1) Hollow shafts can be used where weight reduction is important since only the outer material of solid shafts is stressed to the allowable limit, wasting the inner material. 2) The general torsion equation for solid shafts also applies to hollow shafts under the same assumptions. 3) Helical springs come in closed coil and open coil varieties and are used to absorb shocks and resist sudden forces between devices. They are made of spring steel or stainless steel wire.

1. TORSION AND SPRINGS
UNIT-2

8. TORSION OF HOLLOW SHAFTS:
From the torsion of solid shafts of circular x – section , it is seen that only the material
atthe outer surface of the shaft can be stressed to the limit assigned as an allowable
working stresses. All of the material within the shaft will work at a lower stress and is not
being used to full capacity. Thus, in these cases where the weight reduction is important,
it is advantageous to use hollow shafts. In discussing the torsion of hollow shafts the same
assumptions will be made as in the case of a solid shaft. The general torsion equation as
we have applied in the case of torsion of solid shaft will hold good

9. TYPES
• Laminated (or) Carriage (or)Leaf Spring
• Helical Spring
Open coil spring Closed coil spring

10. Helical Spring
• Helical Spring is a mechanical item
• which is typically used to absorb shock, resist
sudden force or load between two devices.
• Helical Spring is made of either cross-section
square or round spring steel wire or stainless steel
wire from 0.5 mm. to 80 mm. wire dia.

11. Types of Helical springs
• The Closed Coil Helical Spring is called Tension or
Extension Spring
• Open Coil Helical Spring is called Compression
Spring.

12. .

13. Stiffness (K)
• Load required to produce unit Deflection

14. Helix Angle
• It’s a angle made by the coil with planes
perpendicular to the axis of the spring