Drop foot jack

Abstract

This document describes a drop foot jack, also known as a vehicle landing gear or landing gear jack. A drop foot is telescopically borne within an inner sleeve, which is in turn telescopically borne within an outer sleeve. A rotatable screw is situated within the outer sleeve, and it engages the top surface of the inner sleeve so that rotation of the screw will move the outer sleeve and inner sleeve with respect to each other. The drop foot, inner sleeve, and outer sleeve preferably each have a circumference having multiple discrete sides, e.g., each may have a polygonal cross-section. Apertures are spaced along the lengths of the drop foot and the inner sleeve, and a latch plate having a generally planar configuration which can be selectively moved into aligned apertures in the inner sleeve and the drop foot to thereby engage the drop foot with respect to the inner sleeve. The plane of the latch plate is situated generally perpendicular to the lengthwise axes of the inner sleeve and drop foot, thereby enhancing the surface area of the latch plate that contacts the drop foot and inner sleeve; as a result, the shear strength (and load capacity) of the jack is increased. When the latch plate is inserted in the inner sleeve and drop foot, it engages two or more adjacent sides of the drop foot and the inner sleeve, thereby helping to avoid canting of the drop foot with respect to the inner sleeve. The outer sleeve includes a lubrication passage extending between its exterior and its interior, and the top surface of the inner sleeve has a depressed area adjacent the screw. The lubrication passage allows lubricant injected from the exterior of the outer sleeve to access the depression, whereby lubricant may pool in the depression to maintain the screw in a lubricated state.