Abstract: A joint structure for a robot includes a first link and a second link rotatably coupled to each other through a joint part and a first linear-motion actuator and a second linear-motion actuator coupling the first link to the second link at a part separated from the joint part. The first linear-motion actuator and the second linear-motion actuator are each connected with the first link and the second link so as to be rotatable about two axes perpendicular to each other. When the second link is in an upright state, a first shaft member and second shaft members are disposed so that an angle formed by axial centers thereof becomes a right angle and the axial centers are oriented in a horizontal direction.

Abstract: An adapter assembly for selectively interconnecting an end effector and a surgical device includes a housing configured to connect to the surgical device, a shaft assembly extending from the housing, a cable drive assembly, and a coupling member. The cable drive assembly includes a cable supported in the housing. The coupling member is secured to the cable and configured to connect to the end effector. The coupling member is movable relative to the shaft assembly in response to movement of the cable.

Abstract: An artificial joint with a knee axis including a swing-phase control means having a variable friction-based swing-phase controller. The variable friction-based swing-phase controller may apply different resistances at different ranges of motion by altering the torque applied upon the knee axis by altering any combination, or all of the following: the length of a lever arm and a force applied. This may be done to optimize the swing-phase control of the artificial joint to promote natural and smooth walking gait.

Abstract: The invention discloses an implantable facet arthroplasty device suitable for treating adjacent level disease. The device is designed for implantation between a first vertebra and a second vertebra. Components of the device include: a crossbar; a first component having a first attachment mechanism adapted to attach to a first location of a spinal fusion device attached to a first vertebra and a second attachment mechanism adapted to attach to the crossbar; and a second component having a second attachment mechanism adapted to attach to a second location of a spinal fusion device attached to the first vertebra and a second attachment mechanism adapted to attach to the crossbar. The first component articulates relative to the second component and the first vertebra articulates relative to the device itself.

Abstract: A walk behind power equipment device includes a frame (or housing), an engine supported at least in part by the frame or housing, a mobility assembly operably coupled to the frame and to the engine to provide mobility of the walk behind power equipment device responsive to operation of the engine, a working assembly and a handle assembly. The working assembly is operably coupled to the frame and to the engine to facilitate performance of a working function of the walk behind power equipment device responsive to operation of the engine. The handle assembly is operably coupled to the frame via a handle coupler to provide steering inputs responsive to which the mobility assembly moves the walk behind power equipment device via a handle apparatus of the handle assembly. The handle coupler is configured to provide at least vibration isolation and handle apparatus orientation adjustment.

Abstract: A robot includes a support, a movable member coupled to the support to permit gimbal rotation about a pitch axis and a yaw axis, and first and second linear actuators connected to each of the support and the movable member and operable to rotate the movable member about the pitch axis and the yaw axis. The first linear actuator is pivotally attached to the movable member at a first pivot point. The second linear actuator is pivotally attached to the movable member at a second pivot point. The first and second pivot points are each angularly offset from the pitch axis and the yaw axis by about 45 degrees and are located on the same side of the pitch axis.

Abstract: A terminal (10) for a motion transmitting remote control assembly (12) securable to a control member (14) in a vehicle includes a housing (44) for connection to a core element (20) of the motion transmitting remote control assembly (12) with the housing (44) defining an aperture (48) forming at least one open end (50). The terminal (10) also includes a connecting member (60) having a body (62) disposed in the aperture (48) with the body (62) having a cavity (66) for receiving the control member (14) and a groove (84) in communication with the cavity (66).

Abstract: A folding mesh chair includes a seat and a backrest carried between opposite frame sides. The chair has an unfolded seating position in which the seat pivots to extend from the frame sides and bottoms of front and rear legs move apart, and a folded position in which the seat pivots toward the frame sides and the front and rear legs move together. One or both of the seat and the backrest have a continuous sheet of flexible and elastic mesh or patterned open texture plastic held across and substantially covering an opening in an all-plastic hoop fixed between the frame sides.

Abstract: A rotational joint is provided that comprises a first member, second member, rotational shaft member, rotational biasing member and stop ring. The first member has a pair of sidewalls that face each other. The second member has a pair of plate members each disposed proximate to the outer-facing sides of the sidewalls. The rotational shaft member is fitted into shaft holes in each of the plate members and the sidewalls. The rotational biasing member is disposed around the rotational shaft member and its one end is engaged with the first member and the other end with the stop ring fixed to the rotational shaft member. The first member is rotatable with respect to the rotational shaft member that is fixed to the second member. The rotational biasing member and stop ring are disposed between the sidewalls.

