A truck with caged brakes is an unguided missile.
Trying to load it on a trailer can be very dangerous if you are not winching it on and then once it is up on the level deck you have to throw a chock under one or more wheels to stop it.......getting it off is just as tricky unless, as stated above, you uncage the brakes, charge the air system and roll it off that way.....you will only have enough air for one or two stops before the pressure drops off and the brakes engage.
Do not attempt this without someone who has done it before helping you. It is, at a minimun, a three man job.