Combination Valve. Performs 3 distinct functions:
(a) Limits pressure to front disc brakes until a predetermined front input
pressure is reached, which allows for the overcoming of the rear shoe
retractor spring pressure.
(b) Proportions outlet pressure to rear brakes after a predetermined rear input
pressure has been reached.
(c) A bypass feature assuring full system pressure to rear brakes in the event
of front brake malfunction.
Height Sensing, Brake Proportioning Valve (All Except M1009). Provides
optimum brake balance and efficiency by distributing braking force to front and
rear wheels as determined by payload.
a. Consists of the following major assemblies:
(1) Steering Wheel, Column, Intermediate Shaft, and Coupling. Mechanically
activated by operator.
(2) Power Steering Pump. Runs continuously, supplying hydraulic power to power
(3) Power Stearing Gear. Receives hydraulic power from power steering pump and
mechanical force from driver through steering wheel, column, intermediate
shaft, and coupling. Power steering gear can operate mechanically if hydraulic
system failure occurs.
(4) Steering Linkage. Mechanical linkage between power steering gear and
axle-mounted steering components.
(5) Axle-mounted Steering Components. Receive mechanical force from steering
linkage to actually turn wheels.
b. The following illustration shows, in simplified form, how the steering system works.