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Nyphur

Crazy Trannies*

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I would hazard a guess at no on the synchro, but what "constant mesh" means is that all of the ratios of gears are connected to each other at all times, rather than only one gear and you engage said gear by physically moving it to mesh with its' partner.

 

So, a regular gearbox has 2 shafts, side by side. One is connected to the engine, the other the wheels. Along each shaft are sets of gears mounted on ball bearings, in differing ratios. Obviously you can't have them all engaged at once, that doesn't work, but they are free to spin (neutral). What you do is push a locking mechanism into the gearset you want to be active so that they drive the output shaft.

You can make the locking mechanism much more chunky and if it loses the edges off its locking dogs it's not the end of the world because all they have to do is push into their holes- this effectively saves the actual gear teeth themselves because it is an improvement over non-constant-mesh which would smash the gears together using the gear teeth. This meant the gears didn't last long, particularly if made from metals like brass.

Synchromesh just has an extra piece on the locking dogs that pushes against the gear to get it to spin up to speed before you try engage the dogs. Pushing too hard results in the typical gear crunch, which is the locking dogs not being able to push into their holes in the gear.

 

Slightly less muddy?

 

 

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Fuller Roadranger, Eaton Twin Splitter. 

The scammell I‚Äôd say¬†means there is no synchro, so would need a rev match on the way down the gears so clutch in, out of gear, clutch out,¬†rev, clutch in and knock it into gear. A lot of that is ‚Äėfeel‚Äô a bit like driving a car without the clutch, under the right load it should just ‚Äėslot‚Äô in, shouldn‚Äôt crunch.¬†

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Had started to find out if there were any early 70s US cars,  - maybe Cadillacs, Lincolns, etc, fitted with push button autos and found this interesting article. 

http://www.curbsideclassic.com/automotive-histories/automotive-history-the-mysterious-disappearance-of-the-chrysler-pushbutton-automatic-a-government-conspiracy/

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3 hours ago, PhilA said:

I would hazard a guess at no on the synchro, but what "constant mesh" means is that all of the ratios of gears are connected to each other at all times, rather than only one gear and you engage said gear by physically moving it to mesh with its' partner.

 

So, a regular gearbox has 2 shafts, side by side. One is connected to the engine, the other the wheels. Along each shaft are sets of gears mounted on ball bearings, in differing ratios. Obviously you can't have them all engaged at once, that doesn't work, but they are free to spin (neutral). What you do is push a locking mechanism into the gearset you want to be active so that they drive the output shaft.

You can make the locking mechanism much more chunky and if it loses the edges off its locking dogs it's not the end of the world because all they have to do is push into their holes- this effectively saves the actual gear teeth themselves because it is an improvement over non-constant-mesh which would smash the gears together using the gear teeth. This meant the gears didn't last long, particularly if made from metals like brass.

Synchromesh just has an extra piece on the locking dogs that pushes against the gear to get it to spin up to speed before you try engage the dogs. Pushing too hard results in the typical gear crunch, which is the locking dogs not being able to push into their holes in the gear.

 

Slightly less muddy?

 

 

Phil's pretty much got it; the gears, as the name suggests, are always meshed and the individual ratios are selected using dogs as contrasting with a crash box where the gears are physically moved in and out of mesh according to what ratio was wanted. Synchromesh is just a further sophistication on top of constant mesh, incorporating braking rings to slow the relative motion of the two halves of the dog clutch being closed by the operator, reducing to a minimum the unpleasant soundtrack.

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20 hours ago, Nyphur said:

A thready celebrating the weird and wonderful transmissions of this world.

It used to be that 4 on the floor was the norm, then the advent of the 5 spd box changed things up, nowadays we've got DSG. What are some of the more out there transmissions we've seen over the years. I'll start:

NB: Much of this content stolen from Jalopnik.

 

usakkm2k6gw1egtedw9k.jpg.3e2c39fe3cab73531c28fb360af4d882.jpg

 

zfjyhjpe09qpbapldlm8.jpg.765ec8441b28b3b638a9680d7d1ec66d.jpg

 

Please share your favourites. 

