Automatic Gearboxes

A0wen

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Mod Note: Posts #1 - #19 originally in this thread.

I find that selecting the gear which is the first number of the lower limit you want to adhere to works fairly well on most cars.

That is 2nd for 20, 3rd for 30, 4th for 40, 5th for 50 and 6th for cruising at 60 or above.
Doesn't work with an auto though.

And with the increase in electric cars which have what are effectively gearless gearboxes - think CVT - then that approach really doesn't work.
 
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Bletchleyite

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Doesn't work with an auto though.

Yes and no. On most conventional autos you can set a maximum gear, though I don't know if I would or not, I've only ever driven an auto once. And I wouldn't go for a "flappy paddle" if you paid me, they are the worst of both worlds.

And with the increase in electric cars which have what are effectively gearless gearboxes - think CVT - then that approach really doesn't work.

One would hope that (again, I've not driven one) electric cars, being electronically controlled, will effectively adapt for that in the software by varying the accelerator response based on the speed, rather than just mapping the level of pressure directly to an acceleration rate in m/s^2 or an input current value. Some might even vary it based on camera-read/GPS based speed limits.
 

A0wen

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Yes and no. On most conventional autos you can set a maximum gear, though I don't know if I would or not, I've only ever driven an auto once. And I wouldn't go for a "flappy paddle" if you paid me, they are the worst of both worlds.

Having driven quite a few autos - CVT autos don't have the ability to 'hold' the car in gear at all, that's not the way it works.

On Torque-Convertor or DSG gearboxes, you can, but particularly on older ones, the gear ratios are different to manuals. It was common for example to find 3 speed Torque Convertor boxes when the manual equivalent had 5 speed.
 

AM9

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Having driven quite a few autos - CVT autos don't have the ability to 'hold' the car in gear at all, that's not the way it works.

On Torque-Convertor or DSG gearboxes, you can, but particularly on older ones, the gear ratios are different to manuals. It was common for example to find 3 speed Torque Convertor boxes when the manual equivalent had 5 speed.
My last car had a CVT. The cruise & limiter functions were excellent although I rarely used the limiter. The cruise could be set at any speed between 20 & 75mph. It would hold the set speed up and down hills (within the torque/power and braking effect of the engine). The transmission would slide up and down the ratios to keep the roadspeed relatively constant to within about 2mph except on the steepest hills where it might drop back, - but so would much of the other traffic. The limiter had a soft profile but it certainly prevented bookable speeds unless you were very careless.
 

A0wen

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My last car had a CVT. The cruise & limiter functions were excellent although I rarely used the limiter. The cruise could be set at any speed between 20 & 75mph. It would hold the set speed up and down hills (within the torque/power and braking effect of the engine). The transmission would slide up and down the ratios to keep the roadspeed relatively constant to within about 2mph except on the steepest hills where it might drop back, - but so would much of the other traffic. The limiter had a soft profile but it certainly prevented bookable speeds unless you were very careless.

That's as maybe - but the previous poster commented about being able to 'hold' an auto car in a gear to limit the speed - which isn't possible with a CVT auto by its very design.
 

Bletchleyite

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That's as maybe - but the previous poster commented about being able to 'hold' an auto car in a gear to limit the speed - which isn't possible with a CVT auto by its very design.

I did to be fair specify a conventional auto. CVTs in cars are not very common, though they are very common on budget motorcycles/motor scooters.
 

A0wen

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I did to be fair specify a conventional auto. CVTs in cars are not very common, though they are very common on budget motorcycles/motor scooters.

Actually you're wrong - increasingly CVTs are common as many hybrids use them - all the Toyota and Hyundai / Kias are. And Honda use them in both their hybrid and non hybrid powertrains.
 

Bletchleyite

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Actually you're wrong - increasingly CVTs are common as many hybrids use them - all the Toyota and Hyundai / Kias are. And Honda use them in both their hybrid and non hybrid powertrains.

A hybrid is not a conventional automatic, and therefore isn't what I was referring to. Yes, Honda are an exception.

A conventional automatic is an epicyclic gearbox with a fluid coupling/torque converter (I forget which it is), and it's those I was referring to, and those do pretty much all have a selectable maximum gear.
 

cactustwirly

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A hybrid is not a conventional automatic, and therefore isn't what I was referring to. Yes, Honda are an exception.

