With a little creative machining it might be possible to adapt an air conditioner compressor clutch to a hydraulic pump to avoid the problem of the pump running all the time. I don't know if the torque capacity of one of those clutches would be sufficient for heavy hydraulic loads, however.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
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