Hydraulic motor leak

[razor]

The chute rotation motors on my snowblowers are blowing out the shaft seals. I'm lucky if I get a season out of a motor approx 200 hours of use. The blowers originally came with motors that were made in China so I thought it may just be poor quality but I replaced them with Eaton(Char-lynn) motors and I notice that they may also have a shaft seal leak. The replacement motor don't have a cushion valve so I used a restrictor to slow down the speed of the motor, perhaps this could be my problem. My dealer says this happens a lot because salt sits on the shaft and gets it pitted and rips the seals over time.

Is anybody else having this problem with these motors?

 

[RickB]

Repeat shaft seal failure on reversing hyd motors can often be traced back to the control valve operating the motor. If the return port on the spool closes before the supply port when the valve is returned to center, pressure will spike in the motor's return circuit. The easiest path of escape for this return oil is through the shaft seal. Return oil is routed within the hydraulic motor to provide lubrication to bearings, bushings, etc.

 

[AKKAMAAN]

The chute rotation motors on my snowblowers are blowing out the shaft seals. I'm lucky if I get a season out of a motor approx 200 hours of use. The blowers originally came with motors that were made in China so I thought it may just be poor quality but I replaced them with Eaton(Char-lynn) motors and I notice that they may also have a shaft seal leak. The replacement motor don't have a cushion valve so I used a restrictor to slow down the speed of the motor, perhaps this could be my problem. My dealer says this happens a lot because salt sits on the shaft and gets it pitted and rips the seals over time.

Is anybody else having this problem with these motors?

I can see a few error options here....

Many motors have a 3rd line, a "case drain". if this case drain get clogged, kinked or off some other reason restrict the drain flow, it will create casing pressure, the pressure on the seal lip will start wear a grove on the shaft and eventually also blow the shaft seal out. Make sure this case drain is clear. Most applications do not let case drain go thru return filter of this reason. Just straight to tank. (This above applies on pumps with case drain aswelll)



If the motor do not have this 3rd case drain line, high back pressure on the motor outlet (return) side could cause leak on the shaft seal. Same thing here....make sure return line do not restrict return flow..... If it is an one direction motor(single action, like a snow blower), I have seen this return line plumbed direct to return filter, and not thru the control valve. Any back pressure in a motor return line will also reduce power efficiancy.

I assume you did not plumb that restriction on the return side of the motor!!???

 

[RickB]

I can see a few error options here....

Many motors have a 3rd line, a "case drain". if this case drain get clogged, kinked or off some other reason restrict the drain flow, it will create casing pressure, the pressure on the seal lip will start wear a grove on the shaft and eventually also blow the shaft seal out. Make sure this case drain is clear. Most applications do not let case drain go thru return filter of this reason. Just straight to tank. (This above applies on pumps with case drain aswelll)



If the motor do not have this 3rd case drain line, high back pressure on the motor outlet (return) side could cause leak on the shaft seal. Same thing here....make sure return line do not restrict return flow..... If it is an one direction motor(single action, like a snow blower), I have seen this return line plumbed direct to return filter, and not thru the control valve. Any back pressure in a motor return line will also reduce power efficiancy.

I assume you did not plumb that restriction on the return side of the motor!!???

The big challenge here is the motor is used to rotate the chute, requiring the flow to reverse. There is no dedicated 'return side' per se. Perhaps it would be best if the restrictor were removed and the operator feathered the valve to control motor speed?

 

[J_J]

razor ,

Did you match the psi ratings on the motors with the psi rating on the tractor?

I looked at a lot of those motors, and a lot of them are 1800 psi continuous. So if your tractor is 2500 psi, then you could expect them to perhaps leak. You might need a relief valve across the motor to keep the psi within limits. A cushion/check valve is designed to relieve, and you chose to decreased the GPM through the motor to slow it down. .