The drum drive system is the single most problematic source of many rotary drum dryer systems.  It’s difficult to get 50 tons of steel to rotate in perfect alignment on four trunnion wheels held up by concrete and structural steel.  While that chain may look pretty stout, it still needs to be replaced every year or two because it will start to stretch from the strain of rotating the drum.  When it starts to stretch, the teeth and sprocket wear out faster. If out of alignment, the chain can pull the drum backwards or forwards. The tire or trunnion surface has to be lubricated, but not too much or too little. The drum drive and bearings need regular greasing and lubrication.  The more moving parts, the more things that can go wrong.

Keeping the drum rotating is imperative for dryer operation. Any problems in the drum drive system will eventually lead to a shutdown.  Keeping the drum drive system healthy and operating smoothly greatly decreases your chances for unplanned shutdowns.


Problems commonly seen in industry

Drive Chain

  • Drive chain too loose
  • Drive chain too tight
  • Drive chain pulling drum backward or forward
  • Misalignment

Drive teeth

  • Wear
  • Breaking
  • Falling off

Drum drive

  • Misalignment
  • Drum drive gear wear
  • Drive shaft pinion slop
  • Sprocket wear, cracks
  • Gearbox wear
  • Poor lubrication
  • VFD issues

Drum Tire

  • Surface imperfections or flaking
  • Cracks
  • Walking
  • Shim wear,
  • Shims falling out

Trunnion wheels & bearings

  • Trunnion wheel surface imperfections or flaking
  • Frequent bearing failures
  • Misalignment

Bumper wheels

  • Wear, flaking
  • Small diameter
  • Excess pressure on bumper wheel or by bumper wheel


  • Drum tire and trunnion surface
  • Bearings
  • Gears/Gearboxes

Thompson’s Remedies

Drive Chain and Teeth: Decrease stress, thrust, noise and vibration

  • Alignments
  • Replacements
  • Troubleshooting

Drum drive & drive component: Decrease loading and wear

  • Alignments
  • Replacements
  • Troubleshooting
  • Repairs

Drum Tire & Trunnion wheels: Decrease stress, thrust, and vibration

  • Alignments
  • Troubleshooting
  • Repairs
  • Refurbishment
  • Trunnion wheel replacements

Trunnion bearings: Stop unplanned shutdowns and reduce maintenance costs

  • Alignments
  • Troubleshooting
  • Replacements

Bumper wheel: An aligned system won’t be putting pressure on the bumper wheels, rendering them almost unnecessary.  Using trunnion wheels with flanges at the back of the drum allows removal of problem bumper wheels

  • Replacements
  • Troubleshooting
  • Repairs
  • Removal

Recommended preventative maintenance:

  • Drive chain replacement every 1 to 2 years
  • Silver Streak lubricant for trunnion and drum tire surface
  • Maintain regular lubrication schedule for trunnion bearings

Alignment and alignment checks

  • Check trunnion base alignment and suitability for 50 tons of precision rotation equipment
  • Trunnion wheel & bearing alignments
  • Drum drive chain alignment
  • Drum (Master) alignments

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