EducateNXT

GearingLEGO parts required for gearing activities:

GEARS

24 teeth (or 24-tooth crown)

40 teeth

8 teeth

AXLES 16 x 1 LEGO Brick

Bushings

EducateNXT

Gearing

A B

If Gear A turns clockwise, which way will Gear B turn?

Using any two gears with the same number of teeth, make the following gear system.

EducateNXT

A B C

Gearing

If Gear A turns clockwise, which way will Gear C turn?

EducateNXT

A 40 teeth B 40 teeth

Gearing

How many times will you need to turn Gear A so that Gear B turns one rotation?

EducateNXT

B 40 teethA 8 teeth

How many times do you have to turn Gear A to turn Gear B one rotation?

Gearing

You should get five times.

EducateNXT

A 24 teeth

B 40 teeth

Gearing

Before you make this gear train, predict how many times you will need to turn Gear A in order to turn Gear B one rotation.

Now make it and check your answer.You should get a little more than 1.5 times. What is the exact gear ratio?

EducateNXT

3 times

1.67 times

A 8 teethB 24 teeth

C 40 teeth

GEAR RATIO

Gearing

Multiple simple gear ratio =

3 x 1.67 = 5

Check to see that five turns of Gear A will cause one turn of Gear C.

EducateNXT

Compound GearingA compound gear ratio is the total multiplied gear ratio of all gears in a gearbox.

It works by having a smaller gear on the same axle as a larger gear.

EducateNXT

Compound Gearing

Construct the above compound gear train with three axles.

EducateNXT

3

3

Compound Gearing

Total gear ratio =

3 x 3 = 9

Check to see if 9 turns of A = 1 turn of B

A B

EducateNXT

Now make your own compound gear ratio. How big a gear ratio can you come up with?

Compound Gearing

Here’s one way to do it.

EducateNXT

Resources

Gears have been drawn using EasiDraw Gear for Microsoft Word. www.myeasidraw.com

LEGO piece diagrams in Slide 1 from www.peeron.com

EducateNXT