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Two-Cylinder John Deere Engines
Just for my personal edification and maybe that of others, please someone discuss the design and operation of the old John Deere two-cylinder tractor engines including the firing times etc... that gave them their distinctive sound. Thank you.
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Two-Cylinder John Deere Engines
Well, it's just a quirk of math and physics really.
It started out as fluke, based on the "hit & miss" engines of the time, and became the signature sound for a whole reutation based around the "Poppin' Johnnies".
Basically the theory then was not to have a steady, almost continous series of detonations feeding power to the flyweel which smoothed the power out and kept it constant and not just in spurts which is hard on both man & machine.
Bear in mind, the only thing they had to base their designs on at the time was horses or mules or oxen, and anyone who has ever worked a draft animal will tell you, under sever load, or when starting a heavy load, a horse will break stride and kick out. That is to say, they don't push with one leg at a time, they lean forward into the traces against the load, squat slightly and give a big mighty push with both hind legs at once.
So, when 'horsepower' got mechanised, they had only this example. The early engines, especially the hit & miss ones, had an enormous flywheel and a relatively few 'kicks' from the power strokes, spun it up and lept it spinning, and it was just the stored energy in that flywheel that did the work, not each power stroke against the crankshaft like todays engines do.
The math & physics enter into it because when John Deere designed the 2 cylinder engines, the did something unusual, they didn't spead out the strokes over the entire circle. Various historians think this was because they either, designed the engine as a 4 cyl. and cut it in half, or designed it such that it had 'room for expansion' later on. Nobody knows for sure.
We do know, that the two power strokes are at 0° and at 180°, and then the engine coasts for 540° and then the whole process starts over again. It is this 'pop, pop, coast' that gives them their distinctive sound.
Why they didn't have them fire at 0° and 360° to even things out? Well, we do know that there was one really good reason, shake!! Having them fire at 0°& 360° on a 2 cylinder motor would have meant that both pistons hooked to the crank on the same side, the crank would have been a U-shape instead of a Z-shape. This would have caused a huge shake in the machine.
Of course 3 or 4 cylinders would have solved this problem too, but that's not what they did.
Regardless of the reasoning, I'm glad they did it the way they did. I've got a JD AR that has been in the family since new, it still looks that way too. Every year it appears in countless parades, and you can see the people stop and stare, especially the old-timers when it comes pop, pop.....poppin by them. 
Best of luck.
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Two-Cylinder John Deere Engines
Murf that has to be the best non technicial explanation I have every heard.
Good Job Harvey
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Two-Cylinder John Deere Engines
Yep, good job Murf. You're a real asset to TractorPoint and it's good to have you here.
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Two-Cylinder John Deere Engines
Murf,
I agree with KW. I do love a poppin good story.
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Two-Cylinder John Deere Engines
Murf you did well to explain the basic's of the engine with a lot left to as to why they are not on operating farms, the insurance companies have left them for non-operatings farms or as collectibles at best as they have been concieved as an operating a hazard. They also had unique controls as to the rest of the tractor industry at the time and they at this point have been by many insureance companies been declared a hazard. We have several large farms that have been told they are to get rid of there older JD tractors because of the hazards that are left exposed or expect major increases in premiunms. That is no matter who runs them! they are the two cylinder units with the exposed flywheels which covers all the alphebet tractors made.
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Two-Cylinder John Deere Engines
Art; When I was a kid I worked for a neighbor baling hay. He was a real hurry up, and very particular type fellow who couldn't stand to see time wasted. I and his son traded off every other load either driving on the baler or loading bales, every load had to have 64 bales to make his hay fork work out to 8 bales at a time in the mow. He wouldn't let either his son or I help hook up the loaded wagons when he brought the empty racks to the field, you allready know the rest of the story, he stood on the ground behind the right side of the tractor so he could reach the hand clutch and the wagon tounge at the same time to hook up. Even as a kid it scared me to watch. By some quirk of fate he lived into his 90's with only a few minor injurys. We had farmall tractors and had a 2MH picker on an M, talk about hazards, even with the shields in place you were inches from roller chains, the snapping roll shafts, etc. I remember lots of older farmers who lost arms or were killed trying to unplug husking beds or snapping rolls with the picker running. So yes I can believe that insurance companies would get a bit jittery over some older equipment. Keep safe. Frank.
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Two-Cylinder John Deere Engines
At age 14 having had my left hand wrapped around the PTO of our '47 Farmall, it always amazed me that the Deere's flywheel was exposed. Me and my weightier younger sister used to ride on the drawbar for weight when discing while mom drove (soil was very deep humus/compost and tires were nearly bald). Tractor tire hit a big rock underground and Sis fell off and the 8' disc ran over her. Just a scratch on her forehead (and a lifetime of therapy ). Mom never did drive again. And then ther's the time I ran over a bunch of chicken incubators (hey, I was only 8). DOH!
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Two-Cylinder John Deere Engines
Yup, they even get fussy about them up here in Cannuckistan too Art.
I had to 'buy' the tractor from the farm corp. then write up a storage contract and pay the corp. a few bucks a year for 'storage' to even be allowed to keep it on the farm.
But there's still something magical about them.
Best of luck.
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Two-Cylinder John Deere Engines
If you have not seen videos 1, 2 and 3 by John Deere on their tractors you probably would very much enjoy them. They are done for children so you will have no problem understanding them .
Video 4 is a summary of those, so don't buy it. Great Christmas gift for your spouse. You can sit with softdrink and popcorn in front of the fireplace and share a romatic video.
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