Abstract: In an auxiliary-driving system in an engine, a crank pulley, a first auxiliary pulley and an idler pulley having a tensioner function are disposed in a triangular configuration with the idler pulley located in an uppermost position; and a second auxiliary pulley is disposed in a space surrounded by these pulleys. An endless transmitting belt is reeved around the pulleys. An inner surface of the transmitting belt is reeved around the first auxiliary pulley; and an outer surface of the transmitting belt is reeved around the second auxiliary pulley. Thus, the adjustment of the tension of the transmitting belt and other maintenance are facilitated, the transmitting efficiency of the transmitting belt can be enhanced, and compactness of the auxiliary-driving system itself and improvement in mileage can be achieved.

Abstract: A high output light source, such as a stage lighting luminaire, produces light along a path. The belt which drives a driven device is kept away from that path by passing it around the opposite side of the pulley.

Abstract: A transport device in a packaging machine includes a plurality of circulating transport chains which each travel over at least one chain wheel. In order to be able to adjust the transport device to differing formats for the bulk product and/or the packaging, the chain wheels can be adjusted with respect to each other in a peripheral direction upon a support shaft. In order to effect as simple and compact a construction as possible, a hydraulic fastening device is provided for fixing the chain wheels relative to each other, wherein the fastening device can be deactivated by means of a releasing device to effect adjustment. The chain wheels can be radially fixed to the shaft by the hydraulic fastening device. It is however also possible for the chain wheels to be disposed on coaxial shaft members which can be adjusted with respect to each other in the peripheral direction and which can be fixed to each other by the hydraulic fastening device.

Abstract: A tensioning assembly is provided for a synchronous belt drive on a mower deck. A plurality of idlers are mounted for rotation on bracket. One end of the a bracket engages an abutment surface mounted on the deck which restricts its movement, whereas a second end of the bracket is acted upon by a tensioning member which acts in substantially the same direction as the abutment surface. The bracket includes an elongated slot disposed between one of the idlers and the abutment surface, and a member fixed to the deck is engageable with the slot for confining movement of the bracket.

Abstract: A tensioning device for a chain or a belt drive for a motor of a hand machine tool, especially for a chain saw or a grinding or abrasive cutting-off machine, with a longitudinally movable bracket, such as a bracing or an arm, which can be fixed together with a cover with at least one bolt with a screwable nut to a casing or to another part of the hand machine tool, whereby the tensioning device has an adjusting screw extending in the longitudinal direction of the bracket on which a rider screw is movable to-and-fro by rotating the adjusting screw, the rider screw having a trunnion extending through an opening of the bracket so that, for tensioning the chain or the belt drive, the bracket follows a movement of the rider screw.

Abstract: A hydraulic autotensioner for keeping constant the tension in a belt. It has a bolt threadedly fixed to a stationary member, an eccentric ring supported by the bolt at an off-center position so as to be pivotable about the bolt, a pulley rotatably mounted on the eccentric ring, and a tension adjusting spring for biasing the eccentric ring in such a direction that the belt is pressed by the pulley. A hydraulic damper having a damper body is mounted between the stationary member and the eccentric ring so as to abut the eccentric ring for damping the pushing force applied to the eccentric ring from the belt through the pulley. A coupling ring is provided to keep the eccentric ring and the hydraulic damper coupled together.

Abstract: A belt autotensioner including: a support arm having one end supported and the other end biased in a predetermined direction; a tension pulley supported by the other end of the support arm; and a friction member held in sliding contact with the support arm for applying a rocking resistance to the support arm, and having a Rockwell hardness [H.sub.R R] of 30 to 40 in at least a portion in sliding contact with the support arm.

Abstract: Stretcher for a transmission belt comprising a fixed part suitable for being rigidly connected to a support structure, a movable part hinged to the fixed part about a first axis, a pulley carried by the movable part and rotating with respect thereto about a second axis distinct from the first axis and parallel thereto, a spring interposed between the fixed part and the movable part and suitable for loading in use the movable part in the direction tending to keep the pulley in engagement with the relative belt, and a damping element provided with a base wall rigidly fixed to the fixed part and with an annular friction portion extending axially from the base wall and cooperating with a seat produced in the movable part.

