Cleat height and spacing are not catalogue defaults. They are a compromise between three things: holding the product on the incline, providing enough pocket volume for the required flow rate, and keeping the belt light enough to run on the existing pulleys and return path.
This guide gives a starting method, a worked capacity example and a field checklist. Use it to narrow the design before you ask a belt maker or cleat welder for a final specification.
Key Takeaways
– Start with the incline angle and the largest product, not with a standard cleat height.
– Pitch is measured centre-to-centre. The clear opening is what the product actually sees.
– For an 800 mm belt with 150 mm openings, 50 mm cleats and 200 mm pitch, a 60% fill at 30 m/min gives about 32 m³/h.
– Taller cleats do not always increase capacity. They can reduce return clearance, trap material and damage fragile products.
Quick Answer: Start With Incline Angle and Product Size
For a free-flowing bulk material on a 20–25° incline, a 32–50 mm cleat with 200–300 mm pitch is a common starting point. At 30–35°, move toward 50–75 mm cleats and 150–250 mm pitch. Above 40°, use 75 mm or a custom profile and check whether a sidewall is needed.
These are starting ranges, not a standard. The correct height depends on the material’s angle of repose, the belt speed, the product size and the discharge condition. A timed test with the actual material is more valuable than a table.
What Cleat Height Does for Material Retention
A cleat creates a pocket that carries material up the incline. The height of the cleat sets the depth of that pocket and the resistance to rollback.
If the cleat is too short, material rolls over it. The belt may still convey, but the effective capacity drops and spillage increases at the discharge. If the cleat is too tall for the product, the pocket may be deeper than necessary, the belt becomes heavier, and the cleat can interfere with scrapers, guards or the return path.
Cleat height also affects discharge. A tall cleat releases product later and can throw it further. In food or packaged-goods handling, a tall cleat may damage the product or prevent it from sitting flat. In bulk handling, a taller cleat may be the only way to hold a deep bed.
The belt cover matters too. A cleat welded to a thin cover has less material to fuse with. A very tall cleat on a light belt creates a long lever at the base. That is why cleat height and belt construction must be checked together.
How to Calculate Cleat Spacing from Belt Speed
Pitch is the centre-to-centre distance between cleats. The clear opening is:
Clear opening = pitch − cleat base width
The pocket volume is approximately:
Pocket volume = clear opening × cleat height × belt width × fill factor
The number of pockets passing per hour is:
Pockets per hour = belt speed (m/min) × 60 ÷ pitch (m)
So the throughput is:
Capacity (m³/h) = pocket volume × pockets per hour
If you know the required capacity, rearrange the formula:
Pitch = pocket volume × belt speed × 60 ÷ required capacity
Worked example: 800 mm belt, 150 mm opening, 50 mm cleat
- Belt width: 0.8 m
- Clear opening: 0.15 m
- Cleat height: 0.05 m
- Fill factor: 0.6
- Belt speed: 30 m/min
- Pitch: 0.20 m
Pocket volume = 0.15 × 0.05 × 0.8 × 0.6 = 0.0036 m³
Pockets per hour = 30 × 60 ÷ 0.20 = 9,000 pockets/h
Capacity = 0.0036 × 9,000 = 32.4 m³/h
That number is a geometric estimate. It assumes the pocket fills evenly and the product does not roll back. On a steep incline, use a lower fill factor and verify with a test.
Cleat Height vs Belt Width and Sidewall Height
Wider belts need more support across the width. A cleat that is tall relative to its base width can deflect when the belt runs over a pulley. In general, a wider base and a shorter cleat are more stable; a narrow base and a tall cleat are more likely to peel or crack.
Sidewalls change the calculation. A sidewall contains the material at the belt edges, so the cleat does not have to do all the work. On steep inclines, a cleat plus sidewall can carry a deeper bed than a cleat alone. The sidewall should be high enough to contain the bed at the maximum incline; confirm the exact relationship with the belt maker.
Do not size the sidewall from the cleat height alone. The sidewall also has to pass the pulleys, clear the skirtboard and survive the return path. A tall sidewall on a small pulley can fold or crack.
Product Size, Weight and Flow Rate
For packages and parts, the clear opening should be larger than the longest product dimension that can turn sideways, plus clearance. A pocket that is too tight causes jams; a pocket that is too wide reduces the number of items per metre and can let small items slide.
