When worm and worm wheel are used in simple screw jack as shown in Figure 13.15, it is known as compound screw jack. The worm axle is provided with a handle of length L. Let, the pitch of the screw rod be p, number of teeth on the worm wheel be T, the number of revolution of worm wheel, and screw will be 
considering one revolution of the worm.
Figure 13.15 Compound Screw Jack
Distance moved by load = Pitch × Number of revolution = 
Leave a Reply