The P40 semi-automatic transmission is derived from the David Brown Defence Equipment Z51 transmission fitted to the Centurion MBT, of which over 4,000)were produced and these remain in service in declining numbers. The P40 transmission has been tested in a Swedish Army Centurion MBT. As of mid-1999 there was no production application for the P40 transmission.

The P40 concept is available either as a retrofit package to existing Z51 transmissions or as new. The transmission is a layshaft type with five forward and two reverse gears. There is a single input and two in-line outputs at right angles to the input. Gearshifts are initiated by driver command and effected by an electronic controller. The controller operates electrosolenoid valves to hydraulic actuators which engage dog clutches under conditions of synchronous speed. Steering is of the triple-differential type effected by the operation of either of the transmission-mounted vehicle drum brakes. The transmission has an integral filtered lubrication system. Cooling is by convection and radiation through the gearcase, alternatively by a small separate oil cooler.

Development complete. Ready for production.