12a 955 Right brake stop working at once

The brake just stopped working as you where using the machine? If that is the case, you most likely had pin fall out in the linkage.

If you need to remove brake band to read the service manual is easy way. I believe it should be in the members only area Tech Library here to read. But in general remove fuel tank to get to the steering clutch compartment. The band is bolted together and comes out in pieces.

Still most likely a pin is out or the band is broke, if it stopped working instantly.

The brake just stopped working as you where using the machine? If that is the case, you most likely had pin fall out in the linkage.

If you need to remove brake band to read the service manual is easy way. I believe it should be in the members only area Tech Library here to read. But in general remove fuel tank to get to the steering clutch compartment. The band is bolted together and comes out in pieces.

Still most likely a pin is out or the band is broke, if it stopped working instantly.

I have a 955E also 12A8263 (1960) the D315 is yet another project. Ray54 is right the fuel tank and if you have a ROPS they will need to be removed; also if you have a rear attachment they may also need to be removed for access. I'm sure you will need to remove the hydraulic tank (right side), and hydraulic filter (left side) to get better access. A service manual, parts manual and an Operation and maintenance manual are going to be a must have source. Each with its own information you will need. Cat is infamous for putting bolts, nuts and other things in your way and the 12A Traxcavator is three times worse.
Have fun and.Good Luck