2.11 SAFE USE OF ELECTRIC BRIDGE AND GANTRY CRANES
In addition to any specific instructions relating to safe use issued by the manufacturer, the following points should be observed:
All lifting operations should be adequately planned and supervised.
Do not use electric bridge and gantry cranes to lift people without taking the necessary precautions. Lifting people is not within the scope of this code.
Electric bridge and gantry cranes must not be used to raise, lower or suspend a load greater than the marked SWL.
Ensure that the load is directly under the crane. The line of pull should always be vertical, never side lift or drag a load.
The hook should be attached to the load such that no part of the load is in contact with the point of the hook. The sling should be located in the seat of the hook and the safety catch closed.
The hook should not be crowded with terminal fittings of slings. To prevent the hook becoming overcrowded, LEEA recommends that the upper ends of the sling legs are connected by means of a shackle or link of adequate strength.
At the start of the lifting operation, the load should be raised just clear and the lift halted whilst the stability, balance and security of the load is checked. The lift should only proceed if the load is stable, balanced and secure. (See section 1.A3 APPENDIX 3 - LOAD SECURITY - BALANCE AND STABILITY)
Care should be taken to ensure that the crane is not subjected to shock loading. When using cranes with speed control, commence the lift at slow speed before progressing to full speed.
When travelling, care should be taken to prevent the load swinging unduly.
Avoid running the crab, hoist or crane into the end stops as this will cause the load to swing unsafely, put shock loading on the crane and its supporting structure. End stops are a final safety device only.
It should be borne in mind that all new cranes and many older designs are fitted with some form of overload device designed to protect the crane. This may be mechanical, electrical or thermoelectrical. Should the crane fail to lift the load, it is probable that the load exceeds the SWL and should be checked before resetting the controls.
Never change motions (i.e. lift to lower or vice versa) without first allowing the motor to stop running. Quick reversal of direction causes shock loading and heavy current surges. This will result in burnt contacts and imposes unnecessary strain on transmission shafts and gears.
Avoid unnecessary rapid and frequent incremental movements as this causes burning and pitting of contacts. Excessive rapid and frequent incremental movements could result in burning out of the motor.
Avoid excessive or intentional use of motion limit devices, they are a safety feature intended to protect the crane. Where the operation requires regular approach to the highest and lowest possible hook positions, a positional or working limit should be fitted for this purpose.
Ensure the travel path is clear and free from obstructions before operating the crane. The operative must always have a clear view of the travelling hook path to ensure accidental hook engagement or collisions do not occur. When using a remote control, it may be necessary to stop all motions to allow the operative to re-position to a better vantage point before proceeding.
When using a pendant control in close proximity to the load, the operative should take care to stand clear before initiating a travel motion which might cause the load to trap the operative.
A pendant control should not be placed on the load because the weight of the pendant can operate a push button if the button rests on a small projection on the load. If, for any reason, it is necessary to place the pendant control on the load, it should first be deactivated by pressing the stop button.
Unless essential for the operation, do not operate the long travel and cross travel controls simultaneously.
Ensure the operative and other personnel are fully protected from any hazardous materials which may form part of the load.
Loads should not be left suspended from cranes for any length of time unless absolutely essential. In such cases, or where it is as a result of a breakdown, the operative should ensure that the danger area is cordoned off to prevent personnel from being at risk.
At no time should the operative permit either himself or other personnel to be beneath or on a suspended load.
After use the crane should be returned to its parking position and the hook raised to a height where it will not present a hazard and the electrical supply should be switched off by means of the isolator switch.
No person other than someone competent for the purpose should attempt to carry out maintenance or repairs to the crane.
Never remove guards or protective covers such as weatherproof covers or heat shields without the authority of a Competent Person.
For cranes with remote control, observe the following additional points:
The user must make sure that the system is properly maintained, especially the control station. Wear or damage to the seals around buttons or joysticks, and damage to the casing, can allow dirt, water, and other contaminants to enter, causing false commands.
There must be a designated storage place for the control station when it is not in use.
The user must always press the stop button to de-energize the main contactor before leaving the control station unattended. This includes any time the control station is temporarily set down, such as when the crane operator is also slinging the load.