Abstract: A power adapter including a wing deployment mechanism for retaining a wing in a first undeployed position and the second deployed position. One example may provide a housing, a spring, a spring cover, and the wing. In one example, the wing may be pivotally attached to the housing and the spring and the spring cover may be fixedly attached to the housing. The spring may contact a portion of the wing and may, in one example, apply a position dependent force to the wing that biases the wing towards either the first or the second position.

Abstract: A joint device connects a first and second members and allows pivotal motion of one or both members. The joint device includes a housing having a slide surface and a guide surface. First and second rotating members are supported for rotation by the housing to pivot one or both members. A slide member carrying a spring is supported for movement on the slide surface with rotation of the rotating members. The spring is coupled to the first rotating member, and has an arm arranged for movement along the guide surface as the slide member moves along the slide surface. The spring member imparts a bias torque on the first rotating member, where the bias torque magnitude changes as the slide member moves along the slide surface.

Abstract: A method and apparatus for reducing a force. An apparatus comprises a multi-directional joint assembly and a damper associated with the multi-directional joint assembly. The multi-directional joint assembly has a first end and a second end. The first end and the second end move relative to each other. The damper is comprised of a number of elastomeric layers and a number of rigid layers interspersed with each other reducing at least one of a force and a moment.

Abstract: A glide movement controller for use with a hinge connection that includes a shaft, as well as a hinge connection and a power saw including such a controller. The glide movement controller includes a generally U-shaped controller body configured to move towards the shaft in a first direction such that resistance upon the shaft is increased and away from the shaft in a second direction such that resistance upon the shaft is decreased; a pair of apertures extending through the controller body; and an interior bearing surface defined on the controller body. The interior bearing surface is configured and arranged to face the shaft. In certain embodiments, at least a portion of the interior bearing surface is located between the apertures.

Abstract: A rotary shaft location structure is utilized to improve conditions of complicated, inconvenient, time-consuming and troublesome installation of conventional locating components, based. on a compact request. The rotary shaft includes a combination of a shaft body and a cylinder body, in which the cylinder body includes a rigid wall and a chamber defined by the rigid wall and utilized to receive the shaft body. The shaft body includes at least one arc region and a plane region, at least one elastic device is installed inside the chamber of the cylinder body to form a contact or interference condition with the shaft body, and the elastic device and the shaft body generate a frictional resistance in response to a movement of the shaft body, thereby improving conditions such as easy-to-produce deformation and abrasion in conventional locating components.

Abstract: A joint device connects a first and second members and allows pivotal motion of one or both members. The joint device includes a housing having a slide surface and a guide surface. First and second rotating members are supported for rotation by the housing to pivot one or both members. A slide member carrying a spring is supported for movement on the slide surface with rotation of the rotating members. The spring is coupled to the first rotating member, and has an arm arranged for movement along the guide surface as the slide member moves along the slide surface. The spring member imparts a bias torque on the first rotating member, where the bias torque magnitude changes as the slide member moves along the slide surface.

Abstract: A novel handlebar mounting device structured to mount to a mirror mount receiver on a handlebar where a mirror mounting stem supporting a mirror normally resides. The novel handlebar mounting device includes a pivot arm having a pivot base and a coupler interface with therebetween a pivot joint having an adjustable rotational stiffness. The pivot joint is formed of an arm and a hub relatively rotatably suspended therefrom, an elastomeric interface between the arm and the hub, and a means for compressing the elastomeric interface between the arm and the hub. A coupler component is formed on the coupler interface. A connector is adapted for securing the pivot base to a mirror mount receiver on a handlebar where a mirror mounting stem supporting a mirror normally resides.

Abstract: An upright active-sitting seat provides a connection of a seating leg to a base through an articulating joint that allows the user to move a seat front to back and side to side, allowing a more active sitting that encourages blood circulation. The chair includes a seat supported by a post that is connected to a mount via a ball joint rod by a transverse rod that is routed through the ball joint rod end. By way of a coil spring that engages with the mount and the post, the post is spring biased to a home position relative to the mount. When using the chair, a person may move the seat from the home position to a comfortable seating position. When the person stands from the chair after using it, the chair returns to its spring biased home position.

