Belt Tension Adjustment – Hand Fed Brush Chippers

Belt Tension Adjustment

New belts stretch very soon and must be adjusted several times in the first few hours of operation. Adjust after one hour of operation, then every four hours until the belts quit stretching. Failure to do this will cause the belts to burn and fly off, which is not covered under warranty.

GENERAL RULES FOR TENSIONING

  • Check tensioning during the first 2 through 48 hours of run-in operation especially.
  • Over tensioning or under tensioning shortens belt and bearing life.
  • Keep belts free from foreign materials that may cause the belt to slip.
  • Make V-drive inspection on a periodic basis. Never use belt dressing as this will damage the belt and cause early failure.
  • Belts should never be forced over the sheave. Allow enough room for belts to slip on.
  • Always make sure sheaves are aligned properly.

TENSIONING PROCEDURE

Main Drive Belts

Follow all pre-maintenance shut down procedures. Locate the centre of the belt span between the sheaves. Push or pull on the belt until the belt has deflected 3/8” (9.5 mm). Record the push or pull force. The force should be 9 to 10 lbs./belt (4.1 to 4.5 kg/belt). Adjust the belt tension if the force falls outside of this range. If belts are not properly adjusted belts will slip, glaze over, and be ruined.

This is NOT covered by warranty.

  • Remove beltshield.
  • To adjust the belt tension, loosen the four engine mounting bolts and the jam nuts on the engine adjuster on the radiator end of the engine.
  • Adjust the belt tension with the engine adjuster on the clutch end of the engine. If you have to push the engine with the adjuster, the belts will tighten slightly after the engine is realigned.
  • Use the engine adjuster on the radiator end of the engine to realign the engine, so the engine sheave and chipper sheave are aligned. The sheaves can be checked with a string or straight edge.
  • Torque the two engine mounting bolts (see Torque Chart for the correct torque) on the opposite side of the engine from the engine adjusters.
  • Loosen the jam nuts on the engine adjuster on the radiator end of the engine.
  • Torque the engine mount bolt and then tighten the engine adjuster jam nuts on the radiator end.
  • Hand tighten the remaining engine mount bolt. Loosen the engine adjuster jam nuts all the way and torque the engine mount bolt.
  • Tighten the engine adjuster jam nuts on the clutch end.
  • Recheck the belt tension and alignment, if readjustment is needed go back to step 2.
  • Reinstall beltshield.

Pump Drive Belts (If equipped)

  • Locate the centre of the span between sheaves.
  • Push or pull down on the belt until the belt has deflected 1/4” (6.4 mm).
  • Record push or pull down force. The force should be 9 lbs (4.1 kg).
  • Adjust the belt tension if the force falls outside of this range.
  • Do not over tighten the hydraulic pump belt. For best results use a good belt tension tester. Most all pump failures result from too much side load on the pump shaft. Too much belt tension is very easy to detect inside a failed pump. Pumps with this condition will not be covered under warranty.

NOTICE

  • Lbs./belt (kg/belt) is per 1 belt. If equipped with 4 groove poly band belt, lbs./belt (kg/belt) must be multiplied by 4. If equipped with two 3 groove poly band belts, lbs./belt (kg/belt) must be multiplied by 3 for each poly band belt. If equipped with 2 groove poly band belts, lbs./belt (kg/belt) must be multiplied by 2 for each poly band belt.
  • It is a good practice to rotate the belts during tensioning. Then recheck deflections. The belts may need to be tightened again.