NOTE: The strongest threaded joint is one in which the load applied to the fastener when it is installed is greater than the maximum load that will be applied to the joint in service. If a threaded fastener does not fail when it is being properly torqued, it will not fail in service.
Twist the handle until a reference mark aligns with a graduation on the shaft of the wrench indicates the desired torque. Place the correct socket on the wrench and put it on the fastener to be torqued. With the wrench perfectly square to the fastener, apply a smooth pull on the wrench until it clicks. Clicktype torque wrenches do not limit the amount of torque that can be applied; rather, they indicate the set amount of torque being applied when they click. Stop the pull as soon as the wrench clicks.
It is important that the socket is square on the fitting and the force applied to the wrench is concentrated at the pivot point on the handle. The torque read on the wrench (TW) measured in inchpounds is the product of the lever length (L) in inches and the force (F) in pounds.
When using an adapter on a torque wrench that adds to the lever length, you must use the formula below to determine the torque reading on the wrench TW in order to attain the required amount of torque applied to the fastener by the adapter TA.
When the extension subtracts from the lever length of the wrench, use this formula.
当延伸杆减去扳手的力臂长度时,请使用此公式。
Torque Conversions
力矩换算(转换)
Recommended Torque Values
推荐力矩值
The International System of Units (SI) is the modern form of the metric system, and is used in many countries; however, the U.S. continues to use the U.S. customary system. The SI unit for torque is newton meters (N.m); in the U.S. customary units, it is foot-pounds force (ft-lbf ).