Material or article handling – Vertically swinging load support – Shovel or fork type
Patent
1988-08-17
1989-06-13
Spar, Robert J.
Material or article handling
Vertically swinging load support
Shovel or fork type
60431, 123385, F16D 3102
Patent
active
048387550
ABSTRACT:
An excavator has a number of different hydraulically powered functions that are controlled by a closed center hydraulic system that features a pair of variable displacement, engine driven hydraulic pumps, the displacement of which is responsive to the demands of the system. The flow to the various hydraulic motors is controlled by pilot operated load sensing control valves that direct fluid pressure to a load sensing line when one of the hydraulic motors in the system is being operated. The load sensing line is connected to the control system of the pumps to place the pumps in stroke when a flow of pressurized fluid is required. The flow of the load sensing pressure to the controls for one of the pumps can be optionally disconnected to place said pump in a standby condition and thereby reduce the flow capacity of the hydraulic system at the option of the operator. The load sensing line is also connected to a pressure actuated switch that closes when pressure in the line falls below a predetermined point, which occurs when none of the hydraulic motors are being actuated. The closed switch provides electric power to a solenoid through a time delay circuit so that the solenoid shifts the throttle control level on the excavator engine to its idle condition at a delay after the hydraulic pressure demand falls below the predetermined level.
REFERENCES:
patent: 2986291 (1961-05-01), Schick
patent: 3148790 (1964-09-01), Ziskal
patent: 3447556 (1969-06-01), Howeth
patent: 4373850 (1983-02-01), Durham
patent: 4638779 (1987-01-01), Kitada
patent: 4643146 (1987-02-01), Spriessler
patent: 4774921 (1988-10-01), Sakaguchi et al.
Hitachi UH123 Hydraulic Excavator Brochure, 1985, 4 pages.
Komatsu Auto Idle Hydraulic Circuit Diagram, 1 pg.
Hicks Enterprises Backhog Automatic Throttle Control, 2 pgs.
Johnson Steven H.
Williams Lary L.
Deere & Company
Hienz William M.
Spar Robert J.
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