Inside every URAL drive axle, the differential splits torque left and right — and the last gear in that chain before the axle shaft is the side gear 375-2403050-20 (Russian: шестерня полуоси). With 22 teeth and a weight of 2.255 kg, it is one of the most-loaded gears in the truck: every metre the wheels turn under power goes through it. This guide covers the specs, the fitment, and the one replacement rule you must not break.
What the side gear does
The side gear sits inside the differential case (like the 375-2403022 housing from the previous article in this series) and meshes with the spider (planet) gears. It transmits torque from the planet gears to the axle shaft — one side gear per shaft. When the truck turns, the side gears spin at different speeds; when it goes straight, they spin together. Either way, they carry full drive torque.
Worn side gears show up as backlash in the driveline: clunks on take-off, a "slack" feeling when you get on and off the throttle, and metal in the axle oil.
Specifications
| Property | Value |
|---|---|
| Part number | 375-2403050-20 (also written 375240305020) |
| Name | Side gear / шестерня полуоси |
| Brand | URAL |
| Group | Rear axle — differential assembly |
| Teeth | 22 |
| Weight | 2.255 kg |
| Assembly diagrams | Appears on 41 drawings |
Which trucks does it fit?
The side gear serves the middle- and rear-axle reducers of:
- Ural-375
- Ural-4320 (including 4320-31)
- Ural-43202
- Ural-5557
The 41-diagram footprint makes it one of the most widely-used gears in the URAL catalogue. Quantity per vehicle tells the real story: on the Ural-4320 middle and rear axle drawing it is listed ×4 (2 side gears per axle × 2 axles) — a 6x6 truck carries a lot of these.
The golden rule: replace as a set
This is the line from the OEM catalogue that matters most:
When replacing, the side gears and pinions must be renewed as a set.
Gears wear in as matched partners. A new side gear meshed with a worn spider gear wears rapidly and noisily — and you will be opening the axle again within months. The correct overhaul kit is always side gears + spider gears + their washers together.
Before you order
- Match the full number 375-2403050-20 against your parts book.
- Verify the tooth count: 22 teeth.
- Order the complete differential gear set, not single gears.
- Count axles: a 6x6 overhaul needs 4 side gears just for the middle and rear axles.
Where to look it up
Full specifications and all 41 assembly diagrams with position numbers are on the part page:
375-2403050-20 Side gear — kamaz-parts.com
The catalogue covers 87,000+ KAMAZ, URAL, MAZ, MTZ and TATRA part numbers organized by the original OEM drawing structure (brand → model → assembly group → position table), so you can verify any number against the actual assembly drawing before ordering. Wholesale inquiries go straight from the part page — mixed pallets welcome, export paperwork included.
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