The two Globetrotter-cabbed tractors have replaced three eight-wheel rigid trucks, and were supplied by Volvo Truck and Bus Centre North & Scotland.
“Euro VI eight-wheelers are really heavy, so we needed to look at alternatives. It’s been a brave move putting artics into places we’ve never considered suitable before. However, the tag axle Volvo FM tractor units coupled to tandem axle, rear-steer Muldoon trailers have been a revelation,” confirms William Davidson, operations director.
The FMs are powered by D11K engines rated at 454bhp and drive through I-Shift transmissions. They have 8-tonne front axles, while the rear bogies have a 19-tonne capacity. Davidsons also specified Jost JSK 37 cast iron, fixed fifth wheels for the duo, which sport Alcoa Dura-Bright alloy wheels and aluminium air tanks to help payload figures.
“The geometry set up when the tag is raised, combined with the steer trailer, gives better traction off-road. Crucially, there is better weight distribution across the four axles with ground contact. The Muldoon positive steer system uses a linkage connected to a fifth wheel wedge and we’re not experiencing any increased tyre wear rates,” Davidson says.
He adds: “The Volvo FM tractor units are also very good on fuel and there will be more non-tipping trailers in our fleet, after a two-year trial of these pioneering vehicles.”