Spur Gears

The most common type of gears are spur gears, also known as straight-cut gears and can be found in a multitude of applications. They are specifically designed to transmit large amounts of power by placing them on parallel shafts which rotate in opposite directions.

Spur gears have a straight tooth, involute profile which project radially and are parallel to the rotation of the axis. This allows for a smoother operation between each gear and permits greater mounting distances. Spur gears can have a central hub or be hubless and are available in a variety of pitch, hub and bore diameters. The standard pressure angles in spur gears are 14.5, 20 and 25 degrees, and refer to the angle that force is transmitted between the meshing gears.

Spur gears are capable of meshing with other gears, with many gears being used to create large gear reductions. When they are meshed the gear with the most teeth is referred to as the gear, whereas the one with smaller teeth is referred to as the pinion.

What are the advantages of a spur gear?

  • High transmission efficiency
  • Compact and very easy to install
  • Constant velocity ratio
  • No slippage unlike belt drives
  • Highly reliable
  • Can transmit large amounts of power

Types of spur gears

Plastic spur gears are commonly made from acetal or nylon and have many positive characteristics including being lightweight, non-rusting and quiet. They enable low cost and large production capabilities and are also able to operate without lubrication. For hygiene reasons, plastic spur gears are an excellent choice for use in industries dealing with food production and medical equipment.

Metal spur gears have more strength, load-carrying capacity and heat resilience than their plastic counterpart. They are more dimensionally stable compared to plastic and can be made from many metals such as aluminium, brass and stainless steel.

Common applications

  • Metal cutting machines
  • Marine engines
  • Mechanical clocks and watches
  • Fuel pumps
  • Washing machines
  • Gear motors and gear pumps
  • Rack and pinion mechanisms
  • Material handling equipment
  • Automobile gear boxes
  • Steel and rolling mills

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Description Price Module Number of Teeth Material Bore Diameter Hub Diameter Pitch Diameter Face Width
RS Stock No. 503-1920
Mfr. Part No.S30B 30B+0302
0.3 30 Brass 2mm 8mm 9mm 3.2mm
RS Stock No. 503-2052
Mfr. Part No.S50B 20B+0303
0.5 20 Brass 3mm 8.2mm 10mm 3mm