Abstract: A joint having two-axis construction having a distal member and a main member joined in co-linear pivotal relation that provides enhanced joint strength and compactness. Hydraulics further provide variable extension assist and an infinite number of flexion stops for controlled flexion flow, and two gears provide a functional gear ratio that also promotes compact construction by reducing the amount of hydraulic piston travel required for maximum joint extension. A drive gear associated with the main member is positioned between the distal end of the piston and a transfer gear partially press-fit into a cut-out in the distal member, to provide needed radial hydraulic force transfer. Although it is contemplated for joint use to be primarily in orthotic devices that assist the movement of an inadequately functioning body limb, any application for which the mechanical joint's compact configuration would provide assistance or technical advantage is considered to be within its scope.

Abstract: An in-wheel assembly includes an in-wheel actuator and a wheel. The in-wheel actuator includes a driving motor; a hollow shaft which is disposed inside of the driving motor and driven by a rotational speed of the driving motor to rotate; a decelerator which is arranged in an inner space of the hollow shaft and configured to reduce a rotational speed of the hollow shaft and output the reduced rotational speed to an output shaft; and a shaft support which is configured to support the hollow shaft to rotate with respect to the driving motor and the decelerator. The wheel accommodates the in-wheel actuator and is driven by a rotational speed decreased by the decelerator to rotate.

Abstract: In a planetary gear device, a first side plate as carrier is formed to a disc plate shape and secures thereto pins to protrude the pins from one end surface in an axial direction. The outside diameter of the first side plate is formed to be a small diameter on one side in the axial direction and a large diameter on the other side in the axial direction. The first side plate is provided with press-fitting hole portions with the pins press-fitted thereinto and small-diameter side concavities that are formed on the press-fitting hole portions on one side in the axial direction, that open to one end surface in the axial direction of the first side plate and that have internal surfaces being out of contact with the pins at at least parts thereof.

Abstract: An actuating device employed in a steering system comprises an input-side sun gear, which is provided on an input shaft of a steering shaft and is rotated integrally with the input shaft of the steering shaft, an output-side sun gear, which is provided on an output shaft of the steering shaft and is rotated integrally with the output shaft, an input-side planetary gear, which is engaged with the input-side sun gear, revolves around the input-side sun gear, and is provided on a planetary gear shaft, and an output-side planetary gear, which is engaged with the output-side sun gear, revolves around the output-side sun gear, and is provided on a planetary gear shaft, the output-side planetary gear being spaced apart from the input-side planetary gear.

Abstract: A pinion carrier includes a first disc including ring segments, each ring segment extending angularly about an axis and spaced angularly from the other ring segments, a second disc, spacers secured to the discs and separating the discs axially, and retention elements, each retention element secured to one of the ring segments.

Abstract: A planet carrier and clutch housing for a transmission is provided. The planet carrier and clutch housing includes a first deck, a second deck, an annulus and a plurality of planet carrier posts. The first deck has an inner rim, an outer rim, planet shaft bores and control oil bores. The second deck has an inner rim, an outer rim, a piston recess disposed between the inner and outer rims, planet shaft bores and control oil bores fluidly coupled to the piston recess. The annulus extends from the second deck. The planet carrier posts connect the first deck to the second deck, and each post has a control oil bore fluidly coupling respective control oil bores in the first and second decks. The inner surface of each second deck planet shaft bore may include a groove to receive a planet shaft seal.

Abstract: A planetary carrier includes a side plate having a front face and a shaft journal which is arranged on the front face of the side plate. A bearing seating is formed on an outer circumferential surface of the shaft journal on a front-face-proximal end of the shaft journal. The planetary carrier has an annular groove directly adjacent to the bearing seating in coaxial relationship to the shaft journal and undercutting the front face and the outer circumferential surface.

Abstract: A method of mounting a gear train to a torque frame includes providing a unitary carrier having a central axis that includes spaced apart walls and circumferentially spaced connecting structure defining mounts for interconnecting the walls. Spaced apart apertures are provided between the mounts at an outer circumference of the carrier. Gear pockets are provided between the walls and mounts extending to the apertures, and a central opening in at least one of the walls. A plurality of intermediate gears and a sun gear are inserted in the carrier. A first ring gear half is placed about the outer periphery of the intermediate gears, and attach a torque frame to the carrier.

