The angle at which a sling holds a given load influences the effective weight of the load. Stresses are minimal for loads with slings held perpendicular to the load, as shown in Figure A. For distributing the load vertically among more than a single leg of a sling, a spreader bar may be used. As shown in figures B-D, increasing the angle of the sling to the hook from 30 to 60 degrees increases the effective mass of the load from 1154 lbs to 2000 lbs, essentially doubling the weight on each leg of the sling at 60 degrees. The chart in the middle offers a handy guide for assessing the effective angle of the sling to the relative weight. Thus, it is always better to limit the angle of the sling. Further, such changes in sling angle must be accounted for in lifts that are close to the sling weight limit and/or for critical lifts (greater than 90% of the crane limit). Crane operators should download a copy of this chart and carry it with them during crane operations.
Sling position
Crane lifts require the use of slings. Slings are generally made of nylon or wire mesh. Nylon slings have the advantage of being easy to wrap around a load but can be easily cut or damaged if used improperly. Nylon slings which have been mishandled are subject to bleed-through. A red ink mark appears on the surface at the point of damage. Inspect all slings before use. Wire slings should have no more than two wires out of nine broken. Discard all damaged slings immediately. Rigging slings may be utilized in three basic manners. Each sling carries with it a label with rated weight limit capacities for vertical, choker, or basket configurations. The basket configuration, which is analogous to using a spreader bar to distribute the weight on two legs instead of a single vertical sling, represents the highest rated capacity. This basket configuration is roughly twice as strong as the vertical configuration. A typical example would be a basket configuration with a 7200 lbs capacity would have a vertical capacity limit of only 3600 lbs. Taking a single sling and using it in the choker configuration would further degrade the capacity of the sling, dropping the rate of capacity of 3600 lbs in the vertical position to 2900 lbs in the choker position. Thus, in addition to the sling angle, sling position must be considered for all crane lifts.
Operating signal
The emergency stop signal is a horizontal hand wave of the extended arm. It is important to immediately react because the person giving the signal may have knowledge that the
crane operator does not, including: better view, knowledge of hazards, etc. Obey all STOP signals regardless of who gives them. Other than EMERGENCY STOP, signals should be accepted from only one person at a time (normally the spotter for the operator). Use standard crane signals and do not move unless directions are clear. Know standard hand signals (shown above). Hand signals are important because background noise may make communication difficult.
In order to make a safe lift the following information must be known
• Weight of item to be lifted (total).
• Center of gravity of the load.
• How to rig the load.
• How to control the load at all times.
The capacity of the CAMD crane is 4000 pounds. The weight limitation occurs because of the small hook attached to the lifting mechanism. Stabilization of the loads may be made possible by the use of a spreader bar, which gives 2 points of attachment, instead of the usual one point. The weight of the spreader bar must be included in the total weight of the lift. A crane scale is available to ascertain the total weight of the lift . Once the weight has been determined to be within the crane capacity, it is necessary to determine the center of mass. Loads not accurately balanced will tip or swing and result in a hazardous lifting environment. Light loads are apt to swing more readily and may require attachment of one or more tag lines to impair rotation of the load. This requires 1 or more individuals in addition to the crane operator.
• Do not sleep.
• Never divert attention when there is a load.
• Practical jokes are forbidden.
• Do not use alcohol or other intoxicants.
• Do not operate if taking medication.
Crane operation is a serious responsibility which should never be taken lightly. A properly trained crane operator will never approach another crane operator during a lift unless he/she observes a hazardous situation which requires immediate cessation of the lift. People with poor peripheral vision or diminished capacity due to ingestion of pain relievers, decongestant or other medication which may impair their mental acuity should not operate any crane. The use of alcohol or other intoxicants by crane operator is strictly forbidden and will result in loss of crane operator privileges.
• Lower the load to the ground.
• Disconnect the load and slings
• Raise all the hooks to upper limit switch.
• Place all controls to off position.
• Visually check for dangerous conditions
• Never leave a load unattended.
After completion of a safe lift, spot the crane in an approved location. The CAMD crane should never be left directly over the 90 degrees bending magnet of the storage ring because the bulk of the crane can act as a strong scattering force and contribute to sky shine radiation. Never leave a load attached to the crane and if you must absent yourself from the locale of the load, always take the controller with you. Always lower the load completely to the ground and give yourself some slack in the slings before attempting to remove the rigging from the crane hooks. Remember only vertical lifts must be made and dragging of the load horizontally is specifically forbidden. Ensure that the operator can see all potential hazards clearly at all times; otherwise, a crane spotter is necessary for all lifts. Once crane rigging is removed, return crane hook to upper limit switch. This will prevent the potential for the crane hook to hit any potential obstacles when the crane is next moved along its circular path.
• Make sure the load does not exceed rated capacity.
• Know the center of gravity of the load.
• Attach load above the center of gravity for stability.
• Select hitch that will control the load.
• Know the rated capacities of rigging and slinging
• Inspect all rigging before use
• Protect the sling from sharp corners.
• Allow for increased tension due to sling angle.
• Equalize loading on multiple leg slings
• Allow for load reductions when using choker hitches
• Attach tag line prior to lift.
• Keep personnel clear of lift area.
• Wear hard hats when making overhead lifts.
• Lift load a few inches and verify rigging.
• Check for any loose items.
• Know limitations of hoisting device.
• Start and stop SLOWLY! Watch for obstructions (not only hook and load but outboard end of the bridge).
• Check pathway is clear before making a lift (use a spotter for blind spots).
• Verify hook completely closes.
• Use appropriate hand signals.
• Maintain load control at all times.
• Report suspected drum wrappings immediately (if drum has fewer 2.5 wraps remaining).
• Never leave load unattended.
• Person must be 18 years of age and familiar with normal operating practices and procedures.
• Person must have good hearing and vision (with or without correction) and must have good depth perception.
• Person must not be afflicted with any known heart or other health conditions that might cause sudden loss of ability to react.
• Person must have been adequately instructed for crane operation.
• Operator must be qualified to rig the load safely. Qualification is a demonstrated ability to rig a load as a part of crane training.The operator must have recieved training which includes theory, practice and testing.
Before operating a crane with which the operator is not familiar, the operator must read the instructions provided by the manufacturer and note any special instructions, paying particular attention to the function and operation of each control.
Each crane operator should be held directly responsible for the safe operation of the crane or hoist. Whenever there is any doubt as to safety, the operator should stop the crane and refuse to handle loads until safe conditions have been restored. There is a minimum requirement of 18 years of age and fluency in the English language to operate the CAMD crane. Persons must also have good hearing and peripheral vision. These attributes are necessary for safe operation of the crane. All crane operators must
have have received training including: written materials; hands on experience; and testing of knowledge, both written and practical. Persons must also have had some training in the important fundamentals of rigging loads. Crane operators using a new lifting device must be familiar with the manufacturer's directions, noting any special instructions. No lifts over 100% rated capacity may be made without the prior written consent of the CAMD safety operator.
See also: crane training (p.1)
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