Abstract: An accessory such as an alternator is mounted to an automobile with a mounting that includes an upper mounting bracket and a lower mounting bracket, these brackets each being connected to the accessory and to the engine. One end of the upper mounting bracket is fixed to a side of the alternator. A length of the upper bracket is provided with an elongated slot and a fastener passing through the slot is fixed to an upper part of the engine such as at a water pump casing, the upper bracket thus being slidable on the fastener to adjust a positioning of the alternator relative to the engine and correspondingly altering a tension in an engine driven accessory drive belt. Because the upper bracket is thus at the accessory inner side, overall engine width is reduced and belt tensioning achieved in more efficient way.

Abstract: A tensioning system for an endless chain comprising a snail cam mounted on a second shaft parallel to a sprocket shaft which supports a sprocket and chain, a follower running against the snail cam and mounted on a mechanism supporting the sprocket shaft, a ratchet device which selectively limits the rotational direction of the second shaft so that the radius of the snail cam at the follower increases with rotation, a means of applying a controlled rotational force to the second shaft to advance the ratchet device if chain tension is below a predetermined level, but not advance it if chain tension is above a predetermined level.

Abstract: A centrifuge includes an elastically supported centrifuge basket, a drive unit, and an endless drive arrangement, such as a drive belt arranged on a drive pulley of the drive unit and a driven pulley of the centrifuge basket support unit, for driving the centrifuge basket. A tension relieving device is provided for relieving or counteracting the tension forces of the endless drive arrangement. Thus the elastic supporting members of the centrifuge basket support unit are not stressed by the tension forces of the endless drive arrangement, and the tension relieving device can be pre-stressed so that the basket is in a neutral position during operation. For pre-stressing the tension relieving device, it includes an elastic thrust element, such as a compression spring packet, in addition to a length adjustable strut. To avoid tilting moments, the tension relieving device is arranged in a plane of the endless drive arrangement between the two pulleys.

Abstract: A belt tension adjusting mechanism comprises a belt tension adjusting pulley over which the endless belt is placed; a plate having a plurality of recesses in which a rotary shaft of the belt tension adjusting pulley is received; a handle having, at one end thereof, a pin engageable with the recess; and a linking member connected, at one end thereof, with the rotary shaft of the belt tension adjusting pulley and connected, at the other end thereof, with an intermediate portion of the handle.

Abstract: A conveyor belt tensioning mechanism includes a frame assembly, a conveyor belt movable around a head and end pulley on the frame assembly, one of the pulleys being longitudinally movable along the frame assembly, a first adjustment member on the frame assembly for moving one end of the movable pulley longitudinally, to apply tension force to the belt, a second adjustment member on the frame assembly for moving the other end of the movable pulley longitudinally, to apply tension force to the belt, each adjustment member having an indicating member thereon, for indicating when tension force on the belt is within a preselected tension force range.

Abstract: An adjusting device for aligning a drive pulley for an elevator leg or similar belt conveyor. The driving mechanism, normally perpendicular to the axis of the pulley, is pivotally mounted so that the drive shaft may be slightly tilted. The bearing block opposite the driven part of the shaft is mounted on shims to allow the movement of the axis of the shaft.

Abstract: An improved tool is disclosed for use in aligning pulleys. The tool has a shaped configuration with multiple engaging pads adapted to align the pulleys with in about 0.2 degrees.

Abstract: A belt-drive tensioning system for a motor drive positioning system, especially for X-Y digital plotters. The tensioning system employs spring-loading involving motion along only one translational direction to accurately preset and maintain constant the desired belt tension. Preferred embodiments to provide a self-contained modular unit include a dual plate assembly in roller-bearing relationship, and the use of V-shaped mounting springs.

Abstract: An adjustable belt retainer is provided for use with a belt driven mechanism, such as an auxiliary blower for a mower deck. The retainer allows quick and easy adjustment between a belt retaining and a belt removal position. Its L-shaped with one leg being slidably mounted to the housing, the other leg extending adjacent the belt near its contact with the pulley. A releasable stop is provided between the housing and retainer being biased towards engagement to maintain a retainer in its belt retaining position. A finger handle is provided to allow the operator to disengage the stop easily without the need for tools and guide surfaces are provided to allow quick and easy sliding adjustment of the retainer between its two positions.

