I love this kind of video and thought some people on here might like it. A very basic explanation of how a 4 speed gear box works for maybe 40’s/early 50’s. Using a synchroniser, whatever that is.
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I love those old documentaries. Explanation is so damn good and easy to understand.
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This one is pretty cool too
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Synchros basically have some leeway when sliding into the gear, they replaced sliding clutches which required double-clutching or VERY good rev-matching in order to avoid grinding gears. Double-clutching is what you’re supposed to do when driving a big rig as those transmissions don’t use synchros.
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Thank you, someone in the comments on the video tried explaining and it was a little over my head.
These videos are brilliant though, its really a shame that instructional videos wont be done in this style now.
Suspension presentation. If you find these about YouTube, add them to the thread as they can be useful for people who want to learn what some of these things do in simple terms. They’re also just pretty damn cool.
Slightly before Automation times, but a quite full explanation of engine production.
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is it just me or am i the only one that have watched most of this? ( too much free time)
still nice to discuss about though
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Well I’ve seen most, I’m trying to look for some old English ones now as I’ve realised that these are all from the same series, but for 1936 its interesting to see that the car actually is still the same basic beast.
Can anyone educate me on how straight cut gears work?
There isn’t really a way that they work as such, it’s just another type of transmission. But there is a key reason for using them on certain cars.
Axial loads! Helical gears encourage the shafts to move in the direction the gears are cut, eg:
You have a gearbox that is mounted to a transverse engine. The helical gears create forces that act along a transverse plane, basically left or right to the direction that the car is moving.
Now this is fine for most cars, as they don’t produce enough torque to cause problems with this. But on a race car, where you might have 300/400+ ft-lb of torque coming from the engine, that could be dangerous. The gearbox and the engine are going to be moved around a lot, which is very bad if you have a longitudinal engine where the engine mounts are designed to deal with the forces of the engine rotating, not being pushed back and forward.
So, with straight cut gears, you don’t have that issue, hence why they’re used on very powerful vehicles.
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How does it work though? The engineering, the mechanism, how does it work?
they are exactly that. The teeth are cut straight where normal gears are usually slightly helical and the teeth mesh into each other.
Normal gears on top straight on bottom
so basically there is nothing to stop side to side movement of the gear which in turn allows the gear to be shifted into the next/previous gear with no resistance on the gear=faster shifts they also sap up less parasitic power than normal gears as the is less resistance across the gears and transmission as a whole however due to the gears having very little resistance to left/right movement they do not hold as much torque so can be fragile
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Here was a good explanation I found too:
http://automotivethinker.com/transmission/straight-cut-gears-vs-helical/
I wonder why some cars have the reverse gear as the only straight-cut gear? The noise alerts the driver he/she is in reverse?
I think it’s just that its cheaper. Straight cut gears are easier to make than helical gears.
??? No car in many,many decades have had gears that slide around, if EVER.
Only gearboxes like that are used in motorcycles.
And straight cut usually copes with MORE torque than helical,
due to the fact that high torque tries to move the helical gears to the side.
In your picture above, if the left gear rotates clockwise,
the torque tries to move the left gear upwards, and the right gear downwards.
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Another question on gearboxes. It all started when I asked koolkei how the engine can rev up and down so quickly in sequential transmissions, then we talked about dogboxes and etc etc etc - end result: LOTS OF CONFUSION. So, here are all the questions in a list:
- How do sequential transmissions make the engine rev up and down so quickly during shifts? The shift times are like 200ms, how does it even work?
- How exactly do dogboxes work?
- Do dogboxes come with helical gears as well as straight-cut ones?
- So if a lot of motorbikes come with dogboxes, why do they have a clutch? This source claims that the most destructive way of handling a dogbox is with slow shifting and use of the clutch (lifting off the throttle, depressing the clutch, moving the gear lever slowly, releasing the clutch, and applying the throttle).
- Now I’m getting really confused, do dogboxes even have/need clutches?
I need answers, please, this confusion is horrible!! 
Good luck starting from stand still without a clutch.
That is one of the times a seq gearbox NEEDS a clutch.
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4 questions left to go 
1: usually seq gearbox is paired with a light flywheel, that is what makes the engine rew quicker.
2: look at the gears in a 4 speed Harley gearbox. https://catalog.zodiac.nl/en/catalog/09-transmission-and-kickstart/transmission-and-kickstart/transmission-parts-4-speed-big-twin/big-twin-4-speed-transmission-parts/
3: probably only straight, they don’t care about the extra noice.
4+5: see previous
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If you’re really interested in transmissions, check this channel:
This guy is a teacher or something, and disassemble different transmissions and assemble back together and you can see exactly the parts, how they work, the power flow and so on.
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