TM9-2330-207-14
Section IX. BRAKES
Page
Page
Slack Adjusters
Overview
Air Hose Coupling
Description of Brakes
Air Lines and Fittings
Maintenance and Adjustments
Air Chamber (Model M127)
internal Brakes
Air Chamber (Model M127)
Hydraulic Master Cylinder and Air Chamber
Emergency Relay Valve
(All Models except M127)
Air Filters
Hydraulic Lines and Fittings
Air Reservoir
4-37. OVERVIEW
This section covers organizational maintenance of components of both the air and the air-over-hydraulic
brake systems. Included in this section is information on:
Description
.
Adjustment
.
.
Tests
.
Removal
Repair
.
.
Installation
a. General. When the brake system of the semitrailer is properly connected to the service brake system
of the towing vehicle, the service brake pedal on the towing vehicle controls the brakes on both vehicles. All
units needed to produce and maintain a constant supply of compressed air are located on the towing vehicle
and must operate effectively to insure proper performance of the semitraiIer brakes.
b. Type of Brakes.
(1) M127. The brakes are the air-actuated type (fig. 4-34). Air pressure is used to operate the mech-
anical internal brakes at the semitrailer wheels. The brakes are applied in proportion to the foot
pressure applied to the brake pedal of the towing vehicle.
(2) All Models except M127. The brakes are the air-over-hydraulic type (fig. 4-35). Two hydraulic
master cylinders, with air chambers operate the hydraulically actuated internal brakes.
c. Brake system Units.
(1) M127. The brake system consists of the internal brakes, slack adjusters, service air line, emergency
air line, air chambers, emergency relay valve, air reservoir, and connections.
(2) All Models except M127. The brake system consists of the internal brakes, hydraulic master
cylinder, hydraulic lines, service air line, emergency air line, air chambers, emergency relay valve,
air reservoir, and connections.