Lifting gear for precision positioning of load - has mercury floating in tube between contacts to sense small pressures when manoeuvring

摘要

The lifting gear is used for precision positioning of a load and comprises a compressed air cylinder suspended vertically to carry a motorised lifting drum (4). The piston initially lifts the load approximately into position. The air also acts on both sides of a U-shaped tube (17) filled with mercury and when air is shut off, the system is in balance. Power cylinders then partly rotate the main cylinder about its vertical axis to break any friction seal. Downward or upward pressure (f9) on the load unbalances the column, mercury floating between electrical contacts (Co, Cl) to operate the cabld drum in the same direction (f10).