Statement (I): The ideal material for shafts transmitting power is CI.

Statement (II): CI resists compression well.

Concept:

Power transmitting shafts are subjected to axial tensile stress, bending moment or torsional moments or combination their combinations. The design of the shaft consists of determining the correct shaft diameter, from strength and rigidity criterion. Shafts are made up of ductile materials. Commercial shafts are made of low carbon steels. They are produced by hot-rolling and finished to size either by cold-drawing or by turning and drawing.

Cast iron on the other hand has poor tensile strength and does not show appreciable deformation before the fracture.

Cast iron offers the following advantages:

• It has higher compressive strength
• It has excellent ability to damp vibrations
• It has more resistance to wear
• It has low notch sensitivity

Therefore statement I) is incorrect because ideal material for power transmission shafts are low carbon steels.