1. Increased Simultaneous Iterlocking

   Number of teeth interlocking at a time may be more than tripled as compared with a cylingrical worm gear.

2. Improvement in Contact-Line Position

   A contact-line position, or a contact area can be improved by way of changing an inclination angle of a worm tooth.

   Fig.3 shows a good contact area.

3. Reduced Sizw & Weight

   As is shown it  Fig.4, the size of a wheel may be made smaller by about 30% as compared with 

   a cylindrical worm gear, resulting in considerrable reduction also in weight.

4. Grindability

   The teeth surfaces both of a worm and, a worm wheel may be ground.

5. Reduction in Pressure on Unit Surface

   As is explained in the above, pressure on a unit surface is decreased, resulting in reduction

   of temperature rise and wearing.