Deck 12: Reading Linkage, Cam, Gear, and Bearing Prints

Question 1

Cam profile is the actual contour of the cam.

Answer 1

TRUE

Question 2

A complete cam cycle has taken place when the cam has rotated 360°.

Answer 2

TRUE

Question 3

The elements of the gear structure include the face, hub, bore, keyway, and outside diameter.

Answer 3

TRUE

Question 4

Chordal thickness is the straight line thickness of a gear tooth on the pitch circle.

Question 5

Cluster gears always turn in the same direction.

Question 6

Mechanical devices and machines have arrangements of parts called mechanisms.

Question 7

A cam roller follower is the same type as a knife-edged cam follower.

Question 8

A cam profile can be constructed using the related cam displacement diagram.

Question 9

When two gears are in mesh, the larger is called the pinion and the smaller is called the gear.

Question 10

Circular pitch is the distance from a point on one tooth to the corresponding point on the adjacent tooth, measured on the pitch circle.

Question 11

Bearings are mechanical devices used to reduce friction between three or more surfaces, and are designed to accommodate either rotational or linear motion.

Question 12

A cam is a machine part used to convert constant rotary motion into timed irregular motion.

Question 13

The projection from one or both faces that occurs in some gears is called the bore.

Question 14

The components of mechanisms are known as kinetics.

Question 15

A cam displacement diagram is similar to a graph representing the cam profile in a flat pattern of one complete 360° revolution of the cam.

Question 16

Displacement is the total movement of the cam follower that happens in one 360° rotation of the cam.

Question 17

A cam follower is a specialized type of device designed to follow movement.

Question 18

Bearings are dimensioned in relation to the bore diameter, outside diameter, and the width.

Question 19

Dwell exists when a cam follower is constant without moving either up or down.

Question 20

A cam, a cam shaft, and a hub are all basic components of a cam mechanism.

Question 21

If a dwell exists in a cam cycle, the cam follower can jump if the application speed is too high.

Question 22

End thrust is a disadvantage of helical gears.

Question 23

Spur gear teeth are straight and parallel to the gear shaft axis except for those found in the herringbone gear.

Question 24

Uniform accelerated motion is designed to reduce the abrupt change at the beginning and end of a period.

Question 25

Simple harmonic motion can be used for high speed applications if the rise and fall are equal to 180°.

Question 26

Crossed helical gears, which provide for nonintersecting right angle shafts with low load carrying capabilities, are the only mating gears that rotate the same direction.

Question 27

Spur gears and helical gears are designed with parallel shafts.

Question 28

Simple harmonic motion and constant velocity motion can both be used at high speeds.

Question 29

Spur gears carry more load than equivalent sized helical gears and operate more quietly and smoothly.

Question 30

The base circle, which surrounds the cam shaft, is a member of a cam mechanism.

Question 31

Cylindrical roller bearings have a high radial capacity and assist in shaft alignment.

Question 32

Mating spur gear teeth have the same diametrical pitch.

Question 33

Splines are usually stronger than keyways and keys.

Question 34

If you know the gear ratio of a pair of mating gears, you also know the diametrical pitch.

Question 35

Cycloidal motion is the most popular cam profile development for smooth-running cams at high speeds.

Question 36

Constant velocity motion, also known as straight-line motion, is used for the feed control of some machine tools when it is required for the follower to rise and fall at a uniform rate.

Question 37

Cycloidal comes from the word cycloid. A cycloid is a curved line generated by a point on the circumference of a circle as the circle rolls along a straight line.

Question 38

Bevel gears are similar to hypoid gears in that the gear shaft axes in both types intersect.

Question 39

Simplified gear representations are commonly used on prints.

Question 40

When it is necessary for the follower to move in a path parallel to the axis of the cam, a drum cam is used.

Question 41

Which of the following is not part of a cam print?

