Looking for some input/advice. Working on a 770G CAT haul truck . Original complaint is differential filling with hydraulic oil (brake/hoist oil) in this application, I have wheels/final drive/bearings etc removed and I am down to the brake assembly .. I can’t seem to get it separated.. I know it’s on a splined shaft and there are two o-rings seals that seal the brake assembly to differential/axle housing .. I assume it’s just seized good. I have everything removed that would keep it from coming off .. retaining ring , shim and plate. I plan on putting two short rams on the back side to separate.. anymore tricks that people have used before? I might possibly be missing something. Also second thing .. has anyone rebuilt /resealed the brake assembly on one of these ? I know you have to be careful with the springs and spring pressure .. according to cat SIS you need a special line up tool for the friction disc and plates so everything stays in place until bolted down. tool from CAT is unrealistically expensive and only works on these 2 truck models to my knowledge. I’m questioning if it’s worth the investment or not versus just having the dealer rebuild them. Has anyone made this tool? Or have a used one laying around they would sale? Slim chance I know. Looking at all options. have the part number if needed.Thanks in advance for everyone’s help.
Probably is if it's never been removed before. You might have apply some pressure to it then shock it a bit to get it to pop loose. I assume the rear wheel group has been disassembled on the truck leaving the spindle still mounted on the rear axle housing as opposed to removing it as a complete unit then standing the spindle up vertically. In a lot of respects that's the easiest way to do it but may not be practical in your case. I would say that it is possible to get by without using the alignment tool, but it would need a lot of patience and fiddling around with the discs/plates to get the inner splines in alignment so that the splines on the hub will engage with them. Once the brake pack is assembled it will require a portapower applied to the parking brake port to release the brake pack in order to allow the discs/plates to move. You could try this with the brake pack laid flat on the floor of your shop and then lower the wheel hub vertically into it in order to engage the splines. Then once everything is aligned release the pressure and apply the parking brake. That should then hold everything in place so that when the hub is installed on the brake pack during reassembly on the truck (fingers crossed) it ought to slide straight in. It's amazing that these smaller trucks (and some models of motor scrapers) call for the use of an alignment tool when something probably twice the size such as a 789/793 does not.
Thanks for your response , You are correct I have removed the wheel group removed with spindle still on truck .. I am familiar with some of the older trucks 769/771 etc you can removed the whole wheel group/brake assembly as one. Easily. on this 770G you have to remove the wheel group to access a retaining ring and retainer to remove brake group separately.. to remove the whole spindle/brake/ wheel group as one you would have to remove whole axle/differential from the machine. The suspension cylinder and axle to truck frame bracket both bolt to spindle housing where it meets at differential. As far as the brakes the process you mentioned would work great, but even if I had brake housing laying vertical on the ground and got the wheel group with hub slid in place I would not be able to have access to get my retaining plate and ring back in place to hold brake assembly on to spindle. I believe the reasoning behind this line up tool is because do have to assemble vertically so everything stays in place so you can install it on the spindle horizontally and everything stay in place to install wheel group.. it’s a little different than some of the other trucks for sure.. you mentioned 789/793 I have not been around those much but based on some research the appear to be more simple like the 769 and 771s . Thanks for your help.
Maybe I didn't explain it adequately. What I was suggesting was to use the splines on the hub to centralize the teeth on the brake discs with the brake assembly removed from the truck and lying flat on the workshop floor, then lower the hub into the brake pack vertically. Once the discs are centralized, release the pressure in the park brake and remove the hub. At that point you have a brake pack with discs that are (hopefully) centralized well enough that once you have it installed on the splindle and later in the process come to install the hub to said brake pack, that it all slides together.
I understand what you are saying now. I misunderstood.. that will probably work. I appreciate the help, I’ll give that a try.