CAT 955 Brake Adjustment

Good evening,

I’m working on adjusting my left brake on my 955 12A539 traxcavator. The brake becomes more responsive as it heats up but clearly needs to be adjusted. After doing some research I found a set of adjustment instructions.

The instructions mention loosening the lock nut on the support screw. Is this lock nut accessible from the inspection cover under the seat?
Thank you in advance

I suspect you will find the "support screw" is #10 on the diagram. Which comes out under the machine.

I imagine I’d have to take the belly pan off to get to the bottom?

I am not familiar with the 955 but if it is similar to the D4D, the belly pay only covers the transmissions, not the rear case. If you look underneath there should be a bolt with a locknut on it on either side somewhere around near where the diagonal brace connects to the rear case.

This is from a D4D maintenance manual showing what the bottom adjustments bolts might look like on the 955.

I’ll have to check into that. It’ll be Saturday before I get a chance to look at it. Thank you very much for the help!

Should not have to mess with the support screw underneath do you have a low brake pedal if so just adjust number 7 do not make it to tight need about a half a pedal on the brake

Yes support screw is underneath but like Dave said I wouldn't mess with it unless you relined the band.
These 955's were always slow turning until they got warmed up.

The support bolt adjustment is very important and needs doing at every time you adjust the brake, this holds the band in the correct support position and stops undue wear of the top ends of the band, it takes only moments to set these bolts and the pay back is a band that wears evenly and springs free of the drum, when you get used to doing it you will get satisfaction from a job done correctly, when you have to strip out the bands for a re-line you will take every care to make sure it's not the common thing on a 12A as they are right pigs to set free. tctractors p.s. lots of jobs on the 12A are a challenge to do as this was a very early shovel, CAT became better on the build up of things by the late 1960's

I have the inspection cover off and #7 on both the left and right sides won’t turn with a ratchet. I don’t want to put the impact on it for fear of snapping it off. I put some penetrating oil on it with no luck.
The reason I’m adjusting it, is because the left brake goes down to the floor and finally turns once warmed up.

#7 won’t turn in or out freely

The need for a bit of heat is possibly the answer, I did say that the 12A was hard going I feel you will understand my comment, try getting some heat via a gas welding/ cutting kit, stripping the bands out with rusty and stuck parts is some battle. tctractors

The adjustment may be bottomed out will it turn the other way

Dave Neubert said:

The adjustment may be bottomed out will it turn the other way

Click to expand...

Unfortunately not. It’s going to be a son of a gun getting heat down in to get at that bolt