How to Replace the Drive Belt on a Sunmix Easy Line Spiral Mixer

This guide explains how to replace the toothed drive belt on a Sunmix Easy Line spiral mixer and correctly reset the belt and chain tension afterwards. It applies to the Easy Line 6, 10, 15 and 20 machines using the chain-driven layout shown below.

Important: Switch the mixer off, unplug it from the mains and make sure it cannot be switched on before removing the top cover. This work exposes electrical components and moving parts, so it should only be carried out by somebody competent to work on the machine. Never run the mixer with the cover removed.

What you will need

  • The correct replacement toothed drive belt
  • Allen keys for the motor mounting bolts
  • Spanners or sockets for the spiral bearing housing nuts
  • A flat-bladed screwdriver and a small hammer or mallet
  • A one-handed trigger clamp or quick-grip bar clamp
  • A wooden or plastic lever or packing piece

1. Remove the top cover

With the machine completely isolated from the electrical supply, remove the top cover to expose the drive belt, chain, sprockets and motor mounting bolts.

2. Release the chain tension

Loosen the four retaining nuts on the spiral bearing housing. This is item 4 in the exploded parts diagram below. Do not remove the nuts completely.

Once the nuts are loose, slide the spiral bearing housing backwards by a few millimetres. This should create enough slack in the chain to remove the connecting link.


Sunmix Easy Line 6, 10, 15 and 20 spiral mixer exploded parts diagram showing spiral bearing housing part 4

3. Remove the chain

  1. Turn the chain by hand until the split link, also called the connecting or master link, is easy to reach.
  2. Using a flat-bladed screwdriver, carefully tap the spring clip off the link. Covering the link with a cloth can help stop the small clip from flying away.
  3. Remove the outer plate and connecting link, then put all three parts somewhere safe.
  4. Lift the chain off the sprockets and move it clear of the drive belt.

4. Remove the old drive belt

Loosen the three Allen bolts securing the motor. They only need to be slackened, not fully removed.

Slide the motor forwards to release the belt tension, then lift the old toothed belt off the small motor pulley and the large driven pulley.

5. Fit and tension the new belt

  1. Fit the new belt over both pulleys, making sure the teeth are fully seated in the pulley grooves.
  2. Pull the motor backwards to tension the belt.
  3. If a little extra leverage is needed, use a wooden or plastic lever or packing piece between substantial points. Do not use metal directly against the pulley flanges, belt or belt teeth.
  4. Hold the motor in position and tighten the three Allen bolts evenly.

The belt needs to be taut enough that the teeth cannot jump under load, but it should not be excessively tight. Too little tension will allow the belt to skip and quickly damage the new belt. Too much tension can cause premature bearing wear.

Inside a Sunmix Easy Line spiral mixer showing the drive belt, chain, sprockets and adjustable bearing housings

6. Refit the chain

  1. Route the chain around the sprockets in its original path.
  2. Refit the connecting link and outer plate.
  3. Refit the spring clip and make sure it is fully seated in both grooves. The closed end of the clip should face the direction of chain travel.

7. Reset the chain tension

Use a one-handed trigger clamp or quick-grip bar clamp to draw the spiral bearing housing and sprocket towards the front of the machine. Protect the stainless-steel body with a piece of wood or plastic so the clamp cannot mark or dent it.

Apply only enough pressure to remove the slack from the chain. The chain should be taut, not heavily stretched. Keep the drive shaft square and perpendicular to the chassis throughout, as incorrect alignment will cause the chain to run badly.

Once the tension and alignment are correct, tighten the four spiral bearing housing nuts evenly to lock the housing in place.

8. Final checks and test

  1. Turn the drivetrain carefully by hand and check that the belt and chain remain correctly seated.
  2. Make sure all fasteners are tight and remove every tool, clamp and loose part from the machine.
  3. Refit the top cover and all guards before reconnecting the electrical supply.
  4. Run the mixer briefly and listen for any knocking, clicking, chain slap or belt skipping.

If the machine runs smoothly and quietly, the job is complete. If anything sounds wrong, switch it off and unplug it immediately, then recheck the belt tension, chain tension and shaft alignment before using it again.

If you are unsure which belt your machine needs, please contact Pizza Solutions with the mixer model and serial number before ordering.

If you are at all unsure about being able to complete this work yourself, you can send the machine to use for the work to be completed. Please get in touch.

Back to blog