I have a problem with the swing on my PC 35. The symptoms are as follows, 1. Full movement but not a lot of power moving in either direction. example. if trying to use swing to refill a ditch I must take very small sweeps of the loose earth or the boom stalls. 2. When traveling across a slight slope the boom swings to the down hill side. Also, when on the level you can push the boom to either side. 3. When swinging the boom the swing brake stops it dead when the controls are released and then seems to unlocks in a short time and can be moved as above. 4. I had a Komatsu tech from the local dealer come out ( Not Cheap) to take a look at this and several other issues ( all resolved) . I was told to get a replacement swing motor. However, the parts man at the same dealership is spectacle and since neither he or I can seem to locate an after market of rebuilt unit he and I are assuming there is no big demand and therefor not much of a failure rate so I'm curious if any of you have a suggestion. Thanks Joe
There are I think three check valves and a relief valve in the motor head which should be checked, and the pressure setting checked on the relief. The brake, I don't know the exact system on this machine, many excavators are set up so if you are pulling the stick in the swing brake releases to avoid too much side pressure on the boom and stick. Or it could be a valve malfunction somewhere. Need a service manual to understand exactly how the swing brake is supposed to function. It is possible you need to rebuild your swing motor, new rotating group and valve plate, etc. but I would try to eliminate the valves in the motor head as the trouble source first?
How many hours do you have on this machine? Have you had any hydraulic problems with other functions lately? Do you have a gauge that you can use to check hydraulic pressure on the function? I would suggest that a little more troubleshooting be done before removing components. There is one safety valve and two suction valves in the swing motor head. I believe these can be removed from the head of the motor and checked first. I have replaced lots of check and safety valves in the past. I haven't seen much trouble with Komatsu swing motors and they are pretty simple for a bent axis piston motor. If they get broken it is usually because of contamination from some other failure. The most I've done on one is lap the valve plate to the barrel assembly and put them back together.
John. I’m haveing a problem with a swing motor on a pc35mr-3, it acts like it’s trying to spin and dosent and sometimes it spins and acts like it’s trying to catch to stop and just keeps going around and sometimes it will lock once you get it back center and sometimes you can just push it around
Something is broken inside the box. Time to remove and tear it down.
the box is under the hydraulic part of the swing motor correct? Like will have to unbolt from the frame of the machine
Yes
Thank you sir