Hydraulic controls for forklifts uses limiter for lowest permitted consumer pressure and protection device for maximum permitted pressures as infed via inward pressure balance.

摘要

The consumers (2,3,4,5), here forklift lift and tilt etc drives, are protected to differing maximum pressures, using a limiter (35) to produce the lowest permitted pressure for at least one consumer (4,5). At least one consumer (2,3) is fused for maximum permitted pressure via a working pressure protection device (30) as distinct from the limiter (25) for the lower permitted pressure. Control is by load sensing via an inward pressure balance (20) and all consumers have associated control valves (6-9). The maximum pressure protection device (30) operates as pressure cutoff at this level at the balance (20) consumer (2-5) signals. The limiter (35) limits the feed pump for consumers (4,5) to the lower permitted pressure. The system includes a three-way pressure reduction valve (36).