Excavator tracks weak turning

[Welder Dave]

What did the new seals comprise of and what were the original? If they both used O-rings maybe the new O-rings were a bigger cross section? Other thought is if the new seals use a backup ring maybe it was put on the wrong side and the O-ring rolled a bit and got pinched when putting the rotary swivel together?

 

[Nige]

Post a Serial Number for the correct OEM Part Number of the seals for the swivel. From SIS I do not see them being a 2-piece seal.

EDIT: There is only one Part Number of swivel for a 315C, whatever the machine Serial Number happens to be. See the attachment. The five main seals (circled) separating the various hydraulic circuits are basically square in cross-section and are 1-piece. Sounds like wherever you got the seals from gave you the wrong ones.

 

[HDM Apprentice]

Yes that looks like a sliced Oring- possibly giving you a good enough bypass that would make your turning sluggish. Also knowing the problem worsens when hot could be influenced by oils viscosity changing due to temperature- when its hot it becomes alot more water-like, meaning it can pass through tighter tolerances with much less resistance. Oil will always take the path of least resistance. I would definitely check your basic track sag and ground type first like someone previously said. Then I would move to pressures check going to each individual drives and compare with a spec unless its clearly ridiculously low. I would guess some sort of bypass interally- evidenced by the o-ring pieces, is your suspect, especially if it happened randomly and was working fine earlier.

 

[diggerjoe]

What did the new seals comprise of and what were the original? If they both used O-rings maybe the new O-rings were a bigger cross section? Other thought is if the new seals use a backup ring maybe it was put on the wrong side and the O-ring rolled a bit and got pinched when putting the rotary swivel together?

They were twopiece..square cross section . The taller or thicker one was black the shorter one was blue. The blue piece was slightly smaller in diameter and fit nicely inside the black one so that's how I installed them. I recently revealed a hydraulic cylinder that used a similar setup so thot that was the right way but maybe not?

 

[diggerjoe]

Post a Serial Number for the correct OEM Part Number of the seals for the swivel. From SIS I do not see them being a 2-piece seal.

EDIT: There is only one Part Number of swivel for a 315C, whatever the machine Serial Number happens to be. See the attachment. The five main seals (circled) separating the various hydraulic circuits are basically square in cross-section and are 1-piece. Sounds like wherever you got the seals from gave you the wrong ones.

I got them from Cat. No way I was gonna take a chance on something that hard to redo. And now I probably gonna have to anyway.

 

[diggerjoe]

Here's what I found on the return filter. If the pieces were blue I wud know they came from th swivel. I wud have thot the blue seals would have been th ones that were damaged as they wud be th ones th swivel was slipping past.

 

[Nige]

I got them from Cat.

What Part Number did the Cat dealer sell to you.?
Can you also post the machine Serial Number please.

 

[diggerjoe]

I will do some digging and see if I can find th packages or parts invoice. Serial is CJC03144

 

[funwithfuel]

I think i would measure track sag, check the gearboxes for oil, and check pilot pressure to my travel pedals before i tore something like that down a second time. Start at the beginning and work your way forward. Pilot pressure is gonna be crucial, BTW, do you have a straight line travel pedal? Does track power change if you boom up or arm in over relief?

 

[shopguy]

Did you put one track in the air and try to move the one on the ground?

 

[diggerjoe]

I think i would measure track sag, check the gearboxes for oil, and check pilot pressure to my travel pedals before i tore something like that down a second time. Start at the beginning and work your way forward. Pilot pressure is gonna be crucial, BTW, do you have a straight line travel pedal? Does track power change if you boom up or arm in over relief?

Track sag was fine, gearboxes are fine, it does not have a straight travel pedal. I just got my gauges but am waiting on a part so I can start the machine. How and where do I test pilot pressure? I never tried boom up or arm in but will when I get it running.

 

[diggerjoe]

Did you put one track in the air and try to move the one on the ground?

Not th one on th ground. When I lost power to the right track first thing I did was lift that side up. It turned fine in reverse but barely half speed in forwards.

 

[funwithfuel]

I am not a cat guy, the cat techs will have to fill you in on that. The general idea is, from the safety solenoid, there's a line that carries pilot oil to each joystick and to each travel pedal. Each of those 4 valves should have an inlet fitting which acts as a filter. Sometimes they get jammed up with trash , rag debris , hose lining, etc. If the signal is corrupt, the control pressure to the spool caps will suffer.

 

[Welder Dave]

They were twopiece..square cross section . The taller or thicker one was black the shorter one was blue. The blue piece was slightly smaller in diameter and fit nicely inside the black one so that's how I installed them. I recently revealed a hydraulic cylinder that used a similar setup so thot that was the right way but maybe not?

That seems really odd to have one seal fit inside the other. Seems like one seal the right dimensions would work better.

 

[shopguy]

If the swivel is bypassing the one in the air should move when you try to move the one on the ground

 

[funwithfuel]

That seems really odd to have one seal fit inside the other. Seems like one seal the right dimensions would work better.

In high pressure, moving parts. It's common to use a teflon or viton outer seal with a common o-ring beneath as an expander to provide constant tension on the sealing surface.

 

[diggerjoe]

If the swivel is bypassing the one in the air should move when you try to move the one on the ground

I see..that makes sense

 

[Welder Dave]

In high pressure, moving parts. It's common to use a teflon or viton outer seal with a common o-ring beneath as an expander to provide constant tension on the sealing surface.

It appears the 2 piece seals aren't the correct seals the OP needed.

 

[Nige]

I will do some digging and see if I can find th packages or parts invoice. Serial is CJC03144

OK, so I have an update regarding the swivel seal Part Numbers.

There was a service publication in 2003 announcing an the introduction of an "optional 2-piece seal" for the swivel for use in high-temperature applications. At that time the 159-7782 one piece seal in the parts listed I posted earlier was still the factory-fit part but the new 141-2163 2-piece seal was available for parts service for any customer wanting it.

Over the intervening 20+ years it appears as though Cat have decided the 2-piece seal is the way to go, because both 141-2163 and 159-7782 are have been cancelled and service to a single Part Number 609-7007. The new seal is 2-piece, has increased resistance to wear and to water, and allegedly reduces friction in the swivel.

Based on the above if the swivel was as difficult to assemble as you suggest I reckon you might just have cut one or more of those five seals as you were reassembling it.

 

[diggerjoe]

OK, so I have an update regarding the swivel seal Part Numbers.

There was a service publication in 2003 announcing an the introduction of an "optional 2-piece seal" for the swivel for use in high-temperature applications. At that time the 159-7782 one piece seal in the parts listed I posted earlier was still the factory-fit part but the new 141-2163 2-piece seal was available for parts service for any customer wanting it.

Over the intervening 20+ years it appears as though Cat have decided the 2-piece seal is the way to go, because both 141-2163 and 159-7782 are have been cancelled and service to a single Part Number 609-7007. The new seal is 2-piece, has increased resistance to wear and to water, and allegedly reduces friction in the swivel.

Based on the above if the swivel was as difficult to assemble as you suggest I reckon you might just have cut one or more of those five seals as you were reassembling it.

Ok thanks a lot! I found the parts receipt and that part number is on there so apparently they did give me th right seals.