Hydro-Gear vs Tuff Torq: Which Transaxle Do I Have?
Short version: Hydro-Gear and Tuff Torq are two different manufacturers of mower transaxles, and their units are not interchangeable. The quickest way to tell which one you have is the label. A Hydro-Gear model number is letters and digits in groups, like ZD-DNBB-7MDC-24PX (or a numeric one like 1710-1066R on the biggest units). A Tuff Torq unit has a white barcode tag on the back with an 11-character part number in the top-left corner, like 7A646084181. Replace your transaxle with the same brand and the same number.
How to tell them apart
| Hydro-Gear | Tuff Torq | |
|---|---|---|
| Where the label is | A product label on the unit: "on the transaxle," or on a pump, "on the pump housing" | A white label with a barcode on the back of the transaxle (the pulley side, facing the rear of the tractor) |
| Number to order by | The full model number, format XX-XXXX-XXXX-XXXX | The 11-character part number in the top-left corner of the tag |
| Examples | ZD-DNBB-7MDC-24PX, ZC-DUBB-4MDC-3PPA (EZT), ZH-JPBB-SF7B-2XLX (ZT-2800 family), PC-AGCC-MV1X-XXXX (pump); numeric 1710-1066R (ZT-4400) and 1015-1001R (ZT-5400); older units 310-xxxx | 7A646084181, 787Q2124000, 768T2024011, 787T0124021 |
| What the start of the number tells you | The two-character prefix is the series: ZA–ZD = EZT (ZT-2200), ZH–ZM = ZT-2800/3100/3200, ZS/ZU/ZW/ZY/Z6 = ZT-3400, PG/PK/PR/PW… = pumps | The first characters are the part type: 7A646… = complete K46, K57 or related unit; 787Q0… = K58 or K72; 768T… = T40; 1A646… / 187Q… / 187T… = kits and service parts |
| Other information on the label | Serial number, year built and Julian build date; current labels add a 2D QR code | Serial number (top right), needed for repair kits; sometimes the mower maker's part number (bottom right) |
| Family names you may see | EZT, ZT-2800, ZT-3100, ZT-3200, ZT-3400, ZT-3600, ZT-4400, ZT-5400, G700, T2 | K46, K57, K58, K62/K66, K72, T40, TZT7, TL-200 |
Both brands' labels can carry the mower maker's own part number alongside their own (for example an MTD 618- number on a Hydro-Gear label, or a John Deere AM- number on a Tuff Torq tag). If that's the only number you can read, send it to us with your mower's model and serial and we'll work out which transaxle it is.
Can a Hydro-Gear replace a Tuff Torq, or the other way round?
No. They're separate designs from separate manufacturers, and a unit from one brand isn't a replacement part for the other. Even within one brand, the maker's advice is to stick to the original: Hydro-Gear "strongly discourage[s] the use of any model not originally specified by the OEM," and on the Tuff Torq side several part numbers can share one family name, so a K46BT doesn't fit where a K46AC was. Order the same brand and the same full number that's on your current unit.
If you can't read the label
- Clean it first. Grease and grass often hide numbers that are legible underneath.
- Tuff Torq: look under the rear of the machine behind the rear axle; some mowers, John Deere among them, repeat the label on a sticker under the seat pan. Our Tuff Torq part number guide has the details.
- Hydro-Gear: Hydro-Gear's own route for help is its Customer Support line. Our Hydro-Gear part number guide explains the label and prefixes.
- Either brand: send us your mower's brand, model and serial number and a photo of the transaxle, and we'll help identify it. (That's RFQQQ's own advice, not the manufacturers'.)
Find your part
| Hydro-Gear | Tuff Torq | |
|---|---|---|
| Part finder | Hydro-Gear part finder | Tuff Torq part finder |
| Shop | Hydro-Gear transaxles & parts | Tuff Torq transaxles & parts |
| Part number guide | How to find your Hydro-Gear part number | How to find your Tuff Torq part number |
Frequently asked questions
Is Tuff Torq the same as Hydro-Gear?
No. They're different manufacturers with their own designs and their own part numbering.
How do I know if I have a Hydro-Gear or Tuff Torq transmission?
Look at the label. A Tuff Torq unit has a white barcode tag on the back with an 11-character part number such as 7A646084181. A Hydro-Gear label shows a model number in groups such as ZD-DNBB-7MDC-24PX, or a numeric one such as 1710-1066R.
Can I put a Hydro-Gear transaxle on a mower that came with a Tuff Torq?
No. The units aren't interchangeable. Replace it with the same Tuff Torq part number that's on your current unit.
Where is the model number on a Hydro-Gear transaxle?
On the Hydro-Gear product label attached to the unit, which also shows the serial number. On pumps the label is on the pump housing.
Where is the tag on a Tuff Torq transaxle?
On the back of the unit, the pulley side facing the rear of the tractor. Some mowers repeat it on a sticker under the seat.
Sources: Hydro-Gear Model Identification, Cross Reference Guide, User Support, FAQ; Hydro-Gear service manuals BLN-52622, BLN-52441, BLN-0108, BLN-0081; Tuff Torq label details from our Tuff Torq part number guide.
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