The following are some characteristics of zero degree spiral bevel gears: 

1、Spur Tooth Profile: Unlike conventional spiral bevel gears that have a helix angle, zero-degree spiral bevel gears have straight teeth that are parallel to the gear axis. This results in a uniform and constant tooth contact pattern.

2、High Strength Design: Zero-degree spiral bevel gears are designed to provide high strength and durability. It is capable of delivering high torque and can handle heavy loads.

3、Noise reduction: The straight teeth of zero-degree spiral bevel gears help reduce noise and vibration during operation. This makes it suitable for applications requiring quiet operation.

4、Smooth operation: The uniform tooth contact pattern of zero-degree spiral bevel gears ensures smooth and efficient power transmission. It minimizes backlash and improves the overall performance of the gear.

5、Ease of Maintenance: Due to the straight tooth profile, zero-degree spiral bevel gears are relatively easier to manufacture and maintain than traditional spiral bevel gears. This makes it more cost-effective and suitable for a wide range of applications.

It is worth noting that zero-degree spiral bevel gears are less common than other types of bevel gears. Their specific design features make them suitable for certain applications where noise reduction, high strength and smooth operation are critical.