What protection devices are set for overhead gantry crane?
To adapt to special working environment for HZP1600 segmental assembly bridge girder launcher, below automatic protection devices are set for overhead gantry crane for lifting girders:
segmental assembly bridge girder launcher
A Overload protection device: as lifting capacity is over 150t, winch will stop working automatically, only putting down objects is allowed for winch, no lifting.
B Upper and lower limit device for winch: to avoid accident caused by steel wire rope overflow from winding too much, upper limit switch is set up on the winch. Once lifting height is over rated height, the protection device will make winch stop working and that the winch can only move to safe direction. Besides, when the winch put down objects to be lower than rated height, lower limit device will also make winch stop working automatically to ensure 3 circles safety ropes on the drum and avoid accidents caused by rope end extraction.
C weight limit switch
D winch over-speed switch
E brake for winch high speed end and low speed end: block brake for high speed end and disc brake for low end to ensure a reliable brake of winch
F bumper is set at rail end of gantry crane, at two ends of overhead gantry crane are set limit switches, once gantry cranes are near to each other, limit switch will send signals to cut off run loop to brake and avoid collision. In addition, buffers are set at two end of overhead gantry crane
G anti-wind device: with a higher wind speed as the gantry crane is high above the ground, wind alarming device is installed. When wind force is over than expected wind level, alarming device will alarm and cut off oil pump circuit to brake the gantry crane, design working wind pressure for the gantry crane is 300N/m2（wind speed≤22m/s）. as encountering strong wind or stopping for a rest, drive gantry crane to fixed anchoring points and use mechanical anchor on the moving gearbox to fix it. In the non-working condition, mechanical anchor and electro-hydraulic windproof iron wedge brake are used at the same time to avoid strong wind blowing the overhead gantry crane.
Overhead gantry crane power supply system: 3-phase, 380V, magnetic force coupling type cable device features constant cable tension, orderly winder and good synchronism. To make cables move freely, cable drum at one side shall be installed symmetrically and overhead gantry crane is installed symmetrically along longitudinal centre line. The when the cable drum releases and draws back cables, service cables can be put on cable tray at two sides of primary truss of bridge girder launcher.
