1 Mod 49-55 Teeth Spur Gear Transmission Gear With Step 45# Steel Motor Gears

The tooth count determines your gear ratio. Divide the driven gear teeth by the driving gear teeth to get the ratio. For example, pairing a 50T gear with a 25T pinion gives a 2:1 reduction. Choose a higher tooth count (e.g., 55T) for more torque at lower speed, or a lower count (e.g., 49T) when you need a closer-to-1:1 ratio with a similar mating gear.

45# carbon steel offers the best strength-to-cost ratio and suits most indoor mechanical drives. 304 stainless steel adds corrosion resistance for humid or wet environments. Blue engineering nylon is lighter, runs quieter, and requires no lubrication, making it ideal for low-load, noise-sensitive applications such as 3D printers or educational robots.

Measure your motor or shaft output diameter with a caliper. Select the bore that matches exactly — a bore that is too large will cause runout and vibration. If your shaft has a keyway, also match the keyway width and depth (e.g., a 14 mm shaft with a 5×2.3 mm key requires the "14mm(5×2.3mm)" variant).

Yes. All gears in this series follow the 1M (module 1) standard with a 20° pressure angle, which is the most common specification for DIY CNC, robotics, and automation components. They will mesh correctly with any other 1M gear, rack, or pinion of the same pressure angle.

The stepped hub is a raised cylindrical boss on the gear face that extends axially (typically 40 mm on the 52T variants). It allows the gear to be positioned and retained on a shaft without additional spacers or collars. If your design already uses shaft collars or the gear sits against a bearing face, a non-stepped variant may be simpler. If you need a self-locating gear, choose a stepped variant.

For outdoor or high-humidity use, select the 304 stainless steel variants, which resist rust and surface oxidation. The 45# carbon steel variants are best kept in dry, indoor environments or protected with a light machine oil coating. Blue nylon gears are inherently moisture-resistant but may absorb small amounts of water over time, which can slightly affect dimensional tolerances.

Order 1 piece if you need a single replacement or are prototyping. Order 2 pieces for paired drive stages (e.g., both sides of a dual-shaft gearbox). Order 3 pieces if you are building multiple identical axes or want a spare on hand — the per-unit price is lower in multi-packs.