Rockwell triaxle diff lock and lockers

Im betting there is an interlock that unlocks the middle axle when one of the other diffs are locked so that it can pivot on the center axle and allow you to steer. Otherwise it will go straight.

 

Strange. You should be able to lock all 6 wheel ends together. Are you getting air to the center axle actuator? Wonder if the shift fork, linkage or dog clutch are damaged?

 

There's definitely something funky. Most trucks I've worked on were tridrives and if all 3 diff locks and both power dividers are getting air simultaneously, all 6 wheel ends should be locked solid. You should have to jack up all 3 axles in order to rotate 1 wheel with it all locked up.

 

That bolt in front of the actuator goes in the hole where the air line connects to the actuator cylinder to push in the piston to allow the diff to be removed from the housing.
It is stored in its present location.

 

The sensors that operate the lights can be a problem they live in a harsh environment
lots of spray and flying debris.
Try lifting the tires on all three axles on one side only then release the brakes lock them one
at a time and see if you can turn the tires on the lifted side. If the tires will turn then see if the lock cylinder is getting air.
Are the switches that engage the lockers air valves or electrical switches? If they are electrical
then the lockers are probably controlled by a body module.