Spur gear module 3 z=21 with hub
Available product promotions:
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Weight0,92kg
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UPC Code5908453536914
Product Description
Spur gear module 3, z=21, with hub
The spur gear module 3 shown, 21 teeth, with hub, is a basic component of module drives - it meshes with any other gear or gear rack (toothed rack) of the same module and pressure angle 20°. The gear is made of C45E steel (EN 10083-1); the involute tooth profile and 20° pressure angle ensure smooth, quiet meshing with gears or racks of the same module.
Technical data
| Module (m) | 3 |
| Pressure angle | 20° |
| Number of teeth (z) | 21 |
| Type | Gear with hub |
| Outside diameter (De) | 69 mm |
| Pitch diameter (Dp) | 63 mm |
| Hub outer diameter (d) | 45 mm |
| Pilot bore diameter (D) | 15 mm |
| Tooth width (h) | 30 mm |
| Overall hub height (A) | 50 mm |
| Weight | 0.92 kg |
| Material | C45E steel (UNI EN 10083-1) |
Frequently asked questions
How should gears be stored correctly before installation?
Preferably in a dry room, protected against moisture and dust, with a light layer of preservative oil on the teeth and bore - especially important for C45E carbon steel, which can start to corrode without protection.
Are module gears from different manufacturers with the same module interchangeable?
The meshing geometry (module, pressure angle) is standardised, so such gears will mesh with each other, but bore or hub dimensions may differ between manufacturers - when replacing, it is worth checking this before installation.
Do straight-tooth module gears have a specific mounting direction?
No, a straight-tooth gear is symmetrical and can be mounted either way round; direction only matters with helical teeth, where the helix angle must match the mating gear.
Can a module gear be painted or lacquered?
Yes, the external surfaces (sides, circumference) can be protected with lacquer, but the teeth and the mounting bore should remain clean, because the coating would change their actual dimensions and disrupt meshing with the other gear.
Where is this product used?
Used in the construction and servicing of gear reducers and gear transmissions for agricultural and construction machinery, and wherever precise and repeatable torque transmission matters.
When placing your order, please check the current stock level of this gear - the lead time depends on it and is clearly stated according to the quantity available in the given warehouse.
Product photos are for illustrative purposes only.
Product Features
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Weight0,92kg
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UPC Code5908453536914