An AA belt is a double-sided V-belt, V-shaped on both faces (some call it hexagonal), so it can drive pulleys from either side; our AA73 belt is 1/2" (13 mm) wide, 73 inches (1854.2 mm) inside and 75 inches (1905 mm) outside. Our AA73 listing doesn't name a machine, so match the number on your old belt.
If you can read "AA" and a number on the old belt, order that size from the table below and you're done.
| AA section | Size |
|---|---|
| Width (widest point, halfway up the sides) | 13 mm (our listings: 1/2") |
| Height | 10 mm |
| The number is | Inside length in inches |
| Outside length | Number + 2" |
| Sizes we list | 20, from AA51 to AA120 |
| Smallest recommended pulley | 80 mm diameter |
Source: our product listings (number, inside and outside lengths, sizes), read 12 October 2026; belt makers' published section tables for the width, height and pulley size (see Sources).
How to read an AA belt number
On our AA listings the number is the inside length in inches, and each step in the number is 1 inch. The outside is 2 inches longer. So:
- an AA73 is 73 inches (1854.2 mm) inside and 75 inches (1905 mm) outside;
- an AA72 is 72 inches (1828.8 mm) inside and 74 inches (1879.6 mm) outside;
- an AA71 is 71 inches inside and 73 inches outside.
That is the same rule as an A belt: A and AA share the 13 mm width and the +2 inch difference. Our V-belt sizes chart covers the other sections.
Belt makers' tables give AA belts a reference (effective) length in millimetres, which sits about 2 inches above the number. For the AA73 it is about 1905 mm, the same as our listed outside length. So if a manual gives an AA belt in millimetres, compare it with the outside column in our table, not the inside one, and take the nearest size.
Two look-alike codes to watch:
- AA is not AX. An X means cogged, so an AX73 is a cogged A73, a single-sided belt. See AX vs A, BX vs B, XPZ vs SPZ.
- AA is not A. An A belt is V-shaped on one face only. It can't take an AA's place where the back of the belt runs in a grooved pulley, so match the AA number.
The AA section: 13 mm wide, 10 mm high
An AA belt is 13 mm wide, the same width as an A belt, and 10 mm high. The width is measured at its widest point, halfway up the sides, because it has a V on the inside face and another on the back, so the flat top face is narrower. Larger double-V sections include BB (17 x 13 mm) and CC (22 x 17 mm). We don't list BB belts. We list one CC belt: the CC144 mower belt for John Deere EPC201624, listed as the deck belt on the John Deere 1504, 1505, 1515, 1550, 1575, 1580 and 1585, at 144 inches inside and 148 inches outside.
Every AA size we list
Each size has its own listing, and our AA Section V-Belt listing offers all 20 sizes from one drop-down.
| Size | Inside | Outside |
|---|---|---|
| AA51 | 51" (1295.4 mm) | 53" (1346.2 mm) |
| AA55 | 55" (1397 mm) | 57" (1447.8 mm) |
| AA60 | 60" (1524 mm) | 62" (1574.8 mm) |
| AA66 | 66" (1676.4 mm) | 68" (1727.2 mm) |
| AA67 | 67" (1701.8 mm) | 69" (1752.6 mm) |
| AA71 | 71" (1803.4 mm) | 73" (1854.2 mm) |
| AA72 | 72" (1828.8 mm) | 74" (1879.6 mm) |
| AA73 | 73" (1854.2 mm) | 75" (1905 mm) |
| AA75 | 75" (1905 mm) | 77" (1955.8 mm) |
| AA77 | 77" (1955.8 mm) | 79" (2006.6 mm) |
| AA80 | 80" (2032 mm) | 82" (2082.8 mm) |
| AA85 | 85" (2159 mm) | 87" (2209.8 mm) |
| AA86 | 86" (2184.4 mm) | 88" (2235.2 mm) |
| AA90 | 90" (2286 mm) | 92" (2336.8 mm) |
| AA96 | 96" (2438.4 mm) | 98" (2489.2 mm) |
| AA102 | 102" (2590.8 mm) | 104" (2641.6 mm) |
| AA105 | 105" (2667 mm) | 107" (2717.8 mm) |
| AA108 | 108" (2743.2 mm) | 110" (2794 mm) |
| AA112 | 112" (2844.8 mm) | 114" (2895.6 mm) |
| AA120 | 120" (3048 mm) | 122" (3098.8 mm) |
Source: our product listings, read 12 October 2026. Every size is 1/2" (13 mm) wide.
