4. Functions of springs
• To provide cushioning effect
• Reduce the effect of shock or impact load
• To measure forces in spring balance
• To store energy such as in clocks, toys
• To apply forces and to control the motions as in brakes
and clutches.
• To control motions by maintaining contact between two
elements as in cam and followers
5. Types of Spring
• 1. Helical springs.
The helical springs are made up of a wire coiled in the
form of a helix and is primarily intended for
compressive or tensile loads.
The cross-section of the wire from which the spring is
made may be circular, square or rectangular. The two
forms of helical springs are compression helical spring
and tension helical spring.
6. Types of Helical spring
Helix angle more
than 10 degree
Helix angle less
than 10 degree
1)Closed coil helical or Tension spring
2)Open coil helical or Compression spring
7. Advantages of helical spring
The helical springs have the following advantages:
(a) These are easy to manufacture.
(b) These are available in wide range.
(c) These are reliable.
(d) These have constant spring rate.
(e) Their performance can be predicted more accurately.
(f) Their characteristics can be varied by changing
dimensions.
28. End Conditions of Spring = Active coil + inactive coils
Poor Seating
Space
Better Seating
Space than
Plain
Better than
other types in
Seating Space
Its for high stress
model spring
application
30. The designers should find the
following basic things
• Pitch
• Diameter of the coil , D
• Wire Diameter, d
• Number of turns , n
• Free Length , Lf
• Solid Length, Ls
• Spring Stiffness, q
• Type of Ends
42. S.
NO
Springs in parallel Springs in Series
1
They have high load
capacity, this depends on
number of discs
The deflection is
proportional to the
number of discs
48. Belleville Spring
Material
Chrome Vanadium Alloy
Steel
Allowable stress 1500 N/mm2
Young’s Modulus 2 x 105 N/mm2
Poisson’s Ratio 0.3
Thickness of spring 1 – 2 mm
Dia of disc at base 28 – 300 mm
h / t 0.4 – 0.75 for stiffness
49. t / do 0.03 – 0.06
Cone Angle 4 – 7 degree
Best value 6.5
Degree
53. LEAF SPRING or FLAT SPRING
• The spring used not only for absorbing load ,
its also used to carry
• Lateral Loads
• Braque Torque
•Driving Torque
54. Arrangement of leaf Spring
• The design may be of cantilever type or simply
supported type.
55. Limitations in Leaf spring
They are stressed more at one specific location
and the other parts are stressed lightly
So some design considerations needed in this type.
So they increase the width of the plate and keep the
thickness as same
63. INTRODUCTION
Fly wheel is a heavy rotating member
placed between power source and
driving unit.
It act as a reservoir – for storing energy
(its an energy accumulator)
64. Functions of fly wheel
• It will absorb energy when the demand is less
than supply of energy.
• It will release it when the demand is more
than the supply of energy.
69. Maximum Fluctuation of speed
Co-Efficient of fluctuation of speed
The difference between maximum speed and
minimum speed during the cycle is called
maximum fluctuation of speed.
97. Failure Cause
The crank shaft failures are caused by a
progressive fracture due to bending or reversed
torsional stresses .
Thus the crank shaft is under fatigue loading, so
the design is based on the endurance limit of the
material of the crank shaft
