Yanmar travel motor

[DPLoftis]

Yanmar VIO 75 A travel motor stopped pulling. Pulled the cover and gears were stripped. Bought a new drive motor and worked fine for one month then quit pulling with any resistance. Still pulled fine on flat surface. After checking pressures against other motor….pressures are fine. Replaced the motor with another new one and same issue. What am I missing? Thanks Dennis

 

[Welder Dave]

Parking/travel brake not fully releasing on that side?

 

[DPLoftis]

No don’t think so. It travels perfect and turns perfect on level ground. Once you get some incline or rough ground with piles of dirt to give resistance it will stop on that side and with both drives forward or backwards it will stop but release the bad side and the good side continues.

 

[Welder Dave]

Are there individual relief valves for each side?

 

[Jimbob83]

Check your case drain at the center joint.....
Make sure you have very little flow and pressure there.
If you were to walk the machine and operate the boom and stick, what happens then?

 

[DPLoftis]

It operates perfectly normal when level. That’s what I can wrap my head around.

 

[DPLoftis]

Are there individual relief valves for each side?

I’m not sure

 

[Jimbob83]

Your pressures are normal, what about the flow?
Where are you measuring the pressures?

Does it have the same issue walking the machine forward and reverse?

 

[DPLoftis]

Your pressures are normal, what about the flow?
Where are you measuring the pressures?

Does it have the same issue walking the machine forward and reverse?

Yes…. same walking either forward or backward. Measurements were at the drive motors. Pressures were in specs. High end of specs actually.

 

[Jimbob83]

At a shot in the dark I'm thinking there is some debris stuck some where, maybe the center joint and when the machine requires full hydraulic flow to the final driver motor (example, walking up a incline etc) it cant get the oil it requires. You have measured pressure.....not flow. Pressure is created by the final drive motor.....flow is not....if you were to measure the final drive pressure as it was trying to climb an incline I feel that you would see the pressure drop away and flow start to starve....if you were taking these values at the final drive motor.

 

[Jimbob83]

If there is debris stuck in one of the main supply lines it would limit flow in one direction of travel and restrict flow in the other direction of travel....

 

[DPLoftis]

At a shot in the dark I'm thinking there is some debris stuck some where, maybe the center joint and when the machine requires full hydraulic flow to the final driver motor (example, walking up a incline etc) it cant get the oil it requires. You have measured pressure.....not flow. Pressure is created by the final drive motor.....flow is not....if you were to measure the final drive pressure as it was trying to climb an incline I feel that you would see the pressure drop away and flow start to starve....if you were taking these values at the final drive motor.

Yes sir I was. I’m not sure how to check that. I’m not a mechanic. I just work on my own equipment. How can I find out if there’s a restriction .

 

[DPLoftis]

If there is debris stuck in one of the main supply lines it would limit flow in one direction of travel and restrict flow in the other direction of travel....

Ok….how do I find that issue.

 

[Jimbob83]

Without having a flow tester you will need to go old school and start unbolting hydraulic hoses and start cleaning. Unbolt the hoses from the center joint and final drive motors and use compressed air to clean the lines....or a water blaster making sure all hoses are clean and dry after. You need to work back from the final drive motor, start at the two large hoses which are supply hoses and then follow them to your center joint under the belly pan of the machine, unbolt each end and blow though, using a rag at the end you are blowing from to create a seal. You may luck out and see the issue just by unbolting the hose fittings.

 

[Tones]

Your problem isn't flow. Flow = speed Pressure = power and the fact one track is stopping indicates a lack of pressure. Are there any pressure relief valves on the hydraulic motors. If there are swap it with the motor on the other side. The other track will then have the problem if the valve is bad. What make of motor is it?
PS don't adjust the the pressure settings until you complete this test.

 

[DPLoftis]

Your problem isn't flow. Flow = speed Pressure = power and the fact one track is stopping indicates a lack of pressure. Are there any pressure relief valves on the hydraulic motors. If there are swap it with the motor on the other side. The other track will then have the problem if the valve is bad. What make of motor is it?
PS don't adjust the the pressure settings until you complete this test.

Ok thanks for all your help. I’ll try it when I get itback to my shop.

 

[DPLoftis]

Without having a flow tester you will need to go old school and start unbolting hydraulic hoses and start cleaning. Unbolt the hoses from the center joint and final drive motors and use compressed air to clean the lines....or a water blaster making sure all hoses are clean and dry after. You need to work back from the final drive motor, start at the two large hoses which are supply hoses and then follow them to your center joint under the belly pan of the machine, unbolt each end and blow though, using a rag at the end you are blowing from to create a seal. You may luck out and see the issue just by unbolting the hose fittings.

I really appreciate all your help. Thanks

 

[Tones]

If what I suggested in my earlier post doesn't show any difference then you'll need to go to the main control bank. Each motor operates from it's own spool which has 2 relief valves, 1 for each direction. They also can be swapped to check any difference in behaviour.

 

[DPLoftis]

Got cha….thanks for all the help. I’ll let you know what I find