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Showing papers on "Pulley published in 1995"


Journal ArticleDOI
Shigeharu Uchiyama1, J. H. Coert1, L. J. Berglund1, Peter C. Amadio1, Kai Nan An1 
TL;DR: An experimental system was developed that allows direct measurement of friction at the tendon‐pulley interface, and the results were interpreted by use of a theoretical model for friction of a cable around a fixed pulley.

144 citations


Patent
Thomas Schmidt1, Klaus Butenop1, Doris Kröger1, Jörg Barckmann1, Rene Rade1 
11 Apr 1995
TL;DR: A rotary tightening device for a safety belt has a belt retractor including a housing and a belt take-up shaft rotatably supported in the housing as mentioned in this paper, which rotates in the direction of the safety belt.
Abstract: A rotary tightening device for a safety belt has a belt retractor including a housing and a belt take-up shaft rotatably supported in the housing. The belt-take-up shaft has one end of the safety belt connected thereto. Upon triggering of the rotary tightening device, the belt take-up shaft is rotated in a belt take-up direction of the safety belt. A drive wheel is connected to the shaft. The housing has a channel extending in a plane parallel to a radial plane of the drive wheel and extending at least partially about a circumference of the drive wheel. Mass bodies are positioned loosely adjacent to one another in the channel. The mass bodies, when accelerated, act on the drive wheel for driving it. The drive wheel has at the circumference a gearing in which the mass bodies are received for driving the drive wheel. A spacing of the gearing is substantially identical to a spacing between the mass bodies.

115 citations


Patent
02 May 1995
TL;DR: In this article, a steerable catheter consisting of a resilient body member, a manipulation handle attached to the proximal end of the body member and a control wire extending from the handle to the distal end of a catheter for deflection control is presented.
Abstract: A steerable catheter comprising a resilient body member, a manipulation handle attached to the proximal end of the body member, a control wire extending from the handle to the distal end of the catheter for deflection control, and a pulley mechanism for controlling the movement of the control wire. Longitudinal movement of a slide element in the handle causes movement of the control wire and control over the deflection of the distal end of the catheter. The pulley mechanism is connected between the slide element and the control wire to provide greater mechanical advantage to effect deflection of the body member while enhancing deflection control resolution. A stiffening member is also disposed in the catheter body member and its position is controlled by the rotational motion of the slide element. The position of the pulley mechanism is not affected by rotational motion of the slide element.

83 citations


Patent
07 Jun 1995
TL;DR: An overrunning clutch pulley in which a pulley sheave and hub cooperate to define a composite inner cylindrical surface is described in this article, where a coil spring is employed to transfer torque from the pulley heave to the hub.
Abstract: An over-running clutch pulley in which a pulley sheave and hub cooperate to define a composite inner cylindrical surface. A coil spring engages the composite cylindrical surface. The spring is oriented to transfer torque from the pulley sheave to the pulley hub when the pulley sheave is driving the pulley hub. The spring allows slip to occur between the pulley hub and sheave when the sheave is decelerated relative to the hub.

73 citations


Patent
06 Mar 1995
TL;DR: In this paper, a two-axis Cartesian robot is described comprising a first horizontally disposed support having a first carriage selectively movable mounted thereon, and a second support is operatively secured to the first carriage and extends perpendicularly with respect to the longitudinal axis of the first support.
Abstract: A two-axis Cartesian robot is described comprising a first horizontally disposed support having a first carriage selectively movably mounted thereon A second support is operatively secured to the first carriage and extends perpendicularly with respect to the longitudinal axis of the first support A belt pulley is rotated by a reversible drive motor and is operatively connected to the upper and lower ends of the second support by a pulley arrangement A horizontal brake is provided to control the movement of the carriage with respect to the first support A vertical brake is provided to control the movement of the second support with respect to the carriage A workpiece handling member is mounted on the lower end of the second support for manipulating the workpiece being handled

60 citations


Patent
10 Apr 1995
TL;DR: A motorized pulley or roller as mentioned in this paper comprises a stationary roller shaft (14), a generally cylindrical drum (12) mounted for rotation about the roller shaft, and an electric drive assembly disposed inside the cylinderrical drum for rotating the drum about the rollers.
Abstract: A motorized pulley or roller (10) comprises a stationary roller shaft (14), a generally cylindrical drum (12) mounted for rotation about the roller shaft, and an electric drive assembly disposed inside the cylindrical drum for rotating the drum about the roller shaft. The motorized pulley includes an integral electrical connector (100) for connecting the roller to a power supply. The integral electrical connector includes a male connector (102) disposed in a recess formed in one end of the roller shaft. A female connector (104) which registers with the male connector is wired to the power supply. The male and female connectors allow for easy and quick replacement of the motorized rollers by untrained personnel.

