- It gives the mechanical support to the poles.
- It acts as an outermost cover of the dc machine. Thus the insulating materials get protected from moisture, dust and flammable gases.
- It forms a part of the magnetic circuit. It provides a path of low reluctance for magnetic flux.
Materials used for Yoke:
- It is prepared by using cast iron.
- For large machines rolled steel, cast steel and silicon steel is used. They provides high permeability