Perhaps the leading case applying the doctrine of promissory estoppel to subcontractors' bids is a 1958 case decided by the California Supreme Court.3 In that case, a general contractor preparing to bid on a school project received a bid by telephone from a subcontractor for the paving portion of the job.
Basically, four different types of DC motors are used in industrial applications: series wound, shunt wound, compound wound, and permanent magnet. Several factors must be considered when selecting a DC motor for a specific application.
2.) How Motors Work. Electric motors can be powered by alternating (AC) current or direct current (DC). DC motors were developed first and have certain advantages and disadvantages. Each type of motor works differently but they all use the power of the electromagnetic field. We will talk about the very basic principals of electromagnetic fields in motors before you can move on to the different types of motors.