Designated 'LDTA' and available to order in conjunction with the RB662/R660 axle family, the new option can save up to 3% on fuel with the tag-axle disengaged and lifted, depending on operation.
As such, it is said to offer a more sustainable and economic solution for 6x4 and 8x4 applications where a proportion of time is spent unladen or with light loads. When raised, the bogie reduces the vehicle’s turning radius, with lifting taking less than 25 seconds. With normal chassis height and tyres, tag-axle ground clearance approaches 70 mm.
“This is a highly desirable function for customers in a variety of applications, such as construction and timber haulage," says Vincente Connolly, UK sales director for Scania (Great Britain) Limited. "Our engineers have determined that substantial fuel savings are achievable, especially for vehicles which make multiple drops every day and run empty on the return leg. In addition to improved fuel economy, operators also benefit from less tyre wear and increased manoeuvrability.”
The liftable and dis-engageable tandem bogie (LDTA) requires air suspension and increases the truck's kerb weight by 60 kilogrammes. Most of the fuel savings can be attributed to the reduced friction inside the second (disconnected) axle gearing, as only approximately 10% of the savings are derived from reduced rolling resistance. Three bogie design weights – 19, 21 and 26 tonnes – are available and load limits with the second axle lifted are 9.5, 10.5 and 13 tonnes respectively.
The LDTA option can presently not be combined with hub reduction axles or tridem configurations.
In operation, the driver raises the axle by simply turning a knob. A pop-up warning appears in the instrument cluster if the truck identifies an overload situation, in which case the axle will not lift. The lifting can be called for at any speed and the drive-disengagement to the tag axle is performed via a dog-clutch connection. When the tag axle is lowered, drive to the axle is automatically re-engaged. It is not possible to operate the vehicle with the tag lowered and drive disengaged.
"The cost of the unit will rapidly be compensated for by highly positive contribution to our customers’ total operating economy – we expect this option to be included in many truck specifications going forward," adds Vincente Connolly.