# Here are all the answers you want to know about the worm gear

#### What are the characteristics of worm gear mechanism?

Answer: (1) transfer the motion and power between the spatial staggered axes, that is, the spatial mechanism.

(2) In theory, the tooth profile contact is point contact, but the worm gear is added by the hob of the worm engaged with the worm gear, which is actually space curve contact

(3) The transmission ratio of worm and worm gear is calculated with the number of worm heads < the number of lines).

(4) The pitch circle diameter of worm is not the number of heads multiplied by the modulus but the characteristic coefficient multiplied by the modulus, that is, D1 = QM

(5) The center distance of worm is also calculated by the characteristic coefficient. A = m < Q + Z2) / 2 < 6) can obtain large transmission ratio and self-locking when worm gear is active.

#### Which is the standard parameter surface of worm gear? What is the correct meshing condition?

Answer: (1) it is the main section, that is, the section parallel to the end face of the worm gear passing through the axis of the worm is called the main section.

(2) Correct engagement conditions: m A1 = m T2 = m α A1 = α T2 = α β 1 + β 2 = 900 with the same rotation direction.

#### Why is the characteristic coefficient Q of worm determined as the standard value?

Answer: (1) it is conducive to worm standardization and reduces the number of worms.

(2) The number of worm hobs for machining worm gears is reduced.

#### How to determine the steering direction of worm gearing?

Answer: first of all, determine the direction of rotation of worm or worm gear: erect the axis of worm or worm gear. The right side height of spiral line is right rotation, and the left side height is left rotation.

Then determine the turning direction: the right-hand rule is used for right-hand rotation. For the active worm, four fingers of the right hand hold the worm along the worm’s turning direction, and the thumb points in the opposite direction of the node speed of the worm gear, so as to determine the turning direction of the worm gear. 