Hydraulic Motor
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Billrog
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It's circulating oil as long as the motors running.
Texasmark
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Yepper and pressure is just a few psi (low pressure mode on a 2 stage) with the open center control as viewed on the pressure meter at the entrance to the return filter attached to the reservoir.
wdchyd
Elite Member
Some have counterbalance valves, some internal .......most times the control valve a & b ports are blocked in neutral
oldnslo
Super Member
Depends on the application and circuit.
Some examples:
Simple circuit like post hole auger can have a valve with the A & B ports blocked in neutral or can have a motor spool with A & B & T ports all connected together. Typically running slow with limited inertia.
On a wheel application like used on a scissor lift it may have counter balance valves and a brake to prevent free wheeling. You don't want the lift to run away while on a slope.
On hydraulic fan drives where there is high speed and lots of rotating mass they almost always incorporate a "run down" feature to prevent stopping the motor to quickly.
IceStationZebra
Gold Member
"On hydraulic fan drives where there is high speed and lots of rotating mass they almost always incorporate a "run down" feature to prevent stopping the motor to quickly."
This can be a check valve across the motor to allow the motor to keep spinning, a hydraulic spool with A and B connected in neutral (aka motoring spool), an anti-cavitation valve, low pressure relief after the motor, etc. This applies to any hydraulic motor with a lot of inertia like mowers, fans, etc.
And as far as not turning in neutral don't forget that some systems naturally have a lot of friction. Think track drives, worm gearboxes....
ISZ
This can be a check valve across the motor to allow the motor to keep spinning, a hydraulic spool with A and B connected in neutral (aka motoring spool), an anti-cavitation valve, low pressure relief after the motor, etc. This applies to any hydraulic motor with a lot of inertia like mowers, fans, etc.
And as far as not turning in neutral don't forget that some systems naturally have a lot of friction. Think track drives, worm gearboxes....
ISZ
So in theory, you could run a hydraulic motor in place of a log splitter cylinder on a log splitter?
JW 5875
CCWKen
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Everybody is correct but to keep it simple; It depends on the motor design and the design of the equipment. Some will free spin when fluid flow stops and require a brake to stop. Others will stop when fluid flow stops but they will act as a pump if rotation force is applied. Various methods are used on these motors to "run down" or relieve back pressure. Still others are allowed to lock when flow stops.