Abstract: A method and apparatus for a transmission system selectively positioning sets of planet gear support bearings (50, 55, 80, 90) to achieve an optimized load distribution among a set of drive planet pinions (22) and a set of idler planet pinions (70) disposed in engagement between two reaction gears (30, 40) in the transmission system (A, A1), for splitting an applied load between at least two pathways between an input and an output.

Abstract: A planetary gear reduction mechanism is provided in a housing for making up a revolving apparatus, and the planetary gear reduction mechanism is constituted by a sun gear, a plurality of planetary gears, and a carrier. Lubricating oil for lubricating the planetary gear reduction mechanism is stored in the housing. A doughnut-shaped guide member for covering meshing portions of the sun gear and the planetary gears and for receiving the lubricating oil scattered from the meshing portions and guiding it to planetary gear bearings is provided at an upper position of the planetary gear reduction mechanism. Hence, the lubricating oil which is scattered from the meshing portions of the sun gear and the planetary gears can be efficiently guided to the planetary gear bearings through the doughnut-shaped guide member.

Abstract: An exemplary turbine engine assembly includes a first shaft that is rotatably driven by a second shaft of a gas turbine engine and a compressor hub driven by the first shaft. The compressor hub is within a compressor section of the gas turbine engine. An epicyclic gear train is driven by the first shaft. A common attachment point secures the first shaft and the compressor hub to the second shaft.

Abstract: A system and method for fixing a fan drive gear system carrier to a torque frame are disclosed. The carrier and torque frame respectively have a hole and an aperture which are aligned with one another. A retainer pin is inserted in to the aligned hole and aperture in an interference fit relationship with at least one of the hole and aperture.

Abstract: A compact planetary gear reduction mechanism having a universal gear reduction ratio is provided, which comprises: an input shaft rotatable about a first rotational axis; at least one planetary gear having a first and a second gear of the same shape integrated together rotatably about a third rotational axis (O3) but in out of phase with each other; an eccentric rotary plate for transmitting the rotational motion of the input shaft to a shaft mechanism which in turn transmits the eccentric rotation of the eccentric rotary plate to the planetary gear; an external fixed sun gear meshed with the first gear of the planetary gear; and an external driven sun gear to be connected to the output shaft of the gear reducer, having a different number of gear teeth than the fixed situ gear and meshed with the second gear of the planetary gear.

Abstract: A vessel propulsion apparatus includes a prime mover, a propeller shaft, a planetary gear train, a lower case, a cylindrical housing, and a fixing member. The planetary gear train is disposed on a propeller axis. The propeller shaft and the planetary gear train are housed in the lower case. The housing surrounds the propeller shaft about the propeller axis inside the lower case. The housing supports a sun gear such that the sun gear is not rotatable with respect to the housing. The fixing member is fixed to both the lower case and the housing.

Abstract: A low mass, two piece planetary gear carrier having an integrated clutch housing comprises a first carrier flange and clutch housing and a second carrier flange which are secured together by a plurality of threaded fasteners extending through hollow dowels. A plurality of planet gears receive needle bearing assemblies which are, in turn, supported on pins or stub shafts. The stub shafts are retained in the carrier by transverse retaining pins received in the second carrier flange and extending into the shafts. Unitized washers are disposed between both faces of the planet gears and the flanges. The method of assembly is also a feature of the present invention.

Abstract: This disclosure relates to a magnet assembly including an epicyclic gearing system. The epicyclic gearing system including a central gear configured to be rotated, at least one peripheral gear connected to the central gear and configured to rotate and translate relative to the central gear, and an annulus surrounding the at least one peripheral gear and connected with the at least one peripheral gear. The magnet assembly further includes a magnet module connected with the epicyclic gearing system, the magnet module including a support connected with the at least one peripheral gear, the axis of rotation of the support being coaxial with the axis of rotation of the at least one peripheral gear connected with the support.

Abstract: Ring gears with a cylindrical ring gear body having a wall with a longitudinal length extending between opposing first and second ends, the wall having an outer surface and an inner surface. The inner surface has a first portion that extends a first sub-length of the ring gear body and a longitudinally spaced apart second portion that extends a second sub-length of the ring gear body. The first portion extends from the first end of the ring gear inward and the second portion extends from the second end of the ring gear inward. The inner surface of the first portion comprises a plurality of longitudinally extending splines and the inner surface of the second portion is devoid of the splines of the first portion.