54 citations


Patent
24 Feb 1995
TL;DR: In this article, a first and a second support plate 17 and 16 are disposed face to face on a frame, and elongated holes 17a and coupling hole 16a are formed face-to-face through the plates, and a groove 20a is formed into the top face of a support shaft 20 inserted into an axial hole of a drive pulley 10.
Abstract: PURPOSE: To provide a motor driven sliding type variable resistor having a driven pulley easily supported with a frame. CONSTITUTION: A first and a second support plate 17 and 16 are disposed face to face on a frame, elongated holes 17a and coupling hole 16a are formed face to face through the plates 17 and 16, and a groove 20a is formed into the top face of a support shaft 20 inserted into an axial hole of a drive pulley 10. This groove 20a allows the upper and lower ends of the shaft 20 to slide into the interiors of the holes 17a and 16a, utilizing the tension of the belt 11 when inserted into the hole 17a so as to hold the plate 17.

52 citations


Patent
13 Jan 1995
TL;DR: In this article, a single cam compound bow is configured so that the first cable is unwound therefrom at a rate which differs, and is initially lower than, the rate at which the third cable is wound onto the upper pulley assembly.
Abstract: A single cam compound bow includes a lower pulley assembly, an upper pulley assembly and three cables. The lower pulley assembly has an end of all three cables attached thereto and includes a power cam portion. The upper pulley assembly has the other end of the first and third cables attached thereto, and the other end of the second cable is attached to the upper bow limb. The upper pulley assembly is configured so that the first cable is unwound therefrom at a rate which differs, and is initially lower than, the rate at which the third cable is wound onto the upper pulley assembly. The configuration of pulleys causes the nock point of the bow string to travel in a straight line.

51 citations


Patent
29 Dec 1995
TL;DR: In this paper, a concrete saw is provided having an engine aligned along a longitudinal axis of the saw frame to minimize the width of a saw and provide a more balanced system, where a right angle gear box is provided proximate the driven side of the clutch assembly to transfer driving rotational forces from the engine to a transversely aligned driven shaft.
Abstract: A concrete saw is provided having an engine aligned along a longitudinal axis of the saw frame to minimize the width of the saw and provide a more balanced system. A clutch assembly is attached to a forward end of the engine to disengage the saw blade without stopping the engine. A right angle gear box is provided proximate the driven side of the clutch assembly to transfer driving rotational forces from the engine to a transversely aligned driven shaft. The driven shaft includes drive pulleys mounted upon opposite ends thereof, which are aligned with driven pulleys mounted upon opposite ends of a blade support shaft and linked to one another via multiple belts. This alignment evenly balances the load transfer while facilitating the use of vibration isolators between the engine, gear box and frame. A hydraulically controlled depth stop mechanism is included for setting a maximum cut depth. The engine speed is controlled by an electronic governor. A multi-speed transmission is included to afford high and low ranges for the saw. A single control lever is provided to shift between high and low ranges, between forward and reverse directions, and to raise and lower the saw.

50 citations


Journal ArticleDOI
TL;DR: In this article, a simulation model is developed to analyze the response of a vehicle with a metal V-belt CVT to a rapid pulley ratio change, and the simulation results are in reasonable agreement with experimental results.
Abstract: SUMMARY In regard to the belt and pulley system of a metal V-belt CVT, the characteristics of the ratio changing speed is obtained by experiments. It is summarized in a practical and simple experimental equation. By using this equation a simulation model is developed to analyze the response of a vehicle with a metal V-belt CVT to a rapid pulley ratio change. The simulation results are in reasonable agreements with experimental results.

