Abstract
The drawbar and power transmission performance of the hydrostatic tractor Bolens 1250 were measured. This hydrostatic transmission consists of the variable displacement radial plunger pump (max. displacement 30.2cc/rev), the fixed displacement gear motor (55.0cc/rev) and hydraulic valves. The relief pressure is 112kg/cm2.
The maximum efficiency of power transmission at the full throttle opening was about 57% and this efficiency was taken by the pump displacement of about 80% of full opening. In this condition, the drawbar pull on the concrete road was about 200kg and the speed was 1.8-2.0m/sec.
It is important to apply the automatic power control system to this tractor. As the output pressure of hydraulic motor is proportional to the tractor load, it is possible to control the pump displacement by the output pressure of motor.
