Wednesday, August 29, 2007

Mobile Crane Inspection Guidelines for OSHA Compliance Officers

Appendix C - Basic Crane Components

In addition to reviewing the OSHA and American National Standards Institute (ANSI) standards/requirements for mobile construction cranes, it is important that each inspector have a basic knowledge of crane components and their general purpose. The following is a list of basic crane components which should be included in any inspection. In addition to a description or purpose statement photographs are provided to help the inspector recognize each item. The list may not be inclusive, but is intended to be an aid for an inspector who may not be a crane expert.

INSPECTION ITEMS
  1. Manufacturer's operating and maintenance manuals shall accompany all mobile hoisting equipment. These manuals set forth inspection, operation, and maintenance criteria for each mobile crane and not generally available from any other source.
  2. All exposed moving parts such as gears, chains reciprocating or rotating parts are to be guarded or isolated.
  3. The swing radius of the counterweight shall be established and guarded to prevent personnel or other equipment from being struck by the counterweight. Special attention shall be given to guarding of the swing radius when near buildings or other structures. The swing radius guarding is intended to simply be a warning device and not necessarily a barricade guard rail. There are no strength requirements associated with swing radius protection.
  4. High voltage warning signs shall be displayed on the exterior of the equipment on each side and on the counterweight of the crane.
  5. Boom stops are telescoping, shock absorbing, or hydraulic-type safety devices designed and installed in a manner to stop or shut off power to the boom controls. The purpose of the boom stops is to prevent the boom from being raised to a point where the center of gravity is shifted to the rear of the crane causing the boom to fall backwards from to lack of resistance and/or control of boom movement.
  6. Boom stops can be inspected and checked for proper function by raising the boom very slowly until contact is made and power for boom movement is stopped.
  7. Jib stops are restraints designed to prevent the jib from being raised to the point that it overturns onto the boom sections. Jib stops, like boom stops, are telescoping, shock absorbing, hydraulic devices, designed to warn the operator that the jib load block has approached the point at which overtipping/overturning is possible if raising the load line continues.
  8. Boom Angle Indicators are required to indicate the angle of the boom tip from the base section on a horizontal plane. They may be either mechanical (activated by gravity) or electronic, with a display readout in the cab. Accurate readout of boom angle determines load capacity and working radius.
  9. Boom Hoist Disconnects are designed to automatically stop the boom from hoisting when the boom reaches a predetermined high angle
  10. Anti-Two Block Devices are designed to prevent a hoist block and/or load from being hoisted into contact with the boom tip by putting sufficient stress on the wire rope that it is either cut or stressed to the point that the line separates and the load falls onto someone or something. ANSI requires that all hydraulic cranes be equipped with anti-two block devices.
  11. All functions of hydraulic cranes feature "power controlled lowering". Safety devices known as "holding valves" or "counter balance" valves, which prevent uncontrolled decent in the event of hydraulic pressure loss. To test the effectiveness of these safety devices, retract the cylinders or lower the hoist drum with the engine not running. This would apply to the boom lift and extension cylinder as well as the outrigger cylinders and hoist drums. No movement should take place without hydraulic pressure.
  12. Leveling of the crane is extremely important. If a crane is out of level more than 1o it exerts a side load on the crane, and can effect structural capacity. It also can increase the load radius when the crane is rotated to another quadrant of operation.
  13. All sheaves should be checked for cracks, grooving, or damage from two-blocking. Undue looseness in the bearing or bushing should be noted. The sheave's groove surface should be smooth and slightly larger than the wire rope being used. It should be checked with a sheave gauge to be sure it is the proper size for the wire rope being used. On most hydraulic cranes, sheave guards which prevent the wire rope from coming off the sheave, are removable pins. Be sure that all of these pins are in place.
  14. Drum lagging and flanges should be inspected for cracks or other deficiencies and winch mounting bolts should be checked. Any undue movement of the drum on its bearings should be noted. The wire rope anchoring to the drum should meet the manufacturers specifications and must not be "overspooled". In other words, with the rope fully spooled on the drum, the drum flanges must extend above the top wrap of the rope. Any spoiling devices, such as rollers, or drum rotation indicators, must be functioning properly.
  15. All components of the boom assembly should be checked for cracks, bends, or other deformities. On hydraulic cranes, special attention should be given to the topside of the boom where the extension sections exert an upward force. All connecting pins and bolts should be checked. Wear pads should be adjusted properly or replace if necessary.
  16. Hooks should be examined to see if they are cracked or distorted beyond allowable tolerances. No welding or heating should be done on hooks. Hooks and blocks should be labeled as to their capacity and weight.
  17. Connecting bolts on block cheek plates should be checked. Hook swivels and sheave guards should also be checked.
  18. All hydraulic hoses, fittings, swivels, and tubings should be checked for leaking. On flexible hoses, be sure that the working pressure stamped on the hose is more than the working pressure it will be exposed to.
  19. Outrigger beams and housings should be checked for cracks or distortions. Outrigger floats, or pads, should be checked for damage. The floats must have the capacity to be securely attached to the outriggers. Outrigger beams should be marked to indicate when they are fully extended.
  20. A durable load rating chart for the specific model and serial number of the crane shall be accessible to the operator at his operating or work station. All limitations, warnings, specifications and safety data should be displayed
  21. Wire rope should be removed from service when the conditions listed in 29 CFR 1926.550(a)(7) are found. They include outside wire wear, reduction in diameter, broken wires, distortion, corrosion, or heat damage. Special attention should be given to standing rope, such as pendants, at the end fittings. It should be determined that the wire rope is the proper diameter, length, and type of construction for that particular crane and it should be spooled evenly on the hoist drum.
  22. The cab should be clean and free from clutter. All controls should be labeled as to their function and free to return to the neutral position when released, unless designed to do otherwise. All gauges and warning lights should be operable and a fire extinguisher (at least 5-BC) should be mounted in the cab. The seat should be securely attached and the cab door should open outward and operate smoothly. Electrical and other warning signs should be posted in the cab. All glass must be safety glass with no cracks or distortions.
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