The 4WD FM260 History
Over the last few years, RUF, Inc. has received numerous requests for a bigger chassis with more towing and weight capacity. Another common request was for an automatic transmission, and folks with experience off-highway shunned the FG's dual rear wheels and small 16" tires. We clearly needed a new platform, but nothing existed in the US market that was larger than the FG chassis with a cab-over-engine design and factory four wheel drive.
At RUF, Inc., we stress that our vehicles make maximum use of the space they occupy. Others have chosen to build US-market off-highway campers on light duty pickup trucks and medium duty conventional-cab trucks. However, we feel that a cab-forward design is superior as it allows the highest ratio of useable cab-to-axle to overall vehicle length. In simple terms, that means more living space in less total space. As side benefits, the cab-forward design yields superb visibility, a small turning radius, and extremely easy access to engine maintenance and repair.
Our new 4x4 chassis is based on the Mitsubishi Fuso FM260 truck, factory equipped with an Allison five speed automatic transmission, and 243 HP Fuso 6M60 common-rail intercooled turbo-diesel I-6 engine.
We set out from the beginning to design this 4WD conversion to incorporate single rear tires. However, at present, we DO NOT offer a chassis with single rear tires. To read more on the engineering and safety concerns behind this decision, please visit the following page:
For the rear axle, we selected a US-market heavy-walled unit with a GCWR of 60,000 lbs. and GAWR of 22,000 lbs. These axles are specially built for us by Dana Corporation, and offer a driver-controlled pneumatic differential lock as well as Bosch hydraulic disc brakes. Factory ABS is maintained.
With the final drive gearing we have selected, this chassis will run 73 mph on the engine governor, cruise at 65 mph right in the engine's sweet spot, and in first gear/low-range/idle, will crawl along at 170 ft/min. (Slower, of course, with the hydrostatic nature of the torque converter.)
The chassis' Gross Combined Weight Rating (GCWR) is 26,000 lbs, limited by the Allison's GCWR rating. With RUF, Inc's all-new well insulated lightweight composite structure sitting on the back, the 4WD FM will reserve 6,000 lbs to 8,000 lbs for towing capacity, depending on chassis load.