Prime Mover Magazine


Clean Brake: Scania

For Scania, driving down operating costs for Australian transport and logistics companies, remains a matter of precedence and the Scania Retarder is considered one of the secrets to the ongoing success of the pioneering Swedish truck manufacturer.

The Retarder is a hydraulic auxiliary braking system that has been fitted as standard to practically every Scania truck equipped with Opticruise automated gearchanging since the early 1990s.

It provides a significant amount of retardation, which not only lengthens the working life of brake pads but ensures that the service brakes remain cold and in peak conditions for use in an emergency, even when descending the steepest of hills. By not regularly overheating the discs on downhill runs, rotor life is also increased.

In fact, the Scania Retarder is so powerful it outperforms a traditional exhaust brake by delivering up to three times the power. A further benefit is that with such fade-free and reliable braking performance available, trucks are able to descend steep hills at higher speeds, where safe, to enhance journey times.

The latest generation of Scania retarders puts a maximum braking torque of up to 4100 Nm into the driver’s right hand, via the five-stage stepped-travel lever attached to the steering column cowling.

By simply pulling the lever back towards the driver through the five steps offering increasing retardation, the truck is able to be decelerated smoothly and safely or when integrated with the Downhill Speed Control, held at a constant safe speed all the way to the flat.

“The Scania Retarder is easy to use, extremely efficient and a valuable safety feature,” says Benjamin Nye, Scania Australia’s Product Manager, Trucks. “Once our customers have been introduced to the correct way to use the system and benefit from it, they are quickly converted. The Retarder is the driver’s best friend in everyday driving as well as in emergency conditions. It can be activated either by use of the lever on the steering column, or when in ‘auto’ mode, by a light touch of the brake pedal. It couldn’t be simpler.”

By being integrated with the transmission, it means that the system can trigger downshifts to make the most of the available engine braking as possible.

“The Scania Retarder is one of the most frequently used and appreciated technical features on a Scania truck. Once drivers have become familiar with the Retarder, they will not switch back to a truck that does not have one,” Ben explains. “It very quickly becomes an indispensable tool assisting them to drive safely and efficiently whether it is in stop-start traffic at generally low speeds or driving interstate at freeway speeds.”

In service, the Retarder preserves brake linings like no other system. Customers regularly marvel at the lack of wear of their brake pads, with 800,000 km common and one customer, NAD Transport, based in Melbourne, achieving more than 1.25 million km on a set of brake linings fitted to an R 560 V8 prime mover, and they are still going strong.

“The Scania Retarder is capable of dealing with 90 percent of all braking on long haul work, so it substantially increases the service life of the wheel brakes,” says Tomas Selling, a control system development engineer at Scania.

The saved costs of downtime, materials and work for changing the linings and brake pads on a tractor and semi-trailer mean that a Scania Retarder is a very cost-effective feature for companies focused on their total operating economy.

“The Scania Retarder distributes the braking power in a vehicle to as many different systems as possible, keeping the brake pads as cool as possible. In an emergency, the pads can then deliver as much braking as possible,” Tomas says.

The Scania Retarder is integrated into the output end of the truck’s gearbox and uses high-pressure oil as a braking medium. Via a gear transmission, the Retarder acts on the output shaft of the gearbox and thus directly on the propeller shaft.

Once the Retarder is applied, it generates a braking force on the propeller shaft of up to 500 kW, depending on the propeller shaft speed and the applied braking torque. Depending on the position of the automatic exhaust brake switch, the automatic exhaust brake is also activated with increasing brake power to achieve the highest possible retardation.

“Reducing fuel consumption” says Örjan Åslund, who is responsible for Product Affairs at Scania Trucks in Sweden, “is Scania’s main priority,”

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