Pulley

About: Pulley is a research topic. Over the lifetime, 51636 publications have been published within this topic receiving 178220 citations. The topic is also known as: drum & block.

Variable-speed V-belt drive for vehicle

Abstract: A variable-speed V-belt drive includes: a drive pulley; a driven pulley including a fixed sheave with a cylindrical shaft and a movable sheave mounted on the cylindrical shaft so that the movable sheave can rotate and axially move; a V belt extended between the drive and driven pulleys; and a pressure mechanism of applying pressure to the movable sheave of the driven pulley. The pressure mechanism includes a helical cam groove formed in one of the cylindrical shaft and the movable sheave of the driven pulley, and a roller mounted on other of the cylindrical shaft and the movable sheave of the driven pulley so that the roller engages with the cam groove. The cam groove has opposite first and second working surfaces. The second working surface has a retaining surface of retaining the roller thereon when the vehicle travels in the engine-braking mode. The variable-speed V-belt drive can maintain the effect of engine brake at a high level even when traveling down a steep hill.

Some Notes on V-Belt Drives

Abstract: This paper consists of four separate parts: 1) Radial penetration of a V-belt, 2) Formulas for axial forces, 3) Additional slip in varispeed drives, 4) Arc of contact in belt drives. There is a slight connection between the parts in the way that all the results are applicable to variable speed drives. 1 The penetration of a V-belt into the groove depends on wedge angle, friction, elasticity of the belt and belt design. It is shown that certain combinations of these parameters result in zero penetration i.e., there is a kind of blocking. This is different from the well known self-locking phenomenon, where the belt is prevented to move outwards if the wedge angle is less than the friction angle. 2 The axial forces calculated from the theory of V-belt mechanics are not possible to express in simple formulas. However, approximate formulas can be developed. Previously reported formulas are here completed with the influence of belt design and elastic properties of the belt. It is convenient to use formulas in the computerized analysis of variable speed drives. 3 In variable speed drives consisting of e.g. one spring loaded pulley and one rigid (manually adjustable) pulley there are two kinds of speed loss present. Except the ordinary slip between the belt and the pulleys there is an additional speed loss due to a small axial motion of the spring loaded pulley. The additional speed loss depends on spring load, transmitted torque, drive geometry, friction, elastic properties of the belt and, what is important, the flexural rigidity of the belt. On a spring loaded driver pulley the width between the pulley halves always increases with increasing torques whereas the width of a spring loaded driven pulley can both increase and decrease. This means that in the first case the additional speed loss is always positive but in the second case it can be both positive and negative. If the maximum slip is used as a design criterion it is important to recognize this difference. 4 The arc of contact is included in the formulas presented in part 2. The geometric arc of contact differs from the real one due to the curvature of the belt between the pulleys. Previously ordinary beam theory has been applied to calculate the decrease in contact angle. Here a modified analysis is presented—except flexural rigidity also compressibility of the belt is introduced. It appears that the decrease in contact angle in ordinary belt drives is considerably smaller than that predicted by the beam theory. Sometimes the contact angle can increase. In most cases the change in contact angle is negligible and the geometric arc of contact can be used in the formulas in part 2.

Hybrid drive assembly for a vehicle, in particular a scooter

Abstract: A hybrid drive assembly (1) for a vehicle having at least one drive wheel (2),the drive assembly including an internal combustion engine (3); a transmission unit (5) interposed between a drive shaft (4) of the internal combustion engine (3) and a propeller shaft (6) connected angularly to the drive wheel (2), and in turn including a continuously variable transmission (7) having a drive pulley (10) connected angularly to the drive shaft (4) and a driven pulley (11), and a centrifugal clutch (8) having a hub (20) connected to the driven pulley, and a driven bell (26) connected to the propeller shaft (6); and an electric machine (32) having a rotor (35) integral with the bell (26) of the centrifugal clutch (8) . The drive assembly (1) is controlled by a control unit (38), in response to a number of input signals (Ss, Sa, Sf), in a number of operating modes including an all-combustion propulsion mode, an all-electric propulsion mode, a first hybrid propulsion mode wherein the internal combustion engine (3) and the electric machine (32) are connected in series, and a second hybrid propulsion mode wherein the internal combustion engine (3) and the electric machine (32) are connected in parallel.

An investigation of the transmission system of a tendon driven robot hand

Abstract: The transmission system of the Utah/MIT Dextrous Hand (UMDH) is investigated theoretically and experimentally. It is shown that the friction of the routing pulleys is not negligible and should be considered in the force control of the UMDH. In the frequency range of the pneumatic actuators (80 Hz), tendons act like springs and the first mode of the tendons is above that frequency range. >

Compact peristaltic medical pump

Abstract: A compact medical pump includes a linear peristaltic pumping mechanism driven by a motor located within a periphery of a belt of the pumping mechanism. The motor drives a gear set that drives a driving pulley which engages the belt having the rollers. A battery for the pump is positioned adjacent to the gear set. The pump includes a controller and user interface for operating the pumping mechanism as a function of pumping parameters input via the user interface. The controller may sense motor current and determine fluid path characteristics based on the sensed current.