Cat 938GII Axle

[BillG]

Would anyone have a pdf of RENR6066 axle manual? I purchased a complete manual a long time back and never noticed that the axle service manual wasn't in the binder. REN6065 spec is there but not the service part. I hate to buy another complete manual for one section.

 

[Nige]

Online RENR6066 (SysOp plus Test & Adjust) comprises of 31 separate sections, each one of which has to be downloaded separately.
Is it urgent..?

 

[BillG]

Hi Nige, the only section(s) that I really need are for service / repair / brakes. Thanks

 

[Nige]

RENR6066 refers to Power Train, not brakes. There's a small amount of information in it regarding the electrical side of the braking system (e.g. pedal sensor calibration) and how it integrates with the transmission controls, but nothing regarding the brakes themselves.
Also the manual is Systems Operation plus Test & Adjust - not "repair" which would be Disassembly & Assembly - RENR6068

 

[kshansen]

I took a quick look at SIS and for 938G II they show 5 different s/n prefixes.

A complete S/N would be a good start and maybe an idea of what you are looking to do to the machine. Just interested in how they system works or are you looking at taking it apart to replace failed brakes.

Also noted that for at least one of the prefixes they don't, at least for my level of access give much info at all!

 

[BillG]

My screw up, I thought this was just going to be a diagnose problem but it looks as though I will have to tear the brakes apart. I can't remember the full serial but I know the prefix is RTB

 

[Nige]

This should about cover it.
I'm not saying it can't be done but I've only ever seen brakes overhauled with the axle out of the machine and stood up. TBH if you're going into the brakes the rest of the axle components generally also need work done on them, so it seems just as well to pull the whole thing out where you can play with it in comfort. YMMV.

 

[BillG]

Thanks Nige, I'll put that in the book for future reference. I am going to try and see what sections of this manual are missing. Oh, and yes I am going to pull the axle, a lot easier than laying under it.

 

[kshansen]

I missed a chance to get into the brakes on a small loader like that with the inboard mounted brakes. One of our sister plants had one that was, as I recall, leaking internally when I went to look at it. But powers that be decided to send that job out to someone else. I thought it looked like an interesting job and our shop was well equipped with cranes and stuff to do the lifting.

 

[Nige]

FWIW these axles have a spring-loaded relief valve (Ref. #6) on top of the differential housing that looks a bit like a grease zerk. They are famous for allowing dust into the axle, which is why going into the brakes usually ends up in a production bigger than Ben Hur....
TBH we sling the relief valves and install a hose extended up into the front or rear frame with an atmospheric breather element installed on it that we change every 2000 hours. It's a 1/8" NPT thread in the axle housing.
Watch out for the level plug Ref #29 as well. They have been known to let dirt in.

 

[kshansen]

You got to be kidding me they have the level check plug going down from the top of the housing?

Must be that was designed by someone who never saw the conditions these machines work under, "What you mean there is dirt and dust in a quarry or mine? Who would imagine that?"

Even if someone is careful to clean around the plug all it takes is a breeze or bump to knock crap loose to fall in that hole!

 

[Nige]

Read the Service Mag SEPD0697 (Aug 2003) about it - you'll be even more shocked

 

[kshansen]

Read the Service Mag SEPD0697 (Aug 2003) about it - you'll be even more shocked

I don't have that access, not sure why but never been able to view service magazines on SIS.

Just did an online search an found one Ebay guy selling Service Magazines he's offering 9 issues from 1980 for ONLY $55.00!

 

[Nige]

Sorry, forgot about that. The same information applies to the smaller machine models, only the Part # if the dipstick changes.

 

[John C.]

You should see the stuff on top of the axles when they work on dairy farms. Why do you need brakes when you can just drop the bucket?

 

[DB2]

On a side note I loved reading those service magazines. Caterpillar developed a repair procedure for anything that became problematic. We have a few years worth here somewhere.

 

[Nige]

I thought I'd pull some more photos together of this modification done on a 950H. With the axles being similar the basic concept should work on pretty well anything in the 924-966 range AFAIK

The breather #6 (circled in the parts manual illustration) is shown in the photos below. As many people pointed out it's pretty well useless as soon as the top of the axle becomes caked in mud or whatever. This particular loader is used for extracting material from a pit located below a processing plant that usually has about 3ft of water in it, which made the modification a no-brainer. When we saw how well it worked we modified all the other similar machines on site exactly the same way.

What we used was a 9C-4937 Breather element mounted up high in the front frame so that it's accessible for servicing, connected to a 1/8" NPT fitting on the axle housing via a hose as shown in the last photo.

 

[kshansen]

Nige, just a little clarification? Am I right to think that the pressure relief vent shown is used as well as the 9C-4937 Breather element?

 

[Mobiltech]

There’s not much to say in the manual about brake disassembly. You basically stand the axle on end and remove the bolts. Lift the end of axle off and you seee the brake disk. The piston under the brake disk lifts out ,replace seals and push piston back in. Flip axle over and do the other side.
Other than lift equipment the tool list is pretty small.

 

[Nige]

Nige, just a little clarification? Am I right to think that the pressure relief vent shown is used as well as the 9C-4937 Breather element?

No Ken. The threaded pressure relief vent is removed and the hose is screwed into the axle housing using the same 1/8" NPT thread. So the system changes from one that has a pressure relief to one with an atmospheric breather.
The other alternative I have thought about is to use a breaker relief valve in place of the 9C-4937 like the photo below. The sort of thing that would be used on a hydraulic tank. Various Part Number options are available from 5psi to 30psi.