Abstract: A mounting structure for drivingly connecting a belt driven attachment such as an auxiliary blower to a mower deck or similar implement. The connecting structure includes a pivot and sleeve arrangement between one end of the blower and the mower deck for quickly and easily positioning the blower on the mower deck. The pivot then allows for the blower to be swung around adjacent to the mower deck to permit a latching mechanism to be engaged between the mower deck and the blower. The combination latching and belt tensioning mechanism permits generally simultaneous belt tensioning for belt driven blowers as the rear of the blower is latched to the mower deck. Should the latch not be aligned and, therefore, not secure the mower to the blower deck, provision is made for the belt tensioning arrangement to not engage the blower attachment adequately with the mower's belt drive.

Abstract: A centrifugal supercharger system for an internal combustion is directly driven by the associated engine and includes a belt driven drive pulley and bracket for locating an idler pulley for tensioning the belt. A plurality of bosses on the housing plus arcuate slots on the bracket provide for flexibility in locating the idler pulley. The drive pulley drives a gear which engages a driven gear on a separate shaft carrying the compressor wheel which is driven at a multiple of engine speed within a volute. The compressor wheel is recessed into an internal wall of the housing to provide smooth flow of air from the compressor wheel into the volute. Another group of bosses on said housing cooperate with an engine mounted bracket to provide flexibility in mounting the supercharger on various engines.

Abstract: A plough box containing a chain wheel driving a chain to propel a chain used to move a plough is mounted for displacement alongside a machine frame at one end of a scraper-chain conveyor. To adjust the tension in the chain a motor is operated to drive a self-locking worm gearing which employs a worm wheel meshing with a rack fixed to the machine frame and extending in the direction of the chain.

Abstract: The power-take-off conversion unit of this invention is adapted for attachment to a vehicle with a driving pulley rotatable in a generally vertical plane and driving an elastic belt, wherein the vehicle has two mounting brackets located beneath the pulley. The unit has a frame with an arm that extends rearwardly from a rear portion of the frame. Two pins extending from the arm are adapted to engage within the mounting brackets on the vehicle to allow the frame to rotate about a horizontal axis. The frame has a planar locking surface extending therefrom and a cam surface which extends downwardly and outwardly from the locking surface. A driven pulley is rotatively mounted within the frame to engage with and be driven by the elastic belt of the vehicle. A belt-tensioning bar is rotatively mounted to the vehicle about a horizontal axis which is located above the locking surface of the frame.

Abstract: A belt tensioning apparatus using a spring to provide the proper tension in a belt. A belt/pulley assembly is disclosed with one pulley slidably mounted on a bracket. A spring compressed to a fixed distance to provide a known force is attached to the bracket by a screw. The bracket, being initially free to move, transfers the force to the belt/pulley assembly for providing the optimum tension in the belt/pulley assembly. Once the proper tension in the belt is obtained, the bracket can be securely fixed, preventing movement between the pulleys in the assembly. Re-tensioning, when necessary, is accomplished easily by simply loosening and resecuring the bracket.

Abstract: Disclosed is a clutchable pulley system conventionally having an annular first-belt and an annular second-belt, both belts enveloping a plurally-grooved transfer pulley. Also in conventional fashion; the first-belt is constantly tightly trained with a power-source pulley and at least one primary-load pulley; and the second-belt is normally loosely enveloping the plurally-grooved transfer pulley and at lest one secondary-load pulley whereby the secondary-load pulley(s) will not rotate until the second-belt is made to tightly train with the transfer pulley. Departing from the prior art utilization of the idler-pulley principle for controllably tightly entraining the second-belt with the plurally-grooved and secondary-load pulleys, the herein disclosed clutchable pulley system supplants the second-belt idler-pulley by controllably moving the plurally-grooved transfer pulley along an arcuate path.

Abstract: A device is disclosed for tensioning of a pulling element (1) of a printer and in particular of a matrix printer, for a back and forth motion of a part (5) or of a carriage includes a first deflection roller (11) and a second deflection roller (12). A wedge surface (15) is furnished, which upon increasing inclination (16) is slidable in a direction parallel to a frame surface (17) disposed perpendicular to the pulling direction (18) and which wedge is subjected to the force of a tension spring (22) such that the adjustable second deflection roller (12) serves the purpose of an increase of the tensioning force in the pulling element (1).

Abstract: Undesirable noise developing from relative sliding between a belt and a pulley when the traction between the belt and the pulley is loosened to halt the belt from being driven by the pulley is eliminated or alleviated by roughening the inner surface of the pulley to a consistency somewhat like that of sanded wood surface. Preferably, the inner surface is roughened in accordance with published Moldtech Standard 1055-5. The belt has a circular cross-section and is formed of polyurethane. Moreover, the roughened surface on the drive pulley improves the traction between the belt and the drive pulley when the belt is tightened in order to be driven by the drive pulley.

