The Autogard Airjustor is a pneumatically controlled, combined torque limiter and disengaging clutch that offers the power transmission engineer a host of new drive control options.

As a disengaging clutch the air is dumped at the press of a button, the drive balls role out of the seats without skidding to completely disengage the drive, and the plates are held apart by spring pressure so that no drive is transmitted by the coupling. Shield bearings are provided between the hub and main adaptor/ drive plate to give completely free running clutch.

As a torque limiter, overload protection for the drive is provided by the same mechanism. The supply air pressure may be set in the range of 1.4 to 5.4 bar (20-80 psi) to give the precise overload torque requirement using a pressure regulator. This can be done manually during normal running to take account of changing loads, or automatically using a duel regulator system with a timer or other control. This allows high start torque to be accommodated before switching to lower running torque. When the torque setting is exceeded, the balls begin to roll out of their seats, forcing the plates apart against the air pressure. This motion operates a pneumatic limit switch which "dumps" the air pressure, disengaging the clutch and releasing the drive from the overloaded machine. Re-engagement is affected in both cases by simply operating a push button initiating valve. Rotation of the drive will then engage the clutch..