Abstract: An engine comprises a gear system and a coupler. The gear system comprises a sun gear, a ring gear, and a plurality of intermediate gears that engage the sun and ring gears. The coupler is for connecting the gear system to an engine static structure. The coupler is configured to limit deflection of the gear system. Two of the sun gear, the ring gear, and the plurality of intermediate gears are configured to rotate and/or orbit about a central axis. The third of the sun gear, the ring gear, and the plurality of intermediate gears is connected to the coupler and is configured not to orbit and/or rotate relative to the central axis.

Abstract: A planetary gear mechanism converts rotational movement of a drive shaft into rotational movement of an output shaft. The mechanism includes a planetary gear carrier, a planetary gear, and a bearing arrangement. The bearing arrangement includes roller bearings spaced apart between the planetary gear and planetary gear carrier. Each roller bearing has an inner ring and outer ring. The bearing arrangement includes a ring to position the roller bearings on the planetary gear carrier and a collar to secure the planetary gear. The ring is on an outer face of the planetary gear carrier between the inner rings. The collar is on an inner face of the planetary gear between the outer rings. An intermediate ring on the inner face of the planetary gear positions the roller bearings. The intermediate ring has a cutout directed to the collar which corresponds to an axial length of the collar.

Abstract: The invention relates to a planetary gearbox comprising a drive shaft (1) and a driven shaft (2), which are mounted in a gearbox housing, and at least one first (4) and second (5) planetary stage. Furthermore, a single-piece gearbox housing casing (3) is provided, which encloses the first (4) and second (5) planetary stage and is closed at the end face via a housing cover (7). At least one separating wall (6) is arranged in the interior of the gearbox housing, said separating wall dividing the interior into two subchambers. Each subchamber accommodates a planetary stage. The planetary stages (4, 5) are connected to each other by a shaft that is guided through an opening in the separating wall. Ring gears (14, 24) of the planetary stages are fixed at the end face to the separating wall (6).

Abstract: The invention relates to a final drive assembly. An axle final drive assembly includes an axle housing, and axially inner and outer axle bearings supported by the axle housing. An axle shaft has a flange and is supported for rotation by the outer axle bearing. A planetary transmission has a planet carrier fixed for rotation with the flange of the axle shaft. The planet carrier has a neck which is supported for rotation by the inner axle bearing. The planetary transmission also has a ring gear and a plurality of planet gears which are positioned axially between the inner and outer axle bearings.

Abstract: A planetary gearbox, for an automatic transmission of a motor vehicle, comprising two stages, each provided with a sun gear, a ring gear and interposed planetary gears. The ring gear of the first planetary stage also forms the sun gear of the second stage, and the planetary gears of both stages are guided by a common planet carrier, produced from a casting material, which accommodates the planetary gears of the first stage at an axial offset position to the planetary gears of the second stage. The planet carrier is designed as one-piece such that pockets are respectively disposed in the planet carrier for receiving the planetary gears of the first stage at an offset angle, in the circumferential direction, to the pockets for receiving the planetary gears of the second stage, so that it is possible to form the pockets during casting using slides.

Abstract: A method of assembling a planetary gearset includes die-forming a plurality of circumferentially spaced apart teeth on a sun gear, a planet gear and a ring gear. Each tooth includes a pair of tooth flanks in a final net form for engagement with mating gear teeth. The sun gear teeth have a conical shape to allow a first die to linearly move relative to a second die after the gear teeth are die-formed. The planet gears are mounted on a carrier. The sun gear and the planet gear are oriented such that the conical shapes of the respective gear teeth taper in opposite directions from one another and the planet gear teeth meshingly engage with both the ring gear teeth and the sun gear teeth.

Abstract: A planetary carrier of a planetary gearing includes two planet web cheeks interconnected by planet webs. The sides of the planet web cheeks are mutually opposed in the circumferential direction and, together with outer lateral surfaces of the planetary webs, define lateral surface openings. At least one planet pin opening for receiving a pin for mounting a planet gear is provided in at least one planet web cheek. At least one planet web cheek, in the region of the attachment of a planet web, has a transition reducing the axial length of the planet web. The planetary carrier is optimized in terms of weight and strength by way of the transition having a rounded contour in the form of a spherical recess.

