Importance

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Abstract

A lifting apparatus comprises a mobile vehicle, a platform disposed above the mobile vehicle, a single telescopic stretchable boom pivotally joined at the lower end with a pin to the mobile vehicle and at the upper end with a pin to the platform, and a hydraulic control system comprising a control circuit and a hydraulic circuit. The control circuit controls the hydraulic circuit according to detection signals given thereto from an extension detecting unit for detecting the extension of the stretchable boom and an inclination detector for detecting the inclination of the stretchable boom so that the platform is raised or lowered vertically and shifted horizontally on an elevated level through the manual control or automatic control of the control circuit or so that the platform is moved obliquely between the original position and a desired oblique position with respect to the mobile vehicle through the automatic control operation of the control circuit on the bases of recorded information relating to the oblique position. The control circuit also controls the hydraulic circuit so that the platform is always held in parallel to the upper surface of the deck of the mobile vehicle during the platform moving operation.

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First Claim