Hydraulically, servo-operated, automatic, change over valves, utilized in a two ram hydraulic steering gear, serve to __________.

Correct Answer: Option C — prevent either main pump from being hydraulically motored when idle by cross pressure flow

Automatic change-over valves in hydraulic steering systems prevent an idle pump from being 'motored' by the active pump. By isolating the idle pump from the high-pressure circuit, these valves prevent back-flow through the idle unit, which would otherwise cause it to spin and potentially lead to mechanical failure.