A) a chart giving the values of the angles of the follower at each position
B) the cam profile
C) hub dimensions, including cam shaft, outside diameter, keyway dimensions
D) construction lines
E) none of the above

Question 42

Which one of the following types of gears is commonly used when a large speed reduction is required in a small space?

A) helical gears
B) worm gears
C) hypoid gears
D) crossed helical gears
E) none of the above

Question 43

Which of the following is not a basic type of cam?

A) knife-edge cam
B) plate cam
C) face cam
D) drum cam
E) none of the above

Question 44

When it is required for the follower to rise and fall at a uniform rate, ____ is used.

A) constant velocity motion
B) simple harmonic motion
C) Straight line motion
D) both a and c
E) none of the above

Question 45

The terms pitch diameter, addendum angle, dedendum angle, outside diameter, crown height, pitch angle, pitch cone, and face width pertain to which type of object?

A) bevel gears
B) cluster gear drawings
C) rack and pinion gears
D) spur gear trains
E) none of the above

Question 46

A pinion gear operates at 2400 rpm, has 65 teeth, and has a gear ratio of 5:1 with its mating gear. Given this information about the pinion, what information can be found about the gear?

A) The gear operates at 480 rpm, has 325 teeth, and has a diametrical pitch of 5.
B) The gear operates at 12,000 rpm, has 13 teeth, and has a diametrical pitch of 5.
C) The gear operates at 480 rpm, has 13 teeth, and has a diametrical pitch of 3.
D) The gear operates at 480 rpm, has 325 teeth and the diametrical pitch cannot be determined.
E) none of the above

Question 47

The pitch diameter of one gear is 96 in. and the pitch diameter of its mating gear is 24 in. What is the gear ratio, and how many teeth does the smaller gear have?

A) gear ratio = 4:1, smaller gear has 8 teeth
B) gear ratio = 1:4, smaller gear has 8 teeth
C) gear ratio = 4:1, smaller gear has 6 teeth
D) gear ratio = 4:1, not enough information to calculate number of teeth either gear has
E) none of the above

Question 48

Cam displacement diagrams involve the usage of several terms. Which of the following is not associated with a cam displacement diagram?

A) displacement
B) cycle
C) fall
D) dwell
E) none of the above

Question 49

A "lead" is one of the terms used for ____.

A) rack and pinion gears
B) worm gears
C) sleeve bearings
D) hypoid gears
E) none of the above

Question 50

Even in a detailed drawing of a bevel gear, simplified representations are used, so in the circular view, the outside diameter and the root diameter are shown as centerlines, and the pitch diameter is shown as a phantom line.

Question 51

Kinetics is an element of physics that deals with the effects of forces that cause motion in mechanisms.

Question 52

Diametrical pitch is related to the tooth size of the gear in that ____.

A) as the diametrical pitch increases, the tooth size also increases
B) in mating gears, the diametrical pitch as well as the tooth size, must be identical
C) the diametrical pitch can be found by a formula in which the number of teeth are given for that gear
D) both a and b
E) none of the above

Question 53

Helical gears have their teeth cut at an angle, allowing more than one tooth to be in contact.

Question 54

There is a gear ratio of 3:1 between a pair of gears. The pinion gear has 18 teeth. How many teeth does the other gear have?

A) 6 teeth
B) 9 teeth
C) 36 teeth
D) 54 teeth
E) both a and d

Question 55

Which of the following is a disadvantage when working with molded plastic gears?

A) reduced weight
B) increased efficiency
C) greater thermal expansion and contraction
D) corrosion resistant
E) none of the above

Question 56

What is the distance between two shafts of mating gears if the pitch diameter of one gear is 18 in. and the pitch diameter of the other gear is 36 in.?

A) 18 in.
B) 24 in.
C) 30 in.
D) 48 in.
E) none of the above

Question 57

If you know the number of teeth on a gear and you know the pitch diameter, you can find the size of the teeth.

