Slew Bearing  Change out of Platform Crane



ALATAS Singapore was recently tasked with replacing the slew bearing on a client’s American Aero lattice boom crane located offshore in Sabah, Malaysia. This complex project required a detailed plan and was delivered as a turnkey solution. ALATAS utilized a jacking system for the replacement and provided a modular design, with over 75% of components being interchangeable across different crane configurations.


The customer noted an acceleration in the wear particles and increase in the axial clearance measurements was noted indicating wear of the slew beairng. The customer engaged with Alatas to supply the slew bearing, design the jacking system and carry out the offshore mobilisaiton.

ALATAS’ Solution

ALATAS Singapore provided a full turnkey solution, coordinating across multiple offices to ensure high-quality and efficient service. The project involved several key steps:

  1. The ALATAS Singapore engineering team conducted an initial site survey of the crane to gather crucial data for the design process.
  2. The ALATAS UK design team developed the jacking system solution.
  3. ALATAS Singapore fabricated the jacking system’s structural components.
  4. The company supplied the specialist jacking console, and hydraulic cylinders, and produced detailed work packs and RAMS (Risk Assessment and Method Statements).
  5. ALATAS Singapore engineers and field service technicians conducted full onshore trials and completed the offshore delivery of the project.

Job Scope

Jacking Frame Design:

  • Review crane data to select the most suitable jacking method.
  • Create a 3D model of the crane.
  • Design the jacking frame based on the crane’s pedestal and chassis dimensions.
  • Check stress values using predicted loads.
  • Design a skidding frame to facilitate the efficient replacement of the slew bearing.

Jacking Frame Fabrication:

  • Establish Inspection Test Plans (ITP) and quality plans.
  • Fabricate the jacking frame and supply all necessary fixings.
  • Perform Non-Destructive Testing (NDT) and other testing.
  • Provide a manufacturing record book and certification pack.

Jacking Frame Construction:

  • Manage the construction of access and load-bearing scaffolding.
  • Develop a lift plan and rigging for positioning the jacking frame components.
  • Assemble and test the jacking system.
  • Conduct pre- and post-NDT of welds.

Slew Bearing Changeout:

  • Disconnect and remove the slip ring.
  • Remove both slew motors, brake packs, and gearboxes.
  • Remove slew bolts.
  • Perform a controlled trial lift to determine the center of gravity.
  • Jack up the crane.
  • Check pedestal flatness using a laser and provide a condition report.
  • Remove the old slew bearing and install the new one.
  • Jack the crane back down.
  • Install and tension the inner and outer slew bolts.
  • Reconnect the slip ring.


  • Conduct a full visual inspection.
  • Complete backlash, rocking motion, and teeth flank contact checks.
  • Perform a function test.
  • Conduct a load test using water bags and a load cell.

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