There is provided a boom extending and retracting apparatus that can improve the convenience of the telescopic boom while reducing the burden on the operator. The boom extending and retracting apparatus of the crane chooses the mode of the fluid circuit between the normal fluid circuit and the differential fluid circuit to slide a plurality of boom members by one telescopic cylinder. After the operating lever is turned to an extension side and the controller starts extending the telescopic boom using the differential fluid circuit, when the operating lever is turned to the extension side again via the neutral position, the controller chooses the normal fluid circuit to extend the telescopic boom using the normal fluid circuit.
Boom extending and retracting apparatus of a crane
2017-10-10
Patent
Electronic Resource
English
IPC: | B66C Krane , CRANES / B66F HOISTING, LIFTING, HAULING, OR PUSHING, NOT OTHERWISE PROVIDED FOR, e.g. DEVICES WHICH APPLY A LIFTING OR PUSHING FORCE DIRECTLY TO THE SURFACE OF A LOAD , Hub-, Verhol- oder Schubvorrichtungen, soweit nicht anderweitig vorgesehen, z.B. Vorrichtungen mit unmittelbarer Krafteinwirkung auf die Last |