Random ergonomic thought
When you stop and think, push-pull knobs are flatout PECULIAR.
Before 1930 most electrical controls in cars were turn-knobs, just like most electrical controls in houses and radios. Sometime in the '30s, American cars started using pull knobs, and continued with a few exceptions until the late '70s. Pushbuttons had a brief vogue around 1940, and Chrysler returned to turn-knobs briefly in the early '50s. Otherwise it was mainly push-pull for everything. Switches, chokes, vents, door locks, even parking brakes.
Push-pull controls NEVER appeared on house wiring or appliances or radios. After 1940 houses moved from turn to toggle switches
with a few pushbuttons. Radios** and appliances*** continued with turn-knobs until replaced by digital click-buttons or touch screens.
Euro cars mostly**** continued the original turn-knobs, with some toggles on sporty models and rockers in the '60s. Around 1970 Euro and Jap cars standardized firmly on big turn-knobs.
So push-pulls are pretty much gone from ALL equipment now. Do I miss them? No. They were electrically fragile and dangerously protrusive. When used for mechanical purposes like vents or thermostats, they required a 'pushable' cable, which was maximally tricky to maintain.
The real question is why they became universal, not why they disappeared.
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** I can only think of one pull control on a radio. It was an Airline tube portable from 1958, with a pair of little rectangular pull switches for battery and AC power. There must have been a few
*** And one on appliances: the alarm knob on wind-up or analog electric alarm clocks.
**** Some Euro and Jap cars tried push-pull when they first broke into the American market, but didn't stay with it very long. Must have realized the familiarity factor wasn't worth the trouble.
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