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Cold start with hydrostat

Cold start with hydrostat

Cold start with hydrostat

I have a hydrostatic transmission, with a cold start issue.   The hydrostat is a pump/motor combo with a intermediate high pressure accumulator and low pressure reservoir.   The hydraulic fluid viscosity at cold temperature is acceptable (no derate), but the system pressure does not build for full operation, until after a longggg idling time.    The cold start issue is at -20F ambient, even with the hydraulic oil heated to 30F.   Does the reservoir air need to be preheated to maintain its charge and regain performance?.    

RE: Cold start with hydrostat

Does the pump/motor have an unpressurized drain sump?  I'd be inclined to heat that, to try and get the pump body and valves warmed up.


Mike Halloran
Pembroke Pines, FL, USA

RE: Cold start with hydrostat

First, you are not generating much heat when you are idling in neutral. If possible, it is more efficient to work the machine lightly to get it warmed up.

Second, it is a reservoir or an expansion tank? If it is only an expansion tank heating the oil in it won't do much good. If it is a reservoir maybe the flushing valve isn't opening?


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