wherein said centering means includes a plurality of fluid operated pistons disposed with their axes about the axis of said reaction member and means for causing said centering action of said orbiting member in response to movement of said pistons towards said reaction member axis.

7. The actuator of claim 6 wherein said centering means bias is produced by means biasing said pistons towards said reaction member axis and wherein said bias means is overcome by fluid under pressure supplied to said hold-in fluid motor.

8. The actuator according to claim 1 wherein said hold-in means includes a hold-in member connected to said orbiting member and orbiting therewith and wherein said hold-in force is exerted on said hold-in member.

9. The actuator of claim 8 wherein said hold-in member is disposed within a hold-in reaction member and wherein said hold-in means includes a plurality of fluid chambers partially defined by said hold-in member and hold-in reaction member and further includes means for successively pressurizing and depressurizing said chambers so as to produce said force.

10. The actuator of claim 9 wherein said hold-in means includes porting means producing said successive pressurization and depressurization of said fluid chambers in response to said orbiting motion of said hold-in member.

11. The actuator according to claim 9 wherein said porting means includes a stationary hold-in porting plate axially juxtaposed to said member having supply and return ports formed therein connected to a supply source and return respectively, and further including recesses formed in said hold-in member cooperating with said ports in said porting plate to produce said successive pressurization and depressurization of said chambers.

12. The actuator of claim 11 wherein said orbiting means also includes a plurality of fluid chambers defined in part by said orbiting member and said reaction member also includes porting means having a porting plate having supply and return ports formed therein and recesses in said orbiting member cooperating to produce said orbiting movement of said orbiting member by successive pressurization and depressurization of said chambers, and wherein one of said hold-in porting means or orbiting porting means supply and return ports are radially spaced from each other and the other are circumferentially spaced from each other, whereby said porting means successive pressurization and depressurization of one said hold-in member or orbiting member is carried out by radial movement of the holdin or orbiting members and the porting means pressurization and depressurization of the other of said orbiting as hold-in members is carried out by the circumferential movement of the orbiting or hold-in member.

13. The actuator of claim 8 further including a second reaction member having a reaction surface and second orbiting member floating with respect to said second reaction member and connected to said hold-in member and said first orbiting member and also further includes a second orbiting means selectively causing said orbiting member to orbit in engagement with said second reaction member reaction surface.

14. The actuator of claim 13 wherein said hold-in member is connected between said first and second orbiting members.

15. The actuator of claim 14 further including centering means acting on said connected orbiting and hold-in members tending to center said assembly on the axes of said reaction members, said centering means including means for acting on said connected orbiting and hold-in members along lines of action in planes between each of said orbiting members and said hold-in member.

16. An actuator comprising:

at least one reaction member having a reaction surface;

fluid hold-in means separate from said orbiting means producing a fluid force acting on said orbiting member so as to maintain said geared engagement thereof with said output member during said orbiting of said orbiting member, whereby said floating orbiting member may be maintained in geared engagement against forces tending to produce disengagement thereof.

17. The actuator of claim 16 wherein said fluid holdin means includes a fluid motor and means supplying fluid under pressure thereto producing said force on said orbiting member.

18. The actuator of claim 17 wherein said orbiting means includes at least one fluid motor.

19. An actuator comprising:

at least one reaction member having a reaction surface;

orbiting means selectively causing said orbiting memw ber to orbit in engagement with said reaction member reaction surface;

an output member and means producing rotation of said output member in response to said orbiting movement of said orbiting member including a geared engagement therebetween; fluid motor holdin means separate from said orbiting means producing a force on said orbiting member so as to maintain said geared engagement thereof with said output member during said orbiting of said orbiting member; and

means selectively discontinuing said hold-in force produced by said hold-in force whereby said floating orbiting member may be maintained in geared engagement against forces tending to produce disengagement thereof when said hold-in force is produced but is allowed to move out of geared engagement when said hold-in force is discontinued. 20.The actuator according to claim 19 wherein said hold-in means includes a hold-in member connected to said orbiting member and orbiting therewith and wherein said hold-in force is exerted on said hold-in member.

21. The actuator of claim 19 further including centering means positioning said orbiting member concentrically with respect to said reaction member whenever said hold-in force is discontinued.

22. The actuator of claim 21 wherein said centering means includes at least one fluid operated device which is biased to tend to produce said centering action on said orbiting member but which bias is overcome by fluid under pressure supplied to said hold-in fluid motor if of a predetermined magnitude.

Claims

1. An actuator comprising: at least one reaction member having a reaction surface; an orbiting member floating with respect to said reaction surface of said reaction member; orbiting means selectively causing said orbiting member to orbit in engagement with said reaction member reaction surface; an output member and means producing rotation of said output member in response to said orbiting movement of said orbiting member including a geared engagement therebetween; hold-in means separate from said orbiting means producing a force acting on said orbiting member so as to maintain said geared engagement thereof with said output member during said orbiting of said orbiting member, whereby said floating orbiting member may be maintained in geared engagement against forces tending to produce disengagement thereof.

12. The actuator of claim 11 wherein said orbiting means also includes a plurality of fluid chambers defined in part by said orbiting member and said reaction member also includes porting means having a porting plate having supply and return ports formed therein and recesses in said orbiting member cooperating to produce said orbiting movement of said orbiting member by successive pressurization and depressurization of said chambers, and wherein one of said hold-in porting means or orbiting porting means supply and return ports are radially spaced from each other and the other are circumferentially spaced from each other, whereby said porting means successive pressurization and depressurization of one said hold-in member or orbiting member is carried out by radial movement of the hold-in or orbiting members and the porting means pressurization and depressurization of the other of said orbiting as hold-in members is carried out by the circumferential movement of the orbiting or hold-in member.

16. An actuator comprising: at least one reaction member having a reaction surface; an orbiting member floating with respect to said reaction surface of said reaction member; orbiting means selectively causing said orbiting member to orbit in engagement with said reaction member reaction surface; an output member and means producing rotation of said output member in response to said orbiting movement of said orbiting member including a geared engagement therebetween; fluid hold-in means separate from said orbiting means producing a fluid force acting on said orbiting member so as to maintain said geared engagement thereof with said output member during said orbiting of said orbiting member, whereby said floating orbiting member may be maintained in geared engagement against forces tending to produce disengagement thereof.

17. The actuator of claim 16 wherein said fluid hold-in means includes a fluid motor and means supplying fluid under pressure thereto producing said force on said orbiting member.

19. An actuator comprising: at least one reaction member having a reaction surface; an orbiting member floating with respect to said reaction surface of said reaction member; orbiting means selectively causing said orbiting member to orbit in engagement with said reaction member reaction surface; an output member and means producing rotation of said output member in response to said orbiting movement of said orbiting member including a geared engagement therebetween; fluid motor hold-in means separate from said orbiting means producing a force on said orbiting member so as to maintain said geared engagement thereof with said output member during said orbiting of said orbiting member; and means selectively discontinuing said hold-in force produced by said hold-in force whereby said floating orbiting member may be maintained in geared engagement against forces tending to produce disengagement thereof when said hold-in force is produced but is allowed to move out of geared engagement when said hold-in force is discontinued.

20. The actuator according to claim 19 wherein said hold-in means includes a hold-in member connected to said orbiting member and orbiting therewith and wherein said hold-in force is exerted on said hold-in member.