how do cushion valves work

[jonsstihl]

I also realize I was reading the sticker wrong. the pressure setting for the chute rotation should be 1000 psi not 1900 psi. some of their blowers have a rotating drum so you can bypass the chute.

is there any reason why I would be getting a reading of 2300 psi if the cushion valve is set for 1000psi. my gauge is tee-d in between the rear remote and the hose going to the hydraulic motor. does the cushion valve relief internally??

 

[oldnslo]

I also realize I was reading the sticker wrong. the pressure setting for the chute rotation should be 1000 psi not 1900 psi. some of their blowers have a rotating drum so you can bypass the chute.

is there any reason why I would be getting a reading of 2300 psi if the cushion valve is set for 1000psi. my gauge is tee-d in between the rear remote and the hose going to the hydraulic motor. does the cushion valve relief internally??

Is the cushion valve for the hydraulic motor a cross port relief of a counterbalance valve? If relief valve it should relieve pressure from the inlet of the motor to the outlet of the motor. ANY back pressure on the valve outlet (tank side) is additive to the relief setting.

Good luck on getting this resolved.

 

[jonsstihl]

to be honest I have no idea what the difference is between the two but the cushion valve on the chute rotation does have two adjustment screws because the inlet and the outlet alternate depending on which direction you rotate the chute. the cushion valve is mounted directly on the motor.

the dealer mentioned that maybe the valve is bypassing internally and that would explain why i'm getting a pressure reading higher than what the setting should be. I think that is bull but I know only enough about hydraulics to be dangerous. My thinking is if the cushion valve is opening to protect the motor the entire pressure side of the circuit will be at the pressure the valve is set to open at. Am I wrong.

 

[jonsstihl]

I don't have any back pressure in the chute rotation circuit because when I rotate the chute the other way my pressure gauge goes to zero. which should mean that their is no restriction in the return to tank circuit of that particular remote.

 

[oldnslo]

Counterbalance valves use external pilot pressure to open and are used on motors to prevent free wheeling and act like brakes. This pilot pressure is taken from the inlet of the motor to open the valve on the outlet port. I would question why they would be required for chute rotation

I suspect relief valves in this case to limit the motor torque for rotation as a safety to prevent breaking or bending something.

100% agree your pressure readings are puzzling