AIR CIRCUIT FOR THE WHEEL BRAKES

E M E R G E N C Y A N D P A R K I N G B R A KE

BRAKE CONTROL VALVES - TM-5-3805-258-24-1_274

TM-5-3805-258-24-1 Loader Scoop Type DED 4x4 Articulated Frame Steer 2 1/2 Cubic Yard Bucket (CCE) Airborne/Airmobile Manual
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TM 5-3805-258-24-1 A I R S Y S T E M A N D B R A K E S S Y S T E M S O P E R A T I ON AIR CIRCUIT FOR THE WHEEL BRAKES AIR CIRCUIT FOR WHEEL BRAKES 1. Line to EMS warning signals. 2. Air pressure switch for wheel brakes. 3. Line from air reservoir. 4. Air horns. 5. Atr horn valve (foot operated). 6. Line to transmission neutralizer valve. 7, Left brake pedal. 8. Brake control valve for left pedal. 9. Orifice check valve. 10. Double check valve. 11. Air pressure switch for stop lights. 12. Right pedal. 13. Brake control valve for right pedal. 14. Brake air pressure indicator. 15. Air/hydraulic cylin- ders (two). 16. Brake fluid pressure (overstroke) switches. 17. Brake fluid reservoirs (two). 18. Brake fluid pressure indicator. The air circuit for the wheel brakes sends air under pressure from the air reservoir to operate the air/hy- draulic cylinders and the air horns. Switch (2) activates the warning system in the operator’s station when air pressure in the system is too low. Horn valve (5) activates air horn (4). When left brake control valve (8) is activated, the wheel brakes engage and the transmission neutralizer valve is activated. The transmission neutralizer valve stops oil pressure to the directional clutch circuit, which disengages the directional clutch. Since a speed and direction clutch must both be engaged before pow- er goes through the transmission, power does not go through the transmission when the left brake pedal is pushed. The surface area of the neutralizer valve is smaller than the surface area of the air cylinder piston. This difference in area causes the transmission to dis- engage before the wheel brakes are engaged. When control valve (8) is released, orifice check valve (9) causes a restriction to the flow of air from the air cylinders to brake control valve (8). This permits the transmission to engage before the brakes are released. Air pressure from the orifice check valve goes to double check valve (10). Valve (10) lets air go to the air cylinders and will not let air go to control valve (13). When control valve (13) is activated, valve (10) lets air go to the air cylinders and will not let air go to valve (9). Right brake control valve (13) activates the wheel brakes only. When either control valve (8) or (13) is activated, stop light switch (11) activates the stop lights at the rear of the machine. Air/hydraulic cylinders (15) have two cylinders each, one for air (air cylinder) and one for brake fluid (master cylinder). Movement of the air cyl- inder is caused by air pressure. This movement also causes the master cylinder to move and the wheel brakes are activated. The master cylinder is part of the hydraulic circuit for the wheel brakes. AIR PRESSURE SWITCH FOR WHEEL BRAKES L O C A T I O N O F T H E A I R P R E S S U R E S W I T CH 1. Switch. Air pressure switch (1) is activated when the air pressure in the brake system gets below approximately 450 kPa (65 psi). The switch causes the brake air pres- sure indicator and the master fault light in the dash to come ON, and also the fault alarm will sound. Switch (1) is under the floor of the operator’s station. It is fastened to the left brake control valve. 3-79

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