Hydro-Gear
Engine & Drivetrain

Model # 321-0510 Official Hydro-Gear hydro-gear transaxle

Here are the diagrams and repair parts for Official Hydro-Gear 321-0510 hydro-gear transaxle, as well as links to manuals and error code tables, if available.

There are a couple of ways to find the part or diagram you need:

  • Click a diagram to see the parts shown on that diagram.
  • In the search box below, enter all or part of the part number or the part’s name.

Not all parts are shown on the diagrams—those parts are labeled NI, for “not illustrated”.

We encourage you to save the model to your profile, so it’s easy to access parts and manuals for your appliance whenever you log in.

For DIY troubleshooting advice and repair guides, visit our repair help section.

Model diagram and schematic

SEARCH WITHIN THIS MODEL

?

This is the number corresponding to the part on the diagram / schematic

Search
ALL PARTS
Showing 10 of 96 parts  |

Tapping Bolt 178334
#88

Hydro transaxle diagram

Tapping bolt

Part #178334

Replaced by #587798701

?
Manufacturer substitution
This part replaces 178334. Substitute parts can look different from the original.
This item is not returnable
$5.31
16% OFF Phone Price : $6.31
In Stock
Lawn Tractor Transaxle Sealant 178322
#6

Hydro transaxle diagram

Lawn tractor transaxle sealant

Part #178322

In Stock
Compression 170417
#71

Hydro transaxle diagram

Compression

Part #170417

Replaced by #583001401

?
Manufacturer substitution
This part replaces 170417. Substitute parts can look different from the original.
This item is not returnable
In Stock
Spacer #2371 170411
#65

Hydro transaxle diagram

Spacer #2371

Part #170411

Replaced by #583001201

?
Manufacturer substitution
This part replaces 170411. Substitute parts can look different from the original.
This item is not returnable
In Stock
Miter Gear 150792
#37

Hydro transaxle diagram

Miter gear

Part #150792

Replaced by #583244201

?
Manufacturer substitution
This part replaces 150792. Substitute parts can look different from the original.
In Stock
Friction Stud 170421
#76

Hydro transaxle diagram

Friction stud

Part #170421

Replaced by #582998501

?
Manufacturer substitution
This part replaces 170421. Substitute parts can look different from the original.
In Stock
Expansion 173165
#128

Hydro transaxle diagram

Expansion

Part #173165

Replaced by #583057701

?
Manufacturer substitution
This part replaces 173165. Substitute parts can look different from the original.
In Stock
Miter Gear 150793
#38

Hydro transaxle diagram

Miter gear

Part #150793

Replaced by #583244201

?
Manufacturer substitution
This part replaces 150793. Substitute parts can look different from the original.
In Stock
Bearing.30x5 173159
#19

Hydro transaxle diagram

Bearing.30x5

Part #173159

Replaced by #532150771

?
Manufacturer substitution
This part replaces 173159. Substitute parts can look different from the original.
In Stock
Retaining Ring 170405
#53

Hydro transaxle diagram

Retaining ring

Part #170405

Replaced by #583041601

?
Manufacturer substitution
This part replaces 170405. Substitute parts can look different from the original.
This item is not returnable
In Stock

Symptoms for gas walk-behind mowers

Choose a symptom to see related walk-behind mower repairs.

Main causes: engine needs tune up, dirty or clogged carburetor, damaged flywheel key…

Main causes: uneven wheel height settings, damaged wheel, dull or damaged cutting blade…

Main causes: damaged cutting blade, loose cutting blade, damaged flywheel key, engine needs tune up…

Main causes: stale gas, engine needs tune up, bad spark plug, dead battery, bad recoil starter, faulty safety switch, ba…

Main causes: dirty carburetor, bad spark plug, clogged air filter, engine choke problems, clogged gas cap vent…

Main causes: drive control cable failure, worn or broken drive belt, bad transmission, broken drive wheel…

Repair guides for gas walk-behind mowers

These step-by-step repair guides will help you safely fix what’s broken on your walk-behind lawn mower.

How to replace a lawn mower spark plug

How to replace a lawn mower spark plug

Take a few minutes to replace the spark plug during your lawn mower's annual tune-up or if the spark plug is burnt or cr…

Repair difficulty
Time required
 15 minutes or less
How to replace a lawn mower blade

How to replace a lawn mower blade

Check your lawn mower blade regularly and replaced it if it's bent or damaged. …

Repair difficulty
Time required
 15 minutes or less
How to replace a lawn mower flywheel key on a flathead engine

How to replace a lawn mower flywheel key on a flathead engine

When you hit a hard object with your mower, the flywheel can shear to protect more expensive components. Learn how to re…

Repair difficulty
Time required
 45 minutes or less

Effective articles & videos to help repair your walk-behind mowers

Use the advice and tips in these articles and videos to get the most out of your walk-behind lawn mower.

How to enjoy all the online benefits we offer on our Sears PartsDirect website

How to enjoy all the online benefits we offer on our Sears PartsDirect website

Learn about all the convenient features on our Sears PartsDirect website that make your parts purchases easier.…

Introducing new technical repair content that we’re developing for the Sears Technical Institute

Introducing new technical repair content that we’re developing for the Sears Technical Institute

Learn about Sears Technical Institute and the advanced technical content being developed for aspiring appliance techs.…

Top questions about Sears and Sears PartsDirect

Top questions about Sears and Sears PartsDirect

Get answers to frequently asked questions about Sears and Sears PartsDirect.…