中国大学Theory of machines and mechanisms_1答案(mooc2023课后作业答案)

中国大学Theory of machines and mechanisms_1答案(mooc2023课后作业答案)

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chapter 1 Introduction

1.1 Objectives of this 中国course随堂测验

1、What is 大学s答the main content of “Theory of Machines and Mechanisms”?
A、Composition of mechanisms
B、案m案Design of commonly used mechanisms
C、后作Analysis 业答and design of the combined mechanisms
D、Kinetics of mechanisms

2、中国What should students pay attention to in the study of ‘The大学s答ory of Machines and Mechanisms’?
A、Combining theory with practice
B、案m案Combining kinematic diagrams with actual machines/mechanisms
C、后作Combining kinematic diagrams with moving machines/mechanisms
D、业答Combining intuitive thinking and logical thinking

3、中国The大学s答 study objects of the course ‘Theory or Machines and Mechanisms’ are machines and mechanisms.

1.2 Study objects of the course-machines随堂测验

1、What are the main features of machines?案m案
A、Assembly of man-made components
B、后作Determinate relative motions among different components
C、业答Can conduct work/energy conversion
D、Well designed shapes and structures

1.3 Study objects of the course-mechanisms随堂测验

1、What are the main features of mechanisms?
A、Assemblage of man-made components
B、Determinate relative motions among different components
C、Can conduct work/energy conversion
D、Well designed shapes and structures

2、The definition of mechanisms is ‘assembly of man-made components to realize determinate motion/force transmission among different components’.

Chapter 1 Quiz

1、What are the main features of machines?
A、Assembly of man-made components
B、Determinate relative motions among different components
C、Can conduct work/energy conversion
D、Well designed shapes and structures

2、What are the main features of mechanisms?
A、Assembly of man-made components
B、Determinate relative motions among different components
C、Can conduct work/energy conversion
D、Well designed shapes and structures

3、The study objects of ‘Theory of Machines and Mechanisms’ are mechanisms and machines.

Chapter 2 Composition of mechanisms

2.1 Elements of Mechanisms随堂测验

1、What is the difference between a link and a part?
A、A part is a basic component of a machine from a point view of manufacturing. A link is a basic component of a mechanism from a point view of motion transmission. It can be a part or an assemblage of several parts.
B、Links are lines, and parts are entities.
C、Links are virtual, and parts actually exist.
D、Other differences.

2、How many frames can exist in a mechanism?
A、1
B、2
C、3
D、Not sure. Maybe several.

3、What are the composition elements of mechanisms?
A、Links
B、Kinematic pairs
C、Parts
D、Components

4、Which ones in the following are not kinematic pairs?
A、Riveting connection
B、Welding connection
C、Threaded connection
D、Sliding connection

5、What are the characteristics of kinematic pairs?
A、A connection between two links
B、Relative motion exists between the two links
C、The two links are in contact
D、The two links have the same form of motion

2.3 Kinematic diagram随堂测验

1、What are the correct steps to draw a kinematic diagram A. Choose a proper drawing scale B. Analyze the motion of the mechanism C. Choose the drawing plane D. Determine how many links are there? What are they? E. Determine how many pairs are there? What are they? F. Use specified symbols to draw the links and pairs G. Mark the driving link H. Label the links and kinematic pairs
A、A-B-C-D-E-F-G-H
B、B-D-E-C-A-F-H-G
C、A-C-B-E-D-H-G-F
D、A-C-E-G-B-D-F-H

2、Which of the following descriptions is the right definition for kinematic diagrams?
A、A kinematic diagram is a diagram presented by simple graphics.
B、A kinematic diagram is a diagram presented by specified symbols of links and kinematic pairs.
C、A kinematic diagram is a diagram in which links and pairs are represented by some simple lines and symbols to present the composition of a mechanism.
D、A kinematic diagram is a diagram in which links and pairs are represented by some simple lines and symbols to a certain scale to present the composition of a mechanism.

2.4 Degree of Freedom of Mechanisms随堂测验

1、The degree of freedom of a mechanism is
A、The number of moving pairs in a mechanism
B、The degree of free motion of a mechanism
C、The number of independent motion parameters required to specify the configuration of a mechanism
D、The degree of free motion of a mechanism

2、What is the right expression to determine the degree of freedom for a mechanism?
A、F＝3n－2PL－PH
B、F＝3n－2PL
C、F＝3n－PL－PH
D、F＝3N－2PL－PH

3、Passive degree of freedom refers to
A、The degree of freedom of local links and kinematic pairs.
B、The degree of freedom exhibits in a specific link and does not affect the motion of other links.
C、The degree of freedom of some links.
D、The degree of freedom of local mechanism.

4、What results in multiple pin joints in a mechanism?
A、More than two links are joint together to form several rotating pairs at the same position.
B、Unreasonable design of the mechanism.
C、Incorrect drawing of kinematic diagram.
D、Other reasons.

5、Redundant constraints refer to
A、Virtual degrees of freedom in a mechanism
B、Constraints that do not play any role for motion transmission to other links
C、Constraints in a mechanism that do not exist
D、Constraints in virtual mechanisms

6、What is the condition to have a determined motion for a mechanism?
A、DOF>0
B、DOF=number of driving links
C、DOF=number of driving links >0
D、DOF≠ 0

2.5 Principle of composition随堂测验

1、The composition principle of mechanisms refers to
A、A mechanism is composed of links and kinematic pairs.
B、Any planar mechanism with lower pairs can be regarded as the combination of several Assur groups that are attached to the driving link and the frame in sequence.
C、Methods and guidelines to form a mechanism.
D、The principle of how a kinematic chain becomes a mechanism.

2、What is the purpose of composition analysis for mechanisms?
A、Dissect the mechanism into a frame, driving links and Assur groups, then determine the level of Assur groups and level of mechanisms.
B、Dissect the Assur groups.
C、Analyze the specified structure of the mechanism to lay the foundation for strength analysis.
D、Determine the number of links and number and types of kinematic pairs.

