Activity 2.2.2a Mechanical Gears Review
Read each question carefully and place your answer in the appropriate space.
Examine the picture of the VEX model below and then answer the first three
questions.
1. Name the type of movement used as an input
__reciprocating_________________________
_.
2. The output movement has been changed to
__increase, decrease______________ speed
movement.
3. We call this mechanism a ___rack and
pinion____________________________.
4. In the belt drive mechanism, what happens when the belt is crossed instead of
open? moves in the opposite direction
5. In a mechanism, when the input goes from a small gear to an output which is a
larger gear, the speed will ____decrease____________ (increase, decrease).
When this happens, the amount of torque will _increase___________________
(increase, decrease).
6. When a big gear turns a small one, the output provides more _speed__________
but less ____torque_____________ than the input.
7. Which of the following mechanisms moved slower, the worm and wheel or the
rack and pinion? _______worm and wheel______________________________
8. Which mechanism transmits rotary motion to reciprocating? ___rack and
pinion____________
9. The advantage of using a chain drive over a belt drive is __belt drives are faster
and carry more.______________________________________.
10. The advantage of using a belt drive over a chain drive is _____
_speed________________________________________________________.
11. The purpose of an idler gear is to ___spin in the same
direction__________________.
Use the formula below to determine the answers to questions 12 and 13.
Distance moved by rack = number of input turns X pitch X number of teeth on the gear
Problem: A rack with a pitch of 4 mm is used with a 20-tooth gear.
© 2011 Project Lead The Way, Inc.
GTT-AR VEX Activity 2.2.2a Mechanical Gears Review – Page 1
12. How far will the rack move when the input is given one turn?
_80mm_______________________
13. How many turns will be needed to move the rack a distance of 240 mm?
___3_____________
© 2011 Project Lead The Way, Inc.
GTT-AR VEX Activity 2.2.2a Mechanical Gears Review – Page 2