Ratchet

The ratchet is the main component of the ratchet mechanism. The spring forces the pawl to maintain contact with the ratchet wheel. The rocker is hollow on the ratchet shaft, the pawl is mounted on the rocker, and the ratchet is fixedly connected to the driven shaft with a key.

Working principle

When the driving member rocker swings counterclockwise, the driving pawl is inserted into the tooth groove of the ratchet wheel, and the ratchet wheel is pushed to rotate through an angle. At this time, the stop pawl slides on the tooth back of the ratchet wheel. When the driving member rocker swings clockwise, the stop pawl prevents the ratchet wheel from rotating in the clockwise direction, while the driving pawl can slide on the back of the ratchet tooth, so the ratchet wheel is stationary. In this way, when the rocker makes continuous reciprocating swing, the ratchet will make a one-way intermittent movement. Among them, the reciprocating swing of the driving member can be obtained by a cam mechanism of a swing follower, a crank-rocker mechanism, or a hydraulic transmission and an electromagnetic device.

Main type

The gear-tooth ratchet mechanism is simple in structure, convenient to manufacture, and reliable in operation. The size of the ratchet rotation angle can be adjusted in steps, but the pawl slides on the back of the ratchet tooth during the return stroke, which is easy to wear and produce noise. In addition, in order for the pawl to smoothly engage between the teeth of the ratchet wheel, the displacement of the pawl must be greater than the corresponding displacement of the ratchet's angle of motion, which results in lost motion and impact. The friction type ratchet mechanism does not have the above shortcomings, and the rotation angle of the driven wheel can be adjusted steplessly, but because the contact surface is prone to sliding, the accuracy and reliability of its motion are worse than that of the toothed ratchet mechanism. In general, the ratchet mechanism is not suitable for high-speed or high-precision applications.

Silica sol precision casting price