Torque override knob for endoscopes, borescopes, or guide tubes

摘要

A manually rotated knob drive mechanism incorporates a torque override feature. If the knob turning force exceeds a predetermined torque limit the feature permits slippage between the knob and the associated stem or drive shaft. The knob can continue to rotate, under slippage, until the knob and stem are aligned at a predetermined mutual orientation, or home position. This occurs at only one home position. The torque override feature is formed of an insert molded into the knob, and having a bore in which there is an annular shoulder. A hub member fits into the insert and has an annular surface that faces the insert shoulder. The hub member attaches to the stem or shaft and a spring yieldably urges the hub member against the insert. There are protuberances on the insert shoulder and corresponding grooves or recesses on the hub member annular surface, which coincide with one another only at the home position. The knob drive can be employed on the steering control handle of a borescope, endoscope or guide tube.