Specifications for the Howard Rotavator "GEM" Series III model garden tractor by Rotary Hoes Limited. This information was submitted to Gas Engine Magazine in 1999 by Howard Andrews.
Howard Andrews of Rumson, New Jersey sent us a copy of an instruction book and spare parts list he recently purchased from a bookshop in York, Pennsylvania. This illustration shows a Howard Rotavator "GEM" garden tractor, series III model. Publisher of the parts list was Rotary Hoes Limited of Horndon, Essex, England. Here are the specifications of the machine:
Engine: Single cylinder side valve (600 cc.) J.A.P. Mk.III.
Bore And Stroke: 3-3/8-inch diameter x 4 inches (85.7 mm. x 104 mm.)
Engine Speed: 1,800 rpm
Fuel Tank: Fuel and oil tank built as one unit with separate compartments. Fuel capacity 1-1/2 gallons. Oil capacity three pints.
Clutch: Heavy-duty single dry plate.
Gear-box: Three speed and reverse transmission by hardened gears running in oil. All shafts mounted on ball bearings. Differential gear for easy turning automatically locked when rotor is engaged.
Speeds: 1st gear — 0.78 mph; 2nd gear — 1.17 mph; 3rd gear — 1.65 mph; Reverse gear — 1.40 mph
Rotor: Speed 155 rpm 18-inch diameter.
Power Take-off Pulley: 10-inch diameter 4-inch face; 450 rpm; 1,178 feet per minute
Overall Dimensions Of Machine: Length 6-foot 6 inches; Width 2-foot 1-inch *
Weight: 5-1/4 cwt. approximately*
*Standard 20-inch Machine.