When the auxiliary brake button is pressed, the engine does not stop, the dampers in the exhaust pipes do not turn, the trailer does not brake
There may be several reasons: air is not supplied to the auxiliary brake valve, the pipeline leading from the valve to the pneumatic cylinders is pinched or clogged, the valve itself is faulty.
A malfunction is determined by sequential shutdown of pipelines with subsequent restoration of operability or replacement of faulty elements.
If the fuel does not turn off when the auxiliary brake is applied, and the dampers in the exhaust pipes operate, check that compressed air is supplied to the pneumatic cylinder on the fuel pump.
A malfunction is also possible in the mounting of the pneumatic cylinder. Check if the engine stop lever is manually turned to the stop bolt.
The damper mechanisms and pneumatic cylinders that control them operate in the most unfavorable conditions. Therefore, they often fail, most often the dampers jam.
If this happens with both dampers, then the engine does not start, if with one, then the engine starts, but smokes and loses power. On some car models, one damper is installed.
There are also problems in the pneumatic cylinders of the damper drive, the most common of them is the loss of tightness of the piston cuff. This is due to thermal stress and abrasive wear (dirt gets into the cavity of the pneumatic cylinder).
The trailer solenoid switch is located in the left side member of the frame next to the clutch housing.
If the sensor or electrical wiring fails, when the auxiliary brake is turned on, the trailer does not slow down, skidding and folding of the road train are possible.
If the sensor contacts spontaneously close when they are dirty, the trailer will slow down, the brake drums will heat up, and the trailer wheels may block.
If after releasing the button of the auxiliary brake valve, the air from the pneumatic cylinders and from the sensor is not discharged, i.e. the auxiliary brake does not turn off, then check if the atmospheric outlet in the valve is free.
In winter, it often freezes over, a mud-ice plug forms in the atmospheric outlet, which does not allow air to escape from the circuit.
And if in this case the inlet valve in the auxiliary brake valve loses its tightness, the brake will turn on spontaneously, the engine will stall for no apparent reason.
If there is no air in the auxiliary brake circuit, the engine starts, but after a few minutes it spontaneously stops due to the air supply through a faulty valve to the fuel shut-off pneumatic cylinder.
In this case, the crane needs to be repaired.
If there is no spontaneous engine stop, and the engine does not start while driving after releasing the auxiliary brake valve button, it is necessary to clean the atmospheric outlet of the valve.