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    Unit5 Moderate

    Uploaded by

    CHANDRASEKARAN
    The document discusses belt drives and power transmission. It provides answers to multiple choice questions about belt drives, including topics like: how centrifugal tension affects power transmission; forces acting on conveyor belts; replacing belts on motors; increasing key widths based on pulley diameters; types of stresses in hoisting ropes; conditions for maximum power transmission in flat belt drives; velocity ratios in chain drives; and sources of power loss.

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    Download as DOCX, PDF, TXT or read online from Scribd

    Unit5 Moderate

    Uploaded by

    CHANDRASEKARAN
    25 views2 pages
    The document discusses belt drives and power transmission. It provides answers to multiple choice questions about belt drives, including topics like: how centrifugal tension affects power transmission; forces acting on conveyor belts; replacing belts on motors; increasing key widths based on pulley diameters; types of stresses in hoisting ropes; conditions for maximum power transmission in flat belt drives; velocity ratios in chain drives; and sources of power loss.

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    Unit5_Moderate

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    The document discusses belt drives and power transmission. It provides answers to multiple choice questions about belt drives, including topics like: how centrifugal tension affects power transmission; forces acting on conveyor belts; replacing belts on motors; increasing key widths based on pulley diameters; types of stresses in hoisting ropes; conditions for maximum power transmission in flat belt drives; velocity ratios in chain drives; and sources of power loss.

    Copyright:

    © All Rights Reserved
    Download as DOCX, PDF, TXT or read online from Scribd
    Download as docx, pdf, or txt
    25 views2 pages

    Unit5 Moderate

    Uploaded by

    CHANDRASEKARAN
    The document discusses belt drives and power transmission. It provides answers to multiple choice questions about belt drives, including topics like: how centrifugal tension affects power transmission; forces acting on conveyor belts; replacing belts on motors; increasing key widths based on pulley diameters; types of stresses in hoisting ropes; conditions for maximum power transmission in flat belt drives; velocity ratios in chain drives; and sources of power loss.

    Copyright:

    © All Rights Reserved
    Download as DOCX, PDF, TXT or read online from Scribd
    Download as docx, pdf, or txt
    of 2

    With regard to belt drives with given pulley diameters, centre distance and coefficient of friction

    between the pulley and the belt materials, which of the statement below are FALSE? 
    A. Power transmission is greater when belt tension is higher due to centrifugal effects than the
    same belt drive when centrifugal effects are absent.
    B. A crossed flat belt configuration can transmit more power than an open flat belt configuration
    C. A ‘V- belt’ has greater power transmission capacity than an open flat belt
    D. Power transmission is the greatest just before the point of slipping is reached
    ANSWER: A

    In the case of a vertical belt pulley drive with T c as centrifugal tension and T o as the initial
    tension, the belt would tend to hang clear of the tower pulley when
    A. Tc < To
    B. Tc < To/3
    C. Tc > To
    D. Tc < To/2
    ANSWER: C

    Crushed ore is dropped on a conveyor belt at the rate of 300 kg/s. The belt moves at speed of 2
    m/s. The net force acting on the belt that keeps it moving at the same speed is
    A. 30 N
    B. 60 N
    C. 300 N
    D. 600 N
    ANSWER: D

    A 50 kW motor using six V belts is used in a pulp mill. If one of the belts breaks after a month of
    continuous running, then
    A. The broken belt is to be replaced by a similar belt
    B. All the belt are to be replaced
    C. The broken belt and two adjacent belts are to be replaced
    D. The broken belt and one adjacent belt are to be replaced
    ANSWER: B

    In a Belt drive, if the pulley diameter is doubled keeping the tension and belt width constant, then
    it will be necessary to
    A. Increase the key length
    B. Increase the key depth
    C. Increase the key width
    D. Decrease the key length
    ANSWER: C

    In case of belt drives, the effect of the centrifugal tension is to:


    A. Cause the belt to leave the pulley and increase the power to be transmitted
    B. Cause the belts to stay on the pulley and increase the power to be transmitted
    C. Reduce the driving power of the belt
    D. Stretch the belt in longitudinal direction
    ANSWER: D

    In μ is the actual coefficient of friction in a belt moving in grooved pulley, the groove angle being
    2α, the virtual coefficient of friction will be
    A. μ /sin α
    B. μ /cos α
    C. sin μ α
    D. cos μ α
    ANSWER: A
    Consider the following types of stresses in respect of a hoisting rope during acceleration of load 1.
    Direct stress due to weight hoisted and weight of the rope 2. Bending stresses due to bending of
    rope over the sheave 3. Stresses due to initial tightening. 4. Acceleration stresses which of these
    are the correct types of stresses induced in a hoisting rope during acceleration of load? 
    A. 1, 2 and 4
    B. 1, 2 and 3
    C. 2, 3 and 4
    D. 1, 3 and 4
    ANSWER: A

    In a flat belt drive the belt can be subjected to a maximum tension T and centrifugal tension T c.
    What is the condition for transmission of maximum power?
    A. T=Tc
    B. T= √ 3 Tc
    C. T=2Tc
    D. T=3Tc
    ANSWER: D

    For roller chain drive with sprocket having 10 teeth, the velocity of the driven shaft with respect
    to that of the drive will be approximately 
    A. 5% above to 5% below
    B. 5% above
    C. 5% below
    D. Same
    ANSWER: A

    Sources of power loss in a chain drive are given below: 1. Friction between chain and sprocket
    teeth. 2. Overcoming the chain stiffness. 3. Overcoming the friction in shaft bearing. 4. Frictional
    resistance to the motion of the chain in air or lubricant. The correct sequence of descending order
    of power loss due to these sources is 
    A. 1,2,4,3
    B. 1,2,3,4
    C. 2,1,3,4
    D. 2,1,4,3
    ANSWER: B

    Which one of the following statements relating to belt drives is correct? 


    A. The slip increases the velocity ratio
    B. The length of the crossed belt increases as the sum of the diameters of the pulleys increases
    C. The crowning of the pulleys is done to make the drive sturdy
    D. The rotational speeds of the pulleys are directly proportional to their diameters
    ANSWER: B

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