Challenger Terra Gator 3244 Chassis. Manual - part 123

627333-A  

7-13

Schematic

PRIORITY VALVE

The priority valve receives hydraulic pressure from the

hydraulic pump mounted on the transmission and

controls the flow to the steering system and the

auxiliary hydraulic systems. The steering system

maintains priority over the braking system. As the

steering wheel is turned, pressure to the steering unit

drops, which drops the pressure in the line and shifts

the priority valve to supply more oil to the steering unit. 

Priority valve has four ports and a construction hole.

P-port (pressure) is incoming from hydraulic pump.

LS-port (load sense) goes to steering unit. CF-port

(control flow) goes to steering valve. EF-port (excess

flow) goes to auxiliary hydraulic system and power

washer (if equipped). PP-port is used in valve

construction and is plugged.

FIG. 3: Priority Valve (1) right side underneath the cab.

FIG. 3

q000111s

1

q000109s

1

Schematic

7-14

627333-A  

EMERGENCY STEERING (OPTION)

FIG. 4: The electric motor (1) of the emergency

steering will activated when a sensor of the priority

valve (2) detect a fall of the oil pressure. The oil

pressure has to fall below the 10 bar. When the

emergency steering is activated, a warning light (3) on

the armrest will light up, and there will be an acoustic

sound inside the cab.

IMPORTANT: Never use the emergency steering

longer as strictly necessary. Approximately 40

seconds. 

FIG. 4

Q000108S

1

q000109s

2

q000110s

3

627333-A  

8-i

Contents

Challenger

®

Terra Gator 3244

Chassis

SERVICE MANUAL

627333-A

08 - Air System

Contents

AIR COMPRESSOR

Air Compressor Removal ...........................................................................................................................  8-1

Air Compressor Installation ........................................................................................................................  8-3

AIR TANK AND PRESSURE CONTROL CHECK VALVE

Theory of Operation ................................................................................................................................... 8-5

Air Tanks .................................................................................................................................................... 8-6

Air Tank Removal ................................................................................................................................ 8-6

Air Tank Installation ............................................................................................................................. 8-7

AIR DRYER

Description ................................................................................................................................................. 8-9

Air Dryer Removal  ..................................................................................................................................... 8-9

Air Dryer Installation  ................................................................................................................................ 8-10

Air Dryer Components  ............................................................................................................................. 8-11

Heater ................................................................................................................................................ 8-11

Turbo Cut-off Valve  ........................................................................................................................... 8-11

Desiccant Cartridge ........................................................................................................................... 8-12

Outlet Check Valve ............................................................................................................................ 8-12

Regeneration Valve ........................................................................................................................... 8-12

Purge Valve ....................................................................................................................................... 8-13

AIR GOVERNOR

Theory of Operation ................................................................................................................................. 8-15

Air Governor Removal  ............................................................................................................................. 8-15

Air Governor Installation  .......................................................................................................................... 8-16

CAB AIR SUSPENSION

Theory of Operation ................................................................................................................................. 8-17

Cab Air Suspension Removal .................................................................................................................. 8-18

Cab Air Suspension Installation ............................................................................................................... 8-19

PNEUMATIC SCHEMATIC

Pneumatic Schematic  .............................................................................................................................. 8-21

INDEX ......................................................................................................................................................... 8-23

627333-A  

8-1

Air Compressor

AIR COMPRESSOR

The chassis air system consists of an engine mounted,

direct driven air compressor, an air drier and two

storage tanks. The first tank is called a wet tank

because most condensation occurs in this tank as the

air cools from being compressed. The second tank is

called a dry tank since little condensation occurs in that

tank.

From the dry tank, air is sent out to the R-12 relay valve

for service brakes and to the R-14 relay valve for the

parking brakes. Air is sent from the dry tank to the

parking brake and service brake valves in the cab to

serve as “signal” air to control the relay valves.

Air is supplied to the back of the cab and goes to

auxiliary functions in the cab, like the air horn and to the

system requirements such as foam marker systems,

product control valves, boom shut-off, etc. Air to these

auxiliary functions passes through a pressure

protection valve as a safety feature. In the event of a

major air system malfunction (pressure drops to under

4,82 bar (70 psi)), the valve closes off to these auxiliary

functions to reserve remaining air pressure for braking.

AIR COMPRESSOR REMOVAL

m

WARNING: Remove all air pressure from

tanks before disconnecting any air

hoses. Pressurized air can cause serious

personal injury.

m

WARNING: Never open coolant system

when fluid is hot. Hot fluid can cause

serious personal injury.

NOTE: Keep all parts clean from contaminants.

Contaminants may cause rapid wear and

shortened component life.

NOTE: Contain all fluids. Be prepared to collect fluid

with suitable container before opening and

disassembling any component containing

fluids.

Drain coolant from coolant system.

FIG. 1: Disconnect high temperature braided hose

going from compressor to air dryer. Mark and

disconnect coolant lines going to front (1), top (2) and

rear (3) of compressor. Disconnect oil line (4).

FIG. 1

1

4

2

3

N072412002