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Mobile Crane Inspection Guidelines for the Compliance Officers |
Printing Instructions
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Mobile Crane Inspection Guidelines
for OSHA Compliance Officers
Appendix B - General Load Charts and Operational Considerations
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General Load Charts: Manufacturer's operating notes
supplied with the machine contain important information concerning proper
set-up, operation and additional points that need to be considered when
calculating load handling capacities of cranes. Mistakes in calculating capacity
can cause accidents.
Several factors to be considered when calculating a cranes
load capacity, including the following:
- Load Radius: the horizontal distance
between the center of the crane rotation to center of the load.
- Boom length: including the jib, swing
away extension or any other attachments that may increase length of
the boom.
- Parts of line:
- Quadrant of operation: the area of
operation that the lift is being made in; note different quadrants
usually have lower lifting capacities.
- Boom angle: the angle formed between the
horizontal plane of rotation and center line of the boom.
- Weight of any attachments: jib, lattice extension or
auxiliary boom point.
- Weight of handling devices: ball, block, and/or any necessary
rigging.
Operational Considerations:
- When working at boom lengths or radii between the
figures shown on the load capacity chart, the next lower capacity rating
should be used. It is dangerous to guess the capacity for boom lengths
or radii between those listed on the rating plate.
- It is very dangerous to lift a load without
knowing whether it is within the rated capacity while expecting the
crane to start to tip to warn of an overload. Cranes may suddenly tip
over or the boom may collapse if the load is too heavy.
- Always stay within the rated capacity. Operators
must reduce the load capacity under adverse field conditions until, it
is determined, the machine can safely handle the lift.
- Loads shall not be allowed to exceed rated load capacity and
working radius.
- Do not use counterweights heavier than the manufacturer's
recommended weight.
- Even a light wind can blow the load out of control, collapse
booms, or tip machines.
Winds aloft can be much stronger than at ground level.
- Proper precautions shall be taken when the velocity of wind exceeds
20-mph.
- Crane capacity can be adversely effected when the machine set is not
level.
- Do not lift loads when winds create an unsafe or
hazardous condition. Booms should be lowered, if possible, under high wind
conditions.
- Foot pedal brake locks are furnished on some cranes
to allow the operator to rest his legs when suspending the load for short
periods of time. Operators should keep their feet on the pedals while foot
pedal brake locks are in use. Brakes may cool allowing the load to fall.
- No one, except the oiler, instructor or designated
person should be allowed on a crane with the operator when the crane is in
operation.
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