Instruksjonsbok Volvo A25D - A30D

Retardation Systems

Retarder and Exhaust Retarder Activation Easy to use Exhaust retarder and retarder should be used to control speed in all operating situations (except emergencies when service brakes should be used) to minimize service brake wear and for smooth and safe hauling. The retarder and exhaust retarder can be activated in dif- ferent ways: with the separate retarder pedal (C) or by incorporating automatic retarder action in the service brake function or/and exhaust retarder in the accelerator pedal. Retarder pedal The retardation force is modulated to make it possible for the operator to optimize use of retardation force based on different operating conditions. At the beginning of pedal application, the exhaust retarder is activated to give a quick braking response and then the variable retarder function is added together with the exhaust retarder until maximum retardation force is reached when the pedal bottoms. This is a very comfortable and effective operating mode that gives higher productivity and less service brake wear. Retarder in service brake pedal A greater braking force is applied at the beginning of the brake pedal application if the switch (2) incorporating retarder activation in the service brake pedal is on. The retarder remains activated for as long as the service brake pedal is applied. An indicator light (3) on the instrument panel is acti- vated when the service brakes are applied. This makes it possible for the operator to minimize the use of the ser- vice brakes when switch (2) is activated and retarder action is incorporated in the service brake pedal. Retardation capacity Exhaust retarder and the hydraulic transmission retarder with continuous cooling give the A25D and A30D excel- lent retardation performance without using the service brakes. The graph on page 48 shows the highest possi- ble continuous retardation without using the service brakes or overheating the cooling system. Exhaust retarder in accelerator pedal Exhaust retarder action is applied when the accelerator is completely released if the switch for exhaust retarder (1) is activated.

C

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3

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