Not in the table? Send us the number on your old belt and we'll check.
Why double-V belts exist: serpentine drives
A double-V belt is made for serpentine drives, where the belt snakes round several pulleys in one plane and some of them turn the opposite way. The inside of the belt drives some pulleys and the back drives others, so a driven pulley can change direction without crossing the belt. Our AA listings describe them as made for drives where power is transmitted on both sides of the belt, used widely in agricultural machinery, and built to handle the sudden changes of direction as the belt travels.
Mowers use them too. Our AA96 mower belt, the same AA96 size, replaces Kingcat and Cox belt V27 and is listed for Castelgarden (our listing spells it Castlegarden) and Stiga 38" cut rear discharge mowers and the Kingcat Wildcat Savanah side discharge (6999I and 7300J). Our listings name other belts for the Kingcat 7300J too (V25, V26 and V28, on other drives), so check the V number on your old belt.
How to get the right AA belt
- Read the number on the old belt. AA plus a number is all you need.
- No number? Check the shape and measure. A V on both faces means a double-V belt; 13 mm across its widest point (halfway up the sides, not across the flat top) means AA. Measure round the outside and take 2 inches off to get the AA number.
- Find it in the table. Not there? Send us the number or measurements and we'll check.
- Fit it to the maker's routing. On a serpentine drive the routing decides which side of the belt meets each pulley, so follow your machine maker's manual, or have a mechanic fit the belt. Our belt listings say all parts need to be fitted by a licensed technician.
Which Bearings Express belt fits
- Pick the AA73 V-belt for an AA73: 73 inches inside, 75 outside.
- Pick the AA72 V-belt for an AA72, or the AA71 or AA77 for those sizes.
- Pick the AA Section V-Belt, AA51 to AA120 to choose any of our 20 AA sizes from one listing.
- Pick the AA96 mower belt to replace belt V27 on the Castelgarden, Stiga and Kingcat models it lists.
All 20 AA sizes are in the AA section V-belt collection; the AA96 mower belt is listed separately.
Questions people also ask
What is a double V-belt?
A V-belt with a V on both faces, so pulleys can grip it from the inside and the back. AA, BB and CC are the double-V versions of the A, B and C sections.
Can I use an A belt instead of an AA belt?
Not where the back of the belt drives a grooved pulley: an A belt only has a V on one face. Match the AA number on the old belt.
Are your AA belts Kevlar?
None of our AA listings is described as Kevlar. If your old belt had a K in its code, match the old belt, as our Kevlar mower belt guide explains, and send us the number.
What brand are your AA belts?
They're aftermarket belts, PIX brand, with Allwyn supplied where a PIX size is unavailable.
Related reading
- V-belt sizes chart: A, B, C, Z (M) and SPZ widths, and how to read the number
- AX vs A, BX vs B, XPZ vs SPZ: what the X means on a V-belt
- Do I need a Kevlar mower belt? Kevlar vs standard V-belts
Sources
- Optibelt, optibelt DK Double V-Belts product range (profiles AA/HAA, BB/HBB, CC/HCC: belt height and width, minimum pulley diameter, conversion from belt number to reference length), https://a.storyblok.com/f/192292/x/9dd4283262/optibelt-dk-product-range.pdf, linked from https://web.optibelt.com/en/v-belts/optibelt-dk-4076283192253, read 12 October 2026.
- Gates Australia, Industrial Power Transmission South Pacific Catalogue (2018): Hi-Power II Dubl-V, pp. 43 to 44 (sections and AA effective lengths); minimum recommended pulley and idler diameters, pp. 174 to 175. Read 12 October 2026.
Checked against belt makers' double-V tables and Bearings Express product listings on 12 October 2026.
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