Torque Control of Rotary Tiller (IV)

Pitch Control System for Hydrostatic Drive Tractor

Abstract

A pitch control system for a rotary tiller attached to hydraulic power tractor was investigated in field tests.
(1) The hydraulic power system drives both hydraulic motors for tillage and for travel in a hydraulic series circuit.
(2) As tillage torque varies in proportion to tillage pitch in constant rotary speed, it is possible to do a pitch control of torque by changing the travel speed.
(3) As torque for tillage increases, torque for travelling decreases, because the tractor is pushed by forward component of resistant force of tillage.
(4) As tillage torque is changed with this pitch control system, travel speed of the tractor, therefore tillage pitch, is controlled.
(5) Travel speed of the tractor follows total pressure P₁ and disturbance torque of rotary tiller is controlled.
(6) In result of tests, torque of tillage was not always controlled satisfactorily, because the value of gain constant is not suitable for the system and the offset is large. It is, therefore, possible to obtain the better controlling effects by selecting suitablly the system sensitivity and the system elements.