Such a one was the windup (or “impulse”) starter. In the late 1950s they were the very latest thing. The idea was to turn a crank to wind up a heavy spring, then trip a release mechanism so the spring would unwind and turn the engine.
Get a load of this fabulous 1968 Toro Whirlwind thusly equipped; what do you guess this mower cost when it was new, in today’s money?
When the Toro Whirlwind range first launched sometime in the mid-1950s, they were advertised like this:
One seldom sees a windup starter in any condition any more. Me, I have two different new old stock Tecumseh units, one round and one square, but that doesn’t count; my tastes are so far off the bell curve it’s a long-distance call from here. Someday someone as
crazed eccentric as I am will come along and free up some garage space by taking them home off me. Here’s Briggs & Stratton’s first design:
The knob on the side extended a spur between adjacent flywheel fan fins when turned to the CRANK position, thus immobilising the engine and allowing spring tension to build. Turning the knob to START withdrew the spur, permitting the flywheel to spin. Trouble was, the knob could be turned—or, with some wear, could float on its own—into CRANK with the engine running, which would damage the flywheel fins and/or decapitate the spur. The later design replaced the flywheel spur with a lever-operated pawl that blocked the starter drive itself until the lever would be flipped into START. Much better.
Other than that early goofup, Briggs’ was by far the safest of a very unsafe lot. The trouble was that once wound up, such a starter was well and truly armed and dangerous. An adult could walk away from a wound-up mower and a child could touch or jar it, setting off the spring and starting the mower. Or consider the homeowner or mechanic facing a machine with a wound-up impulse starter and a jammed engine or blade: the spring inside, even when not wound up, was strong enough to break bones or worse should it escape its keeper. There was even a Clinton (not the American politician, but the Iowa-based engine company) windup starter for severe-duty applications, with two springs, one atop the other, and a giant bruiser of a drive cup:
There were detailed and warning-laden instructions in the service manuals for neutralising the spring before discard by torching it (at arm’s length) to red-hot at several locations around its circumference within its keeper, but that didn’t address the problem of the armed and jammed mower. Only Briggs & Stratton had the foresight to provide a clever, elegant, simple, and cheap means of putting the pin back in the grenade—by pulling it out: hold the crank handle with one hand, remove its central screw with the other, and the inner end of the spring (which anchored on the central screw) was let go so the wound-up tension was harmlessly if loudly released. And this starter, like Briggs’ coaxial rewind rope starters, used that company’s thoroughly ingenious crankshaft-mounted, centrifugally-disengaged sprag clutch—a highly elegant piece of engineering (the patent for which eludes my search efforts; anyone?).
All in all, the windup starter was a keen idea, but it just made the engine starting effort different, not less; recalcitrant mowers still reduced owners to sweating and swearing. The windups were just too dangerous; even before there was any strong consumer product safety commission to insist, these went away by the early ’70s. Anyhow, better ignitions, compression-relief systems, and miniature automotive-type electric starters were making mowers easier to motivate: