Abstract: A structure of a shift lever apparatus is disclosed in which, after a slider has been assembled at a case, a link is assembled to the case while an intrusion shaft is intruded at a hole. For assembly of the link to the case, an assembly pawl provided at the link is resiliently deformed and inserted at an assembly portion which is provided at the case. At this time, an engaging protrusion is engaged with a surrounding area of the assembly portion by resilient force of the assembly pawl.

Abstract: The present invention discloses a forward force producing system for wheels that generates a forward force using the downward force created by the weight of the load. The force from the weight of the vehicle and the vehicle load is transferred through the forward force producing system and creates a permanent forward force. The forward force provides an impetus to the forward motion of the wheel that serves, not only to counter act the effect of surface friction between the wheel and the surface, but also to propel the vehicle forward.

Abstract: The pivot-less Watt linkage supports a first rigid element relative to a second rigid element and permits relative motion between the rigid elements. The pivot-less Watt linkage comprises an elongate, rigid, floating beam, an elongate first flexible beam, an elongate second flexible beam and a flexible member. The first flexible beam extends in a first direction from a first point on the floating beam to the first rigid element. The second flexible beam extends in a second direction, substantially opposite the first direction, from a second point on the floating beam to the first rigid element. The second point is spatially separated from the first point along the length of the floating beam. The flexible member extends in the first direction from a third point on the floating beam to the second rigid element. The third point is intermediate between the first point and the second point.

Abstract: Apparatuses and methods for configuring an input device. The input device includes a first housing, and a moveable member disposed within the first housing and extending a predetermined distance from the housing. A shaft is disposed in part within the first housing and is coupled with the moveable member. The shaft has a first portion extending a distance from the first housing, and the shaft moves as a function of movement of the moveable member. An interchangeable performance pack is coupled with the first housing and with the first portion of the shaft. The interchangeable performance pack includes a second housing and exerts one of several influences on the shaft.

Abstract: A control has a pivotal part with an operating surface that can be depressed by a person's foot or hand, with pivoting being sensed by a pivot sensor. A spring-operated mechanism urges the pivotal part toward an initial position while allowing it to pivot in both clockwise and counterclockwise directions from the initial position, the sensor indicating the amount of pivoting in either direction from the initial position. A damping unit for limiting the speed of depression includes a cylinder that contains fluid and a plunger that is depressed by the pivotal part into the cylinder to displace the fluid.

Abstract: The invention relates to a control device for controlling machines, especially hydraulic machines, by hand or foot. The inventive device comprises an actuating element (1), especially a pedal or a control lever, which can be moved in several directions. The aim of the invention is to feel a resisting force when the actuating element (1) is displaced or adjusted, whereby said force is on the scale of hydraulic forces having a direct effect. The actuating element (1) engages with a transmitter device (3) which is not hydraulic or is hydraulically decoupled from the hydraulic system. A damping device (6) engages with the actuating element (1). Said damping device defies the movement in at least one direction of motion pertaining to the actuating element (1) by means of a fluid that is moved by the actuating element (1).

Abstract: A signal input device includes a movable operating section for inputting a desired signal by selecting the shift position thereof, a shift position detecting device for detecting the shift position of the operating section, and an indication device for giving an operator information in different modes based on a shift position signal from the shift position detecting device.

Abstract: In a link mechanism, a first link is disposed to be movable by a driving force from a driving source, and a second link is operatively linked with the first link to move a driven unit. One of the first and second links includes a cam groove having a bent portion which is bent by a radius of curvature smaller than a predetermined value, and the other one of the first and second links includes a pin slidable within the cam groove. In the link mechanism, a sliding speed of the pin sliding in the cam groove is reduced when the pin enters into the bent portion in the cam groove, as compared with the sliding speed before the pin enters into the bent portion.

Abstract: Some automobiles have mechanisms for adjusting the height of accelerator and brake pedals, and any clutch pedal, so that drivers large and small can adjust the pedals to the best height. All pedals are adjusted by a single reversible electric motor having a shaft connected directly or by a flexible shaft to the adjusting mechanisms. If any fault develops in any mechanism, the pedals may not be adjusted to the same height, which is hazardous to the driver. A safety switching system detects any serious misalignment of the pedals and de-energizes the motor. The system comprises separate switches which are operable by adjustment of the pedals, and are electrically connected in series with the power supply circuit for the motor. When the pedals are aligned, the bridging contactors of the switches are aligned and are effective to maintain the electrical continuity of the motor circuit. Each contactor has three contact sliders which successively engage staggered tabs on contact strips for the respective pedals.

Abstract: A linkage mechanism for linking for example actuator rods to the nozzle ring of a variable geometry turbine. First and second components of the mechanism are interconnected by at least two links which are displaceable in a predetermined direction relative to the first component and connected at spaced apart locations to the second component. At least one of the links incorporates an element which is pivotal relative to the first component about a first axes and pivotal relative to the second component about a second axis, the two axis being parallel to each other, parallel to the predetermined direction, and offset relative to each other.

Abstract: A locking lever is enabled to lock a drive control system of a working implement in an undrivable state, even if it does not reach a locking stroke end. The locking lever is extended into a state to obstruct the passage into the passageway to a driver's seat thereby to switch a control selector lever of the working implement drive control system into a controllable position through a mechanical linkage. When the driver gets off from the driver's seat, the locking lever is returned from the passage obstructing position to a retracted position thereby to switch the control selector lever to an uncontrollable position through a the mechanical linkage. These operations are switched midway of the rocking stroke of the locking lever by bringing the control selector lever to the stroke end so that the locking lever is made idle to the stroke end of the retracted position while retaining the control selector lever in the switched state.

Abstract: The invention concerns a water sport machine consisting of a hull equipped with a pump-jet, the hull is rigid and provided with an inflatable envelope. The pump-jet consists of a light duty engine combined with a water sucking propeller located in a suction box opening into the hull bottom, the outlet of the suction box opening into a nozzle with decreasing cross-section and a helical wall.

Abstract: A housing structure of a tape player and recorder having a cassette housing and two pairs of link members is installed on both side walls of a deck of the tape player and recorder. The cassette housing is supported on the deck by the pairs of the link members. One of the pair of link members is integrally formed with a shaft connected to one end of the link members in a monolithic structure.

Abstract: An adjustment apparatus for adjusting the position of a back pad or seat pad of a seat has an inner tube with a series of spaced openings for securing at one end to the back or seat pad, and an outer tube telescopically engaged over the inner tube and secured to a support frame of the seat. The outer tube has a pinning opening for alignment with a selected one of the openings in the inner tube. A lever is pivotally secured on a pivot bracket on the outer tube for rotation about a pivot axis with a first end portion of the lever projecting over the pinning hole, and a pinning button projecting from the first end portion towards the pinning hole. The lever is movable between an operative position in which the pinning button extends through the pinning hole and an aligned hole in the inner tube to secure the tubes together, and a retracted position in which the pinning button is spaced from the pinning hole.

Abstract: Apparatus is disclosed for controlling the operational states of a motor vehicle comprising a maneuvering console including a maneuvering lever, a pivot hinge for the maneuvering lever so that the maneuvering lever can be actuated into a number of positions corresponding to the operational states of the motor vehicle, the pivot hinge being mounted to permit pivoting of the maneuvering lever with respect to the maneuvering console about an unlimited number of spatial pivot axes, a plurality of hydraulic pistons and cylinders mechanically coupled to the maneuvering lever for selectively limiting the pivoting movement of the maneuvering lever, a plurality of sensors for detecting a maneuvering force applied to the maneuvering lever and the position of the maneuvering lever so that the pivoting movement of the maneuvering lever can be selectively limited by the plurality of hydraulic pistons and cylinders based upon those detections, and a controller for controlling the plurality of hydraulic pistons and cylinder

Abstract: A pivoting connection is described that uses an H-shaped connector secured within the X-shaped opening of a base. One end of the H shaped connector can be inserted into the X-shaped opening at an angle corresponding to one leg of the X but is secured in the opening when twisted to a vertical position. This pivoting connection provides a reliable connection that is durable, weather resistant, and does not readily seize.

Abstract: The invention relates to a hand-lever control for motor and sport boats with a hand lever having a handle and guided in at least one function plane for controlling the engine. In order to facilitate maneuvering for the pilot, the hand lever or its handle is pivotal about the axis of the hand lever in two directions against a spring force and at least one sensor detecting this rotation is provided whose output controls a steering system.

Abstract: An on-vehicle lever switch having a rotary knob 4, a third lever 22 having the rotary knob 4 fixed to one end thereof and an operating rod 22a at the other end thereof, a second lever 6 having a shaft hollow cylinder 6a into which a shaft 22c of the third lever 22 is inserted, a first lever 3 into which the second lever 6 is inserted, a nonmovable member 18 fixed to the first lever 3, and a nonmovable knob 21 mounted at a location close to a tip of the first lever 3 with respect to the rotary knob 4. The nonmovable knob 21 is formed with a window 21d in its periphery. A slide knob 16 is slidably disposed in the nonmovable knob 21 with a control 16b projecting through the window 21d outwardly relative to the nonmovable knob 21. With this construction, a rotary switch, a slide switch, and a push button switch can all be mounted at an end portion of the third lever 22.

Abstract: A linear guidance device adapted for use in a machine tool such as a hexapod includes a rail having an open region which extends, either completely or partially, in a direction parallel to the longitudinal axis of the rail, and a ball screw having a nut which is fixed to the rail and which either completely or partially penetrates the open region of the rail.

Abstract: An electromagnetically actuated machine balancer including a plurality of peripherally placed magnetic circuits and a power driver which selectively interrupts the magnetic flux through the circuits, thereby moving unbalanced rotors in a desired manner to compensate for machine unbalance.

Abstract: A lid opener for use in a vehicle comprises a base member secured to a vehicle body. A control lever is pivotally connected to the base member. A rear portion of the control lever is connected through a wire to a latch mechanism of a lid member. The control lever is capable of canceling a latched condition of the latch mechanism when pivoted in a normal direction from a rest position to a work position. A spring is used for biasing the control lever to assume the rest position. A first stopper structure includes the rear portion of the control lever and a part of the base member. The rear portion is kept in contact with the part of the base member when the control lever assumes the rest position. A second stopper structure includes a part of the control lever and a stopper member which is defined by either one of the vehicle floor and the base member.

Abstract: An arrangement for attaching a gearshift assembly for a motor vehicle is provided, wherein a shift lever device for performing a gearshift operation of a transmission of the vehicle is installed on an instrument panel, without causing variations in the position of installation of a shift lever. In the present arrangement, the shift lever device is positioned relative to the instrument panel by means of a guide pin, and a console panel is positioned relative to the instrument panel using positioning holes. Thus, the position of the console panel relative to the shift lever device is determined with high accuracy on the basis of the instrument panel, and the shift lever device is mounted on the instrument panel without causing a variation in the position of installation of the shift lever.

Abstract: A link assembly for a vehicle control system comprising a spacer molded of glass-filled nylon and a socket housing mounted on each end of the spacer, both socket housings also being molded of glass-filled nylon. Each housing comprises a male socket component and a female socket component which are mirror-image, identical to each other except for complementary male locator protrusions and female locator depressions formed in opposing relationship on mating faces of respective components. The components are ultrasonically welded together to capture opposite ends of the spacer and the ball ends of respective ball studs.

Abstract: A rear hitch is provided on the rear of a transmission casing. Rear axle casings, disposed at each side of the transmission casing, are provided with brackets. A hinge pin is spanned between rear hitch and each side bracket. A lower link and a check chain are pivotally supported on each hinge pin. A collar is provided on each hinge pin so as to be interposed between the lower link and the check chain.

Abstract: A directional beam antenna device includes: an antenna supporting member which is supported on a base in such a manner as to be rotatable about a first rotational axis; an antenna portion which is supported on the antenna supporting member in such a manner as to be rotatable about a second rotational axis which is perpendicular to an antenna aperture and is inclined at a first angle with respect to the first rotational axis, the direction of an antenna beam being inclined at a second angle with respect to the second rotational axis; a first driving unit for rotating the antenna supporting member about the first rotational axis with respect to the base; and a second driving unit for rotating the antenna portion about the second rotational axis with respect to the antenna supporting member.

Abstract: One operating lever is provided for moving a traveling vehicle with a working machine back and forth and the working machine vertically and operating a sub-transmission. A sub-transmission switch is provided in a recessed portion formed in a grip of a back-and-forth operating lever so that a quick operation can be effected by a single hand without any mistake. In addition, the working machine vertically moving lever is constructed so as to interlock with a spool of a vertical motion control valve via a motor so that the speed of the motor is gradually reduced when the working machine vertically moving lever (32) is in a lowering operation, thereby preventing a drastic lowering.

Abstract: A rotary valve actuator for fluid control valves having improved actuator linkage matching the torque requirements of most rotary shaft valves. A link member is pivotally interconnected to a linear movable actuating member and to a rotatable lever. The link member enables a high actuator torque to be developed and provided during the times when the valve requires a high torque, and a low actuator torque during other times when the valve only requires a lower torque. A high-low-high actuator torque is provided matching the high-low-high torque requirements of most rotary valves.

Abstract: A stopper for robot rotary articulation limits the rotation angle of a shaft where a protrusion is formed. The stopper includes a first ring-shaped bush member, a second bush member, having an inner diameter smaller than that of the first bush member, connected to an inner circumference of the first bush member to form a step surface against the first bush member, and rotatably supported by inserting the shaft therein, a first stop protrusion extending from an inner surface of the first bush member in a radial direction thereof and a second stop protrusion protruded from an outer circumferential surface of the second bush member, in which the protrusion of the shaft during rotation of the shaft slides against the step surface and contacts with the first stop protrusion, to thereby rotate the stopper, and the second stop protrusion contacts with a protrusion fixed to a housing of a robot rotary articulation to thereby stop rotation of the shaft and stopper.

Abstract: An electrical lever assembly includes a lever rockably supported on a main body, a rod vertically sliding with a disc provided on the lever, a potentiometer having a horizontally rotating shaft mounted on the lower surface of the main body, and an arm connecting the potentiometer and the rod. The potentiometer is mounted on the lower surface of the main body in a condition adjustable with respect to a position in a vertical direction and a horizontal direction.

Abstract: A system and process for controlling the steering of a track trencher excavation machine includes a multiple mode steering control that performs a plurality of functions depending on a selection of one of a plurality of operational modes. A computer modifies the functions of the multiple mode steering control depending on a selected operational mode, and coordinates propulsion of the track drives of a track trencher to effect steering changes of the track trencher in response to signals produced by the steering control.

Abstract: A switching device for a multi-lens optical scanner, which comprises a body casing, a sliding lens seat and a driving mechanism; the feature of the switching device is that the power of a scanning device is used for driving a guide rod of the switching device so as to set the mechanism at a given position automatically, and provide an optical scanner with various resolving powers desired.

Abstract: A load balancing arm is shown and described as having improved control including a programmable control element and electronic air regulation to provide precise and controllable lifting force on a load. The disclosed load balancing arm responds to slight operator applied force to aid in movement of the load in overcoming system hysteresis, friction and load inertia without requiring the operator to apply a sufficiently large magnitude force to overcome such counteracting forces in the system. The disclosed load balancing arm further includes automatic load weight detection sensors for accommodating variation in load weights while applying a lifting force to the load which substantially equals the weight of the load. This allows the operator to move the load freely throughout a work space.

Abstract: A Six-Degree-of-Freedom Parallel-Manipulator having three inextensible limbs for manipulating a platform is described in which the three inextensible limbs are attached via universal joints to the platform at non-collinear points. Each of the inextensible limbs is also attached via universal joints to a two-degree-of-freedom parallel driver such as a five-bar lineage, a pantograph, or a bidirectional linear stepper motor. The drivers move the lower ends of the limbs parallel to a fixed base and thereby provide manipulation of the platform. The actuators are mounted on the fixed base without using any power transmission devices such as gears or belts.

Abstract: A system for calibrating an internal balance used in the testing of scale models in wind tunnels including a base; apparatus for rigidly connecting a first portion of an internal balance to the base; force adaptor apparatus for rigidly engaging a second portion of the internal balance; apparatus for securing the force adaptor apparatus to the base, including apparatus for applying selected loads to the force adaptor apparatus so as to cause a corresponding loading on the internal balance; and low friction apparatus for coupling the force adaptor apparatus to the apparatus for securing, including apparatus for transmitting a direct force from the apparatus for applying selected loads to the force adaptor apparatus via a load point whose position relative to the force adaptor apparatus is substantially constant.

Abstract: A trip-free operating mechanism for a load break switch of the type having a fixed contact engageable by a movable contact between a fully closed position and a fully open position. The operating mechanism includes an operating lever connected to the movable contact and rotatable about a shaft to move the contact between its open and closed positions. A follower rotates with the shaft into and out of contact with the operating lever. A closing spring biases the operating lever and the follower towards each other. An opening spring drive connects to the follower to drive the follower to its switch contact open position. A first latch holds the operating lever and follower apart against the force of the closing spring when the operating lever is in its switch contact closed position.