3、A level Ⅱ link group is
A、A link group with two links and three moving pairs
B、A link group with two links and three moving pairs, and each link has two lower pairs connected to other links
C、A link group of which level <=2
D、A link group with two links

4、The characteristics of Assur groups are
A、DOF=0
B、Basic link groups whose DOF=0 and cannot be further separated.
C、Mechanical systems with lower pairs.
D、Immobile mechanical systems with DOF=0

Chapter 2 Quiz

1、What is the right expression to determine the degree of freedom for a mechanism?
A、F＝3n－2PL－PH
B、F＝3n－2PL
C、F＝3n－PL－PH
D、F＝3n－2PL－2PH

2、Lower pairs are kinematic pairs with
A、No contact
B、Point contact
C、Line contact
D、Surface contact

3、Passive degree of freedom refers to
A、The degree of freedom locally exists in a specific link and does not influence the motion of other links
B、The degree of freedom existed in part of a link
C、The degree of freedom existed in several links in a mechanism
D、The degree of freedom existed in part of a mechanism

4、Redundant constraints refers to
A、Constraints that do not play any role for motion transmission to other links
B、Constraints in a mechanism that do not exist
C、Constraints that cannot be seen
D、Constraints that are practically useless

5、Which of the following terms are the proper descriptions of the characteristics for kinematic pairs?
A、Contact
B、Connection
C、Movable
D、Firm

6、What are the composition elements of mechanisms?
A、Links
B、Kinematic pairs
C、Parts
D、Components

7、According to the types of contact, kinematic pairs can be classified into lower pairs and higher pairs. A higher pair refers to
A、Kinematic pair with point contact
B、Kinematic pair with line contact
C、Kinematic pair with surface contact
D、Kinematic pair with body contact

8、The characteristics of Assur groups are
A、DOF=0
B、Basic link groups whose DOF=0 and cannot be further separated
C、Mechanical systems with lower pairs
D、Immobile mechanical systems with DOF=0

9、This is a lower pair connection

10、This is a lower pair connection

11、This is a lower pair connection

12、This is a lower pair connection

13、This is a lower pair connection

14、This is a lower pair connection

15、For a mechanism, when its degree of freedom equals to the number of driving links, it has determined motion.

16、In the calculation of degree of freedom, we should not consider redundant constraints.

Chapter 3 Kinematic Analysis of Mechanisms

3.1 Purpose and methods of kinematic analysis随堂测验

1、Which kinematic parameters can be extracted through kinematic analysis of mechanisms?
A、Force applied to mechanisms
B、Velocity of driven links
C、Acceleration of driven links
D、Displacement of driven links

2、What are the methods of kinematic analysis?
A、Analytical method
B、Graphical method
C、Virtual prototype method
D、Experimental method

3.3 Kinematic analysis by using the instantaneous center of velocity随堂测验

1、The number of instantaneous centers of velocity for a planar mechanism which has N links is
A、N（N-1）/2
B、N（N-2）/2
C、N（N-3）/2
D、N（N-4）/2

2、Characteristics of instantaneous center of velocity include
A、A pair of superposed points
B、Has the same absolute velocity
C、Relative velocity is zero
D、Located on two links

3、"The velocity of the absolute instantaneous center of velocity must be zero, and the velocity of the relative instantaneous center of velocity must not be zero." Is this statement correct?

4、"The instantaneous center of velocity of the two links that form a higher pair must be located at the contact point of the two links." Is this statement correct?

5、"The instantaneous center of velocity of the two links that form a sliding pair must be located at an infinity point perpendicular to the direction of the guide line of the sliding pair." Is this statement correct?

6、"The instantaneous center method can only be used to determine the velocity of the links in mechanisms, not the displacement and acceleration." Is this statement correct?

7、“Kennedy theorem states that three instantaneous centers on a link must be on a same line.” Is this statement correct?

3.4 Kinematic analysis by analytical method随堂测验

1、Choose the correct steps to conduct kinematic analysis by using the analytical method. a. Set up the coordinate b. Build up vector equations c. Express the links with vectors d. Project vectors along x and y axis e. Solve equations to get solutions
A、a-b-c-d-e
B、a-c-b-d-e
C、b-c-d-a-e
D、a-e-c-d-b

2、Among different kinematic parameters in the analytical kinematic analysis, which of the following parameter is normally first to be determined.
A、Displacement
B、Velocity
C、Acceleration
D、Others

Chapter 3 Quiz

1、The instantaneous center of velocity of two links that form a turning pair is located at
A、The center of the turning pair
B、On the circle of the turning pair
C、Any point on the circle of the turning pair
D、One of the two links

2、The instantaneous center of velocity of two links that form a sliding pair is located at
A、Infinity point perpendicular to the direction of the guide line of the sliding pair
B、On the line perpendicular to the direction of the guide line of the sliding pair
C、In the middle of the guide line
D、At the contact point of the two links

3、The instantaneous center of velocity of two links that form a higher pair is located__
A、On the common normal line of the contact point
B、On the common tangent line of the contact point
C、At the contact point of the two links
D、Infinity point along the common normal line of the contact point

4、Instantaneous center P13 is the point at which link () and link () share the same velocity, including the magnitude and direction
A、1,3
B、2,4
C、1,2
D、3,4

5、Choose the correct sequence to conduct kinematic analysis by using the analytical method. a) Set up the coordinate b) Build up vector equations c) Express the links with vectors d) Solve equations to get solutions
A、a-b-c-d
B、a-c-b-d
C、b-c-a-d
D、a-d-b-c

6、Which kinematic parameters can be extracted through kinematic analysis of mechanisms?
A、Force applied to mechanisms
B、Velocity of driven links
C、Acceleration of driven links
D、Displacement of driven links
E、Deformation of driven links

7、What are the methods used to conduct kinematic analysis?
A、Graphical method
B、Analytical method
C、Virtual prototype method
D、Experimental method

8、Characteristics of instantaneous center of velocity include
A、A pair of superposed points
B、The magnitude of absolute velocity is the same, but the direction can be different
C、Has the same absolute velocity
D、Relative velocity is zero
E、Located on two links

9、"The instantaneous center of velocity of the two links that form a higher pair must be located at the contact point of the two links." Is this statement correct?

10、"The instantaneous center method can only be used to determine the velocity of the links in mechanisms, not the displacement and acceleration." Is this statement correct?

Chapter 4 Planar Linkage Mechanisms

4.2 Conditions of crank existence随堂测验

1、In a four-bar linkage shown in the following figure, the length of each link is given. Which link can be taken as the frame to obtain a double crank linkage mechanism?
A、AB
B、BC
C、CD
D、AD

2、For a mechanism shown in the following figure, what is the right answer to make it an offset crank-slider linkage mechanism?
A、b ≥ a + e
B、b ≤ a + e
C、a ≥ e
D、b ≥ a

3、In a four-bar linkage mechanism, when the sum of the lengths of the longest and the shortest links is less than that of the other two links, which type does the mechanism belong to if the shortest link is taken as the frame?
A、Crank-rocker linkage
B、Double-crank linkage
C、Double-rocker linkage
D、Not sure

4、In the four-bar linkage, the two shortest links have the same length, while the rest two links have different lengths. If one of the shortest links is taken as a frame, which type of the mechanism does the mechanism belong to?
A、Crank-rocker linkage
B、Double-crank linkage
C、Double-rocker linkage
D、Not sure

5、For a double-rocker linkage mechanism, is it possible to convert it into a crank-rocker linkage mechanism if different links are taken as frames?
A、Certainly
B、Possibly
C、Certainly not
D、None

