Trucks at Work

Braking and fuel economy

European OEM Scania Trucks is adding some new wrinkles to a component long used not only to augment truck stopping power but boost fuel economy as well: hydraulic retarder technology.

Örjan Åslund, head of product affairs at Scania, noted recently that many trucks have some form of auxiliary brakes and that for almost 20 Scania has offered a hydraulic retarder to help reduce the use – and thus maintenance cost related to – the primary braking system.

Yet the new twist to Scania’s R4100D hydraulic retarder is that it automatically disengages and enters a “freewheeling” mode when not active – thus reducing aerodynamic drag losses as both of the “vaned” wheels within the retarder that provide braking power when rotating in oil are disengaged.

Actual fuel savings will vary depending on road conditions, but an average of a half percent reduction is taken as the rule of thumb, Åslund pointed out.

“Reducing fuel consumption is Scania’s main priority,” he added. “The freewheeling retarder produces further savings that also contributes to an elevated driving experience.”

[Of course such “freewheeling” technology is only one piece of the overall truck fuel economy puzzle.]

Scania also pointed out that drivers don’t have to do anything to gain fuel economy via its hydraulic retarder improvements. When braking power is needed, the “freewheeling” stops and provides increased braking effect at lower engine rpm with the help of higher gear ratios.

“The activation of the retarder itself is either initiated by the driver – via a lever on the steering column or with a light touch of the brake pedal – or when the cruise control requests braking,” noted Åslund. “As soon as the retarder is not in use, it freewheels again on its own. But it remains ready to smoothly and firmly change from free­wheeling to full braking power in no time.”

Scania said that deliveries of its newly improved R4100D retarder begin in the first quarter of 2015 and it will interesting to see how the European trucking community responds to this technology option.

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