A conventional automatic is an epicyclic gearbox with a fluid coupling/torque converter (I forget which it is), and it's those I was referring to, and those do pretty much all have a selectable maximum gear.

The older gearboxes use a torque converter connected to an epicyclic gearbox yes.
A lot of newer cars use a DSG gearbox, which is basically a manual gearbox with two clutches. But it automatically changes the gears.
 

AM9

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A hybrid is not a conventional automatic, and therefore isn't what I was referring to. Yes, Honda are an exception.

A conventional automatic is an epicyclic gearbox with a fluid coupling/torque converter (I forget which it is), and it's those I was referring to, and those do pretty much all have a selectable maximum gear.
We're getting tie up with the use of the word 'conventional' here. Forty years ago I had a Triumph Dolomite with a Borg-Warner BW65 transmission. That had a fixed gear arrangement that was intended to make steep slopes safer to negotiate, e.g. ramps in multi-storey car parks. That's when apart from the DAF 'rubber band' transmission all auto transmissions were epicyclic with a fluid flywheel/torque converter. Things are totally different now as not only are there modern versions of the DAF CVT, but there are also Dual Clutch transmissions (DCT) which is a sort of preselector gearbox that thinks for itself. So there really isn't any conventional transmission now, - apart from a manual setup. The Borg-Warner transmission is just 'old' fashioned now.
On my last car with CVT, it had seven 'virtual gears' which could be selected, and the ratio was held, or lower to protect the engine at low speeds, so the same steep slope facility is still there although I can't say for sure whether the cruise or limiter function could be set in that mode.
 

Bletchleyite

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A lot of newer cars use a DSG gearbox, which is basically a manual gearbox with two clutches. But it automatically changes the gears.

I'd not call that a conventional automatic either, even though it is becoming more common because of its greater efficiency. Typically these ones can be switched to fully manual control via "flappy paddles".

We're getting tie up with the use of the word 'conventional' here.

Yes, true, I was probably being a little defensive over being told my statement was wrong, but rather the poster saying that it was had a different understanding of "conventional" to me. Maybe "traditional" would have been a better word for me to use, but either way I was referring to "slushboxes", not anything more modern and certainly not things like CVTs and electric transmissions.
 

AM9

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I'd not call that a conventional automatic either, even though it is becoming more common because of its greater efficiency. Typically these ones can be switched to fully manual control via "flappy paddles".



Yes, true, I was probably being a little defensive over being told my statement was wrong, but rather the poster saying that it was had a different understanding of "conventional" to me. Maybe "traditional" would have been a better word for me to use, but either way I was referring to "slushboxes", not anything more modern and certainly not things like CVTs and electric transmissions.
Thanks, there's no problem, I suppose it's a sign of the attempts to keep selling IC engined cars. EVs don't need gearboxes for drivers to stir porridge in, - once electric cars are the defacto vehicle on the road, I imagine that electronics will deliver automation like has been suggested in this thread, taking cues from weather, road condition, visibility, energy in battery, and of course, the legal speed for the location. Then it will be interesting to debate who would take the rap for speeding, manufacturers maybe?
 

Domh245

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once electric cars are the defacto vehicle on the road, I imagine that electronics will deliver automation like has been suggested in this thread, taking cues from weather, road condition, visibility, energy in battery, and of course, the legal speed for the location

Most of those will come from cars being self driving, not their being EVs. Just because there's motors and batteries instead of an ICE and gearbox won't magic up all the sensors to make that work. The new S class has several of those features but remains decidedly not an EV
 

AM9

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Most of those will come from cars being self driving, not their being EVs. Just because there's motors and batteries instead of an ICE and gearbox won't magic up all the sensors to make that work. The new S class has several of those features but remains decidedly not an EV
That depends on what you mean by 'self driving'. I think it's a long time before we'll see autonomous cars in any numbers on the road, - there are just too many legal issues surrounding them. But cars the make decisions in terms of limiting drivers' abilities to create hazardous situations are as you say already appearing, but the overhead of interfacing with an IC engine, mechanical transmission and mechanical brakes may well limit their use to higher priced vehicles. The coming of EVs with simple interfacing to all systems will bring these features into the mainstream vehicle market.
 

