4.9
4.9.1
Background
In the 1930s, the electrical manufacturing industry began to realize and attempt meet the demand for small electrical motors.
In the low-voltage range, these included 6- or 12-V dc motors for automotive fans, windshield wipers, window operators, etc.; and 15- to 30-V ac motors for toy trains, erector sets, and other toys. In the household voltage range, these included motors for sweepers, mixers, and hand tools.
These motors were of a two-pole,series-connected arrangement,having a slotted armature, with coils wound into nearly diametrically spaced slots, with start and finish wires connected to adjacent bars on a commutator. Large production rooms were filled with workers using simple tools and equipment to insulate the slots,place the coils therein, wedge them in place, connect them to the commutator, and so on.
The advent of World War II nearly halted the production of these motors for peacetime uses, requiring production of motors to the more exacting requirements of the armed services for navigation and munitions control devices. More handwork was required, and mechanized apparatus was more restricted in meeting the extremely rigid specifications set by the services.
Following the end of the war, peacetime requirements surged. At the same time, labor tended to hold back production rates. It became necessary for the machines to pace the operators, whereas the operators could previously be depended on to pace the production from simple machines and fixtures.
