The yoke that supports the main components of the DC machine is frequently made of:

The yoke of a DC machine provides the structural support and forms the path for the magnetic flux. It is essential that this component has both strength and magnetic permeability. Steel or iron are commonly used materials for the yoke because they possess high magnetic permeability, allowing them to effectively conduct magnetic lines of force within the machine. This property enhances the efficiency of the motor or generator, as it helps in producing a stronger magnetic field that contributes to the operation of the device.

In addition to their magnetic properties, steel and iron are robust materials that provide the necessary mechanical strength to support the machine's components. Other materials like aluminum, copper, or brass do not possess the same level of magnetic permeability and are not typically utilized for the yoke, as their magnetic properties would not enable optimal functionality of the DC machine in terms of performance and efficiency. Similarly, composite materials may offer advantages in weight reduction but generally lack the magnetic characteristics needed for effective flux conduction in this context.