Hello; The engine delivers 606 hp (447 kW) at 2100 rpm, with peak torque of 1950 lb ft (2644 Nm) at 1300 rpm. Other key components include an 18-speed Fuller RTLO-22918B transmission, with a first gear ratio of 14.4:1 through to 0.73:1 in overdrive. Rear axles are Axle Tech STRC-1297 hub reduction (they’re the old Rockwell off-road model) with a final ratio of 9.59:1. The front axle is Rockwell FL941 rated at 9.1 tonne and the 295 mm deep chassis which has a far thicker web and flange than its highway cousins and features a full length double frame. These power trailer units have a Smith built body on the power-trans chassis (they’re the company who built the power trailer unit) and they’re fitted with either Cummins ISX or Signature engines rated at 450 and 500 horsepower. They are coupled to an Allison automatic transmission and tri-drive SISU hub reduction axles. The control of these trailers is via both a cab mounted hand throttle and married to the accelerator pedal. The advantage of this for instance is when the unit is climbing a hill the trailer can be set at full throttle and when the driver changes gear in the Kenworth C510 there is minimal road speed loss as the trailer is still pushing the unit.