As I understand it, the Suzuki (plus I think Honda &/or Yamaha did similar) needed that many gears as the powerband itself was so sharp (all or nothing) and less that 500rpm wide!!!! Wonderful insanity. 

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Anyone on here ever undergone "the change" themselves? 

 

I did briefly consider it myself once, then came to my senses and realised converting a Freelander TD4 from manual to automatic was folly.

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56 minutes ago, willswitchengage said:

I never fully understood how these work but the operating one of these selectors is silky slick.

9062014900_f7706bbc63_b.jpg

SCG (Self Changing Gears), as fitted to almost everything in the 70's and 80's. Take foot off just as changing for a smooth change. Basically an auto box with band brakes (Phil A now knows all about these) that you select which band to engage. This unit operates by electrikery, Leyland's did it using air pressure, so to change gear you slipped it in to neutral, then released the throttle pedal, counted to two and selected the next gear.

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So whilst on this subject, Bristols 5 speed 'box as fitted to FLFs, RELHs etc had the fifth gear only selectable directly from 4th. Unfortunately, that also meant that to get out of 5th you had to drop it to 4th before seriously slowing down. If you didn't, and ended up stationary in 5th, the language from the depot foreman as you explained why the thing wouldn't move was errr, interesting. Then the fitters would turn up to tow you to a high enough speed to get the bastard back into fourth. 

 

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And Bedford had a very amusing gearbox on their SB buses in the late 50s and early 60s. Basically the layout was known as Chinese, everything was back to front on the selectors. Now that really caused a lot of problems for new drivers (who of cause we forgot to warn about), one received a round of applause from the regular passengers when he finally realised where the gears were and had stopped throwing them (the punters) around the bus.

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2 hours ago, Nyphur said:

Anyone on here ever undergone "the change" themselves? 

 

I did briefly consider it myself once, then came to my senses and realised converting a Freelander TD4 from manual to automatic was folly.

I briefly entertained delusions of swapping my Stagea's slush box for a manual but quickly realised I didn't give enough fucks for what is an expensive and involved swappage.

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1 hour ago, busmansholiday said:

So whilst on this subject, Bristols 5 speed 'box as fitted to FLFs, RELHs etc had the fifth gear only selectable directly from 4th. Unfortunately, that also meant that to get out of 5th you had to drop it to 4th before seriously slowing down. If you didn't, and ended up stationary in 5th, the language from the depot foreman as you explained why the thing wouldn't move was errr, interesting. Then the fitters would turn up to tow you to a high enough speed to get the bastard back into fourth. 

 

As an ex owner of a ¬†Bristol L with that same gearbox, I can thankfully say that there is a ‚Äėneutral‚Äô just below fifth so you only coast embarrassed to a halt before ferreting around to select first again and repeat said procedure.

It was described by someone else as a sonata in several movements by unaccompanied gear box. They nailed it there.

Other bus related boxes were the BMMO C5 with all of the right ratios but not necessarily in the right order. It was known as a ‚ÄėW‚Äô change box and gears were not where you‚Äôd expect them to be. Late in life these motorway coaches were used on bus service. My god, after driving one for about 20 miles, the thought of one of these on an ten hour shift on stop start work would fill me with dread.

other notable mentions were the original MCW MetroRider which were manual gearboxes. The idea that a manual box in a minibus around the houses was bad enough but for added fuckwittery the gate was backwards and the linkage slack meaning obtaining fifth usually involved climbing out of the driving seat and heading towards the entrance door, gearstick in hand.

That leaves us with Fords. Six ratios were offered yet the linkage betwixt lever and box meant that of the six offered, it was random chance  that the one selected was any where near the one requested.

Oh yes, may I interject with the Wilson preselect? A wonderful device that in fully manual form could break ones left leg if the selector pedal was sharply pressed and released without fully making sure that the quadrant was properly in gear.. When I say quadrant, some buses didnt use a quadrant to preselect the next gear, oh no. Guys used a gear lever like a manual box just to confuse matters.  The Wilson direct acting preselctive gearbox mentioned above was a mere pussycat compared to what drivers had to endure beforehand.

