I have a 98 312bl with lots of hours on it. One day as i was doing some hard digging the swing suddenly stopped.When i swung in the opposite direction it started working again but a little later it stopped again. When i tried another day it worked fine for an hour,maybe two before the swing got stuck. It seems like the problem appears when the oil gets warm. It is a farm machine so it isnt in daily use. It`s my first excavator so i hope to hear from someone else who knows more about than i.
Swing gears Could be your swing gears. Just replaced them in my JD 690D-LC (9350 hrs). Swung right then it froze in place. Had two of the four gears break .
Could be the swing brake solenoid acting up or power to the solenoid. Read somewhere here its the same as the fast track solenoid so might be worth your while to swap the two and rule out that as a problem at least.
It could certainly be in the swing box. Sounds like your brake ain't releasing or the motor is weak though. There is a solenoid valve that the coil could be week, as it heats up doesn't release brake properly? Could be the piston seals on the brake worn and when the oil gets hot it doesn't hold it released. Could be losing electric current to the swing brake solenoid. There are O-rings on the cartridge of solenoid valve. I would check voltage at solenoid, pretty sure it's 24v. Then ohm solenoid, i would have to look that up tomorrow but if it has really high resistence then that could easily be it. Then remove cartridge assembly from swing motor, check O-rings good and inner spool moves freely. After that, drain some oil off back/underneath and see if there is metal in the swing gear box. If all that checks out good....Probally the motor or brake. Best to let someone in your area used to working on that kind of stuff look at that part though. Hope this helps....check out pics below to see how it is set up. Top two are solenoid then solenoid cartridge assembly. Bottom two are motor. You can see where i circled where the brake valve is located. :drinkup
Someone told me earlier to replace the solenoid so i did, but the problem is just the same. When i`m low on throtle it sometimes will not mowe in either direction when its warm, but when throtteling up a bit it starts mowing again. When digging on full throttle it stopps wery instant, almost like the brake comes on. Maybe i need to look inside the swing motor/brake.
More then likely the swing pressure switch has failed. It is on the top of the main control valve. There are 2 little green pressure switches there, they are next to each other. One of them is the travel pressure switch the other is swing/implement pressure switch. change them both they are cheap!
I think i will swap the pressureswitches and see if the problem changes. Are the valves more common to fail when the hydraulicoil gets warmer? It would be a easy fix
On the end of the solenoid there's a screw you can tighten in order to activate the valve all the time if you want to see if it's the electricals that's acting up. I rarely see the valves fail, often it is the switches or just general wiring issues.
could be low pilot pressure - the brake is released by pilot pressure and spring applied. It takes about 200 psi to get the brake piston to fully clear the brake discs in the motor. When you attempt to swing, is the engine under load?
It does`nt feel like its under too much load when it gets stuck. Hard to say cause it has been a while since i used it. I hope i get the time to use the old cat this weekend and see if any of your tips can help.
Is this solenoid located towards the bottom where the pilot lines come out from the cab
I suggest you post up a new thread with your model and serial number and tell us what's going on. This thread is 13 years old and the original poster never came back.