For bulk material, a common starting rule is a clear opening of at least two times the largest lump size. A very cohesive material may need a larger opening to prevent arching. A very free-flowing material may need a smaller opening to keep the bed deep enough.
Weight matters as much as size. A heavy product on a tall cleat creates a large bending load at the cleat base. If the product is heavy and the incline is steep, use a lower, wider cleat or a different profile rather than a tall thin blade.
Flow rate is the final check. Increasing pitch reduces the number of pockets per hour. If capacity is short, you can increase belt speed, increase pocket volume, or add a second cleat pattern. Increasing height alone may not solve the problem if the opening is already limiting the fill.
HOLO’s PU Timing Belt with Cleats features thermally welded cleats available in Polyurethane, Nylon, or Polyurethane-with-metal-nut variants for maximum grip and holding force.
LEARN MOREStandard Cleat Heights and Their Application Ranges
| Cleat height | Typical application | Practical limit |
|---|---|---|
| 25 mm | Shallow inclines, small parts, low beds | Limited retention above about 15° |
| 32 mm | Light bulk, packaged goods, 15–25° | Product size and fill control capacity |
| 50 mm | General bulk, 20–35° | Check return clearance and base width |
| 75 mm | Steep inclines, deep beds, 35–45° | Heavier belt, larger pulley needed |
| 100 mm | Special bulk duties, custom profiles | Confirm belt, pulley and sidewall design |
The numbers are common nominal heights, not a universal standard. A 50 mm cleat from one supplier may have a different base width and profile from another. That changes the weld area and the clear opening.
What Happens When Cleats Are Too Tall or Too Close
Cleats that are too tall can hit scrapers, guards or the return rollers. They also increase the belt’s rotating mass and the load on the splice. On a small pulley, a tall cleat may crack at the base because it cannot flex around the curve.
Cleats that are too close reduce the clear opening. The pocket becomes small, the belt carries less material per metre, and the cleat bases take up more of the belt surface. Very close spacing can also trap material between cleats and make cleaning difficult.
Cleats that are too far apart create a large unsupported span. The belt may sag between cleats under a heavy load, and the product may roll back before the next cleat arrives.
Field Test and Adjustment Checklist
- Run the conveyor at the normal feed rate, not at a reduced rate.
- Watch the discharge. If material is thrown too far, the cleat may be too tall or the speed too high.
- Check the incline for rollback. If material rolls back, reduce pitch or increase height.
- Check the return path. Look for cleat contact with rollers, guards or structure.
- Check the belt edge. A cleat that is too stiff can make the belt cup or mistrack.
- Check the motor current. A heavier cleat pattern increases starting and running load.
- Check cleat bases after the first shift. Look for lifting, cracking or discoloration.
Shop-floor note: When a customer asks for “the standard cleat spacing,” we ask for a video of the discharge. The right spacing is visible in how the product leaves the belt. A pattern that looks correct on a drawing can throw product or leave a dead pocket in real operation.
FAQ – Frequently Asked Questions
1. What is the standard cleat height for a 30-degree incline?
There is no single standard. A 50–75 mm cleat with 150–250 mm pitch is a common starting range for free-flowing bulk at 30–35°, but the material’s angle of repose, lump size and belt speed can move the answer. Test with the actual product before fixing the pattern.
2. How do I calculate cleat spacing?
Start with the clear opening required by the product, estimate the pocket volume, then divide the required capacity by the volume per pocket to find the number of pockets per hour. Convert that to pitch using belt speed. Always check that the pitch is at least the clear opening plus the cleat base width.
3. Can I add cleats to an existing belt?
Sometimes. The belt cover must be thick enough to weld or bond the cleat, and the belt must be compatible with the process. A worn, contaminated or delaminated cover will not hold a cleat. Check the belt maker’s recommendation before adding cleats to a used belt.
4. Do taller cleats always move more material?
No. Taller cleats increase pocket depth, but they also increase weight, reduce return clearance and can damage fragile products. If the clear opening is the limiting factor, a taller cleat may add little capacity. Match height, pitch and belt speed together.
Need a Cleat Pattern Review?
Send us the belt width, incline angle, product size, required capacity and a photo of the current belt. We will recommend a cleat height, pitch and welding method for the duty.