Abstract: A planet web for connecting two planet web cheeks to form a planet wheel space of a planet carrier of a planet gear has, in the axial direction of the planet carrier, a cavity delimited by peripheral walls. A planet carrier includes the planet web and is improved in relation to the prior art, in particular from a production engineering aspect. This improvement is achieved by the planet web having at least one breach arranged in a peripheral wall of the planet web, which connects the cavity to the planet wheel space. A corresponding planet carrier, a casting core, and a method for manufacturing a planet carrier includes the planet web having the at least one breach.

Abstract: An epicyclic gearbox oil scavenge arrangement. The epicyclic gearbox is of the planetary or differential type and comprises an input sun gear (28); a plurality of planet gears (32) that mesh with the sun gear (28) and are driven therefrom; an annular planet carrier (34) that couples the planet gears (32) in known relative orientation and is configured to precess around the sun gear (28); and a ring gear (38) that meshes with each planet gear (32). The ring gear (38) comprises ejection apertures (44) that extend radially therethrough and the planet carrier (34) comprises at least one lobe (42) that extends radially from the periphery of the planet carrier.

Abstract: A carrier is implemented which is capable of reducing the number of parts and the number of bonding steps. The carrier includes a pair of holding members that hold from both sides in an axial direction L a pinion shaft supporting a pinion gear. A first holding member as one of the pair of holding members includes a coupling portion extending in the axial direction L toward a second holding member as the other holding member. The second holding member is a disc-like member, and has an external outer peripheral gear integrally formed in its outer peripheral portion. The coupling portion is bonded to a coupling bonding portion provided on a radially inner side R1 of the outer peripheral gear in the second holding member.

Abstract: A fan drive gear system for a gas turbine engine includes a carrier supporting circumferentially arranged gears within gear mount sections spaced circumferentially about a periphery. A shelf is disposed between each of the gear mounting sections. A torque frame is attached to the carrier and includes circumferentially arranged finger sections. Each of the finger sections includes first and second ends that are spaced apart to receive the shelf. A pin extends through openings in the shelf and first and second ends to secure the torque frame to the carrier.

Abstract: A gearbox includes a shaft input spherical bearing and a shaft output spherical bearing enabling the ring gear to float within the housing and not engage the housing. The shaft output spherical bearing permits angular displacement of the output shaft with respect to the longitudinal axis of said output shaft. A spline connection enables the ring gear to pivot with respect to the cover. Loads transmitted to the housing of the gearbox are not transferred to the gear systems and the gear systems self-align within the housing.

Abstract: A method and apparatus converts the speed and torque of a motor output and couples the adjusted output to a device or structure, such as a movable barrier. In one example, a conversion apparatus includes a first gear set, a second gear set, a third gear set, and a fourth gear or ring gear. The first gear set may engage a motor output and receive rotational input therefrom. The rotational input is transferred from the first to the second gear set and then to the third gear set, which may engage a ring gear. In one configuration, a carrier is disposed about the gear sets. Carrier fasteners may extend through openings in the third gear set and, as the third gear set travels around the ring gear, the carrier fasteners may revolve around a central axis and rotate a carrier output shaft.

Abstract: Planetary gearing, in particular multistage planetary gearing, is disclosed. The planetary gearing includes at least one drive shaft, an output shaft, a sun wheel, a ring gear, planet wheels assigned to the planetary gear train, a gear casing, in particular a multipart gear casing, a planetary gear train, in particular the second planetary gear train, comprising a planet wheel arm immovably arranged in a casing. The construction of such a planetary gearing is simplified compared to the prior art, thereby saving costs. This is achieved in that the planet wheel arm is integrally formed with a casing.

Abstract: Epicyclical gearing comprising a first and a second gear wheel turning around respective mutually parallel axes, each one comprising a respective first and a respective second crown wheel that are adjacent to each other; the gearing also comprising at least one third and at least one fourth gear wheel that are separate and mutually independent, a support body for the third and fourth gear wheels, the support body having hinge pins formed therewith as a one piece structure, the hinge pins providing a mount for the third and fourth gear wheels on the support body in a rotational manner around a third and, respectively, a fourth hinge axis parallel to the axes, the third gear wheel meshing with the respective first crown wheels and the respective fourth gear wheel meshing with the respective second crown wheels.

