I'm having a problem with my left side tires moving forward and/or backwards. All hydraulics work, the bucket and arms and the right side moves forward and backwards perfectly; to the point that I can even spin out...or in circles now, since the left side completely stopped moving. This problem began shortly after adding a premium hydraulic fluid that subsequently turned the rest of my fluid a milky white. The first noticeable symptom, no noises, was that the left side tires started jerking...work then stop, work then stop, with the hydraulic charge light coming on when I pushed the control arm forward or pulled it backwards. I changed both hydraulic filters. Cleaned the filter/screen in the canister next to the two hydraulic pumps. I pulled the rear pump (the one for the left side) and after pulling it apart found nothing wrong, other than a couple of cracking o-rings. I replaced the rings, put the pump back together and reinstalled the same. Still, however, the left side does not move forwards or backwards. Note though, when I lifted the left side wheels off the ground, and worked the control arm, both wheels responded immediately. Both forward and in reverse. They may not have matched the rpm of the right side but they would rotate. I guess what I'm saying is that the rotation was weaker than normal and that when I grabbed a wheel while it was rotating I could stop it even though the control arm was pushed all the way forward. In reading several threads I saw mention of a hydrostatic pump, could this be the problem and if so where can I find it on my machine and what does it look like? I also saw that a milky looking hydraulic fluid implies that water is in the fluid and should be changed out. Could this be the problem, and if so why would all my other hydraulic devices be operating so well but not the left side wheels? Should I change out my fluid? I then read that a gage can be used to test the pressure coming out of the rear pump (left side wheels). Should I try this and if so what is this gage called and where can I obtain one? Do you know what the pressure is supposed to be? Or, and I suppose this is the worst case scenario, is the problem my left side drive motor (if that is what it is called)? If it is do you have any information on how to take the motor out and check/test it? Finally, I have found the NH part number for the left side drive motor (632483), if it has to be replaced does anyone know where a good used, if appropriate, motor can be purchased around the NC area?
Welcome to Heavy Equipment Forums!!:drinkup From what you've posted, the only thing that can be determined is your flow to the left side drive is not what it should be. I'm not familiar with the hydraulics of your particular machine, but if each side has its own pump, this would be the place to start. First determine if the pump has the proper output and start tracing it from there. Next stop would be the control valve, make sure it is actually opening the full amount with the move of the lever, and check flow on the output side of the valve. After that you'll have to go to the drive motor and check on things. It could be you have blockage of some sort at any one of these places. One thing I forgot to mention is the pickup tube for the pump. There may be a screen filter on it that could be clogged preventing flow. The milky color of the oil usually indicates water contamination. The oil must be replaced and you should determine how the water got in the tank.
Almost back to work today I switched out the right side drive motor with the left side...What a job. The final problem turns out to be..........the motor. Once switched the left side took off like a rocket, throwing dirt, while the right side was now dead in the water. Right now I'm trying to find a rebuild kit, or a motor...used first, then if nothing; knew. Anybody know where they sell used drive motors? This one here is a cessna with the number, one of them anyway, of 71442-3000
Try out "The Parts Book" It is a book of ads for machinery parts nationwide. I have been able to find almost any part in there. Here is the web site (I hope I gor it right) http://www.dodgenet.com/~partsbook/
Just returned from Heavy Equipment Repairs. They told me that the piston block, the end that connects to the back plate, needs the surface ground, because it's raised. That the back plate must be re-hardened, because it has worn through the hardness; this they have to send out to have done. That the flat brass tops on the pistons, that are against the swashplate, must be re-surfaced, because they have minor-here and there- scratches. And, that the spider must be completely replaced, because it's groved from the pistons. I'm waiting to here the estimate. When I asked what caused the damage, Glen told me that it's more likely than not water damage...a lack of quality oil flowing through the motor. He's also going to see what a rebuilt motor would cost. I priced the spider at NH and it's $57.00. Do I truly need the back plate re-hardened, and if i don't what can I expect for the life of the motor as well as loss in power?$810.50 plus shipping to have my cessans rebuilt. I send it out they send it back 4-6 weeks. 180.00 they re-harden the back plate, and I also pay shipping, out and back. Takes 4-6 weeks. $50.00 to re-surface pistons and piston block. spider $57.00 this way equals approximately $320.00. Does any one know where I can buy a used back plate? I really need to save on the 4-6 week deal.