6、To convert a crank-rocker linkage mechanism into a double-rocker linkage, which of the following operations is the right way.
A、The crank of the original mechanisms is taken as frame
B、The link of the original mechanisms is taken as frame
C、The rocker of the original mechanisms is taken as frame
D、None

4.3 Motion transmission characters随堂测验

1、Which is the correct definition of the coefficient of travel speed variation?
A、The ratio of follower’s instant velocity in return stroke to working stroke
B、The ratio of follower’s maximum velocity in return stroke to working stroke
C、The ratio of follower’s average velocity in the return stroke to the working stroke
D、None

2、When a four-bar linkage mechanism exhibits quick-return motion, the angle between the two limiting positions of the coupler is __.
A、Larger than zero
B、Equal to zero
C、Less than zero
D、None

3、In order to make a mechanism realize quick-return motion, what is the requirement for the value of the coefficient of travel speed variation K?
A、K > 1
B、K = 1
C、K < 1
D、None

4、In the following four-bar linkage mechanisms, which one can realize quick-return motion?
A、Crank-rocker linkage
B、Offset crank-slider linkage
C、Crank-shaper linkage
D、Double-crank linkage

4.4 Force transmission characters随堂测验

1、The pressure angle in a mechanism refers to the acute angle between the direction of driving force and the direction of ( ) at the point the force is applied on the driven link.
A、Normal line
B、Velocity
C、Acceleration
D、Tangential line

2、When designing linkage mechanisms, which of the following approach is correct in order to have a better force transmission performance?
A、Increase transmission angle and decrease pressure angle
B、Increase both transmission angle and pressure angle
C、Decrease both transmission angle and pressure angle
D、None

3、Does double-crank linkage mechanisms have dead positions?
A、Yes, it does
B、It may have
C、No, it doesn’t
D、None

4、What conditions must be met for a linkage mechanism to have dead points?
A、The driving link does reciprocating motion
B、The linkage locates at a position where the transmission angle is zero
C、The driving link is crank
D、The linkage locates at a position where the pressure angle is zero

4.5 Design of linkage mechanisms随堂测验

1、The key to design the linkage which have quick-return motion with given coefficient of travel speed variation K is to determine ( )
A、Auxiliary circle
B、Auxiliary line
C、Auxiliary polygon
D、None

2、To design a four-bar linkage mechanism, it is known that the length of the rocker CD is 70mm, the length of the frame AD is 100mm, coefficient of travel speed variation K = 1, the angle between the frame and one of the limiting positions of the coupler is Ψ = 30°. To figure out the length of crank AB and coupler BC by using the graphical method, One solution is shown in the following figure. The answer is: the length of crank AB is 20mm and the length of coupler BC is 70mm. Try to determine whether the solution and the result are correct.

Chapter 4 Quiz

1、The basic form of the planar linkage mechanisms is _____.
A、four-bar linkage
B、crank-slider linkage
C、crank-shaper linkage
D、double-slider linkage

2、For a four-bar linkage that meets the ‘Grashof’s criterion’, try to determine the types of turning pairs A, B, C, and D.
A、Full turning pair, Full turning pair, Full turning pair, Full turning pair
B、Full turning pair, Full turning pair, Full turning pair, Oscillating turning pair
C、Full turning pair, Full turning pair, Oscillating turning pair, Oscillating turning pair
D、Oscillating turning pair, Oscillating turning pair, Full turning pair, Full turning pair

3、For the four-bar linkage mechanisms (shown in the following figure) that meet the ‘Grashof’s criterion’, try to determine the types for mechanism I, II, III, IV.
A、Crank-rocker linkage, Double-crank linkage, Crank-rocker linkage, Double-rocker linkage
B、Double-crank linkage, Double-rocker linkage, Crank-rocker linkage, Crank-rocker linkage
C、Crank-rocker linkage, Crank-rocker linkage, Double-rocker linkage, Double-crank linkage
D、Crank-rocker linkage, Double-crank linkage, Double-rocker linkage, Double-crank linkage

4、What is the definition of imbalance angle?
A、When the rocker is at two limiting positions, the acute angle between the corresponding positions of the crank
B、The angle between the two limiting positions of rocker
C、When the rocker is at two limiting positions, the angle between the corresponding positions of the crank
D、When the crank is at limiting positions, the angle between the corresponding positions of the rocker

5、In the linkage shown in the figure, it is known that lAB = 160mm, lBC = 260mm, lCD = 200mm, lAD = 80mm. The link AB is taken as the driving link and it rotates at a constant speed clockwise. The coefficient of travel speed variation K equals to ___.
A、1.4
B、1.5
C、1.6
D、1.7

6、In a four-bar linkage mechanism, when the angle between coupler and rocker (also known as ∠BCD) is larger than 90°, the transmission angle of the mechanism is γ = ( ).
A、180° - ∠BCD
B、∠BCD
C、∠BCD - 180°
D、∠BCD - 90°

7、In the four-bar linkage shown in the figure, it is known that lAB = 100mm, lBC = 300mm, lCD = 200mm, and lAD = 350mm. Link AB is taken as the driving link. What is the minimum transmission angle γmin of the linkage?
A、53°
B、60°
C、46°
D、32°

8、When a linkage mechanism is in its ‘dead point’ position, the pressure angle α = ( )
A、0
B、30°
C、60°
D、90°

9、Assuming that there is a crank-rocker linkage mechanism ABCD, the length of rocker CD is lCD = 420mm, the angle between two limiting positions of rocker is Ψ = 90°, the angle between the frame and the rocker at the two limiting positions is 60° and 30°, respectively. The coefficient of travel speed variation is K = 1.5. Try to design this linkage mechanism and determine the crank length lAB, coupler length lBC and frame length lAD.
A、lAB = 200mm, lBC = 680mm, lAD = 525mm
B、lAB = 210mm, lBC = 690mm, lAD = 520mm
C、lAB = 215mm, lBC = 685mm, lAD = 530mm
D、lAB = 220mm, lBC = 690mm, lAD = 525mm

10、Given a crank-slider linkage ABC, the stroke of the slider is H = 100mm, eccentricity is e = 15mm, coefficient of travel speed variation is K = 1.2. Please design this crank-slider linkage and determine the crank AB length lAB and coupler BC length lBC.
A、lAB = 48.91mm, lBC = 87.84mm
B、lAB = 50.89mm, lBC = 90.78mm
C、lAB = 45.54mm, lBC = 88.12mm
D、lAB = 48.01mm, lBC = 86.69mm

11、A four-bar linkage for an aircraft landing gear is shown in the figure. The solid line represents the dead position when the landing gear is released and the dashed line represents the position when it is retracted. Given that lFC = 520mm, lFE = 340mm, and FE1 is along the vertical position (i. e. α = 90°), θ = 10o, and β = 60o. Find the lengths of the links CD lCD and DE lDE.
A、lCD = 380mm, lDE = 270mm
B、lCD = 385mm, lDE = 276mm
C、lCD = 390mm, lDE = 286mm
D、lCD = 395mm, lDE = 296mm

12、What are the characteristics of linkage mechanisms?
A、Linkage mechanisms have a large load capacity
B、Linkage mechanisms can achieve various kinds of motions
C、Linkage mechanisms are easy to be manufactured
D、Linkage mechanisms are difficult to perform a high-speed motion

13、What are the geometry conditions of crank existence of four-bar linkage mechanisms?
A、The sum of the lengths of the longest and shortest links is less than or equal to that of the other two links
B、The shortest link is a side link or the frame
C、The sum of the lengths of the longest and the shortest links is larger than the other two links
D、The shortest link is a coupler

14、The geometry conditions of crank existence of following offset crank-slider linkage is b ≥ a + e.

