Quick answer: five dimensions have to match when you replace a 25.4 mm pitch flat top belt: pitch, module thickness, the bottom guide configuration, the sprocket tooth form and count, and overall width. Pitch on its own settles very little here, because 25.4 mm is one inch and it is the most crowded pitch in the range. Six straight running series and three radius series share it. Thickness and open area are what separate them.
Why one inch is so crowded
Modular belting grew out of imperial engineering, and one inch became the general purpose pitch: fine enough to run a small nose radius, coarse enough to build strength into the module. Every maker put a general purpose family there, and our range is no different. Measure a pitch of 25.4 mm and you have removed most of the catalogue and none of the difficulty.
The practical effect on a replacement enquiry is that pitch is the entry ticket rather than the answer. What follows is the shortlist and the properties that split it, and if the old belt still carries a legible code, the fields inside a modular belt part number narrow that shortlist before you pick up a caliper.
Every 25.4 mm series we make
This table is the working document for a one inch replacement. Read down the thickness column first, because module thickness is the fastest way to eliminate candidates with a caliper.
| Series and surface | Thickness | Belt strength | Open area | Material |
|---|---|---|---|---|
| 1000 flat top | 8.7 mm | 16,700 N/m PP, 39,300 N/m POM | 0% | PP / POM / PE |
| 7200 flush grid | 8.8 mm | Not published | Not published | PP / PE |
| 966 flat top | 9.5 mm | 26,800 N/m POM | 0% | PP / POM |
| 966 flush grid | 9.5 mm | 26,800 N/m POM | 25.3% | PP / POM |
| 976 flat top | 10 mm | 14,650 N/m PP | 0% | PP / PE |
| 976 perforated flat top | 10 mm | 14,650 N/m PP | 7.7% | PP / PE |
| 986 flat top | 10 mm | 18,056 N/m PP, 30,851 N/m POM | 0% | POM / PP |
| 986 flush grid | 10 mm | 18,056 N/m PP, 30,851 N/m POM | 22.8% | POM / PP |
| 976 nub top | 11.2 mm | 14,650 N/m PP | 0% | PP / PE |
| 7705 flat top | 12.5 mm | 23,300 N/m PP, 52,800 N/m POM | 0% | POM / PP |
| 966 raised rib | 14.5 mm | 26,800 N/m POM | 25.3% | PP / POM |
Three radius series also run at 25.4 mm: 916 at 13 mm thick and 60% open, 2400 at 13 mm and 44.2% open, and 7100 at 12.8 mm and 44.2% open. These are for conveyors that turn a corner. If your line runs straight, ignore them, and if it curves, none of the straight running series above will work no matter how well the pitch matches.
Look at what the table is telling you. Between 8.7 and 10 mm sit five different closed flat top belts whose strengths run from 14,650 to 39,300 N/m. A 1.3 mm difference in thickness separates the lightest from the strongest. That is why the caliper matters more than the paperwork at this pitch.
The five dimensions, in the order they bite
| Dimension | Why it must match | How to capture it |
|---|---|---|
| Pitch | Decides whether anything engages at all | Measure across ten hinges, divide by ten. 25.4 mm is exactly 1 in. |
| Module thickness | Decides frame clearance, nose bar clearance and transfer plate height. It is also the fastest discriminator between one inch series. | Caliper across a module, top surface to bottom surface, away from any rib or nub |
| Bottom guide configuration | Decides whether the belt tracks. A flat bottom belt in a guided frame walks off within a shift. | Photograph the underside of a module. Count ribs running in the direction of travel and measure the frame slot. |
| Sprocket tooth form and count | Same pitch does not mean same pocket. Tooth count sets pitch diameter, so it sets where the belt surface sits. | Count teeth, photograph one sprocket in profile, measure the shaft |
| Overall width | Decides how many modules the belt is built from, and whether it fits between the rails | Measure edge to edge across the direction of travel, and separately measure the frame opening |
The order matters because each one filters the next. There is no point comparing belt strengths before you know whether the belt is guided underneath by bottom strips, because the guided and unguided versions come from separate moulds.
Strength is the second cut, not the first
Once thickness has shortlisted two or three candidates, use strength and open area to choose between them.
The strength figure is per metre of belt width, and it sets the maximum length you can pull. If the belt you are replacing was 976 in PP at 14,650 N/m and the conveyor has been fine for four years, you do not need 52,800 N/m. What you might need is a different material in the same geometry: the 986 series reads 18,056 N/m in PP and 30,851 N/m in POM at the same 10 mm thickness, so a material change buys strength without touching a single dimension on the machine. That is the cheapest upgrade available on a replacement.
Open area is the other axis. At 25.4 mm pitch you can have 0%, 7.7%, 22.8% or 25.3% without changing pitch or, in the 986 and 966 cases, without changing thickness either. If the original line was specified as a closed flat top and the plant has since started washing product on it, this is the moment to say so, because moving from a flat top to a flush grid at the same series is a straight swap on the same sprockets.
The inch to millimetre trap
Nominal catalogue widths in this industry are inch dimensions written in millimetres, and they do not survive rounding. A flat top chain plate listed at 82.6 mm is 3.25 in. One listed at 152.4 mm is exactly 6 in. The module and width steps behave the same way: 25.4 is 1 in, 38.1 is 1.5 in, 76.2 is 3 in, 304.8 is 12 in.
Two things follow. A catalogue width will not agree with your caliper to the tenth of a millimetre, and that disagreement is normal rather than a sign that you have the wrong belt. And a nominal figure copied off an old order tells us what somebody wrote down, not what is on the machine.
So send us the number you measured, and write the word measured next to it. A supplier can convert a measured figure back to the nearest nominal width and tell you whether it lands on a standard step. A supplier cannot work forwards from a nominal figure to a frame nobody has looked at. If you measured across the belt and separately across the frame opening and the two disagree, send both numbers, because that gap is itself information about how much clearance the line was built with.
What to send with the enquiry
- Pitch measured across ten hinges, stated as measured
- Module thickness to one decimal place
- One photo of the top surface, one of the underside of a module, one of a sprocket in profile
- Belt width measured edge to edge, and the frame opening, both stated as measured
- Metres required and the number of belts
- What the belt carries, whether the line runs wet or dry, and the working temperature
- Sprocket tooth count and shaft size, plus a profile photo of the teeth if you are deciding whether the old sprockets can stay
If you have not taken the four core measurements yet, the method is in our guide on measuring a modular belt for replacement, and the rest of the pitch families are listed in the series index. For a hot or cold line, add the working temperature and read our note on thermal expansion in plastic modular belts before you fix a length.
Photos and caliper readings go through WhatsApp faster than through email, and you can send the same set through the contact form. We will name two candidates from the table above, tell you what separates them, and quote both rather than pick for you. The full one inch family sits in the straight running modular belt range.
