Workhorse Custom Chassis of Union City, Indianna acquired General Motor's P chassis division in 1999 and revolutionized the gas chassis market for Class A motorhomes when it introduced the W22 chassis two years ago. Now they have introduced a new air brake diesel chassis which will become the foundation for many new motorhomes to come.

Teaming up with partners Arvin-Meritor for the suspension, and Onan-Cummins for the power plants, Workhorse has produced a winner for the deluxe coach building industry. Of the seven million RVs on the road today, 43% of new coaches sold last year were based on a diesel chassis. The new R-series diesel platform will be powered by a Cummins rear diesel engine with optional power ranges of 300, 350, and 400 hp. Engine compression braking is standard on the ISL 400 horsepower unit, and exhaust brakes are standard on the ISC 300 and 350 hp versions.

This new chassis is available with either a raised rail or straight rail configuration. The raised rail offers much better storage facilities under the floor. The chassis has a 9-inch high rail that is 2 3/4-inches in width, made from 1/4-inch thick 50,000 psi steel for strength. The cross-members for the chassis are moveable to allow coach builders more options in locating fresh water and waste tanks. Workhorse makes it easier for a manufacturer to build new or existing body layouts on this chassis. To lower the centre of gravity of the coach, the engine has been mounted 1 1/2-inches lower in the chassis with no pipes over the top, giving manufacturers more room for rear bedroom designs. It has also been moved eight-inches farther forward than competing manufacturers, this reduces the amount of overhang at the rear of the coach and opening up the closet space in the rear. Two levelling sensors in the rear and one in the front focus 2/3 of the weight on the rear and prevents tires from being overloaded.

Workhorse uses fixed discharge lines and dual unpartitioned air tanks so that you can automatically expel moisture from the tanks with two heated moisture ejectors. No need to purge the air tanks each morning to get rid of the normal moisture that develops when you compress air. A raceway system is used in the chassis to route wires and color coded air lines, brakes and hydraulic lines for the levelling system from the rear of the chassis to the front, protecting them from highway moisture, cuts, and dirt. This taller raceway allows manufacturers more room to route their own lines throughout the chassis.

Allison transmissions set the base mark in the RV industry with the 3000 series 6-speed automatic. Optional traction control is tied into the antilock braking system to prevent wheel slip. If a wheel is slipping, the system will automatically apply just enough braking to bring it in line with the other drive wheel. The transmission has a separate water to oil transmission cooler and all level checks, fill tubes and the air filter restriction indicator are in the back for easier access.
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(Read full article on page 24 of Vol.31 No.7)