40 citations


Patent
23 Oct 1995
TL;DR: In this paper, a robot with a base, a first link connected to the base by a shoulder joint, and a second link connected with the first link by an elbow joint is described.
Abstract: A robot with a base, a first link connected to the base by a shoulder joint, and a second link connected to the first link by an elbow joint. A shoulder motor drives the shoulder joint, and an elbow motor drives the elbow joint. An upper elbow pulley is coupled to the first link. An end effector pulley coupled to the upper elbow pulley, and a dual-bladed end effector driven by the end effector pulley. The diameter of the upper elbow pulley and the diameter of the end effector pulley are related by a 1:2 ratio. Ferro-fluid seals are used to seal each joint. A static seal joins the seams of the links. Each arm link has a particle filter. The robot can communicate electrical signals through the revolute joints with a conductive slip-ring assembly. Alternately, the joint may have an inner cylinder and an outer cylinder, and a cable may be coiled between the cylinders.

Patent
02 Jun 1995
TL;DR: In this article, a self-locking descender with a drive finger cooperating with a mechanism having a transmission rod movable between an active engagement position with the finger, and an inactive escape position to break said mechanical link after the intermediate position of the handle has been passed.
Abstract: The invention relates to a self-locking descender wherein the pulley in the form of a cam is equipped with a drive finger cooperating with a mechanism having a transmission rod movable between an active engagement position with the finger to establish a unidirectional mechanical link between the handle and cam when the handle is actuated to an intermediate unlocking position in the course of the descending movement, and an inactive escape position to break said mechanical link after the intermediate position of the handle has been passed, causing disengagement of the pulley and automatic return of the cam to the locking position due to the action of the tension of the rope. The locking effect of the rope is thus preserved after disengagement, without maintaining a force on the handle.

Patent
28 Nov 1995
TL;DR: In this paper, a toothed-belt and V-belt for treadmills is described, which consists of an endless belt, provided with a plurality of tread lamellae and which is guided around two deflection pulleys.
Abstract: The present invention refers to a toothed-belt and V-belt for treadmills, comprising an endless belt, which is provided with a plurality of tread lamellae and which is guided around two deflection pulleys. At least one of the deflection pulleys comprises a sliding disk member and a toothed-disk member in juxtaposition, and the belt comprises, in juxtaposition, a toothed-belt area associated with the toothed-disk member of the deflection pulley and a V-belt area abutting on the sliding disk member of the deflection pulley. The main force for driving the belt is transmitted via the sliding disk member and the V-belt area. The toothed-disk member of the deflection pulley preferably has toothed areas and toothless areas, which are alternately and equidistantly arranged throughout the circumferential surface thereof.

Patent
07 Jun 1995
TL;DR: In this paper, a vehicle seat suspension system is provided which includes, in a seat support comprising an upper housing and a lower housing, a scissors linkage support apparatus, a spring fixed to the upper housing, and a cable attached to the spring and wrapping around a pulley attached downwardly to an arcuate or eccentric pulley.
Abstract: A vehicle seat suspension system is provided which includes, in a seat support comprising an upper housing and a lower housing and a scissors linkage support apparatus, a spring fixed to the upper housing and a cable attached to the spring and wrapping around a pulley attached to the upper housing and downwardly to an arcuate or eccentric pulley attached at the scissors linkage axis pivot and an actuator knob which allows a seat occupant to tighten or loosen the cable and raise or lower the seat to provide a vehicle seat suspension system. The present invention provides a suspension system which can be discreetly and infinitely adjustable and which allows a user to adjust the suspension curve characteristics of the seat by utilizing a non-circular drive pulley which is movably adjustable.

Patent
27 Jan 1995
TL;DR: In this paper, a transmission unit for bicycle brakes consisting of a single operating force input (10, 12) connected to a force multiplier (14) which distributes said multiplied force between two operating force outputs (16, 18) via a differential which equalizes the two operating forces outputs while giving preferential motion of one of the outputs in the phase of motion prior to the full equalization of the multiplied operating force.
Abstract: A transmission unit for bicycle brakes consisting of a single operating force input (10, 12) connected to a force multiplier (14) which distributes said multiplied force between two operating force outputs (16, 18) via a differential which equalizes the two operating force outputs while giving preferential motion of one of the outputs in the phase of motion prior to the full equalization of the multiplied operating force. This unit allows a single brake cable (12) from a control lever (10) to connect within the unit to a cam actuator follower which transfers this single operating force by means of a ratio modulating cam lever (26) which incorporates a guide pulley which moves via a fulcrum pivot axle (28) located between the cam structure and the guide pulley structure. This mechanism is combined with a cable (16, 18) which is looped around 180° of the guide pulley and which exits the unit in parallel paths in a direction of opposition to the motion of the cam structure via the pivot axle described. Each end of the pulley-actuated brake cable described connects to one of each of the two wheel brakes allowing equalization of the distributed force. A light friction generating device (32-36) within the unit connects to one of the two operating force outputs to insure preferential actuation of the rear wheel brake within the phase of operation of initial brake-to-wheel contact but prior to full operating force application, during which full equalization is desired so as not to compromise the efficient transfer of the operating force input to the two operating force outputs.