Abstract: A plurality of components of a power tool are coupled to each other to form a component assembly. Positioning members are disposed within a housing body and resiliently support the component assembly from opposite sides in an axial direction.

Abstract: Disclosed is a ball joint, the ball joint capable of preventing damage due to interference between parts even when the ball joint is tilted at a maximum angle and guaranteeing operational reliability, and including a spherical ball stud, a shaft coupled to a side of the ball stud, a holder having a seat portion to surround an outer circumference of the bail stud, and an elastic portion protruding upwards from the holder, having on an inner circumference thereof an inclined surface to limit a tilting angle of a portion of the shaft adjacent to the ball stud, and undergoing elastic deformation when the shaft is tilted at a maximum angle, so that the elastic portion absorbs shock when the ball joint is rotated to the maximum, thus preventing damage or removal of parts.

Abstract: A lamellar rotational flexure pivot is provided. The flexure pivot may include a first pivot end, and second pivot end, and a divider layer positioned therebetween to allow first and second pivot ends to pivot relative to one another. The first and second pivot ends may include a plurality of flat spring layers and spacer layers that are stacked in alternating fashion to form the lamellar rotational flexure pivot.

Abstract: The present invention provides a retractable wheel system for snowmobile skis. The retractable wheel system of the present invention may be installed on a snowmobile ski without affecting its structural integrity by installing the system on the reinforced portion of the snowmobile ski. When a user circulates in a path with little or no snow, the retractable wheel system is positioned in the extended configuration by the user and the system will automatically return to the retracted configuration when the user returns in a snowy zone. This is realized by using a pre-tensioned spring that will reposition the wheel in the retracted configuration. The spring transmits a rotational movement to the member on which the wheel is fixed.

Abstract: A pivot joint for a single blade spring tensioner or double blade spring tensioner generates a biased friction loss at a pivot joint. The friction torque generated in one direction of joint rotation is greater than the friction torque generated in the opposite direction of rotation. In one embodiment, the direction of torque bias at the joints is used to make the damping of the blade spring greater in compression than in extension. High damping in compression and low damping in extension is a desirable characteristic for a tensioner in most applications. The device may be designed to act as a one-way clutch or as a two-way clutch. The device may also be designed to apply large friction torques only when the joint undergoes large amplitude motions (loss of control).

Abstract: A cleaning apparatus includes an elongate rod defined by a proximal end portion having a first linkage member and an opposed distal end portion. The first linkage member is pivotally coupled to a second linkage member of a cleaning head. There is a biasing assembly that is coupled to the elongate rod and to the cleaning head, which tensions the cleaning head to a maximum pivotal excursion relative to the cleaning rod.

Abstract: A device for connecting bony portions, such as a dynamic intervertebral connection device, includes a female member (2) having a cavity (5) and intended to be connected to a first bony portion, a male member (1) articulated in the cavity (5) and intended to be connected to a second bony portion, the male member (1) having a lateral articulation surface (13) coacting with a lateral surface (6a) of the cavity (5) to guide movements of inclination of the male member (1) relative to the female member (2), and resilient elements (8) arranged to exert an action countering the inclination movements. The resilient elements (8) are disposed in a recess (10) of the male member (1) delimited laterally by a surface (12) that is opposite the articulation surface (13).

Abstract: A pivot joint assembly includes a housing having a bore therethrough and a coaxial central axis. A stud is disposed coaxially with the bore, and has a bearing surface. A resilient member disposed between the housing and the stud is biased against the housing to accommodate radial loads transferred therebetween. An inner metal ring disposed between the resilient member and the bearing surface substantially surrounds the bearing surface and is sized for a sliding fit between the bearing surface and an interface surface of the inner metal ring. The stud is configured to pivot about the central axis by a range of at least 40 degrees. The pivot joint assembly may further include a sealing element configured to seal the bearing surface and the interface surface. Another embodiment includes an axial restraint element configured to prevent axial separation of the stud and housing.

