The Allis-Chalmers Model G Rear-Engine Tractor

Allis-Chalmers spurred imitators with production of its Model G rear-engine tractor, which was advertised as a “second tractor” on the farm.

| October 2018

  • rear engine tractors
    The Allis-Chalmers Model G tractor. Company sales literature promoted it as the “central unit of a simplified system of motorized farm tools.”
    Photo by Jim Gay
  • rear engine tractor
    The Midwest Power Plus hydraulic loader was produced for the Allis-Chalmers Model G tractor by Maquoketa Co., Maquoketa, Iowa. It was said to have a 1,500-pound lifting capacity.
    Photo courtesy Farm Collector archives
  • rear engine tractor
    The Russell 3-D Powered Tool Carrier, produced by Russell’s (Kirbymoorside) Ltd., U.K.
    Photo courtesy Farm Collector archives
  • rear engine tractor
    The Hefty Hi-G tractor, built by Holtan Axle and Transmission Co., Juneau, Wis., echoed the Allis-Chalmers Model G.
    Photo courtesy Farm Collector archives
  • rear engine tractor
    The Hefty Hi-G tractor, designed for high-clearance nursery work.
    Photo courtesy Farm Collector archives
  • rear engine tractor
    The GBT 2000, produced by GBT Industries, Madison, Wis.
    Photo courtesy Farm Collector archives
  • rear engine tractor
    Bird’s eye view of the Allis-Chalmers Model G.
    Photo courtesy Farm Collector archives

  • rear engine tractors
  • rear engine tractor
  • rear engine tractor
  • rear engine tractor
  • rear engine tractor
  • rear engine tractor
  • rear engine tractor

In 1948, Allis-Chalmers introduced an unusual tractor with the engine at the rear. The engine was positioned with the flywheel toward the front and attached directly to the integral transmission/rear axle. A tubular arched frame connected the rear portion of the tractor to the front steering axle with a wheelbase of 68-1/2 inches.

A 4-cylinder, 62-cubic-inch Continental water-cooled engine powered the little tractor. The radiator was located above the flywheel housing, just behind the 5-gallon fuel tank that in turn was just behind the operator's seat.

Although few if any Model G tractors were sold in that state, Nebraska Tractor Test No. 398 was conducted from July 16 to July 30, 1948, resulting in 10.33 hp on the belt and 9.04 hp at the drawbar while consuming 1.17 gallons of fuel per hour. For comparison, the Nebraska Tractor Test for the Farmall Cub in January 1956 recorded 10.39 hp on the belt and 9.87 hp at the drawbar.

The maximum drawbar pull for the Model G was 1,167 pounds with a 100-pound wheel weight added to each front wheel, giving a total weight of 1,749 pounds with a 185-pound operator. This resulted in 72 percent of the total weight on the rear axle, but was 82 percent without the front wheel weights, which provided excellent traction.



The 4-speed transmission had two first gears: a "special low" good for 1.6 mph and a regular first at 2.25 mph, both at 1,800rpm rated engine speed. Sales literature stated a ground speed of 0.75 mph could be obtained in "special low" by throttling back the engine speed, which would result in a low idle speed of about 845rpm. Maximum travel speed in third gear was 7 mph. Narrow 4.00-12 front tires and 6-30 rear tires let the tractor work in closely spaced rows.

Wide range of implements for the Model G

Allis-Chalmers produced a full range of implements for the G, all of which mounted under the arched frame behind the front axle. More than 30 are shown in one publication, ranging from a 12-inch 1-bottom plow and a two-way plow to a 4-foot field cultivator and a 5-foot sickle bar mower. Of course, there were many variations of planters and cultivators. Wheel treads were adjustable in 4-inch increments from 36 to 64 inches, which accommodated up to six narrow-row planters.

kevanos
10/3/2018 1:59:23 PM

There is also the Hines by Hines Manufacturing Co of Rocky Mt, NC (http://www.hinesequipment.net/), the fairly new Oggun by Oggun Tractors/Cleber LLC of Paint Rock, AL (http://cleberllc.com/ and http://thinkoggun.com/), and the new Tilmor which comes out next year from Venture Products (Ventrac) of Orrville, OH (https://www.tilmor.com/). Tuff-bilt continues as you mentioned (http://www.tuff-bilt.com/) Other former brands include Saukville of Newburg, WI, Thomas-bilt (which was renamed Tuff-bilt).