1995 Cat 312 SN: 6BL00906 When I track forward or reverse the machine could push a mountain over. Plenty of speed etc... The problem is if I try to turn or try to move one track at a time, it basically falls on it's face. It doesn't stall the engine, it almost seems like fluid is bypassing. Any thoughts on where I should start to look? Initially I thought maybe it could be the rotary manifold that needed to be resealed. A mechanic friend said if the seals where bad that it would also bypass when using both tracks simultaneously. Thanks for any leads.
That depends on how the passageways are stacked. Does this machine have a stick control for steering on one pedal for forward and the other for reverse?
It has a conventional side by side travel pilot valve.
Ok... I can see how depending on the way they are stacked, it could cause my issue. This has one lever/foot pedal for each track.
Centre swivel seals bypassing.?
Good day This may not be the case but worth a check. Kind regards Uffex
I have the same advice as the others, pull the swivel and reseal it.
Nice to see you around Per. I was thinking about you only the other day.
Thanks for the replies! I hope to have time in two weeks to reseal the swivel. For some reason, I've always referred to it as the rotary manifold. I will report back with the results. Cheers!
Swivel, rotary manifold? It just depends on where you grew up.
Also depends how It’s referred to in the OEM’s Parts Manual......
Good day Removing the central passage – rotary joint/ manifold – swivel coupling is not always easy being sure it is at fault costs less time and money and you know if it needs new seals. May be a little drawn out but diagnostics is better that guess work. Please see attached. Kind regards Uffex
I agree, but on a 25 year-old machine I'd bet my bottom dollar that the seals in the swivel are like rock and are bypassing as a result. A complete set of seals for that joint comes to about $70.
Seals are cheap. If are gone hard it’s probably pressuring your case drain as well (which is tee’d into the swing motor) buggering your swing motor. I have the t-shirt!
Swivel seals don't fail by getting hard as rock. They disintegrate in pieces that usually end up in the return filters. While the seals for the case drain can fail it is usually the middle seals that fail and come out. That then lets the pressure side of one bypass into the return side of another circuit. That is why it matters as to how the circuits are stacked in the swivel. Case drain lines are usually only a #4 or #6 size so not a lot of oil can get through at once. On small to mid sized excavators it usually is easier to just pull the swivel and reseal than it is to cap and plug a lot of lines looking for the leak.
Or centre joint.
No time to spend online with 2 small kids it seems, only get to put in an hour here or there nowadays.
Most swivels I have pulled has shown no signs of seals whatsoever, somehow they evaporate with out a trace and leaves only the top and bottom oring, crazy considering the clearances. And yes, when having even the slightest doubt that the swivel might be the cause of problems, just pull and reseal, it's so quick cheap and easy to do.
Good day This may be of interest a center passage devoid of seals, was used througout Akerman production I have no knowledge of failure or replacement must have been good telorance. Kind regards Uffex
Looks like I messed up my reply above. I am anxious to reseal it. I was pulling stumps yesterday and within a short period of time, the machine was not as responsive as it normally is. Particularly when swinging and raising the boom. I told my son, it’s almost as if some seals let go and have become lodged. After reading your comment, I feel confident that resealing will hopefully take care of what’s going on. Thanks! I want to thank everyone for their input. I will report the results when I get it done.
This may help. Lots of assembly lube when reassembling the swivel will hopefully prevent seals getting cut as it goes back together.
Good day and good luck with that, I fail to understand the swing and boom issue connection central joints passing seals will go via the track spools back to main filters - plugging the main hose with a guage did not call for to much effrot even if you avoid eliminating the spool & housing. Our experience removing cemtral passage's in modern machines is bloody difficult take a look at those with short tail swing mabe some folk have rubber arms and flexible spanners.Maybe better gamble to pull the filters first. Keep smiling Uffex
I bought the seals and some hydraulic fluid. I have everything disconnected and hoping to have time tomorrow to reseal and reinstall. Will update soon. Thanks again to everyone... fingers crossed.
Everything is back together. Four of the five seals were gone. Travel works perfectly now and the weird feeling when swinging and booming up is gone. Runs like a new machine. Thanks for all the suggestions and advice!
Looks just like John C described failing seals. . . . .