Spiral bevel gears are typically created from hardened steel. The teeth of these gears are often ground for a far more precise finish allowing for little noise at high speeds. You can specify left hands or right hand depending on the direction you need to run the gears
If you have a high speed application that requires a lot of torque then spiral bevel gears certainly are a great option. The gears operate at 90° to one another and have “spiral” shaped teeth which gives maximum tooth surface contact while rotating. With contact spread over the complete tooth the spiral bevel equipment can be run much faster than the straight tooth bevel equipment and handle harder starts and stops.
We make spiral bevel gears only for industrial applications.
Worm gears are used in large gear reductions. Gear ratio ranges of 5:1 to 300:1 are normal. The setup was created so that the worm 
can turn the gear, but the equipment cannot change the worm. The position of the worm is certainly shallow and consequently the gear is held in place due to the friction between the two. The equipment is found in applications such as conveyor systems in which the locking feature can become a brake or a crisis stop.
The model cross-section shows an average placement and utilization of a worm gear. Worm gears have an inherent security mechanism built-in to its design since they cannot function in the invert direction.