Domh245

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That depends on what you mean by 'self driving'. I think it's a long time before we'll see autonomous cars in any numbers on the road, - there are just too many legal issues surrounding them. But cars the make decisions in terms of limiting drivers' abilities to create hazardous situations are as you say already appearing, but the overhead of interfacing with an IC engine, mechanical transmission and mechanical brakes may well limit their use to higher priced vehicles. The coming of EVs with simple interfacing to all systems will bring these features into the mainstream vehicle market.

My point was that I don't think it's the fact that they need to interface with the engine that is preventing them becoming widespread! It's the cost of getting sufficiently good sensors that limits these features to higher priced vehicles, and the development of autonomous driving technology, be that full automation or just 'enhanced driver support' will be what drives the costs of the sensors and technology down to the point that it can be widely adopted - indeed things like traffic sign recognition are becoming fairly mainstream already now - they're an option with most manufacturers now, and come as standard on most premium brands

As noted, the fact that engines and gearboxes have been fully fly by wire for a while now, so integrating these into an ICE car is just a matter of (many!) hours of software development, which pales in the cost of developing a new car, particularly when said software cost to manufacture is (good as) zero, the cost of a whole host of sensors and processors on each car quickly adds up though
 

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The vast majority of car gearboxes are not fly by wire, unless you consider Bowden cables wires in this context! "Flappy paddles" are still a minority pursuit.
 

Domh245

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The vast majority of car gearboxes are not fly by wire, unless you consider Bowden cables wires in this context! "Flappy paddles" are still a minority pursuit.

Only manuals are connected up with Bowden cables, and are increasingly being phased out in ICE cars regardless of the relentless march of EVs. Even non-DSG autos are entirely electrically controlled (especially with the advent of 'floating' gear selectors which return to a neutral position once a gear has been selected)
 

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Actually you're wrong - increasingly CVTs are common as many hybrids use them - all the Toyota and Hyundai / Kias are. And Honda use them in both their hybrid and non hybrid powertrains.

Rover used to use them, certainly in the 200/400 series anyway. They weren’t very good. Subaru still use CVT’s as well.
 

Bletchleyite

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Only manuals are connected up with Bowden cables

Yes, true.

and are increasingly being phased out in ICE cars regardless of the relentless march of EVs

Only true in premium markets. Hybrids and EVs are phasing them out, but not the vast majority of ICE-only cars purchased, where an auto is a premium option that most people will neither specify nor really particularly want.

This:
As noted, the fact that engines and gearboxes have been fully fly by wire for a while now
...is only true for a minority of pure-ICE cars and will likely continue to be so in European markets as long as pure-ICE cars can be purchased.
 

delticdave

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I'd not call that a conventional automatic either, even though it is becoming more common because of its greater efficiency. Typically these ones can be switched to fully manual control via "flappy paddles".



Yes, true, I was probably being a little defensive over being told my statement was wrong, but rather the poster saying that it was had a different understanding of "conventional" to me. Maybe "traditional" would have been a better word for me to use, but either way I was referring to "slushboxes", not anything more modern and certainly not things like CVTs and electric transmissions.
SWMBO & I have owned 5 DSG equipped cars (still have 3 of them...) moving the selector lever to the left selects manual mode, (push forward to shift up, backwards to shift down). If the car has paddles (sometimes 'tis an option) left paddle is for shifting down. right paddle for upshifts.
But, even in normal D (drive) mode the paddles can always overide the DSG shifitng software, unless the driver is attempting an impossible shift.
The most recent VAG group cars now have a "fly by wire" electric shifter, & the manual hold mode is no longer available.
Typical VAG cost-cutting, higher prices for less car.
 

JohnMcL7

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I've used a Toyota CVT gearbox that did have set gear ratios so it could behave as a normal CVT in auto or you could change up and down manually using the auto shifter or the paddles so it could hold a certain gear ratio. I guess the feature was to give it a more sporty feel but it wasn't a powerful engine and the shifts were slow so it seemed a bit of a pointless feature.
 
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nlogax

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Rover used to use them, certainly in the 200/400 series anyway. They weren’t very good. Subaru still use CVT’s as well.

