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A customer was experiencing catastrophic bearings failures in a rotary coal valve within an Ore Preparation Plant. Failures were occuring up to three times in one year resulting in significant lost production and damage to associated components. NSK Engineers carried out an application review identifying which showed that the current bearing design was inadequate for the high temperatures involved.
NSK recommended a customized RHP HLT bearing insert within a Self-Lube® cast iron FC housing with a special heat isolating spacer. A trial was conducted with NSK Applications Engineering overseeing the correct fitting of the bearing units within the application. The NSK bearings fitted ran for over 12 months with no bearing failure. In addition the need for compressed air cooling was removed. This resulted in a large overall cost saving for the customer.

Key Facts

  • Rotary Coal Valve
  • Overheating of bearings
  • Incorrect lubrication amounts and frequencies
  • NSK Solution: RHP HLT bearing insert within a Self-Lube® cast iron FC housing, with NSK custom designed adaptor plate with additional heat resistant material ring
  • Significant cost saving generated by extended bearing life and by removing the unnecessary compressed air cooling.
  • Rotary Coal Valve
  • RHP HLT Self-Lube® Bearing Unit

Value Proposals

  • NSK engineering conducted an Application Review including a Temperature Survey and a Bearing Condition Report.
  • NSK engineers recommended RHP HLT bearing insert within a Self-Lube® cast iron FC housing, with NSK custom designed adaptor plate and additional heat resistant material ring. Additonal suggested were made for changes in the lubrication intervals and amounts.
  • A trial was conducted with NSK Engineering overseeing the installation and implementation of their recommendations.
  • The customer received increased productivity and reduced maintenance costs.

Product Features

  • Special internal geometry; C5 internal clearance
  • High performance Klueber grease
  • Durable silicone rubber seals
  • Steel cage material
  • Interchangeable with standard Self-Lube® inserts
  • High performance grease and effective lubrication at extreme temperatures, with upper and lower limits of –40°C/-40°F and +180°C/356°F
  • Efficient sealing and protection at extreme temperatures (–40°C/-40°F and +180°C/356°F)
  • Steel cage and special internal features designed to function at extreme temperatures.
  • Increase radial clearance (C5) between balls and raceways to help prevent radial preload

Cost Saving Breakdown

Before Cost p.a. NSK Solution Cost p.a.
$9,004/hour x 8 hours shift x 3 times per year $216,096 No downtime $0
$45/hr x 8 hours shift x 2 engineers x 3 times per year $2,160 $45/hr x 8 hours shift x 2 engineers $720
Cost of bearings x 3 times per year $383 Cost of bearings once per year $128
Annual cost of compressed air $95,358 No compressed air used $0
Total Costs $313,997 $848



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