Power Transmission

Question 1

Define spur gears

Answer 1

The most common gear which connects two parallel shafts. Has backlash

Question 2

Define helical gears

Answer 2

Gear with angled teeth which has less backlash and less noise than spur gears. Has a resultant thrust along the gear axis, which requires a thrust bearing to withstand the load

Question 3

Define bevel gears

Answer 3

Connects 2 perpendicular shafts, but are expensive

Question 4

Define rack and pinion

Answer 4

Pinion is a round gear that transfers rotational motion to linear motion on a rack

Question 5

How would you reverse the direction of power using belts

Answer 5

A) connect the driving pulley to 2 idler pulleys that drive the driven pulley (reversing open belt configuration)
B) cross the belt from the driving to driven pulley (reversing crossed belt)

Question 6

What is the formula for gear ratio

Answer 6

“driven teeth/driving teeth” or “driven ang speed/driving ang speed” or “driving torque/driven torque”

Question 7

Define idler pulleys

Answer 7

A pulley that can change the direction of power, keep the belts in proper tension and reduce vibrations

Question 8

Belts vs chains

Answer 8

Belts: lighter, easier to spot wear, less maintainance, quieter, don’t need lubrication, run on pulleys
Chains: stronger, more precise, don’t slip, narrower, run on sprockets