Worst car I've ever driven was an early noughties Rover 200 rental with an asthmatic CVT. Genuinely feared it was rubber bands and luck getting me up any remotely hilly terrain.
 

robbeech

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A conventional automatic is an epicyclic gearbox with a fluid coupling/torque converter (I forget which it is), and it's those I was referring to, and those do pretty much all have a selectable maximum gear.
Id' say most automatic boxes (traditional, conventional, whatever you want to call them) nowadays have the ability to manually select a gear rather limit the maximum gear.
Interestingly I have an automatic van that does NOT have this feature, instead just limiting the highest gear it will use, where at the same year of manufacture, all the cars the manufacturer made with that exact same engine and gearbox configuration used the other method.
 

superjohn

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I have a Toyota Yaris hybrid which has their magic box of tricks electric transmission. It has the usual PRND selector and also a B option which simulates engine braking. It does this by applying a small reverse force to the motor if you ’coast’ in D. The engine braking sensation is exactly as if shifting to a lower gear in a conventional gearbox and helps retain control on steep downhill roads. Admittedly there aren’t many of those where I live in Suffolk.

It also has a useful anti rollback function for hill starts. It will creep forward as per usual automatics on level roads or slight inclines but, as long as you are in D, it will not rollback on even the steepest inclines. It takes a bit if getting used to but it can be helpful once you learn to trust it.

The cruise control uses the regenerative braking to restrict the speed if necessary, that can be an odd sensation on undulating roads. 40mph on the up, down, up, down road from Aldeburgh to Leiston gives it a real workout!

As an aside, I think an old style automatic gearbox that is entirely controlled by relative fluid pressure variances is an amazing piece of engineering. No electronics whatsoever for such a complex machine.
 

IslandDweller

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"I find that selecting the gear which is the first number of the lower limit you want to adhere to works fairly well on most cars.
That is 2nd for 20, 3rd for 30, 4th for 40, 5th for 50 and 6th for cruising at 60 or above"
But virtually every car sold in the last decade has cruise control, so just use that if you want to stick at a set speed. Most set ups will brake as necessary on a descent to hold the speed. (Ford being the only major manufacturer that I can think of that fits a device that lets the speed runway on a descent.)
A related aside. 2020 was the first year in which more automatic vehicles were registered in the UK rather than manuals.
 

Bletchleyite

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"I find that selecting the gear which is the first number of the lower limit you want to adhere to works fairly well on most cars.
That is 2nd for 20, 3rd for 30, 4th for 40, 5th for 50 and 6th for cruising at 60 or above"
But virtually every car sold in the last decade has cruise control, so just use that if you want to stick at a set speed. Most set ups will brake as necessary on a descent to hold the speed. (Ford being the only major manufacturer that I can think of that fits a device that lets the speed runway on a descent.)
A related aside. 2020 was the first year in which more automatic vehicles were registered in the UK rather than manuals.

Cruise is only any use when not in traffic, unless it's adaptive cruise which is still very much a premium option, because people don't drive at a precise speed. Most cruise control does not use the brakes and so can "run away", though some engines offer better engine braking than others, and obviously the lower the gear the better the engine braking.
 

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AFAIK the Hyundai hybrids use a 6 speed DSG rather than a CVT, I know my step-mums Ioniq sounds nothing like her previous Juke which was a CVT (and a horrid one at that).

Of course one of the big differences in hybrids is that they generally use Atkinson Cycle engines which whist they have less power per litre than a regular engine they are more efficient and as such are suited to applications where there are other methods to make up for the alck of power.
 
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AM9

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Cruise is only any use when not in traffic, unless it's adaptive cruise which is still very much a premium option, because people don't drive at a precise speed. Most cruise control does not use the brakes and so can "run away", though some engines offer better engine braking than others, and obviously the lower the gear the better the engine braking.
My CVT car used the engine very well to keep to the set speed even down some fairly steep hills. Coming south on the A5, I could top the hill and lock in cruise at the start of the 40 limit, and it would hold it to no more than 42 down to the 30 limit start where I could drop. It out of cruise and reset when it reached 30moh, then do the same down to Hockliffe lights. Great for keeping to the limit(s).
I"m hoping that EVs can do the same, and get some extra regen to boot.
 

IslandDweller

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"adaptive cruise which is still very much a premium option"
My Skoda has adaptive, standard fit, on a lower spec version. Virtually every VAG group car that has cruise control gets the adaptive version as standard.
 

Bletchleyite

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"adaptive cruise which is still very much a premium option"
My Skoda has adaptive, standard fit, on a lower spec version. Virtually every VAG group car that has cruise control gets the adaptive version as standard.

It's clearly heading that way, but I'd call most VAG cars premium cars - they are premium brands these days compared to say Ford, Kia etc.
 

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