• Do not lift people and never ride the hoisting load.
• Do not lift load over people. No one shall be under the hoisting load.
• Make sure the sling is well balanced. Avoid tip loading, and loading on hook latch.
• Never lift the load over the rated capacity.
• Do not operate with kinked, twisted or damaged chain.
• Avoid side pull or end pull, and quick reversal operations.
• Never leave the suspended load unattended.
• Make sure you take up slack slowly.

In addition to improper rigging, cranes hitting overhead obstacles represent the most frequent hazards of crane operation. Before beginning a lift, clearly inspect the entire proposed path of the crane, paying particular attention to overhead obstacles (especially overhead electrical hazards which could be fatal) and whether the path of the crane will pass directly overhead of any individuals. Always have a spotter available, particularly in blind spots. Never exceed the crane capacity and never attempt a critical lift unless you have years of experience in utilizing the crane. A critical lift is defined as one exceeding 90% of the rated capacity of the crane. For the crane, a critical lift is greater than 3600 pounds.

A crane is a vertical lifting device. It should never be used to drag or pull a load. Always position the crane directly perpendicular to the load to be lifted. Non-vertical lifts can damage both the crane and the rigging materials and may result in improper wrapping around the drum. If the drum wraps are not seated in the proper position, immediately cease crane operation and inform facility maintenance.

An operator who leaves a load suspended and unattended is subject to disciplinary action, which may include revocation of his or her license to operate the crane.

Crane Inspection and Maintenance:

• Inspection and lubrication are done twice yearly.
• Daily before operating:
  -Check battery
  -Check all controls
  -Visually inspect

-Wire rope for kinks or damage
-Sheaves, drums for damage
-Upper and lower limit switches.

Rigging/Ropes/Chain:

• Loads should be well secured.
• Slings should be adequate to the task.
• Slings should be unlinked and load balanced and secured.
• No sudden stops.
• No obstructions while lifting or traveling.
• No loose items on load or crane before lift.
• Bumping into runway stops is prohibited.
• Hoist line must be vertical prior to the lift (remove slack in the hoist slowly).
• No crane load should pass overhead of personnel, clear the area before making the lift.
• No one is to ride the crane without permission.

The most important job of any crane operation is rigging of the load. Poor rigging may result in personnel injury, property damage, or other serious hazards. Rigging is the most time consuming of any crane operation and represents the single most hazardous potential of crane operation. In a multi-sling operation, each leg must be of the same length and must contribute equally to load distribution. Nylon slings are susceptible to damage by sharp corners on the item to be rigged. Caution must be taken to ensure that slings are not damaged by sharp corners or by excessive loading. Rigging requires years of practice to perfect. If in doubt about the security of your rigging, ask for help. Rigging should be checked by lifting the load a few inches off the ground to ensure that no swing develops and that the load is completely secure. Remember it is important to take the time to accomplish this task correctly. Not doing so may result in catastrophic consequences. One of the most important things to check before lifting a load is to look for loose items, such as screws or tools which may have been used to secure the load. Such items can become projectiles during a lift. This is the reason why crane operators or especially tag line operators should wear hard hats when operating the crane and why it is essential to make sure the path of the crane does not pass over the head of any individual.

Center of Gravity:

 

It is always important in rigging practice to rig the load so that it is stable. A stable load is one in which the center of gravity of the load is directly below the main hook and below the lowest point of attachment of the slings. The center of gravity of an object is that point at which the object will balance. The entire weight may be considered as concentrated at this point. A suspended object will always move so that the center of gravity is below the point of support. In order to make a level or stable lift, the crane or hook block must be directly above this point. Thus a load which is slung above and through the center of gravity will be stable and will not tend to topple or slide out of the slings.

Predicting the center of mass for an object to be lifted is not a trivial matter. It may require several attempts at rigging to find the appropriate balance point. Many objects are not rectangular such that predicting the center of mass is often difficult. In all crane lifts the center of mass must remain below the hook and below the point of attachment for any rigging. A center of mass above the hook is inherently unstable and will cause the load to flip. Similarly, loads which are not balanced in the horizontal plane may slip from the rigging. The overall stability of the load is a combination of balance with respect to center of mass, weight distribution, and rigging tightness.

Weight Vs Angle:

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.

 

Signals:

 

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.

Safe Lifts:

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 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.