Freewheeling braking

A new design for transmission retarders is to be introduced by Scania into Australia next year. The innovation includes a new function, the ability of the retarder to completely disengage from the drive line when not required, consequently reducing drag with the aim of improving fuel consumption.


SCANIA Retarder adds new freewheeling feature in 2015 copy


By disengaging the connection to the two vaned wheels which provide braking power when rotating in oil, the reduced drag on the motion of the truck is reckoned to save around 0.5 per cent on fuel use.


When retardation is required, the free-wheeling automatically stops. The reconnection between driveline and retarder is made smoothly using similar synchro technology to that used in the Scania gearbox.


As well as being more efficient the new retarder design also supplies more braking power to the driver, 4100 Nm (3024 ft lb) instead of the previous 3500 Nm (2581 ft lb). Gear ratios have also been adapted to improve retardation at lower rpm levels.


“Reducing fuel consumption is Scania’s main priority,” says Örjan Åslund, responsible for Product Affairs at Scania Trucks. “The freewheeling retarder produces further savings that also contributes to an elevated driving experience. 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. 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 free-wheeling to full braking power in no time.”




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