Kobelco 5.5t (1998) excavator. This machine is tracking 'off'. It has a new track motor on one side (right), but the thing is that is the slow side! Go figure? I have also reconditioned the centre joint/distribution manifold, but that has made absolutely no difference. So what next? What other factors could lead to uneven tracking? When I have the travel levers pushed all the way forward, or back, there is a whine/whistle which is impossible to trace on a moving machine, of course. But it sounds like a relief valve venting surplus pressure maybe?? Is there such a thing? The whistle occurs when the lever on the left (the fast side) is pushed all the way forward, backing that lever off a tad it goes silent, but that doesn't cure the tracking. I'd appreciate any suggestions as to how to sleuth out the next steps in troubleshooting this. Associated with this is that the high/low speed has stopped working, but that did not appear at the same time. I have not tried to troubleshoot this issue yet, I have no idea exactly how the two speed works. I'm assuming there's a planetary drive in the track motor(s) that is fed via two different oil supplies depending on which way a solenoid is switched? Where is that solenoid likely to be? What's the best way to test it? Maybe that whistle described above could be something to do with it? This is an old machine, but in fantastic order, motor uses no oil, pins/bushes are superb, barely leaks a drop ever, so it's absolutely worthy of bring up to full health!
Did the problem only start after new motor was fitted. Have seen many times aftermarket final drive fitted that have a completely different speed to an original one.
have you run pressures on the travel also you can try swaping the 2 pressure lines coming directly off the pump that will tell you if it is in the pump or somewhere down stream
Hmmm. That I can’t say. Prior to the new track motor the old one was not good. But I do get your point.
Dave, I like that idea. So you’re suggesting swapping at the outlet of the rotary joint to effectively make the left drive the right and vice versa?
You need to check and adjust pressures on both track motors. The new one is out of adjustment and the old one should be checked and adjusted to match the new one.somebody should have a procedure to do it. Maybe post a thread in the excavator section on here.
No just swap the hoses at the main hydraulic pump
My prediction is that the slow side will stay slow. If the slow track happened after you changed the drive motor, common sense says it’s most likely in that motor. Or to word it another way- back up. What did you do?
Mike, as I read it the motor he replaced was completely inop. Sounds like he's new to the machine. Joe H
Sam, just in case you didn't twig to it, sounds like one section of the implement pump runs certain functions (inc. one travel motor) and the other pump/pump section runs all the other functions plus the other travel motor. Therefore if you switch the hoses at the pumps and the problem moves to your other travel motor then you don't have a motor problem - you have a pump problem.
I was new to the machine. The old final drive actually split apart! I managed to get some money back from the vendor. Unbelievably the dead motor had some home manufactured parts in it! Needless to say it was junk. I certainly was very worried as to what other ‘hacks’ this machine contained, but hundreds of hours later it’s a really great machine. Apart from its travelling. I haven’t had the chance to take up any of your fabulous suggestions yet. I’ve been busy sorting a drain. I’ll get the tools out soon. Doing the rotary joint was a fun task. How many hoses can connect to one unit! It will dig all day long, but the drive gets worse as it gets hot. The ability to keep digging would suggest the pump is good. The rotary joint is good. The drives are good. If I lived anywhere near a mechanic I’d get the pressure readings done and that would likely immediately answer a lot of questions. I’ll certainly keep you informed as I sleuth the problem. Nige, surely if the other section of the pump was lazy then other functions than just one travel motor would be lazy too? However I’ll certainly have a go at swapping pipes to try to undergo a process of elimination. I’m learning, I like learning.
On the travel motors there is usually a tag with model numbers. The model numbers equates to the motor size, check both to ensure they are the same models. If the new motor is larger it will rotate slower. To give you a better understanding of all this hydraulic motor size is the amount of oil required to do 1 rotation. For example 50cc motor requires 50cc for 1 rotation. From here you can determine the motor RPMs by dividing the amount of flow (in cc) by the motor size in cc.
To a certain extent, yes. But, and it's a big but, if the machine has been like that ever since it's been in your possession how can you know if any/all the hydraulic functions are correctly up to speed without obtaining some specifications and getting the stop watch out to time them.? It could be a case of "it's always been like this" and you never knew any different. Only the difference in travel speed between one motor and the other is an obvious indication that something somewhere is amiss. What Dave mentioned about swapping hoses between the two pumps is a quick and dirty way of identifying if the pump or the motor is where you should focus. Are you sure that you didn't trap or shave a seal in the rotary joint when you reassembled it.? Very easy to do. Also did re-sealing the swivel make any difference at all to the travelling.?
I didn’t do the rotary joint machining. I got that done by Kobelco so I hope they didn’t roll a seal! I pulled a few cover plates off today and thought I’d get down to first principles… there’s quite a lot of play in the drive lever linkages so I’ve stripped them out. I now have the joy of drilling/reaming out the eyes in a very awkward place. Absolutely no way to take them out. Sigh, we love a challenge. At least I can do the rest on the bench. We will prevail! Once it’s mechanically ok, I’ll then get onto hydraulic integrity. One step at a time!
Sam, Travel Motors Direct will have parts on the shelf for the drive Motors and planetary hubs. They can supply or rebuild. I've had great experience dealing with Murray in Australia, his son runs the NZ operation just south of Tauranga
Was the two speed tracking working ok before the rotary joint overhaul?
Travel motors direct did supply the new drive. The two speed stopped working prior to the rotary joint job. I have not yet tested the power to the two speed switch on the joystick, but I will. What I’d like guidance on is where that signal goes to? I’m assuming there’s a solenoid somewhere that directs oil down to the track motors to get their planetaries to change gears? Or does that change occur up in the valve block under the floor plates? There are 4 hoses going down to each final drive. I’m assuming they represent forward, reverse, return as a set of 3. Then the smaller hose to feed the gear change mechanism? Am I right? In which case the solenoid IS back up under the floor somewhere. Here’s a photo under the floor plates. My finger and thumb pointing to the travel valve blocks. Is the fitting sitting between them a port to which pressure gauges might be attached? Or a pressure regulator/adjuster? There’s two of them, one forward, one reverse I’m assuming?
There's no gears, the 2 speed is simply a change of swash plate angle in the hydraulic motor. A small hydraulic ram when activated does the changing and on some motors uses the oil in the pilot system. In low speed no pressure is required.
Take the cap off and have a look.? There will be no "return" hose. The feed/return function of the two hoses for Forward & Reverse travel will flip-flop depending in which direction you happen to be travelling. There should be a small hose for the case drain (back to tank) from the piston-type travel motor. The last hose should be the one carrying the signal for the 2-speed. I would guess that pressure in that hose engages high-speed, no pressure keeps the motor in low speed.
Three big hoses, all the same size. One small.
The 3 hoses are a casedrain and 2 for travel direction and swap from pressure to oil return The small is the 2 speed. The casedrain usually returns through the rotary joint then connects to the slew motor casedrain then returns to tank.
Just a wee update. I’ve just got Doug going again after pulling all the control linkages apart. My, they were sloppy! Welded up and re-drilled various oval holes and/or drilled them out to the next size. New Clevis pins and R-clips. What a difference! Also cut off a 1/2” positive lug that went onto the 8mm starter bendix stud and power-crimped the correct lug on. Why do people do such sloppy work? Now I’m beginning to get to the position where I can diagnose actual hydraulic issues with a bit more confidence.