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Ferrari gearbox "interlock"


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#1 f1steveuk

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Posted 30 November 2015 - 14:48

Someone, put me out of my misery!!!

 

In conversation the other day, I told a friend of mine that around 1968/69, whereas a "DFV kitcar" driver could change gear down for a corner by going from say 5th to 2nd directly, Ferrari drivers could not. I recall reading years ago, that Ferraris had a gearbox "interlock" that meant going down for a corner, the driver would have to go, 5th, 4th, 3rd then 2nd.

 

My friend doubted me, and queried as to why. Of course now I cannot find the book where I am sure I read it.

 

So, interlock, fact or brain fade? Why (to protect the engine from over revving?), and if my brain is right, from when until when was this device fitted, and fiinally, how would it work?



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#2 bradbury west

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Posted 30 November 2015 - 16:55

Steve, ISTR  it was the same with the ZF box on the Lotuses, hence JC's fail to finish  at Monaco when he was driving "gently" and  the detent locked in 2 gears or something in between  because he did not change down positively enough for the interlock to work. I am sure the engineers will explain it properly. I will look for a similar Ferrari reference

Roger Lund



#3 f1steveuk

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Posted 30 November 2015 - 18:34

Thanks.  The problem I can see is that most 'boxes have an interlock, to prevent the meshing of more than two gears at a time, but the one I am particularly interested in was to prevent the "jumping" of gears in down changes



#4 Henri Greuter

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Posted 30 November 2015 - 19:14

Thanks.  The problem I can see is that most 'boxes have an interlock, to prevent the meshing of more than two gears at a time, but the one I am particularly interested in was to prevent the "jumping" of gears in down changes

 

 

I am not sure but I vaguely remember Heinz Pruller mentioning something like what you mention told to him by Lauda during his years at Ferrari and it being written down in one of the annuals Pruller publiesd over the years.

But where and in which one?

 

Henri



#5 chr1s

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Posted 30 November 2015 - 23:15

I read something about this once too but can't remember where, but I do remember thinking when I read it, that it contradicted something that Ermanno Cuoghi said about Lauda changing gear  stright to the one he wanted rather than going through every gear.  I will try and find the relevant books.



#6 63Corvette

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Posted 30 November 2015 - 23:41

Many gearboxes (motorcycles) have "sequential" shift gear change, whereby the operator MUST shift numerically through the gears, whether up or down. This arrangement precludes up or downshifting (say) from 4th to 1st. It does not require a "lockjout" but rather is a design objective.



#7 Cavalier53

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Posted 01 December 2015 - 02:32

In "Niki Lauda Formel 1" (1975) it reads about the gearbox of the 312B3 and 312T: ... unterbindet ein Schiebemechanismus in der Kulisse, das man beim Runterschalten vom vierten in den dritten Gang den ersten erwischt.....and ....Diese sinvolle Einrichtung vermeidet beim Runterschalten Ueberdrehzahlen durch falsche gangwechsel.... and ....moegliche Dreher...

 

For most of you this is better explained as:  a sliding mechanism in the gate (*) prevents that when downshifting from 4th to 3rd one can catch the 1st... und ...This meaningful device avoids overrevving when downshifting by wrong gearchange... und ... possible spin.

(*) the slots guiding the gear lever, there probably is a better word for it in English.
 

So Lauda/Indra/Voelker explain the basic how and why - for the when back to you. To me it already sounds oldfashioned in 1975. Was it first conceived to protect Ferrari's beloved engines, as a result of a specific incident resulting in a spin, or common practice for (Italian) racing cars in an earlier period?



#8 f1steveuk

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Posted 01 December 2015 - 10:55

You see the driver in me says "I need to get into 2nd from 5th, and I need t do it quickly" so going through the gears in between is merely wasting my time.

 

The engineer in me says, "I need to protect the expensive bit, the engine, so I'll make the driver go slowly down through each gear".

 

I can see that a system in the gate could do it, though I can't see how it could be implemented to force the driver to use each gear going down, mind you, I can't see how it could be done inside the 'box either!!

 

At least I'm not the only one that read it!!



#9 kevins

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Posted 01 December 2015 - 11:19

Jacques Villneuve describes the system in Goodwood

 


Edited by kevins, 01 December 2015 - 11:19.


#10 f1steveuk

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Posted 01 December 2015 - 13:39

That is brilliant!!! I'd like to see under the gear gate plate, but a mechanism in the gate, probably spring loaded plates and some little levers, though the video is much better for the seat!!



#11 kevins

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Posted 01 December 2015 - 17:20

Thanks!

 

Yes, the seat did look a little out of place! I hope he enjoyed his picnic :)



#12 Ray Bell

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Posted 01 December 2015 - 19:46

So we got your view as a driver and as an engineer, Steve...

But what about as a spectator? I remember how great it sounded to hear Mike Hailwood going down through all the gears, heel-and-toeing with each change, braking for Creek Corner at the Farm in the Surtees F5000.

By the way, a driver need not use the gears as he goes through, he might (as in the event of a spin) simply put the lever through the positions without declutching.

Gearboxes with rotary selection are a different kettle of fish. These are those in motorcycles and the ZF/Lotus type, and Roger, I'd suggest it was simply a matter of Clark's careful changes not giving the selecting dog enough inertia to complete the move from one gear to the next. I do remember the word 'inertia' being used in the description of this problem at the time.




.

Edited by Ray Bell, 01 December 2015 - 20:09.


#13 JtP2

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Posted 01 December 2015 - 21:22

Slightly off topic, but I have never understood the Clark gear selection failure at Monaco. Every box I have ever stripped would not allow this to happen if assembled correctly. The one I had to strip for the problem had been rebuilt wrongly with the detent slugs missing. So was the box assembled wrongly by ZF?



