System for controlling the raising ground-contact component of mobile machine e.g. snow plough

摘要

The hydraulic system for controlling the height, for example, of a snow plough blade in relation to the ground uses a push-pull cylinder, controlled by a three-position valve, and a control unit which reacts to the feed-back pressure, due to ground contact, to reduce or increase the pump supply pressure. A snow plough blade (1) is attached to the driving vehicle (3) by a linkage mechanism (2) and a two-way hydraulic cylinder (4). The piston of the cylinder is controlled by a three-position electromagnetic valve (8) which supplies hydraulic pressure to one side (4r) or the other (4k) of the piston. A motor (5) driven pump (6) supplies hydraulic fluid from a reservoir (7) and the output pressure Pp is governed by a control unit (9) which receives feed- back pressure information from the valve through feeds (10a,10b) incorporating a throttle (11). A pressure-limiting valve (8), a back-pressure valve (13) and supply throttle (14) are also provided.