Patent
08 May 1995
TL;DR: A rotator cuff exercise machine has a frame, a body support member spaced from the frame such that the user sits facing the frame, weight resistance, a pulley system mounted 15° to 45° off center to the left side of the frame and a pair of wrist cuffs.
Abstract: A rotator cuff exercise machine has a frame, a body support member spaced from the frame such that the user sits facing the frame, a weight resistance, a pulley system mounted 15° to 45° off center to the left side of the frame, a pulley system mounted 15° to 45° off center to the right side of the frame and a pair of wrist cuffs. The user reaches diagonally downward across his or her body to the lower opposite side of the machine and either grasps a handle or attaches the wrist cuff to cable end means of the pulley system. The user then exercises in a manner which imitates the motion of an athlete throwing a ball, changing the weight resistance as desired.

Patent
10 Jan 1995
TL;DR: In this paper, a spiral one-way clutch is proposed to suppress belt oscillations during low speed engine operation, placing less critical demands on a belt tensioner, if present.
Abstract: An automotive accessory drive linkage is provided with a one-way clutch mounted on any of the pulleys carried by the engine crankshaft, an alternator, an hydraulic pump or generally, on the pulley for any other accessory operated by a belt linked to the engine in order to isolate such driven elements from oscillations in the engine speed. A spiral one-way clutch especially suitable for incorporation in automotive accessory drive system pulley has a high indexing capacity. Such clutch, installed between the pulley shive and spindle operates to suppress belt oscillations during low speed engine operation, placing less critical demands on a belt tensioner, if present. It also operates to prevent belt slippage during periods when the engine is forced to decelerate rapidly during up-shifts of the transmission, effectively eliminating "belt squeal".

Patent
17 Feb 1995
TL;DR: In this article, a steering wheel is attached to the front end of the steering shaft and a powder clutch and an electric motor are located on either side of it, and an endless output belt 18 is mounted around a coupled pulley that is fitted over the steering wheel and a drive pulley (17) for the powder clutch.
Abstract: When the steering wheel is turned right or left from its neutral state, a steering reaction force in a direction opposite to the steering direction is transmitted to an operator. A steering shaft (4) that passes through a case (2) and a panel plate (3) is supported rotatably via housings (5) in which are mounted ball bearings. A steering wheel is attached to the front end of the steering shaft (4), and a powder clutch (12) and an electric motor (19) are located on either side of the steering shaft (4). An endless output belt 18 is mounted around a coupled pulley (8) that is fitted over the steering shaft (4), and a drive pulley (17) for the powder clutch (12), while an endless input belt (23) is mounted around a coupled pulley (16) for the powder clutch (12) and a drive pulley (22) for the electric motor (19).

Patent
24 Oct 1995
TL;DR: In this article, a frictional force between the face and the belt is increased, so that a higher torque than the drag torque can be transmitted to the one-way clutch without causing a slippage of the belt.
Abstract: Irregularities on the face of the pulley groove of the pulley for driving the rotor shaft of the generator through the one-way clutch are positively extended and a frictional force between the face and the belt is increased, so that a higher torque than the drag torque can be transmitted to the one-way clutch without causing a slippage of the belt Since no slippage occurs on the belt, the belt life can be extended Since the one way clutch is positively operated, the inertial energy of the rotor can be effectively recovered

Patent
30 Nov 1995
TL;DR: The plenum chambers of a hydromechanical torque sensor can be connected to or sealed from each other as a consequence of change in the effective dia. of the pulley to change the ratio of a transmission including a pulley as mentioned in this paper.
Abstract: The hydromechanical torque sensor (14) has cam discs (18,19) with conforming cam faces between which are located spreading elements (20) to tend to move the cam faces apart under high torque to act in use on one half of the expanding pulley via first and second plenum chambers (22,23) connected to a source of hydraulic fluid under pressure. Supply to the chambers is via a throttle.The plenum chambers of the torque sensor can be connected to or sealed from each other as a consequence of change in the effective dia. of the pulley to change the ratio of a transmission including the pulley. The connection between the chambers may be allowed by one-way action of a lip seal (67) or by a valve.

