Guide

Linked by
Shared Axle
Driven Gear
Driving Gear
12-Toot h
60-Toot h
Compound Gear
Reduction
= 25 / 1
Say “25 to 1 Compound
Gear Reduction”
(60 / 12) x (60 / 12)
(5 / 1) x (5 / 1)
cont.
G.9
Mechanisms Gear Ratio Exercise #4: Compound Gear Reductions
(Grades 6-8)
Student Name(s):
Teacher/Class: Date:
Review of Key Points:
In a Compound Gear system, there
are multiple gear pairs. Each pair has
its own Gear Ratio, and a shared axle
connects the pairs to each other. The
resulting Compound Gear system
still has a Driving Gear and a Driven
Gear, and still has a Gear Reduction.
However, it is now called a Compound
Gear Reduction that is calculated by
multiplying the gear reductions of each
of the individual gear pairs.
For the example shown with
12-tooth and 60-tooth gears,
the overall Gear Reduction is
calculated this way:
Driving Gear 1 Driven Gear 1 Driving Gear 2 Driven Gear 2
Simplied
Reduction 1
Simplied
Reduction 2
Compound
Gear Reduction
12-toot h 60-tooth 12-toot h 36-tooth
/ / /
12-toot h 36-tooth 12-toot h 36-tooth
/ / /
12-toot h 36-tooth 12-toot h 60-tooth
/ / /
Gear Pair 1 Gear Pair 2
Instructions:
Using the information above from Compound Gears and Compound Gear Reductions (G.3),
demonstrate what you have learned by calculating the correct Compound Gear Reductions.
You may also build and use the VEX IQ Gear Ratio Simulator along with 12-tooth, 36-tooth, and
60-tooth kit gears to help nd answers.