15、The geometry conditions of crank existence of following crank-shaper linkage is b ≥ a.

16、The coefficient of travel speed variation K is a parameter greater than or equal to 1.

17、The offset crank-slider linkage must have a quick-return motion.

18、The coefficient of travel speed variation of crank-shaper linkage can always be expressed as

19、The transmission angle is always numerically equal to the angle between the coupler and rocker.

20、When the transmission angle reaches its minimum value, the crank AB must be along the line determined by the frame AD.

21、In the crank-slider linkage shown in the figure, the slider is taken as the driving link. Please determine whether the pressure angle α and the transmission angle γ marked in the figure are correct.

22、“Dead points” in mechanisms could be practically useful or harmful.

23、In the four-bar linkage shown in the figure, AD is known as the frame, lBC = 50mm, lCD = 35mm, and lAD = 30mm. If the mechanism is a crank-rocker linkage, and AB is crank, then the maximum length lABmax of AB is ____mm.

24、In the offset crank-slider linkage shown in the figure, it is known that a = 100mm, e = 40mm. If AB can be taken as a crank, the minimal length of link b is ___ mm.

Chapter 5 Cam Mechanisms

5.1 Introduction to cam mechanisms随堂测验

1、Which of the following links belong to cam mechanisms?
A、Cam
B、Follower
C、Frame
D、Coupler/Side link

2、Which of the followings are the classifications of cam mechanisms?
A、Cam shape
B、Follower motions
C、Follower shape
D、Constraints to maintain continuous contact

3、How to keep a cam in continuous contact with the follower?
A、Force constraints
B、Geometry constraints
C、Combination constraints
D、Other constraints

4、The functions of cam mechanisms is 'Transmit continuous rotation of the cam to the follower’s reciprocating or oscillating motion'.

5、One of the prominent advantages of cam mechanisms is that almost any specific motion of the follower can be feasibly achieved by designing corresponding cam profiles.

5.2 Working procedure of cam mechanisms随堂测验

1、What’s the definition of the base circle for a cam mechanism?
A、The biggest circle can be drawn to the cam theoretical profile from cam rotation center
B、The smallest circle can be drawn to the cam theoretical profile from cam rotation center
C、The biggest circle can be drawn to the cam actual profile from cam rotation center
D、The smallest circle can be drawn to the cam actual profile from cam rotation center

2、In a work cycle of a cam mechanism, which of the following phases are essential?
A、Rise travel
B、High dwell
C、Fall travel
D、Low dwell

5.3 Follower’s motion随堂测验

1、The figure shows the speed diagram of the follower in a cam mechanism. Which location does the mechanism have the rigid impulse?
A、jA
B、jB
C、jC
D、jD

2、Which of the following motions will cause rigid impulses in a cam mechanism?
A、Constant velocity motion
B、Constant acceleration motion
C、Harmonic motion
D、3-4-5 orders polynomial motion

3、The figure shows the diagrams of the follower speed in a cam mechanism. Which location does the mechanism have the flexible impulse?
A、jA
B、jB
C、jC
D、jD

4、The motion parameters of a follower include:___
A、Displacement
B、Velocity
C、Acceleration
D、Inerti

5、Which of the following motions will cause flexible impulse in a cam mechanism?
A、Constant velocity motion
B、Constant acceleration motion
C、Harmonic motion
D、Cycloidal motion

6、Which of the following motions exhibit no impulse in a cam mechanism?
A、Constant acceleration motion
B、Harmonic motion
C、Cycloidal motion
D、3-4-5 orders polynomial motion

7、‘The follower motion depends on the cam profile’. Is this statement correct?

5.4 Introduction to the design of cam mechanisms随堂测验

1、Which of the following is the basic method used in designing cam profiles?
A、Changing frame Method
B、Kinematic Inversion Method
C、Combination Method
D、Other Method

2、The true statement about the ‘kinematic inversion method’ in the design of cam mechanisms is 'Add a common angular velocity which has the same amplitude and opposite rotating direction to the cam actual angular velocity. As a result, the cam can be treated as fixed. The follower’s guide line relatively rotates at the angular velocity (-ω) to the cam, and moves or rotates to the frame according to the given motion graph'.

5.5 Graphical design of cam mechanisms随堂测验

1、What is the relationship between the theoretical profile and the actual profile of the cam?
A、Equidistant curves
B、Same curves
C、Same kind of curves
D、Wide of the mark

5.6 Analytical design of cam mechanisms随堂测验

1、What is the essential purpose of analytical method to design a cam profile?
A、Establish the coordinate equations for the cam profile
B、Calculate the coordinates of all points on the cam profile
C、Draw the cam profile by calculation
D、Get the cam profile by programming

5.7 Force transmission of cam mechanisms随堂测验

1、The figure shows a disk cam with translating flat-faced follower. What is the pressure angle of the mechanism?
A、60°
B、30°
C、90°
D、0°

2、When the base circle of a cam disk becomes larger, the pressure angle of the mechanism _____.
A、Becomes bigger
B、Becomes smaller
C、Remains unchanged
D、Not sure

3、The pressure angle of a cam mechanism is___.
A、The acute angle between the force and the velocity of the cam
B、The acute angle between the force and the velocity of the follower
C、The acute angle between the force of the cam and the direction of motion of the follower
D、The obtuse angle between the force and the velocity of the follower

5.8 Determination of basic parameters随堂测验

1、What are the methods to avoid the distortion of the actual profile of a cam?
A、Increase the base circle of cam
B、Decrease the radius of roller
C、Change the type of follower motion
D、Increase the pressure angle of the mechanism

Chapter 5 Quiz

1、Theoretically, when the acceleration of the follower is infinite, the impact is called ____. When the acceleration of the follower is a certain amount inertia impact, the impact is called ____.
A、Rigid impulse, Rigid impulse
B、Rigid impulse, Flexible impulse
C、Flexible impulse, Rigid impulse
D、Flexible impulse, Flexible impulse

