FCGear WormGear

Description
The worm can be considered a special case of a helical gear. Imagine that there is only one tooth on a spur gear. Now increase the helix angle so much that the tooth winds around the spur gear several times before it emerges on the opposite side. The result would be a single thread worm.

For a single-start worm, each full turn (360 degrees) of the worm advances the gear by one tooth. So a gear with 24 teeth will provide a gear reduction of 24:1. For a multi-start worm, the gear reduction equals the number of teeth on the gear, divided by the number of starts on the worm.

A worm can only be used with a worm wheel. This is called a worm drive. Like other gear arrangements, a worm drive can reduce rotational speed or transmit higher torque. One of the major advantages of worm gear drive units are that they can transfer motion in 90 degrees. A worm drive is also self-locking.



Usage

 * 1) Switch to the [[Image:FCGear_workbench_icon.svg|16px]] FCGear Workbench.
 * 2) There are several ways to invoke the command:
 * 3) * Press the button in the toolbar.
 * 4) * Select the option from the menu.
 * 5) Change the gear parameter to the required conditions (see  below).

Properties
An FCGear WormGear object is derived from a Part Feature object and inherits all its properties. It also has the following additional properties:

Data

 * : Pitch diameter.
 * : Value of the worm length.
 * : Module is the ratio of the reference diameter of the gear divided by the number of teeth (see also the information in ).
 * : change the rotating direction from right to left.
 * : Number of teeth (see also the information in ).


 * : (read-only) Lead angle (see also the information in and ).


 * : Default is 20° (see also the information in ).


 * : Default is 0,25 (see also the information in ).
 * : Default is 0,00. This value is used to change the tooth height.



Useful formulas

 * = arctan ( * : )
 * = arctan ( : ( * ))
 * = 4,5 * *
 * = 4,5 * *

Worm wheel
The worm wheel must be designed manually. For this purpose FCGear InvoluteGear can be used for a simple construction. In any case, in-depth knowledge of the gear types is required.