초록

A motor grader is provided with an electrical control circuit for automatically effecting engagement, speed, and direction control of an auxiliary hydrostatic front wheel drive system to augment the primary engine-driven rear wheel drive system.

대표청구항 ▼

In combination with a vehicle including a reversible main traction drive transmission system connected to drive main traction drive wheels, and first and second auxiliary traction wheels, an auxiliary traction drive system, comprising; a reversible variable displacement pump including a direction an

In combination with a vehicle including a reversible main traction drive transmission system connected to drive main traction drive wheels, and first and second auxiliary traction wheels, an auxiliary traction drive system, comprising; a reversible variable displacement pump including a direction and displacement controller; first and second hydraulic motors connected in parallel with each other in a closed loop hydraulic circuit connecting the pump to the motors; first and second drive connection means respectively connecting the first and second motors to the first and second auxiliary traction wheels; said closed loop hydraulic circuit comprising a pair of supply-return lines having first ends connected in fluid communication with a first port of the pump and having second ends respectively connected to first ports of the first and second motors, and a further supply-return line connected between respective second ports of the motors and a second port of the pump; and auxiliary drive speed control means connected between the main traction drive transmission system and the direction and displacement controller of the pump for controlling the latter, in response to the main traction drive system, such as to cause the pump to displace fluid to the motors in such direction and quantity as to result in respective rotors of the motors being rotated at speeds which are a preselected percentage of the average speed of rotation of the main traction drive wheels.