Patent
02 Jun 1995
TL;DR: In this paper, the robot has a first rail (1) which extends in one direction and has an attached first slide (2) mounted thereon, the first slide being slidable along the rail.
Abstract: The robot has a first rail (1) which extends in one direction and has a first slide (2) mounted thereon, the first slide being slidable along the rail. A second rail (3) extends away from the first rail, and has one end secured to the first slide. First and second motors (4, 5) are mounted in fixed positions relative to the first rail, the motors driving first and second drive belts (6, 7). The first drive belt is attached to the first slide, thence routed around a first pulley (8) at one end of the first rail, thence around a second pulley (9) at the other end of the first rail, and thence back to the first slide. This produces movement of the first slide along the first rail. The second drive belt is routed from a third pulley (10) at one end of the first rail, thence around a fourth pulley (11) at the other end of the first rail, thence around a fifth pulley (12) mounted on the first slide, thence out the second rail and around a sixth pulley (13) mounted on the second rail, thence back towards the first rail and around a seventh pulley (14) mounted on the first slide, and thence back to and around the third pulley. A computer controls and coordinates the first and second motors to produce movement of the first slide along a first axis by operation of the first motor, and to produce movement along or about a second axis by operation of the second motor in coordination with the first motor. In the preferred embodiment, the second axis movement is movement of a second slide (15), slidably mounted on the second rail for movement therealong, secured to the second drive belt. In an alternative embodiment, the second axis movement is υ or rotational movement of a rotatable element (18) mounted on the second rail.

Patent
12 Dec 1995
TL;DR: In this paper, the transmission has two adjustable sheaves and an endless belt, each of which is controlled by a hydraulic adjusting cylinder, which receives pressurised fluid from a pump and is regulated by a torque sensor.
Abstract: The transmission (2) has two adjustable sheaves (3,4) receiving an endless belt (5). The sheaves are each controlled by a hydraulic adjusting cylinder (6,7). The adjusting cylinders receive pressurised fluid from a pump (14). The fluid pressure and thus the extent of frictional clamping engagement between the sheaves and the belt is regulated by a torque sensor (16).The sensor includes a plenum chamber (27) with an outlet (35) having a variable cross-sectional area which depends on torque variations from the vehicle engine.

Patent
Rene A. Conrad1
17 May 1995
TL;DR: A reversible conveyor belt system has, on at least one surface of the belt, projections arranged preferable in a plurality of asymmetrical rows and columns thereby forming a matrix engagable with an offset mating tracking surface glued to the surface of a pulley.
Abstract: A reversible conveyor belt system has, on at least one surface of the belt, projections arranged preferable in a plurality of asymmetrical rows and columns thereby forming a matrix engagable with an offset mating tracking surface glued to the surface of the pulley The projections are truncated geometrical solids, pyramids, extending outwardly from the surface of the belt When the truncated solids of the belt intermesh in the tracks provided between the rows of truncated solids on the pulley, positive alignment without creep, improved timing and increased drive force are achieved The projections may be used on both sides of the belt, and a second belt with interlocking projections may be mounted around a second pulley and positioned beneath the main conveyor belt for heavy impact loads The drive system includes an easily removable hub assembly wherein the shaft of the pulley defines a flat area which engages a hardened dowel wedge for providing positive drive with reduced shear

Patent
20 Dec 1995
TL;DR: In this paper, the gear lever swivels to its positions for a gear change and the gear box houses a gear shaft and a second gear pulley, which is connected to the first gear by a tension cable formed of an inner flexible cable and two cable covers.
Abstract: The casing (10) holds the gear-lever (12) so that it can swivel while being fastened to a shaft (14) mounted in the housing (16) and holding the first cable pulley (18) rotated by the gear lever as it swivels to its positions for a gear change. The gear box (20) houses a gear shaft (22) and the second gear pulley (24), connected to the first gear pulley by a tension cable formed of an inner flexible cable (26) and two cable covers (28,30). The steel cable (26) has at one end an anchoring pin (32) clamped in a groove (34) of the pulley (18), and then goes in the circumferential groove (36) to the abutments (38,40). Other features are also explained.

