256HC Mast Section Introduction of tower crane safety device
1、 Tower crane safety device
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(1) Hook safety device: a safety device to prevent the sling on the hook from slipping automatically. That is to say, a pressing spring sheet is installed at the opening of the hook head to close the opening. The spring sheet can only be pressed down and opened, and can not be turned up after being put into the sling, so as to prevent the sling from falling off automatically.
(2) Drum safety device: effective measures to prevent accidents caused by improper winding of steel wire rope beyond the drum. The methods are different, mainly welding a steel bar shroud outside the drum, limiting the wire rope to move only within the scope of the drum.
(3) Fixed foundation: the depth of the excavation pit is 600mm, concrete is poured on the lime soil, the surface is flat, with waterproof and grounding protection measures.
2、 Safety protection of tower crane grounding
Aluminum conductor and threaded steel shall not be used as grounding body or underground grounding wire for tower crane installation. A bolted wire must have an end. There are three main ways of grounding:
1. The grounding body adopts normal grounding pile, 33 * 4.5 long 1.5m steel pipe, or 70 * 70 long 1.5m angle steel.
2. The grounding plate is made of steel plate or other extendable metal plate, with an area of 1m2. It is buried at a depth of 1.5m from the ground.
3. Copper conductor with a cross-section of not less than 28 mm or steel conductor with a cross-section of not less than 50 mm shall be buried in the trunking, and the buried length shall be determined by the grounding resistance.
In the above three ways, the cross-sectional area of the copper lead out from the grounding body shall not be less than 25. If the soil has poor conductivity, sodium chloride (table salt) can be buried in the soil. Then water. For traveling tower crane, each rail must be grounded, and two rails shall be connected by conductors. The two rails shall also be electrically connected, and the grounding resistance shall not be greater than 4.
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