A little tangent from my thread on trailer loading issues. Regarding my 322C, previous owner had at the CAT dealer because it was not tracking straight. I think they were just guessing, could not really find the issue, installed a counterbalance valve somewhere, and ultimately someone added play to the RH pedal to fix the problem!!!! Like ok, it tracks reasonably straight with both pedals full forward, but it is insane frustrating trying to make minor jog moves and having to think about and compensate for that little bit of slop they put in the right pedal. So.... I would like to solve this problem. I want it to track straight. Based on power to the tracks alone, I highly doubt it is a drive motor. CAT won't really tell me what all they checked but if it's like everything else the dealer does, it was all a guess anyway. I am leaning towards either pilot pressures not matching side to side, or maybe spool springs or shims are not right? Anyone got some good checks for this? That valve block is totally stupid! They have the pilot bucks on top and bottom so near impossible to get to the bottoms unless I am missing something. This is when I really miss that old CAT mechanic Bob that passed. I think that guy had seen and fixed it all. for reference, right side will outrun left in fwd and rev.
The drive motor spool comes out the top of the valve. The centering springs are on the top end of the spool. Control valve on drive motor. Either one can cause speed issues . Bob
What does that mean?
“CAT won't really tell me what all they checked but if it's like everything else the dealer does, it was all a guess anyway.” You can request a copy of the service report the Tech wrote up. If the local branch gives you crap about it, call the Regional Service Manager or the VP of product support. There’s nothing about a 322C that’s a mystery at this point. Those are well supported machines.
I know a couple guys there. One I think is the district service manager, other is a similar position. But I don't usually hassle them. I think I will jingle the dealer to see about more detailed notes but I think their position and "policy" is they won't turn over written reports to anyone but the paying customer. I might be able to get the previous owner to make the call but otherwise they just "read" the report to you.....swell.....I will get my pen. Anyone have any thoughts on what I am chasing in the machine? Is there any way to verify spool travel or position in operation?
Start with the basics. Block the sprockets and check main relief pressure in all directions. Check the cycle times by running the tracks in the air and timing them with a stopwatch.
Items that may cause different speeds of the tracks include, problems in the travel motors, leakage in the swivel joint, problems in the travel pedal movements, difference in relief valve settings, unbalanced hydraulic pumps. One clue is if the machine travels straight when you move a function like lifting the boom while you are traveling. If one track continues to be weak, then the problem is more likely to be between the main control valve and the motors. If the machine travels straight when you lift the boom, then you might consider looking at pump flows. I'm always a little suspicious of customer talk about what a dealer did or didn't do. I like to confirm the problems on my own or have the operator show me what is wrong and start from there. Many of us have been sent down paths that diverge from the actual issues by loose talk and little actual knowledge of the prior events, limitations and participants.
Thanks John. I agree regarding helpful info vs not useful. I've turned wrenches far longer than I've been operating equipment. I prefer to gather ALL facts and stories from all participants, then sort them like cards. Hate to say that I hate hydraulics mostly because of the mess. I absolutely LOVE electrical problems and prefer the ones no one can solve. I guess case and point, this machine had a blank monitor when I got it. It spent weeks at the dealer and charged thousands. They even tried a new ECU. The owner stopped the bleeding once they said "you need a new wire harness"..... But I was able to use some info from the dealer to refine my own troubleshoot process and I fixed it in 2hrs. So I guess I am in a gathering info phase. Usually a leaking swivel will cause heating of the swivel due to bypassing flow, correct? Also, I would expect weakness? I cannot say either track acts "weak". Climbing hills and such, it seems all the power is there. There is just an offset in pedal positions, which sort of leads me down a road of 'biased flow'. I will mention that I fixed an older CAT that had serious differential speed issues. Each of the two pumps ran one track and it was determined the pump servo had an issue and would not upstroke one pump. This was further proved by slow speeds on certain arm functions. Anyone with SIS, would someone be willing to snag my hydraulics schematic? I fear on this one, without plugging into the machine, I might be handicapped here as some servo information might be helpful.
Fault codes and then, using monitor, see stall pressures of both pumps.
What’s your S/N? Just out of curiosity where in OK are you? Maybe between the two of us we can figure it out. Did Warren work on it? I’m sure I can get the info on it if they did.
Can confirm no fault codes. I will stall the tracks and see what pressures go to. However, I am still not sure what relief pressures would tell us. tracks are not running at relief pressures. Unless someone thinks a relief is leaking and diverting some flow? For reference, when walking out of a field today, I tested all functions while walking. Machines slows down a lot due to another function running, but both tracks slow the same. Zero change in directions. I am not chasing a severe issue here, but pretty obvious something is not right. Every 50-100ft, I have to make a correction. Actually, here is the deal, the right stick has play in it, BUT the left is the one running faster. I have not dug into it yet but that would seem an obvious fix. I think someone added the play in the right to get it close.
I'll send ya a PM.
Try the test Cmark suggested at least you will have a base line to go by . Bob