The pressure switch, labeled as "C", will energize the automatic shutdown circuitry, preventing any additional operating casualty.

Valve "D" will shift to the position shown, with the signal generated from line 'ff' determining the speed of the engine, as the signal is modified by device "A".

By regulating the reduction of the 30 bar air pressure at device "B", the engine speed may be varied proportionally, operating independently of any other control.

Valve "D" will shift, no longer venting line 'cc', 30 bar air pressure is reduced by "B", and is supplied to "A" for speed control, and other functions of lines 'cc' and 'ff'.