I have a D8R (s/n 7xm), when warmed up the brakes seem to be engaged. It will force its self past the brake resistance in second for a short time, then it starts to slip. Even without pushing in first, if i decelerate the dozer will come to a abrupt stop. We have replaced the following within the last year due to other issues: torque converter, transmission, hydraulic pump, and trans pump. Another thing is that the weep hole in the transnmission pump (piggy backed off hydraulic) seeps hydraulic oil. both pumps are brand new, not even 10 hours on either pump. all seals have been checked. Any help would be appreciated!
hi, could you give some background on the previous repairs please ,also could you post your full number or s/n range. are there any active or logged faults? did it happen suddenly or after a repair or service regards Mark
daviesoo2 u should check the streering and brake system which is in the differential drive. if the oil of the transmission is dirty that means u have horn discs and plates. you can take a pressure to see which side u have the problem.
Background: brakes are spring applied pressure released. When you Unlock the handle on the steering tiller pressure is allowed to get to brake Pistons to release them. When you push on the brake pedal it releases the pressure allowing the springs to apply brakes. Both brakes are applied and released at the same time unlike other dozers with clutches and brakes where brakes can operate independently. first thing to checksis linkages on lock out and brake pedal. If this is a newer problem that has occurred after some of your aforementioned repairs someone probably installed these linkages wrong or even adjusted them to make them fit? A heavy dude could have stepped on them after removing the floor plate and bent or broke them! If this all looks good you now need to do pressure checks. Does it pull one direction while trying to drive straight with blade and rippers off the ground? If no then your brakes and seals are probably ok and the problem is a control pressure issue. The brake control valve is an aluminum housing with steel spools, it takes very little debris to gal these to the point the spools won't move correctly....TIO
I just recently went through a similar problem in a D-8T. It was explained to me by the dealer mechanic that the trans pump supplies the brakes as well, and if the brake seals leak, it will rob pressure from the transmission to keep the brakes released. This can cause slippage in the transmission, which was the reason for my trans failure. They would not warranty the transmission unless I agreed to reseal the finals as well, to prevent this issue. I would check brake pressures, and look into a reseal of the finals.
Davies, Did it get fixed?
Not been back here since 5/5 when he posted the original question so I would assume yes.