DAVIT ASSEMBLY, TOWER AB-585()/G. EFFECTS OF PULLEY FRICTION ON DAVIT DEFLECTION,
ARMY ELECTRONICS LABS FORT MONMOUTH N J
Pagination or Media Count:
The testing of the davit assemblies represents an inhouse effort to evaluate the mechanical efficiency of the AB-585G type tower davit and pulley sheaves, and, at the same time, make a comparative evaluation of the production model with a new design of larger diameter incorporating an oilite bronze bushing. The davit shaft is composed of aluminum tubular columns of 3 inch O.D. and .125 inch wall, the upper davit tube and the lower davit tube held together by a spring loaded pin. The two cross arms are mounted perpendicular to the shaft and consist of tubular columns of the same material and dimensions. Pulley sheave slots and guards are located at the top of the davit shaft and at the ends of the cross arms. The davit assy also includes two retaining couplers for mounting and moving the davit shaft along the vertical leg of the tower, a snatch block assembly for hoisting and 250 ft. of 12 inch manila rope. The use of the oilite bronze bushing in the new design, 3 14 diameter pulley sheave, resulted in no significant reduction in pulley friction. There was no noticeable difference in davit shaft deflection which could be attributed to the effects of pulley friction.