Proportion Of Worm And Worm Gears

Machine Design

Gear Drives

Introduction:

Worms proportions include pitch circle diameter, face length etc.

Proportions for Worms

The following table shows the various porportions for worms in terms of the axial or circular pitch ( p_c ) in mm.

Notes:

1. The pitch circle diameter of the worm (DW) in terms of the centre distance between the shafts (x) may be taken as follows :

... (when x is in mm)

 

2. The pitch circle diameter of the worm (D_W ) may also be taken as D_W = 3 pc, where pc is the axial or circular pitch.

3. The face length (or length of the threaded portion) of the worm should be increased by 25 to 30 mm for the feed marks produced by the vibrating grinding wheel as it leaves the thread root.

Proportions for Worm Gear

The following table shows the various proportions for worm gears in terms of circular pitch ( p_c ) in mm.