"Nobody" key hub:

This is a specialized wrench used by plumbers to tighten the band clamp on "hubless" soil pipe couplings. This is a T-handled ratchet wrench combination of courses and clutch, factory calibrated to slip at a torque sufficient to seal the coupling, but insufficient to cause damage. Since the ratchet is not reversible, the key tree includes a folding auxiliary handle to loosen the collars clamping.

Electronic torque keys With electronic (indicating) torque wrenches:

The measure is using a strain gauge attached to the rod twist. The signal generated is converted by the sensor to the necessary unity of force (m N, lbf.ft etc.) and noted on the digital display. A number of different joints (more action or limit values) can be stored. These limits are then programmed permanently displayed during the process of hardening of the LED or display. In same time, this generation of torque can store all measurements in an internal memory of reading. This list of readings can then be easily transferred to a PC via the interface (RS232) or printed directly to a printer. A popular application of this type of torque wrench is for the documentation process or for quality assurance