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Introduction

A customer was experiencing regular wheel bearing failure and loss of grease from the bearings in an automated crane application, within a product distribution centre. The customer had to change 40 wheel hub units over a 5 year period. NSK carried out a bearing failure analysis confirming that the wheel bearings were suffering from lubrication starvation and radial pre load. To overcome this, NSK recommended the use of pre-greased NSK Sealed Double Row Angular Contact Bearings with an increased radial internal clearance of C3. A trial of 8 wheels, using the modified crane wheel assemblies with NSK bearings, was carried out with no bearing failures reported over 12 months. The solution increased productivity and reduced maintenance costs resulting in a significant cost saving.

Key Facts

  • Material handling and warehousing
  • Frequent bearing failure resulting in customer changing 40 wheel hubs every 5 years
  • Bearing failure causing significant production down time and high costs
  • Lubrication starvation & particle ingress
  • Radial pre load problems
  • Expensive OEM parts
  • NSK Solution: pre-greased Sealed Double Row Angular Contact Bearings with C3 clearance
  • Productivity improvement & cost saving generated
  • Crane Wheel Hub
  • NSK Sealed Double Row Angular Contact Bearing

Value Proposals

  • NSK engineering conducted an Application Review and a Bearing Failure Analysis showing lubrication starvation and radial pre load within the original bearings causing subsequent failure and lubrication fall out
  • NSK engineering reviewed the original wheel design recommending the use of a pre-greased sealed NSK Angular Contact Bearing issuing modified wheel machining drawings and a fitting procedure for correct assembly
  • A trial was agreed to modify 8 crane wheels with the use of pre loaded and sealed NSK Angular Contact Bearing
  • The result of the trial was an increase of bearing life, reduction of maintenance costs and increase in productivity resulting in a large cost saving

Product Features

  • Seals RSR: made of nitrile rubber reinforced with an embedded steel disc
  • Contact seals providing excellent protection against the ingress of contamination, reducing wear on the raceways and ball surface, reduced noise, vibration and risk of lubricant failure
  • Accommodate radial and axial forces in both directions

Cost Saving Breakdown

Before Cost p.a. NSK Solution Cost p.a.
OEM parts replacing 40 wheel hubs over 5 years €26.880 Replacement of 8 crane wheel hubs over 5 years €6.000
Loss of production: Cost incurred when crane fails €30.000 Loss in production: no failures
€0
Labour costs: Maintenance time €10.000 Labour costs: Maintenance time €2.000
NSK Engineering consultancy €4.000 Wheel hub modification, NSK bearings & Cost of machining €4.704
Total Costs €70.880 €12.704

Reference:SS-E-2051