2、In the offset knife-edge follower cam mechanism shown in figure, the actual cam shape is a circle and its center locates at point A. The radius of cam is R = 40mm. The rotational center locates at point O. The rotational direction is marked in figure. The distance lOA = 25mm, eccentricity e = 8mm. Then the radius of base circle rb ___(mm); the follower travel distance h ___(mm).
A、14; 49.8
B、16; 50.8
C、17; 51.8
D、15; 51.8

3、In the offset roller follower cam mechanism shown in figure, the actual cam shape is a circle and its center is located at point A, the radius of the cam disk is R = 40mm. The rotational direction is marked in figure. Distance lOA = 25mm, radius of roller rr = 10mm, and the eccentricity e = 8mm. Find the radius of base circle rb ___(mm) and the follower travel h ___(mm).
A、23; 48.9
B、24; 51.9
C、25; 50.9
D、26; 52.9

4、Try to design a disk cam with offset knife-edge follower by using the analytical method. As shown in figure, the radius of base circle is rb = 40mm, eccentricity e = 20mm. It is known that the follower follows the constant acceleration and constant deceleration motion for both rise travel and fall travel. The motion graph is shown in the left figure. Please find the (x, y) coordinate of the disk profile when rotation angle of cam is φ = 90°.
A、x = 50.64mm, y = -10mm
B、x = 52.64mm, y = -15mm
C、x = 54.64mm, y = -20mm
D、x = 56.64mm, y = -25mm

5、The following figure shows a disk cam mechanism with an in-line flat-faced follower. It is known that the radius of base circle rb = 40 mm, angle of rise travel ? = 180°, the follower follows the harmonic motion type and the travel distance of the follower is h = 50 mm. Use analytical method to determine the (xB, yB) coordinate of the disk profile when rotation angle of cam is φ = 30°.
A、xB = 18.24mm, yB = 35.34mm
B、xB = 21.86mm, yB = 37.43mm
C、xB = 23.82mm, yB = 38.45mm
D、xB = 24.85mm, yB = 39.33mm

6、The following figure shows a disk cam mechanism with swing arm roller follower at its starting position (AB ⊥ OB). Given the radius of base circle rb = 40mm, link AB length lAB = 80mm, radius of roller rr = 10mm. The follower follows cycloidal motion type in both the rise travel and the fall travel. The angle of the rise travel is ? = 180°, angle of fall travel is ?’ = 180°, the maximum swing angle of AB is Ψmax = 30°, the rotational direction of cam is clockwise. Try to use analytical method to determine the (x, y) coordinate of the disk profile when rotation angle of the cam is φ = 270°.
A、x’ = 40.71mm, y’ = -1.13mm
B、x’ = 50.71mm, y’ = -2.23mm
C、x’ = 60.71mm, y’ = -2.73mm
D、x’ = 70.71mm, y’ = -3.89mm

7、Cam mechanisms can be classified into different types according to ( ).
A、Contact type
B、Connection type
C、Motion type
D、Fixation type

8、The cam mechanisms can also be classified into different types according to ( ).
A、Cam shape
B、Follower shape
C、Follower motion
D、Constraints to maintain high pair contact

9、Which of the following phases must be included in a work procedure of cam mechanisms ( ).
A、Rise travel
B、High dwell
C、Fall travel
D、Low dwell

10、What will happen if the radius of the base circle and the radius of the roller in a cam mechanism are not designed properly?
A、Distortion takes place in followers’ motion
B、Pressure angle of the mechanism does not meet requirements
C、The mechanism cannot move
D、The mechanism cannot be installed

11、Figure (a) shows a swing-arm follower cam mechanism, assuming the size and rotational direction of the mechanism are known. Its initial location is shown in Figure a. If we want to know the rotational angle Ψ of the following as well as the pressure angle α of the mechanism after the cam rotates about 90°, whether the solution shown in Figure (b) is correct or not.

12、The sum of the angle of rise travel, angle at high dwell, angle of fall travel, and angle at low dwell of a cam mechanism equals to_____ degrees.

13、In an in-line knife-edge follower cam mechanism shown in the following figure, the actual cam shape is a circle and its center is point A, the radius of cam is R = 40mm. The rotational center locates at point O. The rotational direction is marked in figure. The distance lOA = 25mm. Find: The radius of base circle rb =___ (mm); The follower travel distance h =___ (mm). (Separate the answers with a period only)

14、In the in-line roller follower cam mechanism shown in figure, the actual cam shape is a circle and its center is located at point A, the radius of cam is R = 40mm. The rotational direction is marked in figure. Distance lOA = 25mm, radius of the roller rr = 10mm. Find: The radius of base circle rb ____(mm); The follower travel distance h ____(mm). (Separate the answers with a period only)

15、In the in-line flat-faced follower cam mechanism shown in figure, the actual cam shape is a circle and its center locates at point A, the radius of cam is R = 30mm. The rotational direction is marked in figure. The distance lOA = 20mm. Then the radius of the base circle rb of the cam mechanism is ____(mm); The follower’s travel distance h _____(mm).

Chapter 6 Gear Mechanisms

6.1 Features and types of gear mechanisms随堂测验

1、What are the features of gear mechanisms?
A、High efficiency
B、Reliable, long lifespan
C、High accuracy
D、Suitable for any motion type

6.2 Law of gearing随堂测验

1、Conjugate gear profile refers to
A、A pair of gear profiles which satisfy the law of gearing to maintain a constant transmission ratio
B、A pair of gear profiles which can mate
C、A pair of gear profiles which can be assembled together
D、A pair of gear profiles which conjugate with each other

2、To a specific transmission ratio, how many pairs of conjugate profiles are there?
A、1 pair
B、2 pairs
C、3 pairs
D、Infinite pairs

3、If the instantaneous transmission ratio of the gear mechanism is a constant value, which of the following values can be reduced?
A、Inertial force
B、Vibration
C、Shock
D、Noise

4、"The center distance of the gear mechanism is always equal to the sum of the two pitch circle radii, and the transmission ratio is equal to the inverse ratio of the two pitch circle radii." Is this statement correct?

