#12 motor grader

[Leonard J Rousseau]

My cat #12 Motor grader clutch is stuck engaged . i parked it on a hill in gear for two years and now the clutch wont let go.
70D795 oil clutch. any ideas? thank you

 

[Vetech63]

I'm not positive on that model but it sounds like the friction disc is rusted to the flywheel or the pressure plate, or both. In most cases they will free up with a few lunges. Need a CAT guy to confirm any other option.

 

[Leonard J Rousseau]

with an oil clutch will they rust?

 

[ovrszd]

It's my understanding that the "oil clutch" part is the engagement/disengagement method, like a hydraulic clutch system on a pickup or Jeep.

It's possible that your "slave cylinder" that the pedal pushes has lost it's prime and is not disengaging the clutch. They can be bled just like bleeding hydraulic brakes. Look for a reservoir that would indicate oil level.

It's also probable, as indicated by vetech63 that the clutch disc is rusted and stuck.

 

[Leonard J Rousseau]

Thanks for the reply, but there is no slave cylinder. the linkage goes directly from the pedal to the engagement/disengagement part of the clutch. i took the linkage off the pedal and put a comealong on it to eliminate any adjustment issue. In other forums people indicated that in an oil clutch the discs would not rust together. but I'm not sure that's true or maybe i just misunderstood. For the dry clutch people talk about dragging it in gear with the clutch depressed to break it free. I might give that a go. does anyone know, should i use a low gear or high gear?

 

[56wrench]

i personally would try high gear first- less likely to damage anything and try it gently at first

 

[Delmer]

If you're dragging it, use high gear. If you start it in gear, and drive it over a bumpy field, use lower gear.

I suppose an oil clutch could stick if it got condensation and sat for years, that would still be unusual though. You should be able to see a dry clutch through some sort of access plate, you might see an oil clutch, but you'll get a face full of oil first. knowing which should help a little.

 

[ovrszd]

By your own description, it's not a hydraulic clutch. It's mechanical. Pushing the pedal will not break it loose. As suggested, use high gear if you are going to try towing it to break it loose.

Several manufacturers recommend "blocking" the clutch pedal in the disengaged position if parking the machine for any length of time.

 

[Terry140]

Not sure if this is any help, but this is the diagram from the Cat 12 operators manual showing the clutch

 

[Tugger2]

I have a Cat 12 that i bought with a stuck clutch. I loaded it without clutch . Got it back to the shop and tried all kind of pushing with the pedal pushed down ,to no avail . we finally pulled the engine and had to wedge and pry the clutch disc of the flywheel. Hate to say it but thats your fix .

 

[DB2]

I would try backing off the internal adjustment and make a few attempts at starting out in high gear. Trying to get the clutch to slip if you will.

If that doesn’t work it’s probably disassembly as Tugger states.

 

[Old Magnet]

Take the inspection cover off the left side and check to see if the clutch release collar is moving. Might be rusted to splined shaft. Are you getting pedal movement?

 

[ovrszd]

Good stuff Terry!!!! Thanks for posting the manual pic!!!!

 

[Leonard J Rousseau]

Take the inspection cover off the left side and check to see if the clutch release collar is moving. Might be rusted to splined shaft. Are you getting pedal movement?

Take the inspection cover off the left side and check to see if the clutch release collar is moving. Might be rusted to splined shaft. Are you getting pedal movement?

 

[Leonard J Rousseau]

Yes when I looked through the inspection cover the pedal is moving the mechanism inside.

 

[petepilot]

quart of kroil and a long spouted pump oil can` soak it down & let it sit couple days

 

[skyking1]

^that is worth a try!
I can see how it would ultimately rust up as the oil drained down.

 

[Fat Dan]

It doesn't seem likely that an oil clutch would rust but if the oil had emulsified or was replaced by water due to setting for long periods of time it is at a higher risk of rusting.
Great info Terry thanks

 

[Vetech63]

It doesn't seem likely that an oil clutch would rust but if the oil had emulsified or was replaced by water due to setting for long periods of time it is at a higher risk of rusting.
Great info Terry thanks

They DO rust. I know it seems unlikely but I have had to free up too many. I just did another 12 last year that had been sitting forever. I sprayed it down with diesel for 3 days, then lunged it a bit.

 

[skyking1]

I was wondering if you can get some oil on there through that inspection plate on the splines and on everything else to help out.
Thanks VTech. As with Dan, a mechanical grader is on my bucket list too.