Abstract: An exemplary rotatable joint (100) used for a mechanical device includes a socket (10), a rotatable arm (20), a supporting shaft (13), a fastening member (15), an adjusting member (16), and a resilient module (18). A pivot hole (212) is defined in the rotatable arm. The supporting shaft includes a first shaft portion (130) and a second shaft portion (132). A threaded hole (131) is defined in the first shaft portion and the first shaft portion extends through the pivot hole. The second shaft portion is fixed to the socket. The fastening member includes a threaded portion (152) for engaging in the threaded hole of the supporting shaft. The adjusting member is disposed at the threaded portion of the fastening member. The resilient module is disposed between the rotatable arm and the adjusting member for providing an axial resilient force. The axial resilient force is fine tuned by moving the adjusting member.

Abstract: A ball stud system that provides a ball stud that will not loosen easily under the application of repetitive side loading on the ball portion of the stud. The ball stud is secured to the vehicle steering knuckle arm using the combination of a tapered nut and tapered washer. The tapered nut includes slots and the pin of the ball stud an aperture. A cotter pin may be placed through the slots and aperture in order to further prevent rotation of the nut.

Abstract: A rotational supporting mechanism, which supports a main body and a cover, includes an eccentric cam. The main body and the cover are superposed in a closed position. From the closed position, the cover is rotated 180 degrees and stopped at a 180-degree rotational position in an open position. The eccentric cam rotates eccentrically. The pressing means presses a cam surface of the eccentric cam in a direction of a line connecting a portion of the eccentric cam corresponding to the closed position and a portion of the eccentric cam corresponding to the open position when the main body and the cover are superposed in the closed position. Rotation of the cam is stopped in the open position and the closed position.

Abstract: A resilient flexure has one end attached within a cavity in a rigid member, and the other end attached within a cavity in a structural mode. The cavities are shaped to limit the flexure's bend radius. The member and the node have mating surfaces that abut to constrain the amount of rotation of the member. The aforementioned elements are shaped to prevent the strain in the flexure from exceeding its design limit when the joint is at its maximum angular deflection and the attached member is fully collapsed.

Abstract: The invention relates to a device for fastening at least one component of an exhaust system to at least one member of a motor vehicle, including a component leg that is designed for rigid fastening to the at least one component of the exhaust system and one member leg that is designed for rigid fastening to the at least one member of the motor vehicle. A coupling body with or made of an elastomer is provided, the coupling body being connected on the one hand fixedly to the component leg and on the other hand being fixedly connected to the member leg.

Abstract: A ball joint assembly includes a housing (12) defining a socket chamber (18) and having an opening (32); a composite ball joint bearing (20) disposed within the socket chamber; a ball stud (24) supported by the composite ball joint bearing and having a shank portion (30) which projects through the opening of the housing; and a seal assembly (40) adapted to seal the opening between the ball stud and the socket chamber. The composite ball joint bearing is formed from a first plastic material (20A) and a second magnetostrictive alloy material (20B) which is adapted to change its shape when in the presence of a magnetic field to thereby change the rotational and oscillation properties of the ball joint assembly.

Abstract: A pivot has a low friction rotational property by allowing the elastomeric bushing to rotate with respect to the inner metal. A low friction material can be incorporated between these two components to facilitate the rotation, if desired. The elastomeric bushing helps to isolate the pivot joint and prevent the transmission of vibrations. In one embodiment, the elastomeric bushing is also allowed to pivot about an axis generally perpendicular to its axis of rotation.

Abstract: A rotation device of a buckle for use in an automobile seat belt is provided with a base having a plate-like shape to be mounted on a bottom surface of a main body and provided with a circular plate portion at its one end, the circular plate portion provided with a through hole formed therethrough, and a pair of side walls bent upwardly each of which has a lug bent inwardly to be integrally formed with the circular plate portion as well as the pair of side walls, a stalk whose one end is rotatably mounted on an upper surface of the circular plate portion of the base has a hole formed therethrough and a stopper portion formed around the end of the stalk and provided with a protrusion for being contacted with an inner surface of the side wall of the base and an abutment for limiting a rotation angle of the main body, the stalk having a protrusion for stopping a rotational movement, an elastic member whose one end is contacted to the protrusion for stopping a rotational movement and having an elasticity and a th

Abstract: A tensioner, for a timing chain, belt or the like in an internal combustion engine, has a projection-preventing hook that secures a spring-urged plunger in a withdrawn condition prior to installation of the tensioner, but releases the plunger during operation so that the plunger can exert a force on a pivoted chain- or belt-engaging tensioner lever. A resisting member is provided on a fulcrum pin on which the hook is pivoted, in order to exert a frictional force on the hook, thereby preventing the hook from unexpectedly returning to its plunger latching condition and preventing vibration noise to movements of the hook. The tensioner can be mounted without regard to its direction, and therefore a threaded mounting can be used, simplifying mounting and demounting of the tensioner.

