Exhaust brakes are a familiar option on heavy trucks, helping to reduce speeds without having to use the regular service brakes. Excessive use of the brakes on mountain roads, for example, can cause the brakes to overheat and fade. Exhaust brakes are especially beneficial when carrying heavy loads, on hilly terrain and when using the tractor in traffic. Exhaust brakes are used to reduce speed on long downhill sections, lessening the need to use the regular brakes and maintaining their stopping power for emergency situations. Exhaust brakes also slow down the tractor gently, increasing driver comfort and safety.
The exhaust brake works by closing the exhaust pipe by a flap valve between the turbo and silencer. The closing and opening action is done by a hydraulic cylinder using low-pressure hydraulics. When the exhaust is closed, the engine works as compressor, causing the braking effect. The injection pump is adjusted to the idling mode during braking. The exhaust brake can be used at speeds above 10 km/h. When applying the brake the best retardation can be achieved when the Powershift control is in Auto 1 mode. This changes gears for slower speeds and increases braking power as the gear ratio is increased.
The exhaust brake is operated by using either the main brake pedals together or by a separate brake pedal on the cab floor. The driver can choose the operating mode
by a switch located on the instrument panel next to the driver. If the driver selects to use the main brake pedals, the pedals must be connected to each other. The exhaust brake is activated by the same electronic impulse that activates the brake lights.
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