Abstract: The apparatus includes a static base, a platform, a first arm assembly, and a second arm assembly. The first arm assembly has a first terminal portion pivotally connected at a first pivot point to a first portion of the static base and a second terminal portion pivotally connected to the platform at a second pivot point. The first arm assembly is so constructed to permit changes in the distance between the first and second pivot points, but is concomitantly constrained to movement in a desired first plane. The second arm assembly has a respective first terminal portion pivotally connected at a third pivot point to a second portion of the static base and a respective second terminal portion pivotally connected to the platform at a fourth pivot point. The second arm assembly is so constructed to permit changes in the distance between the third and fourth pivot points but is constrained to movement in a desired second plane which is angularly disposed from the first plane.

Abstract: A device with a pivoting work arm for carrying and positioning a tool which is moved by a modified Watts linkage powered by a linear actuator having a true straight line motion. The modified Watts linkage has relatively short links resulting in the center of the middle link following an arcuate path. The center of the middle link is drivingly connected to the linear actuator by a pivoting link or a cam. To provide shock absorption for the work arm as it reaches its fully extended position, the modified Watts linkage is coupled to a follower arm yieldably biased by a spring.

Abstract: The backlash spring of a fuel control linkage is enclosed by an elastomeric sleeve which absorbs the energy of multiple resonant modes stimulated in the spring by vibratory fields. Deflections of large amplitude in the spring are minimized thereby. The sleeve has a plurality of ribs which extend axially therein and which provide an interference fit with the coils of the spring. The sleeve ribs contact as many of the spring coils as possible but minimize interference of the sleeve with the motion of the spring during the normal articulation thereof.

Abstract: A fluid-powered, laterally tiltable quick disconnect bucket actuator. A bucket has a pair of bucket clevises, and an actuator has a generally cylindrical body with an output shaft rotatably disposed therein with an axis in general parallel alignment with a forward rotation plane through which the bucket is rotatable on a backhoe arm by the operation of a rotation link. A bracket is attached to the body and has a pair of clevises for pivotal attachment to the vehicle arm and rotation link. The output shaft has a pair of shaft attachmetn forks for each end for attaching the shaft to the corresponding bucket clevises. The one pair of shaft attachment forks is attached to and moves axially with a member which is selectively extendable relative to the shaft to move the pair of forks between a locking position holding the bucket and a release position allowing disconnection of the bucket.

Abstract: An interactive system for guiding the use of a surgical tool uses at least one imaging technique, such as CT scanning. A mechanical arm has a fixed base at a first end and a tool holder that holds the surgical tool at a second end. A display displays one or more images from the image space of a patient's anatomy. A computer is coupled to the display and the mechanical arm. The computer tracks the location of the surgical tool through physical space, performs a transforming rotation of the physical space to the image space, and causes the display to display the location of the surgical tool within the image space.

Abstract: A cable suspension compliance mechanism has a top plate for attaching the mechanism to a robot and a bottom plate for attaching the mechanism to a gripping device. Steel cables interconnect the plates and maintain the plates substantially parallel relative to each other. Pneumatic cylinders are also disposed between the plates to adjust the mechanism's stiffness by adjusting the tension of a selected number of the steel cables. The mechanism is also equipped with magnetic inductance sensors to sense the position and classification of the article to be gripped. Additionally, the mechanism has an overtravel sensor to indicate the presence of unexpected obstacles, and to stop the mechasnism in response thereto.

Abstract: An inflatable structure, particularly adapted for use in outer space, employs one or more inflatable links which are connected at a base of the structure. A distal end of an outer most link is provided with a gripper assembly which can be remote controlled, and suitable encoders are included to indicate the angular position of each of the links. The motors for driving the at least one link is situated at the base to thereby reduce the mass of the at least one link and correspondingly reduce moments of inertia during operation.

Abstract: A six-legged, insect-like, self-propelled walking robot (hexapodal arthrobot), includes twistor-pairs in the waist, hip and knee of each leg and walks by pr0gramming fluid pressure in these twistor-pairs at the joints of respective legs in a predetermined controlled sequence. As a result of a predetermined sequence of six controlled variable pressures, this six-legged robot firmly plants three of its legs on the ground for providing stable ground support for walking. The three legs on the ground are propelling the robot forward with walking motion, while the other three legs are lifted and swing forward to an advanced position and are then lowered onto the ground for taking over their support and walking role in their turn, while the first three legs are then being lifted and swung forward to an advanced position, and so forth, for providing a stable forward walking motion. By reversing the sequence of six controlled variable pressures, a stable reverse walking motion is produced.

