Ways to Transmit Power

Question 1

belt drives

Answer 1

a belt mounted on a pulley to transmit power

VCR, sewing machines, clothes dryers and bikes

adjustment is critical because slippage occurs when belts are too loose and friction increases when belts are too tight

Question 2

Which has more MA?

a small pulley with a belt turning a larger pulley

or

a large pulley with a belt turning a smaller pulley

Answer 2

a small pulley with a belt turning a larger pulley

smaller pulley is easier to turn & will rotate at a higher rpm

when the input pulley is larger than the output pulley, there will be an increase in the speed of the output pulley but it will be harder to turn the input pulley

Question 3

RPM

Answer 3

revolution per minute

Question 4

How do you find the ratio between two pulleys?

Answer 4

counting the number of input pulley turns needed to turn the output pulley one turn

Question 5

Equation for the MA of belt drives

Answer 5

comparing the ratio of diameter of the pulleys

MA Ratio = output pulley diamete / input pulley diamete

Question 6

Compound belt drives

Answer 6

used to increase or decrease the rpm when a greater MA is needed

two or more sets of pulleys are used to assemble a belt drive train

Question 7

Compound belt drives formulas

Answer 7

MA Ratio = output D / input D x output D / input D

Question 8

Chain drives

Answer 8

chain mounted pm a sprocket to transmit power

can transmit more power because of the strength of the chain

chain adjustment, weight, noise and chain wear are disadvantages

Question 9

gear system

Answer 9

a wheel with teeth spaced around the circumference of the rim

performs the same function as a belt or chain drive but can transmit more power and never slips

Question 10

Why do gears last longer than belts?

Answer 10

each gear wheel transmits power to the next gear directly through the meshed teeth

Question 11

Spur gear

Answer 11

most common type of gear

Question 12

Idler gears

Answer 12

the gear that is placed between the input and output gears

their purpose is to change the direction the output gear turns, but does not affect the ratio between the input and output gear

Question 13

How can the MA of an gear system increase?

Answer 13

by using a smaller input gear and meshing it with a larger output gear

MA Ratio = output gear teeth / input gear teeth

Question 14

Gearing up

Answer 14

when the bigger gear turns the smaller gear

Question 15

Gearing down

Answer 15

when the smaller gear turns the bigger gear

Question 16

When are gear trains used?

Answer 16

when MA or rpm has to be greater than one set of gears can handle

MA Ratio = (output gear teeth / input gear teeth)(output gear teeth/input gear teeth)

Question 17

Worm gear

Answer 17

designed to mesh with spur gears and allows a 90 degree change in the direction of the motion

can only be used as input gears

Question 18

crown gear

Answer 18

change the direction of motion

does not have as much MA as the worm gear because of its size

to change direction, a crown gear can be combined with a small spur gear

Question 19

bevel gear

Answer 19

formed by cutting a 45 degree angle into one side of the gear teeth

can also be used to change direction of motion

when two 45 degree bevel gears are meshed, rotational energy is transferred by 90 degrees

no speed reduction – same amount of teeth

Question 20

rack and pinion gears

Answer 20

used when straight line linear motion is needed

Question 21

rack

Answer 21

a block of material with teeth mounted on it

Question 22

How does a rack and pinion gear cause linear movement?

Answer 22

when the pinion gear rotates and moves the rack

one revolution of the a pinion gear will move the rack the circumference of the pinion

the large the gear, the more the rack will move

automobile steering systems uses the rack and pinion

Question 23

Why do cars use rack and pinions?

Answer 23

Rack and pinions are simple mechanisms where a pair of gears come together to steer a vehicle by circular and lateral motions. As the pinion, which interlocks with the rack, makes circular movements, the rack is moved side-to side.

Steering Mechanism Processes
As a steering wheel is turned, it spins the pinion, resulting in a series of other movements. Because the pinion moves in a circular fashion, and is attached to the rack, centrifugal force slides the rack back and forth. Tie rods are connected to each end of the rack, which activate the steering arms. Steering arms are connected to each wheel, and cause them to turn.

Question 24

Differential gears

Answer 24

used so that each wheel of a motor vehicle can travel a different distance when making a turn

can automatically transfer energy to two different shafts

the shaft with the least amount of friction will turn

Question 25

Cams

Answer 25

used when repeating linear motion is needed

trains & conveyor belts

Question 26

periodic motion

Answer 26

movement for a certain amount of time in the same direction

Question 27

oscillatory motion

Answer 27

axle movement first in one direction and then in another

achieved by connecting a bar to two gears