How to Select Sidewall Height and Cleat Height for a Corrugated Sidewall Conveyor Belt

Two dimensions decide whether a corrugated sidewall conveyor belt works: the sidewall height and the cleat height. They are quoted together so often that buyers start treating them as one number, or assume the pair that ran on the last conveyor will run on the next one. Neither holds up.

Get the pair wrong one way and material spills over the top of the pocket on every pass, six days a week, onto a walkway that nobody wants to clean. Get it wrong the other way and you are buying rubber you cannot use: a 400 mm sidewall standing over a 200 mm cleat looks impressive in a photo, wastes belt width on every metre, stiffens the carcass, and forces a head pulley larger than the layout drawing allows.

This article works through the two heights in the order a project actually decides them: what each dimension does, how they are matched, how the angle sets the ratio, what the calculator cannot see, and where each of the seven industries commonly lands.

The cleat height sets the depth of the pocket. It is the dimension the capacity calculation cares about, because the pocket is what carries the material up the incline. The sidewall height sets the retaining wall above and beside that pocket. It does not add capacity on its own - it keeps the load where the cleat put it, absorbs the surge at the loading point, and contains dust while the belt is climbing.

In practice the sidewall stands 20–60 mm above the top of the cleat, which on the common sizes works out to roughly 1.1–1.25 times the cleat height. Matching them exactly is the single most common error in a sidewall conveyor belt specification. Equal heights leave nothing to catch the surcharge that builds behind each cleat at speed, and the fines find their way over the wall.

Everything sits inside one range, which is worth remembering when a quote arrives with only one number on it: sidewall heights run 40–630 mm and cleat heights 55–600 mm, in matched series rather than free combinations. QBF Rubber builds both dimensions across that range, so the pair can be matched to your tonnage and angle instead of being picked off two unrelated stock lists.

Start here before touching the capacity maths. The pairings below are the ones that show up in real projects; anything far outside them needs a reason.

A pocket on a 30° incline fills almost to the cleat tip. The same pocket at 75° is only partly full, because the material is sliding on a face instead of settling into a trough. If you size the belt at a horizontal fill ratio and then install it on a steep lift, the belt arrives on site with a capacity that exists only on paper.

Fill ratio, cleat profile and cleat pitch move together with the angle:

Two rules keep the pitch honest. The cleat spacing should be roughly 1.5–2.5 times the cleat height, tightening toward the lower end above 70° - a 200 mm cleat on a 70° lift wants something near 300–350 mm. And the pattern has to be laid out symmetrically about the belt centreline, or the belt will track badly no matter how good the rest of the spec is.

Capacity on a sidewall conveyor belt is a volume calculation. Work it in this order:

1. Required capacity (tph) ÷ bulk density (t/m³) = volume per hour (m³/h)
2. Volume per hour ÷ belt speed (m/s) ÷ 3600 = volume to be carried by one metre of belt (m³/m)
3. Volume per metre ÷ fill ratio ÷ cleat height (m) = the effective pocket width you need (m)
4. Match that width to a base belt width and sidewall height pair from the section drawing

That third step is where the arithmetic gets a reality check. Effective pocket width is not belt width. The sidewalls and their base strips occupy the edges, and a 1,000 mm base belt with 200 mm sidewalls typically carries an effective pocket width in the 550–650 mm range, not 800. Buyers who size on nominal width end up 25–35% short on capacity and cannot see where the shortfall came from.

Four physical limits sit above the maths and will override it. Check them before the number is written into a specification.

• Pulley diameter. A tall cleat cannot wrap a small pulley. As a starting point, a 160 mm cleat wants a head pulley of 630 mm or more and a 240 mm cleat wants 800 mm and above; the supplier's minimum pulley table is the authority. On a retrofit, the pulley that already exists is the ceiling on cleat height - that constraint routinely pushes the answer from a taller cleat on a narrow belt to a shorter cleat on a wider one.
• Lump size. For lumpy material, cleat height should be at least 2–2.5 times the maximum lump dimension. Below that, a lump bridges the pocket, rides over the cleat, and starts a slow chain of damage that ends in a torn cleat.
• Loading zone geometry. The skirt boards, chute and acceleration distance at the feed point have to fit the sidewall height. A deep pocket under a badly shaped chute fills unevenly, and an unevenly filled belt is a belt that will not track.
• Take-up travel and return idler spacing. Taller cleats mean a stiffer belt for the same carcass, which changes minimum pulley diameters at both ends and tightens the return idler spacing needed to keep the belt from walking.

