Worm Drive

The worm drive is a type of transmission that transfers motion and power between two shafts that are intersecting in space.

The angle between the two shafts can be any value, but is typically 90 degrees.

The worm drive is utilized for transmitting motion and power between the offset shafts.

A worm drive with a single spiral on it is referred to as a single-headed worm. This means that the worm rotates one full turn, causing the gear to rotate one tooth.

A worm drive with two spirals is known as a double-headed worm. In this case, the worm rotates one full turn, causing the gear to rotate two teeth.

Characteristics

The worm drive has a high transmission ratio, compact structure, and is relatively small and lightweight.

The drive is characterized by its smooth and quiet operation.

Due to the continuous, uninterrupted helical shape of the worm tooth, it meshes seamlessly with the worm gear teeth, resulting in smooth operation with minimal impact, vibration, and noise.

The worm drive also has self-locking capabilities.

When the angle of the worm’s helix is small, the worm can only drive the worm gear and cannot be driven by the worm wheel.

However, the worm drive is known for having low efficiency.

It is widely accepted that the efficiency of the worm drive is lower compared to that of the gear drive, with self-locking worm drives having an efficiency of less than 0.5 and a general efficiency ranging between 0.7 to 0.9.

Additionally, the worm drive generates a significant amount of heat and its tooth surface is prone to wear, making it a costly option.

Transmission type

Worm drives can be classified based on their shape:

• Cylindrical worm drive: characterized by a cylindrical shape of the worm.
• Toroidal worm drive: characterized by a toroidal or doughnut-shaped worm.
• Cone worm drive: characterized by a cone-shaped worm.