A micrometer torque wrench has settings to allow tightening of bolts to an exact measurement in foot-pounds. Mechanics use torque wrenches on auto repair projects so all bolts are not over- or under-tightened for safety purposes. The tool works as a standard wrench until it meets the setting that the operator designates and then it produces a clicking noise and will no longer tighten the bolt. This signifies achieving the correct measure of torque.
Hold the micrometer torque wrench in one hand by the handle.
Pull the lock ring down towards the handle. The lock ring is a metal band between the handle and the shaft of the torque wrench.
Turn the handle to set the torque wrench while lining up the settings on the handle and the shaft. The handle has numbers of zero to nine and the shaft has numbers of zero to nine. For example, to set the micrometer torque wrench to 28-foot pounds, turn the handle so the two on the handle is in the zero to nine range on the shaft. Continue turning the handle until the two on the handle reaches the eight on the shaft.
Push the lock ring back up to hold the setting in place.
Tighten bolts with a torque wrench by using a fluid movement without stopping until the micrometer wrench clicks. Stopping the movement before the correct setting is achieved can cause friction between the wrench and the bolt, which may cause a variance in the tools measurements. Micrometer torque wrenches operate in either direction on standard bolts with standard threads and on left-handed bolts that turn left to tighten. A ball inside the micrometer torch wrench moves straight forward on the end of a spring to apply pressure. When the wrench achieves the set pressure, the balls moves to the side of the spring, causing the clicking sound and does not continue tightening the bolt.
Do not drop a micrometer torque wrench on a hard surface. This action causes the tool to measure inconsistently and it will need recalibration at a tool shop.