6.3 Involute gear profiles随堂测验

1、The shape of the gear involute profiles depends on the
A、Base circle
B、Pitch circle
C、Reference circle
D、Addendum circle

2、Along an involute gear profile, the pressure angle on ___ equals to zero.
A、Base circle
B、Pitch circle
C、Reference circle
D、Dedendum circle

3、As tooth profiles of gears, the involute profiles have the advantages of
A、having a constant transmission ratio
B、the transmission ratio does not change with center distance
C、direction of normal pressure does not change, transmission is stable
D、high strength

4、Features of involute curves include
A、The length of the straight line rolled along the base circle equals to the arc length rolled on the base circle
B、The normal line of any point along the involute gets tangent to the base circle
C、The farther the involute is away from the base circle, the larger the radius of curvature
D、The shape of the involute curve depends on the size of the base circle

5、If a point on the involute curve goes further from the base circle, the pressure angle on the point becomes smaller

6.4 Geometrical dimensions of spur gears随堂测验

1、What is the function of the reference circle?
A、A reference to the gears
B、A reference of designing gears
C、A mark of the gear size
D、A circle for the measurement of gears

2、When is the minimum tooth number that makes the dedendum circle to be bigger than the base circle?
A、40
B、41
C、42
D、43

3、What are the basic parameters of involute standard spur gears?
A、Module
B、Pressure angle
C、Addendum coefficient
D、Clearance coefficient

4、Which of the basic parameters of involute standard spur gears have standard values
A、Module
B、Pressure angle
C、Addendum coefficient
D、Clearance coefficient

5、Compared with gears, racks have characteristics of
A、Same pressure angle along the tooth profiles
B、Same pitch distance at different locations
C、Low transmission efficiency
D、Changing transmission ratio

6.5 Conditions of mating, installation, and continuous meshing of spur gears随堂测验

1、What is the correct mating condition for involute spur gears?
A、Same tooth pitch on the base circle（Pb1=Pb2）
B、Same tooth pitch on the addendum circle（Pa1=Pa2）
C、Same tooth pitch on the dedendum circle（Pf1=Pf2）
D、Other conditions

2、What is the continuous mating condition?
A、Contact ratio ≥ 1
B、Contact ratio ≥ 0.5
C、Contact ratio ≤ 1
D、Contact ratio ≤ 0.5

3、What is the relationship between single tooth mating zone length (Ls) and base circle pitch (Pb) of an involute standard spur gear with contact ratio =1.4
A、Ls = 0.4Pb
B、Ls = 0.6Pb
C、Ls = Pb
D、Ls > Pb

4、What is the relationship between double teeth mating zone distance (Ld) and base circle pitch (Pb) of a involute standard spur gear with contact ratio =1.4
A、Ld = 0.4Pb
B、Ld = 0.6Pb
C、Ld = Pb
D、Ld > Pb

5、When a pair of involute spur gear is in transmission and the contact ratio equals 1, the length of actual meshing line is equal to
A、Base circle pitch
B、Reference circle pitch
C、Pitch circle pitch
D、Other answers

6、What is the correct mating condition for involute standard spur gears?
A、Same module
B、Same pressure angle
C、Same tooth number
D、Same tooth pitch

7、What is the correct installation condition for involute standard spur gears?
A、Side clearance is 0
B、Side clearance is standard
C、Tip clearance is standard
D、Tip clearance is 0

8、What are the characteristics when two involute standard spur gears are installed according to standard center distance?
A、The center distance is equal to the sum of the radii of two gears
B、Reference circles are superposed with pitch circles
C、Pressure angle on the reference circle = meshing angle on the pitch circle = meshing angle
D、No side clearance

9、When involute gear mesh with a rack, and the rack moves away from the gear, the meshing angle becomes bigger

10、When a pair of involute standard spur gears is installed with the standard center distance, the relative position between the two reference circles is tangent.

6.6 Manufacturing of gears随堂测验

1、When manufacturing involute standard spur gears with generating cutting method, the minimum teeth number to avoid undercutting is
A、15
B、16
C、17
D、18

2、What is the reason for undercutting in the generating method of gear machining?
A、The addendum line of the rack cutter is higher than the tangent point
B、Too many teeth
C、Too little teeth
D、None of the above

3、When manufacturing involute standard spur gears with generating cutting method, methods to avoid undercutting include
A、Reduce the tooth height of the tool knife
B、Increase the number of teeth of the machined gear
C、Moves the cutter away from the gear under machining
D、None of the above

4、Methods of machining for gears include
A、Form cutting method
B、Generating cutting method
C、Knitting method
D、Stacking method

5、Gears with same module and different tooth numbers can be machined by generating cutting with a same gear cutter?

6、When a standard rack cutter is used to machine a positively modified external involute spur gear, the relative position of the center line of the tool and the reference circle of the gear is tangent.

6.7 Undercutting and modification manufacturing随堂测验

1、What are the advantages of modified gears?
A、Actual center distance can be adjusted
B、Nearly same lifespan of the two gears
C、Avoid undercutting
D、None of the above

2、Do gears under standard machining, positive addendum modification, and negative addendum modification have the same reference circle?

6.8 Helical gears随堂测验

1、Increase helix angle may result in
A、Contact ratio decreases, axial force increases
B、Contact ratio decreases, axial force decreases
C、Contact ratio increases, axial force decreases
D、Contact ratio increases, axial force increases

2、Compared with standard spur gears, helical gears have advantages of
A、Center distance can be adjusted by changing helix angle
B、Contact ratio is big with large load capacity
C、Transmission is more steady
D、Axial force exist

6.9 Bevel gears随堂测验

1、A bevel gear mechanism is used to transmit motion and power in between two bevel gears of which axes are___?
A、Parallel
B、Intersecting
C、Perpendicular intersecting
D、None of the above

2、Advantages of bevel gears include 1.Two axes can intersect 2.More designing parameters, easy to meet the different requirements

6.10 Worm and worm gears随堂测验

1、What is the central section of worm and worm gear mechanism?
A、A plane perpendicular the worm gear axis and through the axis of the worm
B、A plane in the middle of the worm and worm gear
C、A plane in the middle of the worm
D、A plane in the middle of the worm gear

2、Advantages of worm and worm gear mechanisms include
A、Smooth transmission
B、Large transmission ratio
C、Compact structure
D、Self-locking happens

3、The helix direction of the worm is right-handed.

4、The helix direction of the worm gear is right-handed.

6.11 Summary随堂测验

1、The standard parameters of bevel gears are defined at____?
A、Small end
B、Middle end
C、Big end
D、Not sure

2、What is the function of the back cone of bevel gears?
A、To obtain the tooth profile of the big end of the bevel gear
B、Perform geometric calculations
C、Estimate the size of the gear
D、Carry out gear strength calculation

3、The geometric calculation of bevel gears is performed at the big end is because
A、Big end parameters are standard
B、Relative error is small
C、Big end is big, and therefore easy to calculate
D、None of the above

Chapter 6 Quiz

1、The shape of the gear involute profiles depends on the
A、Reference circle
B、Dedendum circle
C、Base circle
D、Addendum circle

2、On the involute profile, pressure angle on the ( ) circle is zero, pressure angle on the ( ) circle is the largest?
A、base; addendum
B、addendum; addendum
C、dedendum; base
D、dedendum; dedendum

3、If the center distance of the two gears changes, the instant gear ratio remains the same. This is because
A、Same pressure angle
B、Same meshing angle
C、Same pitch circle radius
D、Same base circle radius

4、For a pair of correctly installed standard involute spur gears, pitch circles coincide with ( ) circle, and meshing angle equals to the pressure angle on the ( ) circle .
A、Reference; reference
B、Reference; addendum
C、Dedendum; dedendum
D、Base; base

