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.
Small DC motors are used in tools, toys, and appliances. The universal motor can operate on direct current but is a lightweight motor used for portable power tools and appliances. Larger DC motors are used in propulsion of electric vehicles, elevator and hoists, or in drives for steel rolling mills.