Plastic Spur Gear 55mm 85 Teeth for DIY Robotic

The Plastic Spur Gear 55mm 85 Teeth has a 55mm outer diameter, 85 teeth, and 6mm center hole diameter in yellow plastic, designed for DIY robotics and gear reduction builds. This spur gear has the highest tooth count of any gear in StemVolt’s spur gear lineup — 85 teeth on a 55mm body, distinct from the 55mm blue spur gear with 50 teeth covered separately, which shares the same diameter but has fewer, larger teeth and a completely different gear pitch that makes these two gears incompatible for meshing despite identical outer dimensions.

This 55mm spur gear’s 85 teeth enable the highest single-stage gear reduction available in the lineup — paired with the 15-tooth pinion gear, it delivers 85:15 = 5.67:1 reduction, reducing output shaft speed to less than one-fifth of motor speed while multiplying output torque nearly sixfold, all within the 55mm footprint. This plastic spur gear’s extremely fine effective pitch from packing 85 teeth into 55mm means each tooth is proportionally very small, which produces the smoothest possible mesh engagement but also the lowest individual tooth strength in the lineup.

One practical trade-off: the 85 teeth on 55mm fine pitch means this gear for robotics is the most sensitive in the lineup to shaft misalignment and debris — small particles or slight shaft angle errors that would not affect coarser gears can disrupt the fine tooth mesh and cause accelerated wear. Available from StemVolt, this unit is suitable for engineers working on high-reduction fine-pitch gear builds and practical spur gear robotics and DIY projects.

Related Products:

• Checkout Plastic Bevel Gear 50mm 24 Teeth

Features:

• 85 teeth — highest tooth count in StemVolt’s spur gear lineup
• 5.67:1 reduction with 15T pinion — highest single-stage ratio available
• Fine pitch gives smoothest mesh engagement in the gear range
• 6mm center bore fits standard DC motor and robot shaft sizes
• Yellow plastic — distinct from the 55mm/50T blue variant in lineup

Technical Specifications:

Applications:

• Spur Gear used for highest single-stage reduction robot joint build
• College project uses 55mm spur gear for maximum ratio comparison
• India robot uses plastic spur gear 85T for slow precision arm drive
• DIY gearbox uses 85 teeth spur gear for ultra-slow output stage
• Precision mechanism uses gear for robotics for fine-pitch low speed

Package Includes

• 1 × Plastic Spur Gear 55mm 85 Teeth