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.

Shape memory alloy rotary actuator

Abstract: A rotary actuator which provides a differential pulley pair having a shape memory alloy wire The shape memory alloy wire is thermally cycled through its phase change transition temperature and contracts Tension forces applied by the ends of the wires to opposite sides of the pulley pair result in a net torque which causes relative rotation between the pulley pair and a reference base The large mechanical advantage of the differential pulley converts a large force working through a small distance into a relatively large angular rotation

A method and apparatus for controlling an infinitely variable transmission of a motor vehicle

Abstract: In apparatus for controlling the transmission ratio of an infinitely variable V-belt transmission having variable pitch input and output pulleys operable by hydraulic cylinders, each pulley being formed of a pair of conical discs, at least one of which is axially movable relative to the other disc of that pair and the input pulley being driven by a power source: a hydraulic control valve for operating the cylinders, the valve having an internal axially movable spool; a device responsive to the speed of the input pulley for urging the spool in one direction; a compression spring urging the spool in an opposite direction, the spring being loaded through an intermediate connecting assembly by an external loading device; and a regulating device connected to the intermediate connecting assembly, the regulating device being responsive to an operating variable of the transmission.

Variable speed reciprocating lever drive mechanism

Abstract: A pedal drive mechanism for a rider-powered vehicle. In a preferred bicycle version, pedal lever arms are pivotally attached to each side of the frame near the rear wheel hub for reciprocal rotation within a limited angular sector. Downward forces exerted by a rider on the pedals are transmitted through flexible tension members on each side of the bicycle anchored either to first attachment points intermediate the ends of the lever arms or to second attachment points on the frame above the lever arms and leading around pulleys mounted at the other of the first and second points. From the pulleys each tension member leads over and around a corresponding rotary driving member that is connected through an overrunning clutch to the rear wheel. Means interconnecting the lever arms return one arm to the upper starting position while the other arm is in the downward power stroke. Manually operable control means vary the location of the second attachment points with respect to the frame to change the torque delivered to the driving member for a given driving force on the pedals. Additional idler pulleys mounted at the tension member anchor points may be used to "gear up" the mechanism for higher speeds and lower output torque. Disconnect means disengage the overrunning clutches from the rear wheel hub to prevent damage to the mechanism when the bicycle is backed up.

Four-cable wrist with solid surface cable channels

Abstract: A wrist mechanism for an instrument used in minimally invasive medical procedures employs only four drive cables for control of the pitch, yaw, and grip of an effector. To reduce part count, no pulleys are used. Instead, solid surfaces of clevises in the wrist mechanism cradle the drive cables and are curved in multiple directions to maintain a fixed moment arm for cable torques and eliminate the need for large cable wrap angles. Further, the stiffness of each of the four drive cables can be controlled for improved clinical performance. In particular, the stiffness of the two drive cables that cause grips to close can be greater than the stiffness of the remaining two drive cables that cause the grips to open. The arrangement can minimize cable slack, improving fidelity of motion.

Hand-truck with attachments

Abstract: A two-wheeled hand-truck with attachments, with an elevating mechanism incorporated into the body. The upright rails are tubular, and open on the bottom ends. A crank operated cable and pulley system forcibly extends the elevator downwardly. The attachments allow the body to be converted into a four wheel cart with a variable width wheelbase, and a crank operated, pulley assisted, fork lift, or hoist.