Question 58

This is used when a change in direction is desired between the gear and pinion:

A) bevel gears
B) spur gears
C) herringbone gears
D) rack and pinion gears
E) none of the above

Question 59

Kinematics is the study of mechanisms without reference to the forces that cause the movement.

Question 60

There is a gear ratio of 3:1 between a pair of gears. One gear has 18 teeth. How many teeth can the other gear have?

A) 6 teeth
B) 9 teeth
C) 36 teeth
D) 54 teeth
E) both a and d

Question 61

Identify the type of motion designed to reduce the abrupt change at the beginning and end of a period. It is recommended for moderate speeds, especially when associated with a dwell. The advantage of this motion is its use when constant acceleration for the first half of the rise and constant deceleration for the second half of the rise are required.

Question 62

In a cam cycle, this is a segment of follower operation such as rise, dwell, or fall.

Question 63

What is a cam?

Question 64

Name the type of gears that are conical in shape, allowing the shafts of the gear and pinion to intersect at 90° or any desired angle. The teeth have the same shape as the teeth on spur gears except they taper toward the apex of the cone, and provide for a speed change between the gear and pinion.

Question 65

A prime circle ____.

A) has a diameter equal to the diameter of the base circle added to the radius of the cam follower
B) is only used in the construction of an inline follower plate cam profile
C) passes through the center of the follower at the 0° position
D) both a and c
E) none of the above

Question 66

The size of teeth of a gear can be found if given the proper type of information. For example, the circular pitch of the gear is equal to p (3.1416) divided by the diametrical pitch, and the outside diameter is equal to the pitch diameter added to twice the amount of the dedendum. The trick is to know which pieces of information will help find the answer in the least amount of time. If you are given values to any of the answers below, you will be able to find the size of teeth of this particular gear. Which one will give you the answer in the least amount of time?

A) You are given the circular thickness.
B) You are given the addendum and the whole depth.
C) You are given the circular pitch and the number of teeth.
D) You are given the number of teeth, the pitch diameter, and the diametrical pitch.
E) You are given the outside diameter, the addendum, the whole depth, and the number of teeth

Question 67

Gears are rugged and durable and can transmit power with up to _____ efficiency with long service life.

A) 80%
B) 90%
C) 98%
D) 100%
E) none of the above

Question 68

When it is necessary for cam followers to travel in a path that is parallel to the axis of the cam, ____.

A) a drum cam is used
B) a cylinder with a groove machined in the surface in the shape of the cam profile is used
C) the cam displacement diagram shows two parallel lines along its entire length
D) both a and b
E) all of the above

Question 69

This is similar to a graph representing the cam profile in a flat pattern of one complete 360° revolution of the cam.

Question 70

Define gear train, give the function of gear train, and define the terms gear and pinion in you discussion.

Question 71

Identify the type of motion that is the most popular cam profile development for smooth-running cams at high speeds.

Question 72

Describe the A, B, and C gear hubs.

Question 73

Some gears have nonintersecting shafts that are at right angles. Which of the following is not in this category?

A) worm gears
B) crossed helical gears
C) bevel gears
D) hypoid gears
E) none of the above

Question 74

What are the three types of cams? Which is the most common?

Question 75

Identify the type of cam used when it is necessary for the follower to move in a path parallel to the axis of the cam.

Question 76

What is a gear and for what is it used?

Question 77

Given the following example of an SAE spline specification, identify the components A through D.
SAE 2 1/2-10 B SPLINE
(A) = SAE
(B) = 2 1/2
(C) = 10
(D) = B

Question 78

Define dwell related to cam terminology.

Question 79

Identify the type of motion, also known as straight-line motion, used for the feed control of some machine tools when it is required for the follower to rise and fall at a uniform rate, and is only used at slow speeds because of the abrupt change at the beginning and end of the motion period.

Question 80

Identify the type of motion that can be used for high-speed applications if the rise and fall are equal at 180°. Moderate speeds are recommended if the rise and fall are unequal or if there is a dwell in the cycle. This application causes the follower to jump if the speeds are too high.