Abstract: A pivoting joint for pivotally joining a brake head to a brake beam of a railway car allows the brake head to modify its radial and lateral direction with a controlled degree of rotation with respect to a bogie wheel, allowing the brake shoe to adapt to the wheel contour, and achieving an adequate force distribution along the brake shoe, and thus optimizing the utilization of the brake shoe material.

Abstract: A door assembly includes a swinging door with an extendible hinge disposed along an inner edge of the door. The extendible hinge allows the door to pivot through a range of pivotal positions and, when necessary, allows the door to move through a range of extended positions. The pivotal positions allow the door to open and close normally across a doorway, while the extended positions help protect the door assembly from damage in the event the door is forced to swing beyond its pivotal positions. In some embodiments, the door includes a spring-tensioned chain that draws the inner edge of the door against an anchor attached to a side edge of the doorway. The flexibility of the chain allows the door to pivot, while the compliance of the chain's spring allows the door to shift away from its normal pivot point and move to various extended positions.

Abstract: A swivel joint according to the present invention includes first and second base members. A spider includes first and second arcuate surfaces which form joints with the first and second base members, respectively. Furthermore, the spider includes first and second pins both opposed from each other and third and fourth pins opposed from each other. A first mechanism is coupled to the spider and the first base member and is adapted to effect a force between the first arcuate surface and the first base member. Also, a second mechanism is coupled to the spider and the second base member and is adapted to effect a force between the second arcuate surface and the second base member.

Abstract: A pivot socket of the present invention incorporates a stud shaft component having a tapered head portion disposed within a housing cavity, and an axial pin extension extending upward into the cavity therefrom. The tapered head portion seats against a tapered bearing surface disposed within the housing cavity, and the axial pin extension is enclosed within a resilient bushing. During use, lateral and axial loads imparted on the stud shaft are transformed into radial and axial component forces at the bearing surfaces. Angulation loads are resisted by the tapered head portion, and converted to axial forces. The radial force components are distributed to the interior walls of the housing cavity, while the axial force components are transferred axially through the resilient bushing to the end closure components secured to the housing, or directly to the housing through the tapered bearing surface.

Abstract: An adjustable locking mount system permits rotation about at least one of x, y, and z axes. Methods provide for rotating and rocking the mount to obtain the desired position, fixing the mount in the desired position, and mounting an object onto the mount.

Abstract: An adjustable locking mount system permits rotation about at least one of x, y, and z axes. Methods provide for rotating and rocking the mount to obtain the desired position, fixing the mount in the desired position, and mounting an object onto the mount.

Abstract: A pivot socket of the present invention incorporates a stud shaft component having a partially spherical head portion disposed within a housing cavity, and an axial pin extension extending upward into the cavity therefrom. The partially spherical head portion seats against a partial spherical bearing surface disposed within the housing cavity, and the axial pin extension is enclosed within a resilient cushion. A Belleville washer is interposed between the resilient cushion and the partial spherical bearing surface. During use, lateral and axial loads imparted on the stud shaft are transformed into radial and axial component forces at the bearing surfaces. The radial force components are distributed to the interior walls of the housing cavity, while the axial force components are transferred axially through the resilient cushion to the end closure components secured to the housing.

Abstract: A pivot device has a seat and a pivotal axle pivoted with the seat. The pivotal axle has a retaining shoulder, a retaining portion and a pivot portion respectively formed at two ends of the retaining shoulder, a threaded end formed at one end of the pivot portion, and multiple positioning holes defined in the retaining portion to receive screws for fastening the pivotal axle to screen. The seat comprises a flat portion defined with multiple retaining holes, a plate formed at a first edge of the flat portion, a hole defined in the plate, and a pivotal ring formed at a second edge being adjacent to the first edge. The threaded end and the pivot portion are inserted into the pivotal ring and the hole through multiple washers and elastic rings, and then a free end of the threaded end is fastened with a nut.

