Elements of Machine Design-09

  1. Fundamentals of design
  2. Design of joints, levers and offset links
  3. Design of shafts, keys and couplings
  4. Design of power screws
  5. Design of springs
  6. Design of bolted and welded joints
  7. Selection of anti-friction bearings and gears

Design of Springs

1   A leaf spring in automobiles is used
    (A)   To apply forces
    (B)   To measure forces
    (C)   To absorb shocks
    (D)   To store strain energy
2   The load required to produce a unit deflection in the spring is called
    (A)   Modulus of Rigidity
    (B)   Spring stiffness
    (C)   Flexural rigidity
    (D)   Tensional rigidity
3   In spring balances, the spring is used
    (A)   To apply forces
    (B)   To absorb shocks
    (C)   To store strain energy
    (D)   To measure forces
4   Which of the following function can the spring perform?
    (A)   Store energy
    (B)   Absorb shock
    (C)   Measure force
    (D)   All of the mentioned
5   The helix angle is very small about 2⁰. The spring is
    (A)   Open coiled spring
    (B)   Closed coiled spring
    (C)   That small angle isn’t possible
    (D)   None of the listed
6   The helical spring ad wire of helical torsion spring, both are subjected to torsional shear stresses.
    (A)   TRUE
    (B)   FALSE
7   Find the shear stress in the spring wire used to design a helical compression sprig if a load of 1200N is applied on the spring. Spring index is 6, and wire diameter 7mm.
    (A)   452.2N/mm2
    (B)   468.6N/mm2
    (C)   512.2N/mm2
    (D)   None of the listed
8   Find the mean coil diameter of a helical compression sprig if a load of 1200N is applied on the spring. Spring index is 6, and wire diameter 7mm.
    (A)   7/6 mm
    (B)   42 mm
    (C)   1200×6/7 mm
    (D)   None of the listed
9   A railway wagon moving with a speed of 1.5m/s is brought to rest by bumper consisting of two springs. Mass of wagon is 100kg. The springs are compressed by 125mm. Calculate the maximum force acting on each spring.
    (A)   1200N
    (B)   1500N
    (C)   1800N
    (D)   2000N
10   Find total number coils in a spring having square and ground ends. Deflection in the spring is 6mm when load of 1100N is applied. Modulus of rigidity is 81370N/mm². Wire diameter and pitch circle diameter are 10mm and 50mm respectively.
    (A)   7
    (B)   6
    (C)   5
    (D)   4
11   The longest leaf in a leaf spring is called
    (A)   Middle leaf
    (B)   Master leaf
    (C)   Center leaf
    (D)   None of the listed
12   Multi leaf springs are not recommended for automobile and rail road suspensions.
    (A)   TRUE
    (B)   FALSE
13   Active and inactive, both types of coils support the load although both don’t participate in spring action.
    (A)   Active coils don’t support the load
    (B)   Inactive coils don’t support the load
    (C)   Both active and inactive don’t support the load
    (D)   Both active and inactive support the load
14   The longest leaf in a leaf spring is called
    (A)   Middle leaf
    (B)   Master leaf
    (C)   Centre leaf
    (D)   None of the listed
15   Multi leaf springs are not recommended for automobile and rail road suspensions.
    (A)   TRUE
    (B)   FALSE
16   If uncompressed length of spring is 40mm and number of coils 10mm, then pitch of coil is?
    (A)   4
    (B)   40/9
    (C)   40/11
    (D)   None of the mentioned
17   Springs are used
    (A)   To absorb shocks and vibrations
    (B)   To store and release energy
    (C)   To measure force
    (D)   For any of the above functions
18   The type of spring used to absorb shocks and vibrations in vehicles is
    (A)   Helical extension spring
    (B)   Leaf spring
    (C)   Spiral spring
    (D)   Belleville spring
19   If a spring has plain ends then number of inactive coils is?
    (A)   1
    (B)   2
    (C)   3
    (D)   0
20   Spring having square ends has 1 inactive coil.
    (A)   TRUE
    (B)   FALSE
21   Martin’s factor compensates for curvature effect in springs.
    (A)   TRUE
    (B)   FALSE
22   The angle of twist for the equivalent bar to a spring is given by? (Symbols have their usual meaning)
    (A)   8PD2N/Gd4
    (B)   16PD2N/Gd4
    (C)   16PDN/Gd3
    (D)   8PDN/Gd3
23   The axial deflection of spring for the small angle of θ is given by?
    (A)   328PD3N/Gd4
    (B)   8PD3N/Gd4
    (C)   16PD3N/Gd4
    (D)   8PD2N/Gd3
24   A spring of stiffness constant k is cut in two equal parts. The stiffness constant of new spring will be k/2.
    (A)   TRUE
    (B)   FALSE
25   For two spring connected in series, the force acting on each spring is same and equal to half of the external force.
    (A)   TRUE
    (B)   FALSE
26   For two springs connected in series, the net deflection is equal to the sum of deflection in two springs.
    (A)   TRUE
    (B)   FALSE
27   For two springs connected in parallel, net force is equal to the sum of force in each spring.
    (A)   TRUE
    (B)   FALSE
28   Find the Wahl’s factor if spring index is 6.
