Spur gears – find manufacturers and suppliers

Spur gears transmit rotational motion and torque between two parallel shafts.

They belong to the category of gear drives and are the most important design in engineering.

What makes them special:

• The teeth are arranged on a cylindrical wheel body.
• The rotational movement is transmitted positively by the engagement of the teeth.
• This allows the speed and torque to be changed.

Types of spur gears

a) Straight-toothed spur gears

• Teeth run parallel to the wheel axis.
• Advantage: Simple and inexpensive to manufacture.
• Disadvantage: Tooth engagement results in ‘jerky’ transmission → leads to rattling noises and vibrations, especially at high speeds.
• Application: Lower speeds, simple gearboxes.

b) Helical spur gears

• Teeth are inclined at a certain helix angle (usually 15–30°) to the wheel axis.
• Advantage: Several teeth are in mesh at the same time → smooth running, higher load capacity, less noise.
• Disadvantage: The helical cut creates axial forces that must be absorbed by bearings.
• Application: Motor vehicle gearboxes, machine tools, high-performance gearboxes.

c) Special types

• Double helical teeth (arrow teeth): Two helical teeth in opposite directions → axial forces cancel each other out.
• Internal gearing: Teeth are located on the inside of the wheel. This allows planetary gearboxes to be constructed.

Mode of operation

• When the tooth flanks roll, a pure rolling motion occurs (theoretically without sliding).
• In practice, there is a small amount of sliding → lubrication is necessary.
• The transmission ratio is determined by the pitch diameter or the number of teeth.

Advantages and disadvantages

Advantages

• Very high efficiency (up to 98%).
• Simple design, comparatively easy to manufacture.
• Wide range of torque and speed possible.
• Long service life with good lubrication.

Disadvantages

• Only suitable for parallel shafts (unlike bevel gears or worm gears).
• Straight teeth: noisy and prone to wear at high speeds.
• Helical teeth: additional axial forces → more stable bearings required.

Applications

Spur gears are found in almost all areas of mechanical engineering and vehicle construction:

• Vehicle transmissions (manual transmissions, automatic transmissions).
• Mechanical engineering (machine tools, conveyor systems, pumps).
• Energy systems (e.g. wind power transmissions).
• Household appliances (mixers, drills).