Coal at 0.85 t/m³, 300 tph, 70° incline, belt speed 1.6 m/s, maximum lump 80 mm.

• Volume = 300 ÷ 0.85 = 353 m³/h
• Per metre of belt = 353 ÷ 3600 ÷ 1.6 = 0.061 m³/m
• At 70° the fill ratio is 0.75, so effective width × cleat height must reach 0.061 ÷ 0.75 = 0.082 m²

First pass: a 1,000 mm base belt with a 200 mm TC cleat and a 240 mm sidewall. Effective pocket width comes out at roughly 600 mm, giving 0.60 × 0.20 × 0.75 = 0.090 m³/m, which is 518 m³/h, or about 440 tph. That is a 45% margin over a 300 tph duty - more belt than the job needs.

Second pass: keep the 1,000 mm base belt and the effective width, drop to a 160 mm TC cleat at 300 mm pitch. That gives 0.60 × 0.16 × 0.75 = 0.072 m³/m, or 415 m³/h, about 353 tph - 17% margin, which is the sort of number a project wants. Lump check: 160 mm cleat against an 80 mm lump is exactly 2×, acceptable but tight, so the honest recommendation here is to stay at a 200 mm cleat if the lump size can vary upward.

The sidewall follows the rule rather than the calculation: 160 mm cleat pairs with a 200 mm sidewall, 200 mm cleat pairs with a 240 mm sidewall. Pitch, fill ratio and pulley diameter are the three numbers that close out the spec - and the cleat height on its own tells you nothing until all three are fixed.

The pairings below are starting points for a conversation, not answers. Each one is driven by a structural reason rather than a habit.

Mining
Mining sizes the cleat from the rock, not from the tonnage. A 300 mm lump under a 240 mm cleat will bridge and roll back, which is why the ore side of the industry sits on 240–350 mm TC-XS cleats with 300–400 mm sidewalls. On the underground side the pocket is often tighter than the open pit wants, because the shaft or incline was driven before the conveyor was designed.
QBF Rubber's mining configuration is built around this: the cleat height is set from the maximum lump dimension first, then the sidewall follows, then the pitch is calculated to fill the pockets at the specified tonnage.
Steel
Steel plants rarely have an angle problem. They have a height problem - there is no room to build a longer incline inside an existing bay, so the belt is pushed steeper than the layout would ideally allow. Sinter and coke are angular enough that the cleat edges take the wear that the cover rubber would otherwise absorb, and 160–240 mm cleats with 200–280 mm sidewalls are the working range.
Tunnelling and water projects
In a tunnel, the diameter is decided by the boring machine before anyone asks about conveyor geometry. That single fact pushes the specification toward the narrowest belt that still carries the muck, which means modest cleats and taller sidewalls relative to them: 120–200 mm cleats on 160–240 mm sidewalls at 30–45°. Water projects add a second case - aggregate feed for the batching plant, more often than not on a constrained site.
Power
Dry coal is easy. Wet gypsum and ash are not, and they are what sets the specification on the wet side of a power plant. Sticky material does not fill a pocket evenly, so the cleat height usually ends up one step above what the tonnage calculation alone would suggest, and the sidewall has to be high enough that nothing squeezes over the top at the loading point.
Chemical
Fertiliser, soda ash and salt are lifted into the top of silos, which makes the vertical section unavoidable. The pocket doubles as containment for a product that is both moisture-sensitive and unpleasant to clean up, so the pair is set by the lift angle and by how tightly the product must be enclosed: 140–240 mm cleats on 180–280 mm sidewalls, with cover compounds chosen for the chemical involved.
Port
A bulk terminal measures its resource in square metres of stockyard, and steep inclines are how it fits more material into the same footprint. Tonnage and lump size drive the cleat: 240–350 mm cleats with 300–400 mm sidewalls at 45–60°, which is also the range where spillage rules are enforced hardest.
Cement
Clinker is hot and abrasive, and the lifts into the silos are tall. Cleats of 200–300 mm on 240–350 mm sidewalls handle both, but the detail that matters on cement is the wear profile: the cleat base and the lower 50 mm of the sidewall take the impact, and buying a marginally shorter belt there is a false economy. 