    (A)   1.202
    (B)   1.2424
    (C)   1.2525
    (D)   1.5252
29   Which of the following function can the spring perform?
    (A)   Store energy
    (B)   Absorb shock
    (C)   Measure force
    (D)   All of the mentioned
30   The spring index is the ratio of wire diameter to mean coil diameter.
    (A)   TRUE
    (B)   FALSE
31   If spring index=2.5, what can be concluded about stresses in the wire?
    (A)   They are high
    (B)   They are negligible
    (C)   They are moderate
    (D)   Cannot be determined
32   A spring with index=15 is prone to buckling.
    (A)   TRUE
    (B)   FALSE
33   If the spring is compressed completely and the adjacent coils touch each other, the length of spring is called as?
    (A)   Solid length
    (B)   Compressed length
    (C)   Free length
    (D)   None of the mentioned
34   If number of coils are 8 and wire diameter of spring 3mm, then solid length is given by?
    (A)   None of the listed
    (B)   27mm
    (C)   24mm
    (D)   21mm
35   Compressed length is smaller than the solid length.
    (A)   TRUE
    (B)   FALSE
36   Pitch of coil is defined as —–
    (A)   Axial distance in compressed state of the coil
    (B)   Axial distance in uncompressed state of the coil
    (C)   It is same in uncompressed or compressed state
    (D)   None of the listed
37   1-A spring is defined as a (an) – machine element.
    (A)   Plastic
    (B)   Elastic
    (C)   Special purpose
    (D)   None of the above
38   In which of the following item(s), spring is used to store energy.
    (A)   Clocks
    (B)   Toys
    (C)   Circuit breakers
    (D)   All of the above
39   In compression springs, the external force tends to
    (A)   Shorten the spring
    (B)   Lengthen the spring
    (C)   Both A and C
    (D)   Keep the length same
40   Torsional shear stresses are induced in the spring wire when
    (A)   Spring is under compression
    (B)   Spring is under tension
    (C)   Both A and B
    (D)   None of the above
41   The helix angle in case of closely coiled helical spring is
    (A)   Less than 10 deg
    (B)   10 deg to 15 deg
    (C)   15 deg to 20 deg
    (D)   More than 20 deg
42   The helix angle in case of closely coiled helical spring is
    (A)   Less than 5 deg
    (B)   5 deg to 7 deg
    (C)   7 deg to 10 deg
    (D)   More than 10 deg
43   Helical torsion spring is used in
    (A)   Door hinges
    (B)   Door closers
    (C)   Automobile starters
    (D)   All of the above
44   The longest leaf in Semi-elliptic leaf spring is known as
    (A)   Chief leaf
    (B)   Master leaf
    (C)   Major leaf
    (D)   Higher leaf
45   Springs are widely used in———-
    (A)   Machines
    (B)   Instruments
    (C)   Devices
    (D)   All of the above
46   The leaves of multi-leaf springs are subjected to
    (A)   Bending stress
    (B)   Shear stress
    (C)   Axial stress
    (D)   All of the above
47   Multi-leaf springs are used in
    (A)   Automobile suspension
    (B)   Railroad suspension
    (C)   Both A and B
    (D)   None of the above
48   The spring index (C) is
    (A)   Mean coil diameter / wire diameter
    (B)   Wire diameter / mean coil diameter
    (C)   Wire diameter x mean coil diameter
    (D)   None of the above
49   The spring index indicates the relative sharpness of the – of the coil.
    (A)   Length
    (B)   Curvature
    (C)   Thickness
    (D)   None of the above
50   Axial length of the spring which is so compressed that the adjacent coils touch each other.
    (A)   Compressed length
    (B)   Solid length
    (C)   Free length
    (D)   None of the above
51   Common types of spring
    (A)   Compression spring
    (B)   Tension spring
    (C)   Torsion spring
    (D)   All of the above
52   Which of the following function can the spring perform?
    (A)   Store energy
    (B)   Absorb energy
    (C)   Measure force
    (D)   All of the mentioned
53   Spring having square ends has 1 inactive coil.
    (A)   TRUE
    (B)   FALSE
54   If a spring has plain ends, then number of inactive coils is?
    (A)   1
    (B)   2
    (C)   3
    (D)   0
55   The angle of twist for the equivalent bar to a spring is given by?
    (A)   8PD2N/Gd4
    (B)   16PD2N/Gd4
    (C)   16PDN/Gd3
    (D)   8PDN/Gd3
56   A spring is defined as a (an) — machine element.
    (A)   Plastic
    (B)   Elastic
    (C)   Special purpose
    (D)   None of the above
57   The helix angle in case of closely coiled helical spring is
    (A)   Less than 5 deg
    (B)   5 deg to 7 deg
    (C)   7 deg to 10 deg
    (D)   More than 10 deg
58   When spring index increases, the value of Wahl’s stress factor
    (A)   Increases linearly
    (B)   Decreases linearly
    (C)   Remains same
    (D)   Increases exponentially
59   A spring index from — is considered as best for manufacturing considerations.
    (A)   4 to 12
    (B)   12 to 20
    (C)   20 to 28
    (D)   28 to 36

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