793c py ajustes aire frenos

Pruebas y Ajustes

793C and 793C XQ Off-Highway Truck Air System and Brakes

Braking System Troubleshooting SMCS - 4250-035

Performance Checks For Air System And Brakes

If the Performance Checks indicate that pressure air is not available at the supply passages of the control valves, loosen the connection at the supply passage and use soapy water in order to check for pressure air.

If the Performance Checks give an indication of leakage through the control valves, disconnect the delivery hose at the end that is opposite the delivery passage. Put the end of the hose in a pan of water in order to check for leakage.

Problem: The service brakes do not engage correctly.

Cerrar SIS

Pantalla anterior

Producto: TRUCK Modelo: 793C TRUCK ATY Configuracin: 793C Off-Highway Truck ATY00001-UP (MACHINE) POWERED BY 3516 Engine

Nmero de medio -SENR1592-08 Fecha de publicacin -01/08/2008 Fecha de actualizacin -06/08/2008

i01032929

NOTICECare must be taken to ensure that fluids are contained during performance of inspection, maintenance, testing, adjusting and repair of the machine. Be prepared to collect the fluid with suitable containers before opening any compartment or disassembling any component containing fluids.

Refer to Special Publication, NENG2500, "Caterpillar Tools and Shop Products Guide", for tools and supplies suitable to collect and contain fluids in Caterpillar machines.

Dispose of all fluids according to local regulations and mandates.

Do not check for leaks with your hands. Pin hole (very small) leaks can result in a high velocity oil stream that will be invisible close to the hose. This oil can penetrate the skin and cause personal injury. Use cardboard or paper to locate pin hole leaks.

Pgina 1 de 5793C Off-Highway Truck ATY00001-UP (MACHINE) POWERED BY 3516 Engine(SEBP3022 ...

01/22/2009https://sis.cat.com/sisweb/sisweb/techdoc/techdoc_print_page.jsp?returnurl=/sisweb/sisweb/product...

Probable Cause

There is no pressure air at the inlet passage of the service brake air control valve.

Wear or damage to the service brake air control valve restricts the release of pressure air at the outlet passage.

There is wear or damage to the double check valves.

Wear or damage to the brake air relay valve restricts pressure air at the delivery passages to the brake master cylinders.

There is wear or damage to the brake master cylinders.

There is wear or damage to the slack adjusters.

There is air in the oil for the brake hydraulic system.

There is wear or damage to the brakes.

Problem: The service brakes do not release correctly.

Probable Cause

Mud or dirt under the pedal does not allow the service brake air control valve to release fully.

Wear or damage to the service brake air control valve restricts the release of pressure air from the lines to the brake air relay valve.

Wear or damage to the brake air relay valve restricts the release of pressure air from the brake master cylinders.


Wear or damage to the parking brake air control valve prevents the release of pressure air to the parking and secondary brake valve.

Wear or damage to the secondary brake air control valve releases pressure air to the secondary brake inverter valve.

Wear or damage to the secondary brake inverter valve prevents the release of pressure air to the parking and secondary brake valve.

There is wear or damage to the one-way check valves and/or to the double check valves.




Problem: The secondary brakes do not engage correctly.

Probable Cause



Wear or damage to the secondary brake air control valve prevents the release of pressure air to the parking and secondary brake valve and the secondary brake inverter valve.

Wear or damage to the secondary brake inverter valve allows the release of pressure air to the parking and secondary brake valve.

There is wear or damage to the parking and secondary brake valve.


There are broken brake springs.

Problem: The secondary brakes do not release correctly.

Probable Cause

Mud or dirt under the pedal does not allow the secondary brake air control valve to release fully.

There is no pressure air at the supply passage of the secondary brake inverter valve.

There is no oil pressure to the parking and secondary brakes.

There is a low setting of the relief valve in the parking and secondary brake valve.

A brake piston seal leakage exists.

Wear or damage to the secondary brake inverter valve restricts the release of pressure air to the parking and secondary brake valve.


Wear or damage to the parking brake air control valve restricts the release of pressure air to the parking and secondary brake valve.

Problem: The parking brakes do not engage correctly.

Probable Cause

Wear or damage to the parking brake air control valve allows the release of pressure air to the parking and secondary brake valve.



There are broken brake springs.

Problem: The parking brakes do not release correctly.

Probable Cause

There is no pressure air at the supply passage of the parking brake air control valve.

There is no oil pressure to the parking and secondary brake valve.




There is a low setting of the relief valve in the parking and secondary brake valve.

A brake piston seal leakage exists.


Problem: The retarder does not engage correctly.

Probable Cause

There is no pressure air at the supply passage of the retarder air control valve.

Wear or damage to the retarder air control valve restricts the release of pressure air at the outlet passage.

Wear or damage to the secondary brake inverter valve prevents the release of pressure air to the parking and secondary brake valve.

There is wear or damage to the double check valves.

Wear or damage to the brake air relay valve restricts pressure air at the delivery passages to the brake master cylinders.





Problem: The retarder does not release correctly.

Probable Cause

Wear or damage to the retarder air control valve restricts the release of pressure air from the line to the relay valve.

Wear or damage to the brake air relay valve restricts the release of pressure air from the brake master cylinders.



Wear or damage to the secondary brake air control valve releases pressure air to the secondary brake inverter valve.

There is wear or damage to the one-way check valves and/or the double check valve.




793c py ajustes aire frenos

Documents