Western Star Trucks used a new 4900 EX highway tractor at the Mid-America Trucking Show to introduce changes intended for the entire product line following the effective date of new engine emission regulations in January 2007. The show truck has an 82-inch Stratosphere sleeper and is powered by a Detroit Diesel Series 60 engine.
To meet the new emission standards, Western Star trucks will all include updated cooling and exhaust systems. In particular, the new engines will require more cooling capacity, which requires an increase in radiator size. To fit larger radiators under the traditional Western Star grille and hood, the company has added a drop front frame casting.
One result of the changes to the radiator mount is an improvement in the front suspension, which uses a 56-inch asymmetric spring that is shorter forward of the axle mounting than from the axle to the rear spring hanger. The shorter front spring length provides more roll stiffness and better handling in turns while the longer rear section maintains a soft ride characteristic. New steering gear provides improved road feel, better wheel cut and a shorter turning radius.
Changes to the exhaust system offer horizontal and vertical frame mountings with vertical tailpipes. The aftertreatment components required to meet emission standards are packaged for easy filter maintenance.
In addition to showing chassis changes to meet the 2007 emission standards, Western Star used a 4900 SA tractor to demonstrate its ability to build lightweight equipment. The show truck is built with currently available Western Star options including aluminum frame crossmembers, an Airliner front suspension, Mercedes-Benz MBE 4000 engine, aluminum disc wheels on all 10 positions, and a 48-inch high-roof sleeper weighing less than 15,000 lb.
To help fleets and operators cut fuel consumption and engine idle time, Western Star offers auxiliary power units from two vendors as factory-installed options. Idle Solutions and Rigmaster generator sets for heat and air-conditioning without idling the tractor engine are available on Western Star products with sleepers. These auxiliary power units also have 120 vac outlets for appliance use.