Bobcat T190 drive problem

[partsandservice]

Earlier I meant case drain check for the left pump , as you had already mentioned checking the motors independently. Like mike stated you must now address the left drive pump AND the new left motor. If you only replace the pump now, contamination in the loop can get to the new pump. Round and round it goes.

 

[Potterx]

So i wanted to follow up for the records, what my issues were.

So i ended up pulling out the engine and gained access to the pumps. Sent the pumps in for repair. The report back was the valve plates were broken inside the left and right pumps. Left was in worse shape. The charge pump was okay, so it must have been due to the broken plates in the drive pumps allowing oil to push through not allowing full charge pressure to build up.

Once the rebuilt pumps were installed, charge pressure returned to spec 250lbs+, and the "delay" in the joystick is now gone. Everything is running good now.

Thanks to final drive parts and Dave with DMC equipment for the pump rebuild, good quality job. Thanks for all the troubleshooting advice as well.

 

[willie59]

You've spent some money on that T190 Potterx, both drive motors and now a drive pump rebuild. It's one of those things that no one knows just how deep something will get, but once you commit you pretty much have to follow thorough, it happens. Just some advice after you've done all this work, check your hydraulic filter frequently depending on how much you use the machine. The thing about a Bobcat is they're not a true "return to tank" system, they work more on a hydraulic loop system and the reservoir simply keeps the loop full. Additionally, oil in the drive system just loops within the drive system, doesn't go through the main hydraulic filter. Oil going through the loader function valve goes through the hydraulic filter. My point is, oil in a Bobcat doesn't always go through the filter all of the time, but eventually all of the oil does find a route through the filter. Depending on how much you use the machine, let's say you use it everyday, then I'd remove the filter at least once a month after the oil is warmed up a bit. Place your hand over the open end of the filter and agitate the filter. Pour the contents into a clean pan and see how much metal debris comes out. Pour some solvent or diesel in the empty filter and repeat agitation, pour into clean pan again to check debris. Continue this check process to get a feel of when the system is running clean of debris and then service the hydraulic filter according to a normal schedule.

 

[Potterx]

So, more to the story. All my final tests were with the unit still jacked up. Once I put it back on the ground, it appeared I had more torque, but I was still restricted to my 25% power after driving it around. Unit still pulled to the left, and the left drive stick still seemed to have the delay. Popped the top again and took a look around, while facing the rear of the unit I stroked the lever arms and was looking to see if a bushing or bearing up towards the front had a issue. I did not find anything there, but looked back towards the pumps and saw the pintle arm on the left side was moving 5-10 degrees before it would engage the square pump drive. After taking things apart again and looking, I found that the square pump shaft has little notches on each corner to hold the " pinch" bolt that holds the pintle arm at the right height and clamped to the square shaft. The notch on the corner that the bolt utilized was worn down 1/4 inch and even with the pinch bolt tight the pintle arm was allowed to drop down causing the pintle arm to be loose on the shaft allowing movement befor it engaged.

Solution since I was not pulling the pump again and replacing the pump shaft was not an option now. We drilled and tapped the pintle arm about an inch from where the square pump shaft slides in, and placed a 1/4 bolt with an extra large washer on it that covered over half of the square shaft opening. This prevents the pintle arm from sliding down towards the pump and keeps the pinch bolt in the proper position.

After that everything appears to be running correctly now. Unfortunately I believe this was my root cause issue. My pumps and drives we probably not in the best shape but it was running. Rebuilt pumps and drives were not the main issue but no doubt they were going to need to be replaced in the future.

A lot of money and a lot of time, but learned a lot and now have a unit that should last me a long time.

Thanks