Abstract: A pressing machine has a drive pulley secured to a press crank shaft, an intermediate shaft parallel to the press crank shaft and an input shaft of a material feeding device, the intermediate shaft being supported by a tension adjusting device which is rotatably supported by the crank shaft and the input shaft of the material feeding device, a first intermediate pulley which is secured to one end of the intermediate shaft and is drivingly connected to the drive pulley through a first endless torque transmission device, and a second intermediate pulley which is secured to the other end of the intermediate shaft and is drivingly connected to an input pulley secured to the input shaft of the material feeding device through a second endless torque transmission device.

Abstract: A mechanism which maintains a required power level for an electrical use device even though the power level would otherwise drop below that which is necessary at engine idle or alternator speed would increase beyond an acceptable maximum at engine hi idle. The apparatus includes a variator pulley along with mechanism for moving the pulley between first and second positions thereby increasing or decreasing the ratio of alternator speed to engine speed.

Abstract: A belt adjusting device for "V" belts which uses a gear made integrally with a nut, in cooperation with a locking mechanism, and gear teeth on a plate to produce relative movement between the plate and the mount, thus tensioning or loosening the "V" belt as desired, and allowing it to be locked into position with the locking mechanism, once adjusted.

Abstract: A telescopic belt tensioner includes a pair of housings mounted to the sides of a conveyor bed. Each housing has an outer tube telescopically mounted in it, and an inner tube telescopically received within the outer tube. The inner tube includes means for rotatably supporting a conveyor belt roller. Bolt and nut means between the inner and outer tubes reciprocate the inner tube with respect to the outer tube to provide fine adjustment of the belt tension. A quick release mechanism between the housing and outer tube provides rapid adjustment of belt tension. The quick release mechanism comprises a lever mounted to the housing and a hook mounted to the outer tube, with a pivotable link connecting the lever and hook.

Abstract: Method and apparatus for adjusting tension on a timing belt of an engine. The engine includes a driving pulley on its crankshaft, a driven pulley on its camshaft, an auxiliary pulley, a timing belt bridging over the pulleys and a tension pulley pressing against the belt at one side. The driving pulley is first reversely rotated while the driven pulley is held fixed in position thereby tensioning the portion of the belt between the auxiliary pulley and the driven pulley. The driving pulley is then rotated normally to overtension the tension side portion of the belt while the tension pulley is advanced to take up any slack. Thereafter, the tension pulley is retracted while the driving pulley is reversely rotated until deflection of the tension side portion of the belt reaches a predetermined target adjustment value. The tension pulley is then fixed in position.

Abstract: A belt tensioner for a belt and pulley system is disclosed. The tensioner has a camming surface upon which a pulley axle rides, maintaining substantially uniform tension in the belt despite competing forces of the belt tension and a tensioner holding spring. The camming surface profile is generated, for example, when using a spring holding mechanism, by differentiating Hooke's Law.

Abstract: An automatic tension adjusting mechanism for a winding and transmitting device for an automatic door includes a base fixed in a casing; a mount for a transmission wheel around which a belt is wound; the mount being disposed on the base slidably in the right and left directions where the mount forces the belt to be strained and relaxed, and being resiliently energized at all times in one of the directions where the mount forces the belt to be strained; a saw-toothed stop part provided on the mount and adapted to extend in the right and left directions; and an engagement piece provided on the base and adapted to be moved between an engagement starting position with the stop part and a disconnection position from the stop part; a spring between the base and the engagement piece for energizing the engagement piece in a direction where the engagement piece is engaged with the stop part; a tapped hole made in one of the members of the base and the mount; and a bolt screwed into the tapped hole.

Abstract: A typewriter carriage cable snubber which is automatically reset at the time power is turned on is described. The cable is normally tensioned by a mechanism which is spring driven to maintain the cable tension at the proper value, and a snubber is provided to prevent the positioner from allowing the cable path to shorten under the increased tension that occurs during carriage acceleration. When the power is turned off, the cable tends to shrink due to the decreased temperature. When power is turned on, the carriage is initialized by positioning it at the left end of its range. At this position the cable tensioning mechanism can be reset to allow a shorter cable length by having an extension of the carriage disengage the snubber, allowing the positioning mechanism to reset itself to a shorter cable length.

