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.
Repeatedly brushless and brushed DC motors are used in portable robots and AC motors are used in industrial robots. These motors are preferred in systems with lighter loads, and where the predominant form of motion is rotational.