1918-1921

Although it was assigned an official test number, the Gray 18-36 had more than its share of problems during the 43 hours of running time required to complete various test sections. Initially, the manufacturers representative was dissatisfied with the tractor’s performance and was permitted to install new cylinders and pistons. During the limbering up run, the Bennett carburetor shipped with the tractor was replaced with a Stromberg M-3 style, and it was used for all test procedures. When the governor was set to give rated speed and 30 horsepower, it had no control of the engine when the load was removed, making it necessary to control engine speed by hand at this point. The Gray 18-36 was the first tractor tested entirely on gasoline fuel. During the maximum load test it developed 32.2 brake horsepower with a fuel consumption of 4.83 gph, for an equivalent of 6.67 horsepower hours per gallon. At the drawbar, a maximum pull of 3,390 pounds was noted with a ground speed of 2.12 mph. Thus, 19.15 maximum drawbar horsepower was recorded. Although the Gray Drum-Drive design was touted as being the ideal design, a slippage of 25.21% was recorded on the maximum drawbar load test. Regular equipment of the 6,500 pound Gray 18-36 included a four-cylinder vertical L-head engine with a 43A x 6% inch bore and stroke, and a rated speed of 950 rpm. Two forward speeds of 2lA and 23A mph were provided.

Engine: Waukesha

Cylinders: 4, vertical, 4 3/4 x 6 3/4 inches

Bore & Stroke: 4.75 x 6.75

RPM: 950

Fuel: Gasoline/Kerosene

Carburetor: Bennett

Drawbar HP: 19.15

Belt PTO HP: 32.2

Weight: 6500 lbs

Plows Pulled: Four, 14-inch bottoms

Valve Arrangement: L head

Ignition: K. W. or Bosch magneto with impulse starter

Lubrication: Circulating splash

Cooling System: Centrifugal pump

Pulley: Face, 7 inches; diameter, 11 inches; RPM 850

Turning Circle: 20 feet inside diameter

Traction: One driving drum, 54 inches in diameter, 54 inches wide

Speeds: Miles per hour, 2 and 2 1/2