Power plants – Pressure fluid source and motor – Condition responsive control of motive fluid flow
Patent
1990-08-23
1991-11-05
Look, Edward K.
Power plants
Pressure fluid source and motor
Condition responsive control of motive fluid flow
60468, 60493, 60494, F15B 1104
Patent
active
050622668
ABSTRACT:
A slewing control device for a crane for supplying a discharge oil from a pump through a direction selecting valve to a slewing motor and for controlling a rotational direction of the slewing motor. The device includes a selector provided in a main circuit between the pump and the direction selecting valve for selecting either an unload condition of the pump where a hydraulic oil in the main circuit is communicated with a tank or an on-load condition of the pump where the communication from the main circuit to the tank is blocked. A controller outputs a select signal to the selector to select the unload condition in response to detecting a dangerous operating condition. The controller also outputs a pressure control signal to an electromagnetic proportional pressure control valve provided between the direction selecting valve and a discharge port of the slewing motor to control oil pressure on a discharge side of the slewing motor when slewing needs to be stopped. Accordingly, the motor can be automatically braked to rapidly brake a slewing body of the crane.
REFERENCES:
patent: 4520625 (1985-06-01), Sato et al.
patent: 4586332 (1986-05-01), Schexnayder
patent: 4845948 (1989-07-01), Tha et al.
Kabushiki Kaisha Kobe Seiko Sho
Kapsalas George
Look Edward K.
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