Nuts, welding, and riveting, including rivets on the electric hoist casings rope anchorage, should be checked to ensure they are secure. Examine the rail endstops and seating of the bumpers and endstops. Crane wheels are clearly visible when the bumper plates are removed from the endtruck. Also inspect the flat cable used to supply current to the trolley, hoist, or crane. No visible damage or sharp bends should be present. Collector heads of the downshop power supply should be free from oil, grease, paint, and dirt. Badly bent busbars must be straightened or replaced immediately. Carbon sliders should be regularly checked for wear and replaced immediately when worn to prevent damage to the busbars or short circuit conditions. When heavy wear is found on wheel flanges, the crane runway should be examined to determine whether it still conforms to tolerances and requirements. Damaged cables, in particular the round cable to the push button pendant in the floor control must be replaced immediately.
Inspection
A daily visual inspection is important to safe crane operation. In addition, a complete inspection at 1-to-12-month intervals is recommended. A crane idle for more than a month should be inspected thoroughly. Several deficiencies should be looked for during this inspection:
Deformed, cracked, or corroded members
Loose bolts or rivets
Cracked or worn sheaves or drums
Worn, cracked, or distorted parts, such as pins, bearings, shafts, gears, rollers, and locking and clamping devices
Excessive wear of chain drive sprockets and excessive chain stretch
Cracks on crane hooks using magnetic particle or other suitable methods
Pitting or any deterioration of controller contractors, limit switches, pushbutton stations, or other electrical apparatus.
Periodic inspections of wire ropes are not only necessary, but also required by OSHA regulation, and, as a result, must be properly documented. A thorough inspection should be performed at least monthly.
The reason for the critical nature of the inspection is that the wire rope itself is literally "consumed" during use. The rope gradually loses strength during its life and must be carefully checked to assure that it retains sufficient strength to perform the required work during the period before the next inspection.
Wire ropes should be relaxed and at rest when inspected. Each rope must be treated individually. There are several possible areas of deterioration:
- Reduction of rope size below nominal diameter due to loss of core support, internal or external corrosion, or wear of the outside wires
· Number of broken outside wires and degree of distribution or concentration of these wires
· Worn outside wires
· Corroded or broken wires at end connections
· Corroded, cracked, bent, worn, or improperly applied end connections
· Severe kinking, crushing, cutting, or unstranding.
Critical points along any given rope should receive more attention than others, because some areas are usually subjected to greater stresses, forces, and hazards. Critical areas include pickup points, or sections of rope which are repeatedly placed under stress when the initial load of each lift is applied, such as those sections in contact with sheaves. Other critical points include end attachments; equalizing sheaves or sections of a rope in contact with and adjacent to sheaves, as on boom hoist lines; drums; and sheaves. The inspection should look for signs of heat exposure and "bright spots" which indicate abuse, such as contact with cross members of a trolley frame or load. Regular lubrication extends the life and properties of wire rope. If in doubt as to safe working strength or condition, do not hesitate to install a new wire rope. Make sure the equipment is right for the application when new purchases are required. Qualified technicians should carry out planned or preventive maintenance contracts or repair service. Employee safety and productivity both benefit with an awareness and concern for safe working practices.
Typical crane inspection checklist
Endtruck
· Check wheels for wear
· Girder bolts (410 ft-lb)
· Drive unit bolts
· Check wheel bearings for lubrication if not lifetime sealed
· Grease open gearing
· Adjust brakes
· Power pick up arm installation
· Check endtruck bumper
· Check oil level in gearboxes
Girder
- Check tagline and trolley endstop installation
· Check trolley rail for wear
- Inspect condition of walkway/platform
Electrical
· Check contactor points
· Tighten electrical connections on all motors and terminals
· Examine pendant and taglines
· Verify proper function of master switches and electrical accessories
· Ensure proper fitting and condition of all cables
· Ensure supply voltage within ï% when hoist is operating
- Ensure amperage on all motors equal on all phases
Hoist/Trolley
· Torque drive unit bolts (see endtruck)
· Check oil level (grease) in drive gear
· Check oil level in hoist gear if not lifetime sealed
· Check bottom block for deformation/ cracks and free sheave movement
· Adjust hoist, trolley, and bridge travel brakes
· Check trolley bumper
· Lubricate and inspect rope guide, pressure ring, and wire rope
· Limit switch bar movement (if applicable)
· Check limit switch up and down
· Check sheaves for wear
· Check trolley wheels for wear
- Check bridge wheels for wear (endtruck)
General
· Check power feed and collectors
- Examine runway endstops, rail alignment, and splices
Functions
· Test hoist brakes with full load
· Run trolley in low and high speed full length of girder
· Test accessories for proper function
- Run crane in low and high speed full length of runway
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