Crane Alignment Issues

An overhead crane that is out of alignment and skewing as it travels down the runway can cause significant stresses and damages to the entire crane system. The problem with a crane that isn’t tracking properly is that over time, forces that weren’t accounted for in the design and installation of the overhead crane cause stresses to the runway beams themselves and also to the tie-backs or building support structures.

These types of stresses can result in:

  • Accidents
  • Crane failure or derailment
  • Equipment downtime and productivity loss
  • Costly repairs and replacement of parts

A crane that isn’t tracking properly also causes extensive wear to the wheels, wheel bearings, and wheel flanges—as well as premature wear to the motor drives and other equipment.

There are certain signs that your crane may not be aligned properly and is skewing as it moves down the runway. When your crane is in operation, be aware of the following:

  • Loud scraping sounds
  • Broken or cracked wheel flanges
  • Abnormal wear on the wheels, wheel bearings, and rails
  • Extra power required to move the crane through certain areas of the runway
  • Wheels that float or climb over the rail and then crash down

The best way to prevent overhead crane skew and alignment issues is to have your crane regularly inspected by a reputable third-party service provider. A crane service provider can survey your crane rails and runway systems to identify and correct any issues before they become bigger problems.

A crane service provider can make sure that your overhead crane system is in compliance with the allowable tolerances specified by the Crane Manufacturers Association of America (CMAA) for the design of the runway system.

  • CMAA Specification #70 – 1.4.2: “Rails shall be straight, parallel, level, at the same elevation and at the specified center to center distance, within the tolerances given…”
    • Crane Span Tolerance:
      • Less than 50 feet: ± 3/16”
      • 51-100 feet: ± 1/4″
      • Greater than 100 feet: ± 3/8”
    • Straightness Tolerance: ± 3/8”
    • Elevation Tolerance: ± 3/8”
    • Rail-to-Rail Elevation Tolerance:
      • Less than 50 feet: ± 3/16”
      • 50-100 feet: ± 1/4″
      • Greater than 100 feet: ± 3/8”
  • CMAA Specification #70 – 1.4.5: “Rail joint misalignment can be a significant factor in the wheel, axle, and bearing failures. It is recommended that horizontal rail separation at joints not exceed 1/16”. Vertical and horizontal alignment at joints should be maintained as closely as possible. Rail joints should be ground flush as necessary to provide a smooth transition from each rail segment to the next.”

– Overhead Crane Solutions Inc.

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