Abstract: A one-way clutch of an inscribed gear type has a cylindrical outer member having an inner gear at an inner circumference thereof; an inner member rotatably disposed in an inside space of the inner gear, and having gear receivers and a lock edge on one side in a circumferential direction of the gear receiver; and a planetary gear received rollably in each of the gear receivers to mesh with the inner gear. Shafts are projecting from both ends of the planetary gear, and bearing recesses are formed on the gear receiver to receive the shaft. By the engagement between the shafts and the bearing recesses, the planetary gear allows a circumferential displacement within a predetermined range with respect to the inner member required for engaging to or disengaging from the lock edge, and the planetary gear is prohibited from being displaced inward in a radial direction of the inner member.

Abstract: A planetary gear assembly includes a sun gear, planetary gears engaging the sun gear, a ring gear arranged about the planetary gears, the ring gear engaging the planetary gears, and a carrier frame including one or more pairs of bearing containment bands, a plurality of connecting segments, a plurality of spoke portions, and a hub portion, wherein each pair of bearing containment bands is connected to an adjacent pair of bearing containment bands with a connecting segment of the plurality of connecting segments and a spoke portion of the plurality of spoke portions connects each connecting segment to the hub portion.

Abstract: A driving device includes a planetary gear deceleration mechanism in a transmission path that transmits driving force from a driving motor to a driven member, in which the deceleration mechanism includes first and second support units into which a housing that constitutes a mechanism main body is divided, the first support unit includes carriers of at least one stage and pinion gears supported thereby, and is provided with an output unit in the carrier of the final stage, the second support unit includes an output shaft that is detachable from the output unit and a supporting unit for the output shaft, and the output shaft is supported in an insertable and removable manner with respect to the output unit of the carriers in the first and the second support units that are joined to each other.

Abstract: A turbomachine epicyclic gear system includes a sun gear rotatable around an axis, a ring gear radially outward of the sun gear, and a plurality of intermediate gears meshed with the sun gear and the ring gear. A plurality of journal pins are each configured to support one of the plurality of intermediate gears. Each of the plurality of journal pins has an asymmetric rim.

Abstract: A pinion carrier includes a shell including a face plate, a lip spaced axially from the face plate, a hub including a plate spaced from face plate and a collar spaced axially from the lip, posts, each post spaced angularly about an axis, secured to the plate and face plate by welds, shafts spaced angularly about the axis, secured to the plate and face plate, and pinions, each pinion supported on one of the shafts.

Abstract: The planetary gear train includes a first sun gear driven by the motor, a first ring gear, a first carrier, and a plurality of first planetary gears arranged at one side of the first carrier and meshing with the first sun gear and the first ring gear. The first sun gear, first planetary gears and first ring gear are helical gears so that meshing surface is increased. Helical teeth formed on an inner surface of the first ring gear mesh with the helical teeth of the first planetary gears. Therefore, the operation is stable and the noise is low. The planetary gears are made of plastic to further decrease the noise. The first ring gear is made by sintered powder metallurgy.

Abstract: A planetary gear system and a method. The planetary gear system includes a carrier body configured to receive planet gears, at least one pin received by the carrier body, and flex means positioned between the carrier body and the at least one pin. The method includes preparing the carrier, upon which a plurality of planet gears is mounted through planet pins, and providing flex means between the planet pins and the carrier, the flex means configured to enable movement of the planet pins in response to a force directed thereon.

Abstract: A pin for coupling a planet gear to a carrier in a planetary gear system is disclosed. The pin includes a first end, a second end, and an outer surface extending between the first end and the second end. In some embodiments, the pin further includes means for modifying the compliance of the pin at an interface between the pin and the carrier. In other embodiments, the pin further include a compliance feature defined in the outer surface, the compliance feature allowing greater compliance of the pin in the tangential direction than in the radial direction.

Abstract: A planetary gear unit inside a case includes coaxial sun and ring gears, a planetary pinion gear that meshes with the sun and ring gears, and a carrier that holds the planetary pinion gear, the ring gear being fixed with respect to the case, and a flange disposed inward of the ring gear. The ring gear is fixed to a case wall, via the flange, the wall extending radially inward, and the flange being prevented from rotating with respect to the wall by a rotation prevention mechanism. The rotation prevention mechanism includes a plurality of case holes on the same circle in the wall, flange holes in the flange at positions corresponding to the case holes, and rotation prevention members fitted into the case and flange holes to prevent rotation of the flange with respect to the wall with the flange relatively movable axially with respect to the wall.

