Retarders hold back Darts
Page 18
If you've noticed an error in this article please click here to report it so we can fix it.
• Dennis Specialist Vehicles is fitting Telma electro-magnetic retarders as standard on its 9.8m Dart, and as an option on its shorter midibuses.
The Focal 90, which Telma claims reduces brake, tyre and axle component wear, is being fitted on the 9.8m version because it has a larger seating capacity and tends to be used on longer distances at higher speeds than the 8.5m and 9m Darts.
Telma says its retarder pays for itself in the first third of a bus's life and enhances safety by reducing service brake wear.
The retarder has been fitted to 5,000 small buses in the UK over the past four years. It is complimentary to the vehicle's foundation braking system, is installed directly on to the vehicle's Eaton 08-18 driving axle and can provide up to 80% of the bus's braking requirement.
Dennis held more than 18 months of trials, and used operational results from operators including Go-Ahead Northern and Stagecoach. Further testing was carried out in Hong Kong, where hills and large passenger loads make conditions arduous.
Dennis expects about 30% of Dart production to have the retarder, which is said to have a braking torque of 680Nm, offering smooth deceleration even in neutral.
"In addition to the economic benefits that the Telma can bring to Dart operators, it also provides an additional endurance braking effect, giving extra safety and comfort to both driver and passengers," says DSV bus sales director, Roger Heard.
Other manufacturers which have taken Telma retarders are Mercedes-Benz, Renault, Iveco Ford and Optare: the Renault Dodge S75 is equipped as stan dard, as are most of Optare's 25 and 33-seat MetroRiders, Telma which has sold more than 500,000 retarders worldwide for light commercial and truck operations as well as PCV, says the Dart installation was "particularly challenging", because of limited space to fit the retarder.
But adds "we were able not only to engineer the project to Dennis' requirements but also co-ordinate the final design with Eaton, to ensure that the axle and retarder unit functions as a totally integrated unit."