What Is a Worm Wheel?

Worm gears are commonly used to transfer motion and power between two staggered axes. Worms and worms are equivalent to gears and racks in the middle plane, and worms are similar in shape to screws. The gear reduction ratio of the worm gear is generally 20: 1, sometimes as high as 300: 1 or more.

Introduction

If you want a larger gear reduction ratio, you need a worm gear. The gear reduction ratio of the worm gear is generally 20: 1, sometimes as high as 300: 1 or more.

Many worm gears have an interesting feature not found in other gear sets: worms can easily turn gears, but gears cannot turn worms. This is because the protruding angle on the screw is shallow. When the gear tries to rotate the screw, the friction between the gear and the screw will keep the screw in place.

Properly meshed

1. The modulus and pressure angle of the worm and the worm gear in the middle plane are equal, that is, the end face modulus of the worm gear is equal to the axial surface modulus of the worm and is a standard value; the end pressure pressure of the worm gear should be equal to the axial pressure angle of the worm and is standard value.

2. When the stagger angle of the worm gear and worm gear is, it must be ensured, and the helical direction of the worm gear and the worm gear must be the same. ^[1]

1, can get great

The worm lead angle is the angle between the tangent of the helical line on the worm indexing cylinder and the end face of the worm. The relationship between the worm lead angle and the screw helix angle is that the larger the helical angle of the worm gear is, the higher the transmission efficiency is. The mechanism is self-locking.

The worm diameter factor q was introduced to limit the worm gear

Worm gear difference

(1) Worm gear is equal to gear; worm is equal to rack.

(2) The worm is the driving member; the worm wheel is the follower.

(3) Many worm gears have an interesting feature not found in other gear sets: worms can easily turn gears, but gears cannot turn worms. This is because the protruding angle on the screw is shallow. When the gear tries to rotate the screw, the friction between the gear and the screw will keep the screw in place. ^[3]

Judgment of worm gear rotation

Determine the direction of rotation of the worm or worm gear: Set the axis of the worm or worm upright.

Judgment of steering: use the right-hand rule for right-handed rotation, the right-handed worm is right-handed, and the four fingers of the right hand are used to hold the worm in the direction of the worm.

If you want to judge the rotation of a gear at hand, you can lay the gear flat in front of you and watch the tooth direction. If the left is high, the right is low. Vice versa

Determination of helical gear rotation:

Left-handed rule: Left-handed, left-handed, right-handed thumbs coincide with the axial direction, four fingers point to the upward direction of the helical teeth, left-handed is left-handed, right-handed is right-handed (always with the back of the hand toward yourself). ^[3]