5、The continuous meshing condition for standard involute spur gears is
A、Actual meshing length >= normal pitch
B、Actual meshing length < normal pitch
C、Theoretical meshing length >= normal pitch
D、Theoretical meshing length < normal pitch

6、Contact ratio ε of standard involute spur gears equals to______
A、The ratio of theoretical meshing line to tooth pitch
B、The ratio of actual meshing line to tooth pitch
C、The ratio of theoretical meshing line to tooth pitch on the base circle
D、The ratio of actual meshing line to tooth pitch on the base circle

7、What is the continuous mating condition for a gear mechanism?
A、Contact ratio εα<0
B、Contact ratio εα=0
C、Contact ratio εα<1
D、Contact ratio εα>=1

8、What is the reason for undercutting in the generating cutting method to machine gears?
A、The addendum line of the rack cutter is higher than the tangent point
B、The addendum line of the rack cutter is lower than the tangent point
C、The addendum line of the rack cutter passes through the tangent point
D、None of the above answers

9、Use the generating cutting method to machine a gear with m=2mm, ha*=1, z=14, to avoid undercutting, the minimum amount of displacement of the cutter moving away from its standard position in the radial direction is ____ mm.
A、0.253
B、0.353
C、0.453
D、0.553

10、Here are two gears. One is machined with positive modification machining, the other is a standard gear. They have the same module, teeth number, and pressure angle. Compared with the latter one, the former one has ___ tooth thickness, ___ base circle, and ___ dedendum.
A、Larger; smaller; same
B、Larger; same; smaller
C、Smaller; bigger; same
D、Smaller; smaller, smaller

11、When a standard involute spur gear meshes with a rack, if the rack moves away from the gear, the meshing angle in between the two ______.
A、Increases
B、Decreases
C、Remains the same
D、Not sure

12、What is the correct meshing condition for a pair of involute helical gears?
A、mn1=mn2=m, αn1=αn2=α, β1= - β2
B、mn1=mn2=m, αn1=αn2=α, β1=β2
C、mn1=mn2=m, αn1=αn2=α
D、None of the above options

13、What are the basic parameters of involute standard spur gears?
A、Module m
B、Pressure angle α
C、Addendum coefficient ha*
D、Clearance coefficient c*
E、Tooth number z
F、Tooth pitch

14、What are the correct installation conditions for standard involute spur gears?
A、Tip clearance is standard
B、Side clearance is 0
C、Same module and pressure angle
D、Reference circle coincide with pitch circle

15、In the generating cutting method to machine gears, which of the following motions are involved?
A、Cutting motion
B、Generating motions of cutter and the gear under machining
C、Feeding motion
D、Gear back off motion

16、Pitch point is the instantaneous center of velocity of the two mating gears.

17、Center distance = the sum of radii of two pitch circles (r1'+r2')

18、The angle αk is the pressure angle at point K on the involute profile.

19、If the four basic parameters (module m, pressure angle α, addendum coefficient ha*,clearance coefficient c*) of a spur gear are all standard values, the gear should be a standard involute spur gears.

20、A gear with a pressure angle α=15° can mesh with a gear with pressure angle α=20°.

21、Methods to machine gears include the form cutting method and the generating cutting method.

22、Assume the contact ratio for a gear mechanism εα=1.4. This means, when the meshing point moves along the action line, (_____) % of the time two teeth are in contact, and (_____)% of the time one pair of teeth is in contact. (答案用一个空格隔开)

23、Machine a standard involute spur gear using the generating cutting method. It is known that m=2mm, α=20° ha*=0.8, c*=0.3. The minimum teeth number to avoid undercutting is (___).

Chapter 7 Gear Trains

7.1 Definition and classification of gear trains随堂测验

1、What is the main difference between ordinary gear trains and epicyclic gear trains?
A、The planet gears exist or not
B、The number of gears
C、The spatial gears exist or not
D、The idler gears exist or not

2、What is the relationship between the axes of planet gears and the axes of the central gears in epicyclic gear trains?
A、Be perpendicular
B、Be parallel
C、Be spatially crossing
D、Intersecting

3、The classifications of gear trains include_____.
A、Ordinary gear trains
B、Epicyclic gear trains
C、Combined gear trains
D、Differential gear trains

4、The combined gear trains are composed of_____?
A、Ordinary gear trains
B、Epicyclic gear trains
C、Spatial gear trains
D、Planar gear trains

5、What are the basic compositions of the epicyclic gear trains?
A、Planet carrier
B、Sun gear
C、Planet gear
D、Ring gear

7.2 Gear ratio of ordinary gear trains随堂测验

1、What are the problems need to be solved in gear ratio calculation for gear trains?
A、The magnitude of the gear ratio
B、The direction relationship between output and input gears
C、The problem of whether it is accelerating or decelerating
D、The problem of self-locking

7.4 Gear ratio of combined gear trains随堂测验

1、Which of the following procedures are involved in the process of solving the gear ratio of combined gear trains?
A、Divide the combined gear trains into ordinary gear trains and epicyclic gear trains
B、Calculate gear ratios for each gear train
C、Find the relationship between each gear trains
D、Solve the gear ratio equations

7.5 Design of planetary gear trains随堂测验

1、Among the conditions need to be satisfied for the number of teeth of each gear in the epicyclic train, which ones have expressions of unequal relationships?
A、Ratio condition
B、Concentric condition
C、Assembly condition
D、Adjacent condition

2、What are the conditions need to be satisfied when determining the number of teeth of each gear in an epicyclic train?
A、Ratio condition
B、Concentric condition
C、Assembly condition
D、Adjacent condition

3、Among the conditions need to be satisfied for the number of teeth of each gear in an epicyclic train, which ones have expressions of equal relationships?
A、Ratio condition
B、Concentric condition
C、Assembly condition
D、Adjacent condition

7.6 Applications of gear trains随堂测验

1、What applications do the gear trains have?
A、Obtain large gear ratio
B、Change rotational directions and speeds
C、Realize multiple output motions
D、Conduct motion decomposition and synthesis

Chapter 7 Quiz

1、When the gear train runs, gear trains which rotation axes of all gears are attached to the frame are called ___; gear trains which at least one gear can rotate about other gears are called ___.
A、ordinary gear trains; ordinary gear trains
B、ordinary gear trains; epicyclic gear trains
C、epicyclic gear trains; ordinary gear trains
D、epicyclic gear trains; epicyclic gear trains

2、If the degree of freedom of a epicyclic gear train is equal to 2, then we call it ___, however, if the degree of freedom is equal to 1, we call it ___.
A、differential gear train; differential gear train
B、differential gear train; planetary gear train
C、planetary gear train; differential gear train
D、planetary gear train; planetary gear train

3、The number of teeth of gears shown in the following figure are all known, z1 = z2’ = 25, z2 = z3 = 20, z4 = 20, zH = 100. Then the ratio of the gear train is i14 = ___. (precise value, including direction)
A、0.072
B、-0.072
C、0.8
D、-0.8

4、The figure shows a hand-operated lifting mechanism. Given the number of teeth, z1 = 20, z2 = 50, z2’ = 15, z3 = 15, z3’ = 1, z4 = 40, z4’ = 18, z5 = 54. Then, the gear ratio i15 is ___.

