One, used for foundry moulding operation, in front of a furnace to undertake the liquid iron, are driving to mold for casting two, main technical parameters and dimensions 1, hanging bag form, bidirectional rotary 2, gearbox, double worm gear 3, ratio 4 (see chart ), dimension (e.g. chart) three, features 1, reasonably choosing the center of rotation, convenient operation, after casting the basic to complex in 2, double worm gear drive. Although the manufacturing requirement is high, but the transmission flexible, two-way reversible 3, derrick by forging, safe and reliable than steel plate welding pieces of 4, package body plate is thicker, the package bottom structure, adopts the taper bottom hoop, welding combined three insurance, which prolongs the service life, and ensure the safety of the operator. In 5, main body and suspenders, reduction box and a handwheel, are provided with a chain board can be locked. 6, two ear axis and the boom to a self-aligning bearing, good consistency