On the subject of Guy buses, there was available at the same time a sliding mesh gearbox and a constant mesh gearbox, both ‚Äėcrash‚Äô i.e with no synchromesh. The difference was that one was backwards gate (with the gear pattern reversed so fist was wheee tnird was etc; and one was normal gate. The only difference was that one had a red gearknob and the other black. After a few years in service, the knobs were mixed around so you could never get in a Guy and confidently pull away in first, first time. Bastard things.

Back to cars (well this is a cr sige after all, isn’t it?) Honourable mention must be given to the Cotal gearbox. A car version of the above picured  semi-auto with its own version of a miniature  gear-lever mounted upon the steering column. Exactly like  the later bus box but about 30 years earlier.

 

I’ll shut up now.

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I was wondering when someone would mention a pre selector gearbox :)

its interesting as I entered the car scene coming from buses, which caused me to get a few confused looks when I just casually mentioned a preselector gearbox like i expected them to know what that was

because I knew of them from the RT, but apparently they were not really a thing in cars apart from some high end luxury cars of the 40s i think and the daimler scout car IIRC

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On 10/7/2019 at 10:28 PM, JeeExEll said:

^ Deleted in error (phone).  Edit, I can't work out how the levers work, there may be some info on the net.

It's just the same kind of 10 speed you would get on an adult bike. Left lever chooses between two chainrings, right chooses between five sprockets. I think it was only America that got the 10 speed. 

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Friend of mine paid to have a MK2 cavalier converted from auto to manual.

Madness. He only had the car because he had sold a newish MK3 to help with a house deposit.

Even using second hand parts it  must have cost as much as the car was worth but apparently he liked the car, just not the auto.

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That 90s tan brown with lots of billet ally hotrod interior on p.1 made me think of the Lenco transmission which was popular in Pro Street and drag cars in the 90s. I think that is one. You have a separate box with its own lever for each gear and you pretty much just stack them up one behind each other. 5 gears = 5 boxes = 5 levers. I think they might be clutchless because they're planetary gears. Great for drag racing but they're supposed to be (or at least they used to be) a complete nightmare to drive on the street.

lenco 1.jpg

lenco 2.jpg

lenco 3.jpg

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I was looking at this vid yesterday of the Lenco.  It's a poor quality vid so I didn't post it, but it's here if anyone's interested.  Jump to about 1.00 minute.  

Quick burnout at around 2.00 mins then launch at about 2.20.

 

Imagine one of these installed behind a Marina A-series 1300 or a Viva 1256?   Would make going to the shops interesting.

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18 hours ago, Richard said:

It's just the same kind of 10 speed you would get on an adult bike. Left lever chooses between two chainrings, right chooses between five sprockets. I think it was only America that got the 10 speed. 

I see it now after zooming into the pic.  Had assumed it somehow used 3 levers but just couldn't see how that could be possible. The small lever running in it's own slot must be attached to the middle lever.  

(Or maybe we're both wrong and the small lever is for reverse, like a Lenco.  Pedal forwards but bike goes backwards.  Cool.).

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On 10/8/2019 at 4:58 PM, JeeExEll said:

Had started to find out if there were any early 70s US cars,  - maybe Cadillacs, Lincolns, etc, fitted with push button autos and found this interesting article. 

http://www.curbsideclassic.com/automotive-histories/automotive-history-the-mysterious-disappearance-of-the-chrysler-pushbutton-automatic-a-government-conspiracy/

My Dad had a Renault 8 with a push button auto ūüėĮ

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^  That's fantastic, I never knew Renner did that.   Some info on Wiki.

https://en.m.wikipedia.org/wiki/Renault_8_and_10#Automatic_transmission

Can't find R8 auto pic, nearest is this.  So much potential for transmission disaster in this pic.

7Smi3yO.jpg

Can you imagine a R4 or R16 or R17 or R30 with push-button auto??

Or maybe a late 80s R5 GT Turbo?  

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