Abstract: A shift lever assembly for use in a bicycle wherein a wire connected at its one end to a derailleur is wound up or paid out to operate the derailleur. The assembly comprises a lever pivot fixed to the handlebar of the bicycle; a shift lever having a base-end boss portion rotatably supported by one end of the pivot and an arm portion extending from the boss portion; wire winder separate from the lever and rotatably supported by the pivot; a lever-coupled member provided between the boss portion and the winder and supported by the pivot so as to be rotatable with the winder; and a clutch for transmitting the rotation of the shift lever to the lever-coupled member. The shift lever is so biased by a spring as to return to a neutral position for starting rotation toward the wire winding direction and the wire paying-out direction.

Abstract: A drive system includes a vehicle propulsion drive having a speed change gear box which drives tracks through a pair of planetary gears and a steering drive having a pair of variable hydrostatic drives. The hydrostatic drives engage a neutral shaft which superimposes rotation on the planetary gears to provide steering control for the tracks. The neutral shaft is separable into two segments. A differental reversing gear may be employed to selectively couple the neutral shaft segments. When the vehicle travels at high speed, the neutral shaft segments are coupled for unitary rotation. At low vehicle speeds, the propulsion drive is blocked and the neutral shaft segments are uncoupled so that both propulsion and steering are provided through the hydrostatic drives.

Abstract: A mechanical steering device for the rear wheels of motor cars with four-wheel steering, including a front steering unit (4) and a rear steering unit (5) coupled for rotation with each other by a longitudinal transmission shaft (6), in which the rear steering unit (5) includes a transverse bar (11) connected to the rear wheels (2) by respective steering joints and tie rods (9, 10). The rotation of the longitudinal shaft (6) is transformed into translation of the transverse bar (11) by a positive cam (12).

Abstract: A manipulator having an end effector (1) displaceable by means of a four-rod mechanism, a comparatively light and stiff construction being obtained in that each of the rods (3,5,9,11) has a tubular support (73,79,159,181), which is secured by a bridge (147,149,169,191) to the bearing plate (87,93,119,193). The manipulator is particularly suitable for use in automatic mounting equipment.

Abstract: The invention relates to a balancing unit (1) for, for example, a movable arm in an industrial robot. The unit comprises a cylinder (2) with a piston (3) and a piston rod (4) arranged in the cylinder (2). The cylinder (2) is completely closed except for a sealed exit opening for the passage of the piston rod (4). On one side of the piston (3), the cylinder space is connected to a medium which is under high pressure, and on the other side of the piston (3) the cylinder space is connected, via a connection at the end of the cylinder (2), to a closed isolated space.

Abstract: A device for balancing the forces acting on a robot arm (10) hinged to rotate about an axis (A), said device comprising an even number of auxiliary parts (24.sub.1, 24.sub.2) hinged about respective mutually parallel axes (B.sub.1, B.sub.2) which are also parallel to the axis (A) of the arm, with each of said parts supporting two transverse arms (28,30) whose ends are suitable for bearing against a rectilinear portion (48) of a moving member (50) subjected to a return force towards an initial position, the auxiliary parts (24.sub.1, 24.sub.2) being driven at angular speeds which are equal in absolute value but which are in opposite directions in pairs, said speeds also being equal to one half of the angular speed of the robot arm.

Abstract: A vehicle with a plurality of legs which selectively alternately support and advance the vehicle in horizontal straight line motion, each of the legs comprises a support member, and in one embodiment, a first gear nonrotatively affixed to the support member, a first link pivotally connected to the support member at one end thereof, a means for rotatably driving the link about the pivotal connection, an idler gear pivotally mounted to the first link intermediate the ends thereof and in driving engagement with the first gear, a second link pivotally connected at one end thereof to the first link at the second end thereof, the second link having a planet gear affixed thereto and engaging the idler gear, whereby when the first link is pivotally driven by the drive means through the idler gear and the planet gear produces angular motion of the second link about the pivotal connection between the links, the first link is constructed and arranged to limit the angular movement of said second link in either direction,