Robotics Education & Competition Foundation
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Continuously Variable Transmission


Entry ID #: 4783
Created: Tue, Jan 9, 2018 1:41 PM

A Continuously Variable Transmission, or CVT, is a transmission that can seamlessly change to any ratio within a continuous range of gear ratios. This design is based off the variable diameter pulley, which is composed of two pulley sheaves that move toward and away from each other. Two sets of these pulleys form the input and output shafts, with a flexible belt transmitting power between them. The pulley sheaves are moved with "push plates", which themselves are moved by turning VEX worm screws.

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Here, the CVT is operated manually. In order to change gear ratios, the middle shaft is turned, which rotates the three shafts with worm gears. These move the two push plates which in turn move the pulley sheaves in and out. The drive shaft is turned at the same time so that the belt does not remain stationary and become crushed between the pulley sheaves.