I see old ('60s) Cessna 150s often have a ‘pull starter’, which was later replaced with a key starter. What is a ‘pull starter’? I keep getting visions of a recoil starter, like on a lawn mower. 
(ETA: I know it’s not a recoil starter. 
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So what is it?
You post a **lot ** of aircraft related stuff here and I get the feeling you know the answers to most everything you ask.
I know a little about a lot. Or a lot about a little. I don’t know the answer. Never flew one.
I’ve flown one, but don’t know exactly how it worked. It didn’t require a terribly hard pull, so I don’t think one is doing a lot of mechanical work to engage the starter. I liked it - weird little quirk that made people give funny looks when they saw me start it up.
It appears to me that it’s a mechanical replacement for the plunger solenoid. There was still an electrical starter when you turned it over wasn’t there?
yep, thats the logical deduction …
here’s proof.
Big switch on the pull start one, taking the place of the starter solenoid…
First C-172’s had them also.
Just replacing the electrical solenoid with a mechanical lever that was pulled from the inside of the cockpit. Cheap, very dependable & robust.
Like mechanical flaps, I much prefer those things over electrical operated ones.
As funky as it was, I preferred the mechanical gear on the Money.
So it was literally a lever that you pulled that cranked the engine, mechanically equivalent to pulling a cord on a lawnmower engine?
I always knew that small private aircraft engines were fungible with lawnmowers! 
(ETA: I actually flew gliders more than actual, y’know, airplanes, so forgive me if I’m uneducated in details like these. )
No, it used an electric starter but the starter didn’t have an electrical solenoid that engaged the starter. That part was manual.
A Cessna 150 would have something like a 200 cubic inch engine with a compression of 75 psi over 4 cyclinders. not really possible to pull start it like a lawnmower.
I remember my dad on more than one occasion, would bring his tool kit if my car was ever stranded. He would usually start at the battery and terminals, and quickly work his way to the solenoid. Amazing how a pair of pliers could get the thing up and running again by touching the two poles of the solenoid with the pliers. It was like magic.
Johnny, I flew a Cessna 140 that had the pull starter too. I think they are great, nice not to have to mess with a key and if I’m understanding correctly, it’s just a manual way of skipping having a solenoid altogether.
Perhaps on my Bearhawk project I hope to start early next year, I may rig it up like this too. It would be one less thing that could go wrong in the bush, out in the middle of nowhere.
OK, now I’m going to have to look up how a starter actually works! I think the way it works with a solenoid is that when you turn the key (or step on the starter in my old jeep) the solenoid pushes a gear that engages the engine’s flywheel. When the gear is engaged, the starter motor turns, turning the gear that the solenoid engaged with the flywheel, turning the flywheel, which turns the crank that moves the pistons, etc.
So AINUI, you pull the lever and it manually engages the gear instead of having an electric solenoid do it. When the gear is manually engaged, a circuit is closed that turns the motor.
Isn’t there a key to engage the magnetos?
Thanks for the answers, everyone.
Most small Cessnas and other small planes had a pull start. You primed the engine, then stood in front of the plane and pulled on that propeller-shaped double lever. Electric start is much much better, but spinning the prop was a fallback. BE SURE THE WHEELS ARE CHOCKED OR THE BRAKE IS ON!!
Tractor enthusiasts may remember the John Deere models that had a flywheel which had to be wound up to get it started. I think some WW2 planes used the same system.
There was also the cartridge system, where a couple of blanks were used to get the pistons moving.
I saw a Wildcat started with a shotgun shell at Oshkosh last year. It was an original WW-II shell used. Pretty cool system. Really spins the prop around like no electric start could.
Yes, although it also acts as a relay that sends power straight from the battery to the starter. On all newer cars, one solenoid does both jobs, with the electromagnet both engaging the ring gear and closing the contact to send juice to the starter motor. On older cars, though, there were usually two. The one that engaged the ring gear was on the starter, but the one that sent power to the motor was usually mounted on a fender near the battery. Ford kept this arrangement on their RWD cars well into the 1990’s. It made razncain dad’s trick pretty easy if the solenoid went out!
My brother has a beautifully restored ’44 poppin’ Jonnie JD he spent thousands of man hours and years getting it to showroom quality. That is one cool tractor. And yes, his has the flywheel start. The back of the flywheel has indentions on the back side of it for fingers to get a good grip on it. It could start better, often it takes him about 5-10 tries. It’s only something like 18hp, but gosh, it’s geared down so low, that he was taking my Ford Ranger pickup and dragging it down the street with me having my brakes completely locked up. He had to do that to set his rings.
I actually don’t recall the 120 and 140’s having keys to it. Some may have.
That’s how I understand solenoids too, by the way you described it. In it’s most basic sense, I think of it as just two wires, that are bare on each end, and when they touch, they engage the starter gears to the flywheel to turn the engine over.
A lot of Lycoming engines have direct starters with a Bendix on them.
Magneto switches are only to unground the “P” leads of the magnetos. That is how you make them ‘hot.’ Can be a switch that uses a key or just a toggle switch. There will be one for each mag. That is usually why twins us toggle switches and keys for the door. Small Cessna’s had the same key for the door and the mag switch.