16.02-1: Delco 1945 25 Cycle Capacitor-Start Motor

HHCC Accession No. 2006.156HHCC Classification Code: 16.02-1

A mid 20th century, high tech, 25cycle capacitor-start motor, an early design engineered for a new generation of high starting torque refrigeration motors made possible by the electrolytic, chemical capacitor, equipped with fuse-style, overload protection, and designed for ‘V’ belt drive applications, with pivoted motor mounting and automatic belt tension device, Delco, Circa 1945.

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16.02 Electric Motors - Single Phase Capacitor Start and Capacitor Run Motors




McKinnon Industries, St. Catherines Ont.



Serial No.:



11 x 8 x 7’h


35 lbs.




Exhibit, education, and research quality, illustrating an early, 25 cycle capacitor start FHP induction motors, designed for electrolytic capacitor and engineered for refrigeration system operation [capacitor not included].

Patent Date/Number:

From York County (York Region) Ontario, once a rich agricultural hinterlands, attracting early settlement in the last years of the 18th century. Located on the north slopes of the Oak Ridges Moraine, within 20 miles of Toronto, the County would also attract early ex-urban development, to be come a wealthy market place for the emerging household and consumer technologies of the early and mid 20th century.

This artifact was discovered in the 1950’s in the used stock of T. H. Oliver, Refrigeration and Electric Sales and Service, Aurora, Ontario, an early worker in the field of agricultural, industrial and consumer technology.

Type and Design:

Mid 20th century, high tech, FHP, capacitor-start motor design, 1/6th horsepower 25cycle, 110 volt, alternating current,
heavy, steel laminated body, designed to reduce magnetic [hysteresis] losses and reduce heat to improve electrical efficiency High starting torque motor for reciprocating refrigeration compressor application, Internal, centrifugally operated switching for automatic control of starting winding Early design engineered for a new generation of capacitor start motors made possible by new, electrolytic, capacitor technology, Equipped with early fuse-style, induction overload protection, Designed for ‘V’ belt drive applications, Ventilated, drip-proof housing, Slotted base to facilitate belt adjustment and tightening
Pivoted motor mounting, Automatic belt tension device.

Special Features:

Built for 25 cycle, 110 volt alternating current, representative of motor design used in Ontario prior to frequency standardization in the late 1940’s With a toe crushing weight this 1/6th HP motor weighs in at 35 lbs., illustrating the greater weight of 25 cycle rotating equipment, over 60 cycle a factor in moving to a higher cycle, in order to help reduce equipment costs.

Performance Characteristics:
Control and Regulation:
Targeted Market Segment:
Consumer Acceptance:
Market Price:
Technological Significance:

Built for 25 cycle, 110 volt alternating current, a rare example, representative of motor design used in Ontario prior to frequency standardization in the late 1940’s 1940’s style, high tech, capacitor-start motor, designed for top mounted electrolytic capacitor [not included]
Representative of a class of innovations introduced by Frigidaire, to provide automatic control of belt tension, using a simple, extension coil spring, with motor pivotally mounted on base plate. Maintaining proper belt tension, on refrigeration compressor drives was a perennial problem, due to close coupling of motor and compressor and large compressor fly wheel diameter.
Includes an early form of overload protector, the fusetron. Socket provided fusetron not included. Over load protection was an on-going challenge through the early years in the development of unitary, fully automated refrigeration equipment, designed to operate un-attended in the home - without the attention of skilled work force. This type of overload operated much like a standard instant blow fuse, but calibrated to carry the high starting current characteristic of induction loads. Its disadvantage was that it was a non-recycling device, which means that the refrigeration system could be off without the homeowner knowing it. Later devices would be automatically recycling [see ID# 281].

Industrial Significance:

The production of FHP electric motors under the Delco name was a marker of the post W.W.II doom in Canada’s appliance industry. Delco was a brand name, held by General Motors, under which auto electric components were manufactured and marketed. McKinnon Industries was a feeder plant to GM, located in St Catherines The development and commercial production of the capacitor-start single phase FHP motor, starting in the mid 1940’s was a seminal event in the history of the HVACR field. The capacitor-start motor would come to replace the more costly and complex repulsion induction motor, RI [See Group 16.01], with one with fewer moving mechanical parts, quieter, more reliable and maintainable, typically at lower cost. By allowing for electrical switching between starting and running windings, it would facilitate external relay control, rather than internal mechanical mechanisms, as with the RI motor. It would therefore be amenable for use in hermetically sealed refrigeration systems. Early experimentation, leading to the eventual commercial development of the FHP, capacitor start-motor, began with the work of Steinnmetz [American engineer and inventor 1865 ‘ 1923], 40 years before. But commercial production had to await the development of practical capacitors of sufficient capacity, the chemical, electrolytic capacitor. Early, paper and foil style capacitors, large enough to provide the required phase shift for motor starting, where larger than the motor itself, and were subject to short operating life span [see Reference 3] Conventional industrial practice for refrigeration systems, with compressors operating at conventional speeds, in the 1930’s through 60’s, saw these motors attached by ‘V’ belt drive to the refrigeration compressor with a compressor fly wheel about three times that of the diameter of the motor pulley. [see reference #4]. Maintaining belt alignment and tension was a constant challenge, due to close coupling of motor and compressor for space saving .

Socio-economic Significance:
Socio-cultural Significance:

Not-with-standing a major depression and two world wars the first half of the 20th century was a period of exceptional ferment in the development and popular dissemination of FHP electric motor technology. Associated with the development were a number of driving forces, mutually supporting and interacting: Scientifically, the theoretical ground work for development of an astonishing array of electrical and electro-magnet devices had been laid by the early years of the 20th century, through the efforts of Faraday and Steinnmetz, among many others, Technologically, the work of Thomas Edison, among others, laid the foundation stones on which urban and rural electrification would proceed, enabling an new era in human experience, favoured with consumer goods and services, previously unimagined,
Economically, a favourable climate for capital investment in manufacturing capacity, methods and materials emerged, part of North America’s second industrial revolution, Socially and culturally the consumer society was born, nurtured by a pent up demand for an easier, more comfortable, pleasurable lifestyle, and the sense that 20th century electrical and electro-motive technology might be able to help. The FHP electric motor, engineered for 110 volt, single phase house current, revolutionized life in the Canadian home. It enabled an astonishing list of appliances and labour saving devices. The revolution would take place in an astonishingly short period of time - for much of urban Canada much less than a decade. The electro-mechanical mechanization of the Canadian home was accomplished for much of urban Canada by the late 1930’s. But the early 20th century wonders of household mechanization would be dependent , in turn, on household ‘electrification’ Between them electrification and electro-mechanical mechanization changed everything. Almost over night it altered what Canadians do in the course of their day, how they live and their expectations of what their world had in store for them - in labour saving devices, devices of convenience, health and safety. The fractional horsepower electric motor [FHP] became an ubiquitous part of the Canadian household by the mid 1930’s. Cyril Veinott reported, December 1938:

‘Practically every electrified home today makes use of one or more fractional horsepower motors. This kind of motor may be used in a washing machine, refrigerator, vacuum cleaner, clock, oil burner, hair drier, room heater, sewing machine, razor, health machine, fan, air conditioner, stoker, ironed, floor waxer, or food mixer. In industrial use, the number of useful tasks performed by fractional horsepower motors is legion. In the United States alone, the value of fractional horsepower motors sold amounts to approximately $50,000,000 annually.’ See reference #1

Similarly, more than half a decade earlier Daniel Braymer had commented on the proliferation of this mind and life changing technology for home electro-mechanization. He observed that what had made it all possible was the invention of single phase alternating current motor, in a number of subtypes, small quiet, self starting, reliable and affordable motors for the home, motors which were compatible with the rapid standardization of single phase, alternating current, electrical distribution systems then spreading across north America. See reference #2 Among the types of single phase alternating current motors which quickly populated the Canadian home were: repulsion induction [see Group 16.01] for heavy duty, high starting torque applications such as refrigeration appliances; capacitor start [see Group 16.02] for advanced high torque applications, requiring quiet operation; split Phase [see Group 16.04] for light duty low starting torque applications; and shaded pole [see Group 16.04] designs for small devices such electric fans. The FHP single phase induction motor, often unobtrusive, out of sight in a dark corner, has, none-the-less, been a principle foundation stone on which Canadian, popular consumer and household technology has evolved, throughout the 20th century and into the 21st - a driving force of profound, typically un-recognized, social, cultural and economic change [See reference 6]. Electro-motive technology [the FHP motor], along with electric and electronic communications technology [the telephone and broadcast radio] would invade the Canadian home starting in the 1920’s. Throughout the balance of the 20th century these technologies would trigger a vast, new, popular consumer culture, a ‘popular technological revolution’. Yet, simply because technology has so shaped the Canadian reality, it has also shaped much profound Canadian though about the technological experience, its meaning and significance for humanity. Included among the works of Canadian writers with an international reputation are: Arthur Kroker, George Grant, Ursala Franklin, Heather Menzies, among many others [See references 7, 8, 9, and 10]. From the vantagepoint of the 21st century noted Canadian writer Jane Jacobs asks, ‘Now we stand at another monumental crossroad, as agrarianism gives way to a technology-based future. How do we make this shift without losing the culture we hold dear’ [See reference 11]


G. Leslie Oliver, The T. H. Oliver HVACR Collection

HHCC Storage Location:
Bibliographic References:

‘Fractional Horsepower Electric Motors’, Cyril Veinott, McGraw Hill New York, 1948 ‘Rewinding Small Motors’, Daniel Braymer and C.C. Roe, McGraw Hill, 1932 ‘Theory and Application of Capacitor-Start Induction Motors’, G. L. Oliver, Bachelor Thesis ,University of Toronto, Session 1951-52 ‘Modern Refrigeration and Air Conditioning’, Electric Motors, Chapter 7, Andrew Althouse and Carl Turnquist, Goodheart-Wilcox, 1960 ‘A course in Electrical Engineering, Volume II, Alternating Current’, Chester Dawes, McGraw Hill, 1934, Starting single Phase Induction Motors, P. 362. ‘The Fractional Horsepower Motor and its Impact on Canadian Society and Culture’, G. Leslie Oliver, Material History Review, Vol. 43, Journal National Museum of Science and Technology, 1996. ‘Technology and the Canadian Mind, Innis/ McLuhan/Grant’, Arthur Kroker, New World Perspectives, 1984. ‘Technology and Empire’, George Grant, Anansi, 1969, ‘The Real World of Technology’, Ursula Franklin, Anansi, 1993. ‘Fast Forward and Out of Control’, Heather Menzies, Macmillan, 1989 ‘Dark Ages Ahead’, Jane Jacobs, Random House, 2004


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