Air System; Description; Theory Of Operation; Maintenance - Manitowoc Grove TMS800E Service And Maintenance Manual

UNDERCARRIAGE
Table 8-4Long- Stroke Clamp- Type Brake Chamber
Data
Outside
Type Diameter
(in)
16 6 3/8
20 6 25/32
24 7 7/32
1
7 7/32
24
30 8 3/32
1
For 3 in maximum stroke type 24 chambers.

AIR SYSTEM

Description

The air system (Figure 8-65) provides the air supply to
operate the service brakes, parking brakes, air suspension
system, inter-axle and cross axle differential locks, tire
inflation option, and other air accessories.
The air system is pressurized by an engine-mounted air
compressor and the pressurized air is stored in six air
r e s e r v o i r s u n d e r n e a t h t h e f r a m e . T h e a i r s y s t e m
components are operated by the air that is stored in these
reservoirs.
An air dryer is mounted on the carrier frame just behind the
front bumper. It is connected between the outlet of the
compressor and the front primary supply reservoir. Oil,
water, and contaminates are removed from the air during the
compression cycle and when the governor is unloading, the
contaminates are removed from the dryer.
The air system is split into a primary system and a secondary
system. The systems are isolated from each other so that in
the event of a failure of one system, air is retained in the
other system. By means of pressure protection valves, check
valves, and spring brake valves, a reserve of air pressure
remains to operate the spring brakes through normal use of
the brake pedal. Any unusual loss of pressure should be
investigated immediately and corrected, so as to restore the
full backup capability of the system.

Theory of Operation

Through reciprocating motion, the piston in the compressor
compresses air with every cycle. The compressed air passes
through the supply dump valve and air dryer and into the
supply reservoirs. A 10.30 bar (150 psi) safety valve is
installed on the air dryer module for protection from excess
pressure. The pressurized air flows to the primary service
reservoirs and secondary service reservoirs. Both primary
and secondary air reservoirs provide the supply for the dual
8-46
Brake Brake
Adjustment Adjustment
Limits (in) Limits (in)
2.0 50.8
2.0 50.8
2.0 50.8
2.5 63.5
2.5 63.5
Published 01-29-2014, Control # 496-00
TMS800E SERVICE MANUAL
brake and spring brake control valves. Air to the service
brakes on axles #3, and #4 is supplied by the primary
reservoirs. The secondary reservoirs provide the supply for
the service brakes on axle #1 and #2.
Pressure protection valves are set at 7.31 bar (106 psi) and
are basically check valves. They open at 0.69 to 1.03 bar (10
to 15 psi) above it's closing pressure. These valves protect a
circuit if a line is ruptured to ensure a priority supply to the
brakes. Pressure protection valve for tire inflation is set at
5.86 bar (85 psi).
The compressor which is mounted on and driven by the
engine, is regulated by an air governor which vents the
compressor when a pressure of 8.96 bar (130 psi) is sensed
in the air system. When pressure drops to 7.58 bar (110 psi),
the governor will allow the compressor to supply the air
system to maintain proper system pressure.
Braking
The top priority of the air system is to provide braking. Each
rear wheel has a spring brake chamber and a service brake
chamber. The spring brake is applied by a spring and
released by pressurized air. The spring brakes on all four
rear wheels are released by the parking brake push-pull
knob on the right hand console in the cab. Pushing in on the
parking brake causes air pressure to enter the spring brake
chamber on each wheel and compress the spring, releasing
the brakes. At least 2.80 bar (40 psi) is required to keep the
parking brake valve engaged. If supply pressure to the valve
drops below 2.80 bar (40 psi), the valve will release, applying
the brakes.
The service brakes are applied by air pressure. Depressing
the foot brake pedal on the cab floor causes pressurized air
to enter the service brake chamber on each wheel and apply
the brakes. In the event of a loss of supply pressure to the
service brakes, the spring brake valve will allow the operator
to release or bleed off the air pressure in the spring brake
chamber by depressing the foot brake pedal to apply the
brakes.

Maintenance

Depressurize both air systems completely before
disconnecting air lines or components.
CAUTION
Do not expose nylon tubing to flames or heat. Replace
tubing if outside covering shows white. Eliminate cause of
chafing or other damage.
CAUTION