Trinova Limited

Brian John Reid

Isidoro Livraghi

A fluid power control system for use in a mini-excavator, in which a first control section (S2) includes first and second control valves respectively connectable to first (2) and second (4) implement functions; and in tandem with one another. A first gear pump (P2) supplies the actuator connected principally to the first implement (2), and a second gear pump (P3) supplies working fluid to the interconnection between the first and second control valves. The advantage of this arrangement is that, as the first control valve switches from its neutral position to a position selecting its associated implement (2), progressively more of the fluid passing through the second control valve is supplied by the second pump (P3) until, when the implement (2) to which the first control valve is principally connected is fully selected, the two implements (2, 4) are supplied separately by the respective gear pumps (P2, P3).

Hydraulic control system

An hydraulic circuit controlling an actuator including a main signal branch which includes a pump (11), a valve (12) and an actuator (18) coupled in series, the valve being responsive to first and second applied biasing pressures (19,23), the first biasing pressure being operable to bias the valve (12) into a closed position and the second biasing pressure being operable to bias the valve into an open position; an auxiliary branch (20,21,22) connected in parallel with the actuator (18); the first biasing pressure (19) being derived from the main signal branch downstream of the valve (12) and the second biasing pressure being derived from the auxiliary branch.

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Southampton, United Kingdom

Brian John Reid