Ferroequinologist

I had the exact same symptoms on my XM818- I had rebuilt the MC, and a few months later the brakes were locking up on me on the way to Charlotte for the Memorial day display. It was a mis-adjusted brake pedal. The rod was too tight and not allowing the piston to return all the way in the MC to vent the pressure, so everytime you applied the brakes they got tighter and tighter.

Very easy to check, much less fix. If that isn't it, I would also check for a sticking MC.

Like Jwaller said, they will get hot in a hurry! Fix it where it sits.

__________________
And when at last he came upon the vehicle, he perceived the distress of the engine therein and forthwith struck it with a hammer and it was good. Thereupon the engine ignited and was filled with strength...

1985 M1008 w/'hyrail' gear, EX-Ft Stewart Railroad
1983 M915a1 'Rosie'
1980 MKT-75A
1979 M967 Refueling tanker
1970 M818 'Boxer' aka M818 of DEATH
1969 40ft USA Boxcar in OD green
1968 M101
1968 M270
1967 M543 'Becka tha Wrecka'
1953 60ft Troop Train Kitchen car
1953 60ft 8 room Domitory car
1929 Plymouth 10 ton gas loco, EX-USN

Wife's MVs-
1967 M109A3 'Bella'
1963 M37B1

kstate90

Yesterday we drove the 5ton into town to the mechanic. Brakes were unlocked and we drove the truck using the transmission to slow up for corners. They looked the truck over from front to back and ended up taking on of the rear duals apart to determine what was going on. After inspecting the brakes they determined that the brakes were out of adjustment and that the wheel cylinders were fully extending to apply the brakes. They adjusted all of the brakes and test drove the truck. It now has brakes that will stop the truck on a dime. The chief drove it back to the station and he said the brakes were very good on it. They could find nothing else wrong with and could not get the brakes to lock up after they adjusted them. I will update the thread if it acts up again. Thanks for the help.