Patent
29 Sep 1995
TL;DR: In this paper, a window regulator employs a drive cable to regulate opening and closing of a window in a vehicle, attached to a glider which is attached to the window, and extends around a loop which includes first and second guide elements and a drive drum.
Abstract: A window regulator employs a drive cable to regulate opening and closing of a window in a vehicle. The drive cable is attached to a glider which is attached to the window, and extends around a loop which includes first and second guide elements and a drive drum. Rotation of the drive drum causes movement of the cable which in turn causes movement of the window. One of the guide elements is coupled to a torsion spring which causes the guide element to be forced outward to increase the circumference of the loop traveled by the cable and thereby to maintain tension on the cable. The guide element may take the form of a rotatable pulley.

Journal ArticleDOI
TL;DR: In this article, the torque transmitting mechanism of a CVT metal pushing type belt was investigated by theoretically analyzing working forces on steel bands and blocks, and the relation between belt slip limit and pulley clamping force was derived with enough accuracy for practical use.
Abstract: This paper investigates the torque transmitting mechanism of a CVT metal pushing type belt by theoretically analyzing working forces on steel bands and blocks. Measuring these working forces, the drive model presented in this paper is shown to be appropriate. Applying this analysis, the relation between belt slip limit and pulley clamping force is derived with enough accuracy for practical use.

Patent
27 Apr 1995
TL;DR: A dynamic wrist rest for use with a computer keyboard for the prevention of carpel tunnel syndrome is provided in this paper, which provides a constant up and down motion of the wrist through an internally mounted pressure sensitive air bladder.
Abstract: A dynamic wrist rest for use with a computer keyboard for the prevention of carpel tunnel syndrome is provided. The wrist rest provides for a constant up and down motion of the wrist through an internally mounted pressure sensitive air bladder. The up and down motion can also be provided by a motor and gear driven belt and pulley system that provides a lower speed and high torque which functions to rotate a roller along the interior surface of the support surface of the wrist rest thus creating the up and down motion. The up and down motion can also be provided by a motor driven, internally mounted oblong roller that is mounted for rotation about its axis.

Patent
14 Dec 1995
TL;DR: In this paper, a torque transmitting power train for use in a motor vehicle employs a transmission with two adjustable pulleys and an endless flexible element trained over the pulleys, adjustable by a torque sensor and primary hydraulic adjusting units in dependency upon the magnitude of transmitted torque.
Abstract: A torque transmitting power train for use in a motor vehicle employs a transmission with two adjustable pulleys and an endless flexible element trained over the pulleys. The pulleys are adjustable by a torque sensor and primary hydraulic adjusting units in dependency upon the magnitude of transmitted torque, as well as by an adjustable selecting valve and secondary hydraulic adjusting units in dependency upon the desired or required transmission ratio. The primary and secondary adjusting units can receive a pressurized hydraulic fluid from a common source.

Journal ArticleDOI
TL;DR: In this article, a method for calculating the loads on belt and pulley teeth given the belt strand forces as a function of time is presented for timing belt drives transmitting fluctuating torques.

Patent
06 Feb 1995
TL;DR: In this paper, a disc player both translates and rotates a disc using a pair of parallel drive belts contacting opposed edges of a disc, each drive belt spans a drive pulley and a passive driven pulley.
Abstract: A disc player both translates and rotates a disc using a pair of parallel drive belts contacting opposed edges of a disc. Each drive belt spans a drive pulley and a passive driven pulley. The pulleys are supported on one of two sliding plates. The sliding plates are connected by a pair of pantograph-type rotatable mounting arms such that movement of one drive belt toward the disc forces the other drive belt to move an equal amount toward the disc. Each drive pulley is driven by a motor causing the drive belt to revolve. A spanning portion of each drive belt is urged against the edge of the disc, thereby establishing friction engagement between the belts and the disc such that the disc rotates when the belts rotate. A disc advance control system moves the disc linearly through an optical beam by differing the rotational frequency of one belt relative to the other. Disc advance may be accomplished with, or without, disc rotation. The position of the belts at opposed locations about the circumference of the disc cancels out any linear pressure applied by the belts.