Hello gentlemen. I am hoping to get a few answers on a problem I am having with my excavator. It is a 4300C Link Belt. It seems that the swing brake will not release. After having the swing motor rebuilt, and having all my hydraulic components cleaned, (tanks, lines, cylinders, new filters installed, new oil and an extensive amount of cleaning) I still have no swing left or right. It wants to swing when I pull the lever to the left the motor bogs way down and starts to swing but stops. When I move the lever to the right it bogs the motor down. I have pilot pressure at 560 pounds. All of my other functions work (bucket, dipper, boom, tracks, forward, reverse). There is a plate under the swing brake on top of the swing motor with three hoses coming out of it. The two hoses coming out of the front go to a solenoid which works when I put 24 volts to it, which when energized does not let oil flow back to the tank. When not energized oil returns to the tank. When my safety switch is not energized I have no functions. When energized I have all my functions like it should except brake release. And here's the kicker... this machine has no computer functions. All of the computer inside the cab and switches etc. have been removed and bypassed by previous owner. It has a throttle cable, an ignition key, and one switch for the safety and that's it. Back to the plate under the swing brake, the hose out the back is not getting pressure. Should it have pilot pressure when one of the controls is moved? At this time my pressure gauge is showing zero during all functions. :Banghead Also, on the #3 pump there is an electrical solenoid which has full 24 volts all of the time. Is this for pilot pressure or pump pressure? I realize all these controls should function together through the computer, but this machine has been used without it for years running a magnet in a scrap yard. Hopefully some of you have worked on some of these older machines and can shed some light on my problem. Thank you.
I don't know if this applies but the 2800cII swing brake work's off of a 12v system in the alternator (yes it's a 24v machine) but i've never had one not swing it just drags when it's not working right
Thanks, clintm. I have manually connected 24 volts to the solenoid for the swing brake with no luck. I have also put voltage to the other solenoids with no luck either. These solenoids basically have been ran in the past just being wired to the batteries. It seems that I have a problem with no pressure to the brake. I am thinking that each of these solenoids could be wired on a switch since I have no computer system and I should get operation. When running, the machine tries to swing left and right but the brake action only lets it move 3" to 6" or so. It's like it's not allowing itself to build pressure to release the brake.
if it does work off 12v --24v may have burned the solenoid out I would get a electrical drawing and start from there
The sol with 3 hoses to it between swing motor and battery box is the free swing sol. Swing brake sol is in pump compartment at the front wall 1/3 way up closest to engine and should be 50 ohms.
Thanks, DJK, for the info. I know where that solenoid is on the pump. I will check it for voltage. I haven't had any luck with it so far. I might have to see if it is hanging up. That could be the problem that I am having. I might not get to work on it until the weekend. Is that solenoid just a sliding spool with a seat on the end of it? I know that the spool is directly wired (right now). I wonder if it is wired backwards and if it will make a difference. I'll check it this weekend. This excavator is starting to engulf my life.
First thing going through my mind is just because you have correct voltage at the solenoid, it does not mean oil is getting to where it needs to be, as in the valve not moving in the spool. Also if I read this right, you say it will swing without moving the control ? If that is what I`m reading, you have a few more problems to deal with.
Thanks, GregD1, for the response. The machine only tries to swing when I move the pilot controls -- not on its own. I think you are right in saying that just because it has voltage doesn't mean that the spool is stuck. I think I can remove this solenoid by removing the #3 pump. Then I will see if the spool moves in and out freely. Hopefully if it is burnt out, I can somewhere find a replacement or rebuild.
I think u can manually push the spool in by using a small object and pushing the middle in
Hi guys. You are giving me a lot of useful information and tips. I took the electric solenoid off beside the #3 pump for the electric brake. It does operate on 24 volts. I cleaned it up, took it apart, cleaned out the spool and made sure it's working freely. My question is: when the plunger is pushed in is that brake on or off? When the plunger is out, is that on or off? My schematics don't really show me that. The toggle switch in the cab does not have on or off markings.
Hi gentlemen. I worked on the excavator over the weekend. I pulled apart the brake solenoid on the pump. I found it to be operating correctly. I tried it with the plunger pushed in and pulled out. There is still no change. The motor still bogs down when I try to swing left or right. I think I am going to try something... I'm going to remove the brake on top of the swing motor. I will lift the swing motor up out of the planetary gear so that I can see the shaft and connect the swing hoses directly to the swing motor to see if I have operation left or right. Has anyone else ever tried this? It might be worth a shot before I sent the swing pump out to see if something else is wrong in it. This way I can isolate the could-be problem of the swing brake or swing motor. Let me know what you think.
How did you ever make out with your swing motor
The swing motor was blowing out oil out the overflow because of the trash that went through it from a bad bearing . The slipper balls in the pump cut a groove in the awash plates half inch deep. I sent pump out west to a professional pump place and they tried to press it apart with the pins in it and it exploded I got it back and built my own parts and put it back together. I ran it all summer with no problems. Cut open return filter and is clean.