Abstract: Beverage brewing apparatus suitable for use in a vending machine has a frame supporting a vertically movable open bottom cylinder and a piston slidably disposed within the cylinder. A brewing cavity is disposed beneath the cylinder to enable reciprocation horizontally between a brewing position and a rest position. The horizontal movement of the cavity is controlled through a cable running around a pulley rotatably supported on the frame. The pulley is provided with a mechanism for adjusting the position thereof to determine the brewing position and rest position of the cavity to ensure secure engagement between the cylinder and brewing cavity.

Abstract: A belt stretching mechanism to adjust the tension in a belt wound around pulleys by turning an adjust bolt and moving a slider which is fastened together with a stay to an adjust bar by means of a stay-fastening bolt, wherein the axis of the adjust bolt and the axis of the stay-fastening bolt are in the same plane, so that no bending moment acts on the adjust bolt and smooth tensioning of V-belt is ensured.

Abstract: An insertion machine has a stationary table for holding inserts, and a linearly movable table for receiving and holding envelopes. The moving table jogs left or right to align the insert and envelope so that the insert may be pushed into the envelope. A parallelogram drive mechanism has a first pair of belt drives which form vertical parallel arms. As the table moves back and forth, the length of the parallel vertical drive mechanism does not change appreciably so that the ends of the vertical arms float up and down. There is no need for sliding gears, shafts, or the like to transfer power to the table. A second pair of belts drive the vertical belts from a stationary point at a center of the side of the parallelogram which is opposite the table. The second pair of drive belts enables the lower ends of the first pair of drive belts to float up or down slightly without causing any dislocation as a result of table movement.

Abstract: A belt tensioner for use of a V-belt which is spanned between a driving member and a driven member. The belt tensioner has an adjust bolt to be rotated by a worker, a bracket which slidably supports a slider secured to the driven member. The adjust bolt comprises a head portion, a first shaft portion which has a threaded relation with a hole within the bracket, and a second shaft portion which has a thread relation with the slider. Further, a spring is provided between the head portion of the adjust bolt and the bracket to bias the adjust bolt in such a direction as the head portion of the adjust bolt is separate away from the bracket, thereby obtaining an optimum belt tension force.

Abstract: A V-belt stretching mechanism to adjust the tension of the V-belt in an internal combustion engine wherein a spring plate has two arms with ends staggered in the longitudinal direction of an adjust bolt. A slide cam has hooks which engage with the arms. Engagement and disengagement of the cam with the arms of the spring plate makes it possible to automatically adjust the tension in the V-belt.

Abstract: In manually operated mobile storage apparatus which moves back and forth in guided movement by floor mounted tracks and which includes a manually operable drive wheel accessible by the user and connected to a storage unit drive shaft by a chain there is provided a chain tensioning device to eliminate slack and provide the appropriate tension. The chain tensioning device comprises a bearing block with a roller bearing which is journalled on the shaft and which can be drawn by bolts to deflect the shaft and tighten the chain.

Abstract: A belt tensioner has an elongated support bar formed with a transversely throughgoing aperture and an annular inwardly directed lip around the aperture. A hardened metallic inner bearing race is centered on and elongated along a bearing axis and has one end extending into the aperture and formed with a circumferential radially outwardly open groove in which the lip is snugly fitted. An outer race is mounted on and coaxial with the other end of the inner race and is supported thereon by means of roller-bearing elements. The nonmalleable one end of the inner race does not need to be deformed to secure it in the support bar; instead the support bar, which is normally made of malleable steel, is deformed to make the connection.

Abstract: Two embodiments of V-belt tensioning devices are employed in a cooling system of a vehicle having an engine (20) transversely mounted for rocking motion relative the vehicle frame (42). The cooling system includes an engine cooling radiator (22) mounted forwardly of the engine and substantially parallel to the rotational axis of the engine crankshaft; a cross-flow fan (24) having a rotational axis fixed against movement relative to the vehicle frame, substantially parallel to the crankshaft axis, and between the crankshaft axis and the plane of the radiator; a V-belt drive (32, 34 36) for rotating the fan in response to rotation of the crankshaft; and the two embodiments of the tensioning devices which maintain the V-belt tension as the distance between the crankshaft and fan axes varies in response to rocking motion of the engine. In one embodiment the tensioning device (90) is a split pulley (36). In the other embodiment the tensioning device (108) is a spring loaded idler pulley (110).