1. Specifying one height for both dimensions. Equal sidewall and cleat heights leave no surcharge allowance, and fines go over the wall at speed.
2. Sizing on belt width instead of effective pocket width. Losing 300 mm of usable width between two sidewalls is normal; pretending it is not there is how a belt ends up 30% short.
3. Choosing the cleat height from tonnage and forgetting the pulley. The existing head pulley caps the cleat height on every retrofit, and that cap is discovered at installation.
4. Using a horizontal fill ratio at 70°. Capacity drops by 15–25% between a shallow incline and a vertical lift, before anything else changes.
5. Under-sizing the cleat for the lump. A pocket that bridges on the biggest lump stops being a pocket. Cleat height should be 2–2.5 times the maximum lump dimension.

QBF Rubber builds corrugated sidewall conveyor belts across a 40–630 mm sidewall range and a 55–600 mm cleat range, with T, C, TC and TC-XS profiles, base belt widths from 300 to 2,400 mm and tensile strength from 250 to 10,000 N/mm. The sidewall and cleat are hot-vulcanized to the base belt rather than bonded cold, with adhesion above 17 N/mm across the range - on a steep lift that bond, not the rubber, is what usually decides how long the belt lasts.

In practice the sequence runs the other way round from how quotes are usually written: maximum lump size sets the cleat height, the cleat height sets the sidewall height, the angle and tonnage set the pitch and the fill ratio, and the existing pulley diameters set the belt width. The output is a cross-section drawing with all five numbers on it. If a supplier cannot produce that drawing, they are estimating, and the estimate will be discovered on site.

Six lines settle most of this before a supplier is contacted:

1. Angle under 25° → 55–90 mm cleat, 80–120 mm sidewall, or no cleats at all.
2. Angle 25–45° → 80–160 mm cleat, 100–200 mm sidewall, T or C profile.
3. Angle 45–60° → 140–240 mm cleat, 160–300 mm sidewall, TC profile.
4. Angle above 60° → 200–350 mm cleat, 240–400 mm sidewall, TC or TC-XS.
5. Lump size present → cleat height at least 2–2.5 times the largest lump.
6. Retrofit onto an existing conveyor → cleat height capped by head pulley diameter; reduce the cleat and widen the belt if the two conflict.

Eight items produce a drawing instead of a price:

• Material, bulk density (t/m³), and whether it is abrasive, sticky or hot.
• Required capacity (tph), average and peak.
• Incline angle (°) and the lift height (m).
• Maximum lump size (mm).
• Belt speed you intend to run (m/s), or whether it is open.
• Existing head and tail pulley diameters (mm), or "to be sized".
• Space available for the loading zone, including chute and skirt geometry.
• Whether the belt is a new install or a replacement on an existing structure.

The answer should come back with a base belt width, a sidewall height, a cleat height, a cleat profile, a cleat pitch, an estimated capacity and a cross-section drawing. Anything less is a guess with a price attached.

If there is a belt in front of you that is spilling, or a layout where the pocket has to fit under an existing pulley, send the eight items above to sunny@bestfriendrubber.com or WhatsApp +86 139 6972 9233. QBF Rubber's engineers will size the sidewall and the cleat against your lump size, angle and tonnage, and send the cross-section drawing back with the quote.

And if the spec you are holding has only one height written on it, that is the first thing to question.

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