5、The following figure shows a differential gear train. Given the number of teeth, z1 = 40, z2 = 20. The rotation speed of gear 1 is n1 = 120r/min, if the rotation speed of planet carrier is nH = 0, then the rotation speed of gear 3 is ___r/min. (indicating the magnitude and direction)

Chapter 8 Other mechanisms

8.2 Ratchet mechanisms随堂测验

1、The conditions that the driving pawl can smoothly slide into the ratchet wheel and automatically compress the tooth root (the inclination angle of the driving pawl α and the friction angle between the ratchet wheel φ) is
A、α<φ
B、α=φ
C、α>φ
D、Not sure

2、Composition of ratchet mechanisms includes
A、Oscillating arm
B、Driving pawl
C、Ratchet wheel
D、Locking pawl

3、Ratchet mechanisms can be classified according to
A、Structures
B、Engagement
C、Follower’s motion
D、Ratchet wheel’s motion

4、Ratchet mechanisms are not suitable for
A、High speed motion
B、Low speed motion
C、High precision motion
D、Low precision motion

5、Usage of ratchet mechanism includes
A、Intermittent feeding motion
B、Emergency brake
C、Translocation and indexing
D、Overrunning clutch

8.3 Geneva mechanisms随堂测验

1、Motion parameter k of the geneva mechanism is defined as
A、k = t2 / t1
B、k = t1 / t2
C、k =(t2 - t1)/ t1
D、k =(t2 - t1)/ t2

2、What is the relationship between the number of driving rollers n and the number of slots z in an external geneva mechanism?
A、n ≤ 2z/(z+2)
B、n ≤ 2z/(z-2)
C、n 3 2z/(z-2)
D、Not sure

3、The geneva mechanism consists of
A、Locking disk
B、Geneva wheel
C、Frame
D、Locking device

4、Types of geneva mechanism include
A、External geneva mechanism
B、Internal geneva mechanism
C、Spatial geneva mechanism
D、None of the above

5、Features of geneva mechanism include
A、Simple structure
B、Easy to manufacture
C、Reliable
D、High efficiency

6、Increasing the number of slots will result in
A、Reduce the variation of acceleration
B、More steady motion
C、Improved dynamic characteristics
D、Increased structure size

8.4 Intermittent gear mechanism随堂测验

1、Intermittent gear mechanism can be classified as
A、External intermittent gear mechanism
B、Internal intermittent gear mechanism
C、Spatial intermittent gear mechanism
D、None of the above

2、Properties of motion transmission of intermittent gear mechanisms include
A、Feasible to achieve types of intermittent motion transmission
B、A rigid impulse at the beginning and end of motion for the driven gear
C、The driving and driven gears are interchangeable
D、None of the above

3、The driving gear of an intermittent gear mechanism must be incomplete gear

8.5 Screw mechanisms随堂测验

1、What are the composition of screw mechanisms?
A、Screw
B、Nut
C、Frame
D、None of the above

2、Properties of screw mechanisms are
A、Simple structure
B、Easy to manufacture
C、High motion precision
D、Large reduction ratio and thrust

3、Types of screw mechanisms are ordinary screw mechanism and differential screw mechanism.

8.6 Universal joint随堂测验

1、Composition of universal joint includes
A、Driving shaft
B、Driven shaft
C、Cross shaft
D、Frame

2、A universal joint is a
A、Spatial spherical mechanism
B、Spatial linkage mechanism
C、Spatial four-bar linkage
D、None of the above

3、A double universal joint must meet the needs of
A、The angle between the driving shaft and the middle axis = the angle between the driven shaft and the middle axis
B、The two surface on the two ends of the middle shaft should be on the same plane
C、Driving shaft and driven shaft should be parallel
D、None of the above

Chapter 8 Quiz

1、To ensure the minimum rotation angle θmin=16°, tooth number z should at least be
A、23
B、46
C、12
D、34

2、The number of slots z should be greater or equal to
A、1
B、2
C、3
D、4

3、For a geneva mechanism, it is known that the number of slots z=4. There is one driving roller. The motion parameter k=
A、0.15
B、0.25
C、0.35
D、0.45

4、In a screw mechanism, A is left-handed, lA=5mm; B is right-handed, lB=6mm. When screw 1 rotates an angle φ=10°, the displacement of nut 2 equals to
A、0.1
B、0.2
C、0.3
D、0.4

5、The key components of a geneva mechanism include locking disk, geneva wheel, and frame.

Chapter 9 Friction and Efficiency of Mechanisms

Chapter 9 Quiz

1、The initial states of the sliders are stationary. Try to determine the motions of the following sliders.
A、Accelerated motion; Stay still; Stay still
B、Stay still; Accelerated motion; Accelerated motion
C、Accelerated motion; Stay still; Accelerated motion
D、Stay still; Accelerated motion; Stay still

2、In the following figure, given Q = 5000N, G = 500N, α = 30°. The coefficient of friction f between link 1, 2, 3 are all same. Slider 2 moves rightward with constant speed while slider 1 is in equilibrium. Then the coefficient of friction f = ___; driving force F = ___N.
A、0.0825; 866.025
B、0.0866; 825.025
C、0.0825; 825.025
D、0.0866; 866.025

3、The initial state of following shaft is stationary, try to determine the motion of the shaft.
A、Accelerated motion; Stay still; Stay still
B、Stay still; Accelerated motion; Accelerated motion
C、Accelerated motion; Stay still; Accelerated motion
D、Stay still; Accelerated motion; Stay still

4、Assuming that the friction angle between slider 1 and plane 2 is φ = 10°, and that the velocity of slider 1 relative to plane 2 is v12. Then, the angle between the whole reaction force R21 on slider 1 and the speed v12 is ___ degrees.

Chapter 10 Balance of machinery

10.1 Introduction随堂测验

1、What is the purpose of machinery balance?
A、To reduce or eliminate the unbalanced forces acted on links
B、To reduce the weight of the mechanism
C、To increase the strength of the mechanism
D、None of the above

2、What are the disadvantages of unbalanced machinery?
A、Lower efficiency
B、Lower strength
C、Lower reliability
D、More vulnerable to fatigue

3、Types of machinery balance include
A、Balance of rigid rotors
B、Balance of flexible rotors
C、Balance of the mechanisms
D、None of the above

4、Methods of machinery balance for rigid rotors include
A、Theoretical calculation method
B、Testing method
C、Virtual prototype method
D、Virtual reality method

10.3 Dy