TM 5-3805-258-24-1A I R S Y S T E M A N D B R A K E SS Y S T E M S O P E R A T I O NAIR CIRCUIT FOR THE EMERGENCY AND PARKING BRAKEengaged. The transmission control lever must be heldin position, with a much higher force than normal, toA I R C I R C U I T F O R T H E E M E R G E N CYA N D P A R K I N G B R A KE1. Line from left brake control valve. 2. Line to transmis-s i o n n e u t r a l i z e r g r o u p . 3 . C o n t r o l v a l v e f o r e m e r g e n c yand parking brake. 4. Brake chamber for emergency andparking brake. 5. Quick release valve. 6. Emergency andparking brake. 7. Air pressure switch.The components of the air circuit for the emer-gency and parking brake are a control valve, anair pressure switch, a quick release valve, a brakechamber and a brake.Air pressure (from the left brake control valve)goes to control valve (2), which controls the opera-tion of brake chamber (6). When air pressure issent to the brake chamber, emergency and parkingbrake (7) is disengaged (released). When air pres-sure to the brake chamber is released, a spring inthe brake chamber engages (activates) the emer-gency and parking brake.Quick release valve (8) decreases the time it takesto engage emergency and parking brake (7). Theair is released at the quick release valve instead ofat control valve (2).Switch (4) activates the warning system in theoperator’s station when the parking brake controlknob is in the ON position.The emergency and parking brake is used to stopthe machine in an emergency when the machine is inoperation. It is also used as a parking brake when themachine is not in operation. Brake (7) is activatedautomatically when the air pressure goes below 275kPa (40 psi). When the parking brake is activated,the transmission is automatically shifted into neutral.The transmission neutralizer group prevents dam-age to the parking brake when the parking brake isactivated. The machine can be moved, in an emer-gency, a very short distance with the parking brake3-74move the machine in this condition.CAUTIONThe machine can only be moved a very shortdistance with the parking brake engaged or thebrake will be destroyed.CONTROL VALVE FOR THE EMERGENCYAND PARKING BRAKEControl valve (1) for the emergency and parkingbrake is fastened to the lower end of the steeringcolumn. The valve is activated either manually orautomatically. The valve is controlled manually by acable assembly that is connected to knob (2) on theupper end of the steering column. The valve is acti-vated automatically when pressure in the air systemis too low.L O C A T I O N O F T H E C O N T R O L V A L VE1. Control valve.When the machine is started, the air reservoir willbe discharged. The control valve will be in the ONposition (pulled out). Valve (9) will be against valvebody (4). The air can not go through outlet port (7)or exhaust port (11). The air pressure in the reservoirwill go up to the correct pressure for operation.
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