Page 68 - Alex Ruscuklic - Complete Works

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Equipment
A bridge crane.
Bridge and gantry cranes
This guide covers bridge and gantry cranes such as those shown (left).
A bridge and a crab (winch trolley assembly) run on two fixed overhead binary runways.
A bridge crane (or overhead travelling crane) is defined as a crane comprising a bridge beam or beams mounted to end carriages at each end, capable of travelling along elevated runways and having one or more hoisting mechanisms arranged across the bridge.
A gantry crane comprises a bridge beam or beams, which are supported at one or both ends by legs mounted to end carriages, capable of travelling along runways and has one or more hoisting mechanisms.
Bridge and gantry cranes may be operated from within a cabin mounted on the crane bridge or remotely from the ground, either through a hard-wired pendant control or radio control.
The major components of bridge and gantry cranes are:
• therunways
• thebridge
• the hoist unit
• the crab or hoist trolley used to transverse the load
• the winch drum and hoist rope
• the rope termination points, the hook and hook block, which may contain one or more sheaves
• the braking systems
• the ‘crane operating area’
• the electrical supply and its isolation points
• the provision of access for service and maintenance/repairs, and
• the load limiting devices, which prevent the rated capacity being exceeded.
Crane controls
It’s advisable they:
• have ‘fail-safe’ control buttons (i.e. constant pressure type)
• have appropriately labelled function buttons
• are of waterproof construction, and
• are fitted with a manually reset emergency stop button.
Additional for cabin controls
Modern cabin controlled bridge and gantry cranes will normally have joysticks to control all movement on the crane.
Cabins may be cramped in design. Ensure controls are protected so that the operator getting in and out of the cabin seat will not cause accidental operation. Dead man’s brake pedal or mechanical protection of joy stick control levers can prevent this.
A gantry crane.
A gantry combination crane.
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Handbook / Working safely with bridge and gantry cranes WorkSafe Victoria