G Type vs GD Type Universal Joint: What Is the Difference?

When selecting a precision universal joint, one of the first questions is whether to use a G type or GD type universal joint.

Both are designed to transmit torque between shafts operating at an angle, but their structures and application conditions are different.

What Is a G Type Universal Joint?

A G type universal joint is a single universal joint configuration.

It is generally used when two shafts require angular transmission and the shaft arrangement is relatively straightforward.

Typical advantages

• Compact structure
• Simple installation
• Suitable for angular shaft transmission
• Suitable for many machine-tool applications
• Easy to customize

What Is a GD Type Universal Joint?

A GD type universal joint is a double universal joint configuration.

Two joint sections work together to provide greater flexibility for shaft arrangement.

GD configurations are particularly useful when the transmission system involves more complex shaft geometry.

G Type vs GD Type

Which One Should You Choose?

Choose a G type universal joint when:

• You only need angular transmission
• Shaft arrangement is relatively simple
• Installation space is limited
• A compact design is preferred

Choose a GD type universal joint when:

• Shaft alignment is more complex
• Parallel offset needs to be considered
• Greater articulation is required
• A double-joint arrangement is suitable for the machine design

Important Angle Consideration

A common mistake is to assume that a double universal joint automatically means that each joint can operate at 90°.

This is incorrect.

The allowable angle of each joint depends on its design.

For Apex precision universal joints, a single joint is generally specified for up to approximately 45°, while a suitable double arrangement can provide greater overall articulation.

Always confirm the actual angle according to the model.

G/GD Universal Joint Customization

Apex supports customized:

• Bore
• Keyway
• Hex hole
• Square hole
• Spline
• Shaft connection
• Length
• Material
• Bearing configuration

For a custom G/GD universal joint, provide your shaft dimensions and operating requirements.

See the [Apex U Joints product page] for available configurations.