Abstract: A pivot socket of the present invention incorporates a stud shaft component having a partially spherical head portion disposed within a housing cavity, and an axial pin extension extending upward into the cavity therefrom. The partially spherical head portion seats against a partial spherical bearing surface disposed within the housing cavity, and the axial pin extension is enclosed within a resilient cushion. During use, lateral and axial loads imparted on the stud shaft are transformed into radial and axial component forces at the bearing surfaces. The radial force components are distributed to the interior walls of the housing cavity, while the axial force components are transferred axially through the resilient cushion to the end closure components secured to the housing. Little or no lateral force components are transferred to the resilient cushion from lateral loads imparted on the stud shaft, thereby reducing wear on the pivot socket components and extending the useful life thereof.

Abstract: A hinge engages a cam such that the hinge first rotates relative to the cam, then linearly engages the cam. Preferably, the hinge includes a guiding post that rides along a raised arched surface on the cam during the rotary motion of the hinge. Linear motion between the hinge and the cam preferably begins when the guiding post rides off the end of the arched surface. The rotary motion of the hinge is constrained by one or more engagement assemblies. In a preferred embodiment, one or more cams are mounted on a receiving structure and one or more hinges are mounted in corresponding locations on a detaching structure, where said detaching structure is physically separable from the receiving structure. Engagement between the one or more cams and the one or more corresponding hinges allows the detaching structure to first rotate relative to, then linearly engage, the receiving structure, providing for reliable blind mating between connectors on the detaching structure and connectors on the receiving structure.

Abstract: A faceshield that is securable to a protective helmet or headband having an indexable pivot joint which utilizes an interference fit between an O-ring and radially spaced lug sets. The O-ring is compressed when the crests of the two sets of lugs are radially aligned. This interference holds the faceshield in a desired indexed position.

Abstract: An intervertebral link device including at least one damper element constituted by a cage and a pin designed to be connected to bone anchor elements. The pin being engaged in a housing of the cage and being fitted with two elastically deformable members operating in opposition to an applied traction force or compression force. The damper element includes a pin that is mounted inside the cage by a joint allowing multidirectional relative pivoting between the pin and the cage, at least about the axes contained in a plane perpendicular to the pin and angular abutment between the cage and the pin enabling the multidirectional relative pivoting to be limited in amplitude to a determined value of about 4°.

Abstract: A swivel coupling for coupling together two vehicles, in particular two rail vehicles. The swivel coupling rests on a shared bogie between the two vehicles and has a rotation function and a shock-absorbing function. Each of these functions is performed by distinct elements of the swivel coupling structure.

Abstract: A connecting device enabling spring-suspended connection of a shaft or a guiding bar (3) to a hand-operated vibrating plate which has two pairs arranged at a fixed distance from each other in the direction of a vertical pivotal axis (8), each pair has a first connecting element in the form of a rubber buffer (5) and a second connecting element in the form of a ring (4a) surrounding the rubber buffer (5) substantially free of play and sliding coaxially in relation to the pivotal axis (8). One connecting element (5) of each pair (4a, 5) is fastened to the upper section (1a) and the other connecting element (4a) is fastened to the shaft of guiding bar (3).

Abstract: A pivot joint includes two mounting plates respectively fixedly fastened to two parts of an apparatus and coupled together by a rivet for enabling the two mounting plates to be turned relative to each other, an axle sleeve mounted on the rivet between the two mounting plates, a first washer and a second washer respectively mounted on the rivet and attached to one mounting plate at two opposite sides, wherein the axle sleeve has an embossed end edge at one end disposed in contact with the second mounting plate and a recessed coupling hole at an opposite end; the rivet is a stepped rivet having a shoulder from the head thereof and fitted into the recessed coupling hole at the axle sleeve, an annular groove at the head around the shoulder, and a plain end axially extended from the shoulder and inserted through the axle sleeve and the first and second mounting plates and hammered down to form another head; the second washer is made of friction rubber and mounted in the annular groove at the head of the rivet, hav

Abstract: A pivot joint includes two mounting plates respectively fixedly fastened to two parts of an apparatus and coupled together by a rivet for enabling the two mounting plates to be turned relative to each other, an axle sleeve mounted on the rivet between the two mounting plates, a first washer and a second washer respectively mounted on the rivet and attached to one mounting plate at two opposite sides, wherein the axle sleeve has a recessed hole at one end, and the second washer is made of friction rubber, having a first part received in the recessed hole at one end of the axle sleeve, and a second part stopped against one mounting plate at one side.