TECHNICAL PRINCIPLES OF OPERATION
SYSTEMS OF THE M871 AND M871A1 SEMITRAILERS
(1) ELECTRICAL SYSTEM. Connects to towing vehicle electrical system to
activate the 12 or 24 volt system. Includes 12 and 24 volt wiring for
operating taillights, clearance lights, and composite lights.
(2) BRAKE SYSTEM. Air brake system for service and emergency operation.
Includes air reservoirs, drain cocks, gladhands, emergency relay valve,
multi-function valve, spring brake chambers, lines and fittings.
(3) SERVICE BRAKE SYSTEM. Air pressure activates the air chambers, which push
the slack adjusters. The slack adjusters turn the camshafts causing the
brake shoes to expand against the brake drum.
(4) SUSPENSION SYSTEM. Includes springs, u-bolts, axles and trunnion tube for
ease of travel on improved and unimproved roads.