Abstract: A gas turbine engine includes a fan section. A turbine section is coupled to the fan section via a geared architecture. The geared architecture includes a torque frame and a flex support spaced apart from one another at a location. A gear train is supported by the torque frame. A damper is provided between the torque frame and the flex support at the location.

Abstract: A transmission assembly is provided and includes a load, an input shaft rotatably driven by a low pressure section of a turbomachine and a transmission coupled to the load and the input shaft. The transmission is operable to transmit rotation of the input shaft to the load and configured to convert a first rotational speed range of the input shaft to a second rotational speed range for transmission to the load. The second rotational speed range is narrower than the first rotational speed range.

Abstract: A planetary gear assembly includes a sun gear, planetary gears engaging the sun gear, a ring gear arranged about the planetary gears, the ring gear engaging the planetary gears, and a carrier frame including one or more pairs of bearing containment bands, a plurality of connecting segments, a plurality of spoke portions, and a hub portion, wherein each pair of bearing containment bands is connected to an adjacent pair of bearing containment bands with a connecting segment of the plurality of connecting segments and a spoke portion of the plurality of spoke portions connects each connecting segment to the hub portion.

Abstract: A gear set arrangement for a planetary transmission comprising at least first and second simple planetary gear sets, each having sun and ring gears and a carrier supporting planetary gears. The gear sets are coaxially nested with the first gear set being radially within the sun gear of the second gear set in a common radial plane or radial planes which are only slightly axially offset. The ring gear of the inner first gear set and the sun gear of the outer second gear set, and the carriers of the two gear sets, are coupled in a fixed manner. To avoid forced movement of the gears, only one of the sun gear, the ring gear or the carrier, of each of the first and the second gear sets is radially supported substantially free of radial play on a centrally disposed transmission shaft or with respect to a centered supported component.

Abstract: A differential mechanism includes a case including first and second portions, the first portion including a first surface interrupted by recesses, the second portion including a second surface interrupted by second recesses, contacting the first surface, and secured to the first portion, a pin extending though the recesses, and a ring gear secured to the portions and overlapping the surfaces and the pin.

Abstract: A fan drive gear system for a gas turbine engine includes a carrier that supports circumferentially arranged gears. A torque frame has circumferentially arranged fingers with each finger including a bore having a bore axis. A bushing is arranged in each bore and provides an aperture. At least one bushing has a bushing axis offset from the bore axis. A pin is disposed in the aperture and secures the carrier to the torque frame.

Abstract: A differential flange assembly is disclosed herein that includes a flange member and a washer member. The flange member is defined by an engagement face and having an aperture therethrough. At least one slot is formed on the engagement face so as to extend radially outward from the aperture. The washer member has at least one tab extending from a peripheral edge of the washer member and at least one opening. The tab is configured to be seated within the slot to mate the washer member to the engagement face of the flange member. The interaction of the slot of the flange member and the tab of the washer member prevent rotation of the washer member with respect to the flange member.

Abstract: A speed changer assembly for changing the rotational speed of an engine's (or other prime mover's) output to that required by the input of a process machine. In operation, a first gear is in meshing engagement with an idler gear, which in turn, is in meshing engagement with a second gear. When operation of the speed changer assembly is halted, the idler gear is pivotable about one of the first and second gears. A center distance between the idler gear and the gear about which the idler gear is pivoted remains constant while the center distance between the idler gear and the other gear is varied. The idler gear is taken out of meshing engagement with the other gear, permitting replacement of said other gear. The idler gear is then pivoted to establish meshing engagement with the replacement gear and the speed changer is configured with a new speed ratio.

Abstract: A zero backlash planetary gear train, comprising: a shell, a planetary gear set, and at least a sun gear set. Planetary gear set is disposed in said shell, and includes a planetary arm rack having output axis, such that planetary arm rack in said shell is provided with a plurality of double-layer planetary gears. The planetary gear set includes a first planetary gear and a second planetary gear. A buffer mechanism is provided between first planetary gear and second planetary gear. Said first planetary gear is engaged with at least an internal gear on an inner rim of shell, and second planetary gear is engaged with at least a sun gear set. Sun gear set is provided with a sun gear connected to a driving motor. Said zero backlash planetary gear train is capable of eliminating backlash between gears.