Abstract: A belt tensioning tool for tensioning an endless belt that passes around a plurality of spaced apart pulleys with one of the pulleys being mounted for adjustable movement relative to the other pulleys. The belt tensioning tool has as its basic components an actuator assembly including an extensible rod member, a reaction assembly mounted to one end of the actuator assembly, and a slidable assembly mounted to the extensible rod member. The reaction assembly includes a reaction arm member which extends in a cantilevered fashion away from the extensible rod end of the actuator assembly. Similarly, the slidable assembly includes a cantilevered, slidable arm member which is mounted to the extensible rod member and is slidably movable along a track in the reaction arm member. The reaction arm member and slidable arm member include opposed adapter members having pulley engaging ends that extend in opposite directions.

Abstract: Disclosed is a vehicle having a liquid-cooled engine (20) transversely mounted for rocking motion relative to the vehicle frame (42); an engine cooling radiator (22) mounted forwardly of the engine and substantially parallel to the rotation axis of the engine crankshaft; a cross-flow fan (24) having a rotational axis substantially parallel to the crankshaft axis and disposed between the crankshaft axis and the plane of the radiator; the fan is engine driven by a belt (36), and a viscous coupling (29) to vary the fan speed in response to engine cooling requirements. In one embodiment the engine moves relative to the fan and the radiator. In this embodiment an air inlet duct assembly (40) is defined by a portion (26a) of the engine and members extending from the radiator to the engine. In the other embodiment the fan is fixed for movement with the engine and an air inlet duct assembly (126) allows movement between the fan and the radiator.

Abstract: A drive transmission gear unit is constructed to make possible adjustments in the relative spacial relationship between the unit gear wheels and a load shaft. The adjustment in the relative relationship between the unit and the load shaft may be carried out without varying the engagement relationships of the rotary elements within the unit. A centering arrangement is provided in the unit whereby the gear housing portion is rotatable about a driven shaft, thus enabling the gear unit to adjust for slack developing in any belt or chain tension means used to transmit rotary motion to a load shaft.

Abstract: Disclosed is a vehicle having a transversely mounted engine (20), an engine cooling radiator (22) mounted forward of the engine and substantially parallel to the rotational axis of the engine crankshaft, a cross-flow fan (24) mounted for rotation about an axis substantially parallel to the crankshaft axis and between the crankshaft axis and plane of the radiator, and a mechanical drive (32, 34, 36) which rotates the fan in response to rotation of the crankshaft.

Abstract: The driven head shaft of a drag elevator type conveyor is mounted at the roller end of a shaft mounting frame which is in the nature of a first class lever. A mid-portion of the shaft mounting frame is mounted onto an upper end portion of the conveyor main frame for pivotal movement about an axis which is parallel to the axes of both the head shaft and the tail shaft. A turnbuckle is interconnected between the upper portion of the shaft mounting frame and an upper portion of the main frame. The shaft mounting frame end of the turnbuckle is connected to a mid-portion of a lever arm which is at its upper end pivotally attached to the shaft mounting frame. The lower end of such lever rests on a pair of laterally spaced apart compression springs. The turnbuckle provides a way of adjusting the tension in a pair of roller chains which are portions of an endless carrier which extends between and is mounted on the head shaft and the tail shaft.

Abstract: A module including a frame which supports a motor, reduction gearing and a belt driving pulley is mounted in a sewing machine for position adjusting movements in one direction effective to set tension in a shaft timing belt, and position adjusting movements in another direction effective to set tension in a hook shaft timing belt.

Abstract: A pulley on an output shaft of an engine is coupled via a belt to a drive pulley which is mechanically coupled to the drive wheels of a vehicle. The tension of the belt is controllable by forward movement of a control lever from a neutral position; the control lever being arranged to shift the drive pulley relative to the output shaft pulley. The controlled variations in the tension of the belt caused by movement of the control lever produces a controlled degree of mechanical coupling between the output shaft pulley and the drive pulley to control the forward speed of the vehicle. A friction surface, provided on a circumferential periphery of the drive pulley, is capable, upon reverse movement of the control lever from the neutral position, of directly engaging with the output shaft pulley to cause reverse movement of the vehicle.