Handwheel

Front damper doors on each hopper and the back damper door of the centre hopper are opened and closed by screw gear worked from a handwheel on the fireman's side of the cab.

When the large handwheel seen in the illustration of a 68000 class cab is moved from "stop" to "run", the traction circuit contactors are closed and the locomotive moves off with the diesel engine running at idling speed.