#14 chr1s

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Posted 01 December 2015 - 22:28

Cavalier53 your translation  is right but you left out the last part. I have the same book, in English and this is what it says :   A slide mechanism built into the gate stops us accidentally selecting 1st gear when we change down from 4th to 3rd.  Only after 2nd gear has been engaged is the slot for the lever to enter first gear opened... 

 

I also found this in "For the Record" on page 42. (Monaco 1976) "About fifteen laps before the end I come round by the Casino and go into second instead of third. The motor screeches, I quickly correct it"

 

Also for the engineers on here, this is what Ermanno Cuoghi had to say on the subject of gear changing... "On the gearbox, he (Watson) is the same as Niki,changing straight for the gear he wants on a tight corner after a straight. So, he comes from fifth to say second... Nelson at the moment is not doing this, he is changing gear by gear.  That is not hard on the car the way Niki and John do it. There is less wear on the gearbox, no surge on the driveshafts and less chance of a mistake. From fifth to second in one go may be slightly harder on the engine, but on the transmission it is better"...


Edited by chr1s, 01 December 2015 - 22:29.


#15 Ray Bell

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Posted 01 December 2015 - 22:49

Originally posted by JtP2
Slightly off topic, but I have never understood the Clark gear selection failure at Monaco. Every box I have ever stripped would not allow this to happen if assembled correctly...


I have seen something of the insides of the Queerbox Lotus used...

From memory it has a hollow shaft and the selector picks up the gear from the inside or something. It's nothing like a regular gearbox.




.

Edited by Ray Bell, 01 December 2015 - 22:49.


#16 chr1s

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Posted 01 December 2015 - 23:11

Steve, to put you out of your misery I've just remembered where I read that the Ferrari drivers had to go through all the gears in sequence. It was in a Motorsport track test of a 1978 312T3.

 

The question now is whether the tester, (Mark Hales) was mistaken and the gear shift  worked as described by Lauda in his book OR that by the time the T3 came into service the gearshift had been re-designed so you had to go through all the gears in sequence?



#17 JtP2

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Posted 01 December 2015 - 23:26

Ray, surely the 62 ZF did not work like a queer box. Clark was skipping gears on the way down for the gasworks hairpin when it selected 2 gears together and that is surely totally impossible with queer box



#18 Roger Clark

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Posted 01 December 2015 - 23:52

The Jim Clark incident was at Monaco 1963. They were using the ZF, not the Lotus "queer box". This is what DSJ wrote at the time:

"On that same lap, as Clark came along the harbour front from the chicane and prepared to change down for the Tobacconist corner, the Lotus gearbox jammed in gear and he coasted round the bend struggling desperately to sort out the gears. All the way down to the Gasworks hairpin he tried to get the gear-lever to coincide with the selectors in the gearbox, but the damage was done and as he tried again at the hairpin 2nd gear as well as 4th engaged, and the Lotus came up all-standing with its wheels locked solid, and Clark's race was run.

Being so far in front Clark had begun to ease his pace and instead of flicking the gear-lever from one notch to another he had begun to ease it gently and this was his undoing, for the selector and spring-loaded plunger movements in the ZF gearbox are very small and rely on a certain amount of their own inertia in order to engage properly. By flicking the gear-lever briskly this is achieved, but easing it gently from one notch to the next did not impart the necessary inertia to ensure full engagement and on the fateful gear-change on the harbour front the selector had sprung back the wrong way"

An interlock mechanism was used by Mercedes-Benz in 1955.. The W196 gears did not conform to the usual H pattern and Moss had problems with it. He said, in Design and Behaviour:

"I found it difficult the avoid going over that (the rev limit) simply by reason of sorting out which gear I was going to be in next. I always expect to pull straight back to change up and .... I reckon to push across, away from myself, to change down - hence up, pull towards; and to change down across, back.

"Not so with the complicated arrangements on the five-speed Mercedes-Benz gate, and I was always changing from third to second when I meant to go up to fourth and this did verve the engine but mercifully didn't break it. This was bad and frightened me and I got Uhlenhaut to make up some rather complicated stops so that I couldn't get into the wrong gear"

#19 Ray Bell

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Posted 02 December 2015 - 00:03

Originally posted by JtP2
Ray, surely the 62 ZF did not work like a queer box. Clark was skipping gears on the way down for the gasworks hairpin when it selected 2 gears together and that is surely totally impossible with queer box.


If that's the case, your original point is quite valid...

How could that happen if detent slugs and springs were assembled correctly?



.

Edited by Ray Bell, 02 December 2015 - 00:06.


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#20 Spa65

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Posted 02 December 2015 - 10:32

I have always been puzzled as to why racing drivers would choose to go down through the gears if their gearbox would allow a direct change from e.g. 5th to 2nd. Surely all that clutch work and heel and to-ing could never have been as efficient for getting the very latest braking point for the corner. All lumpy instead of smooth.

 

Two situations from the past remain with me:

 

In 1965 (or maybe 66) I read (or perhaps it was Raymond Baxter's commentary) that Stewart in a BRM went from top gear to bottom gear in one swoop for the Gasworks hairpin at Monaco. Hill in an identical car went down through the gears.

 

In a biography of Prost I read about some of his early racing drivers school episodes. Apparently he was told to go down through the gears for the hairpin. As I remember he just told the "experts" that was what he did. In reality he did the downshift in one fell swoop.. I got the impression that Prost knew he was better than the guys teaching him, but kept his thoughts to himself. He may have been sandbagging on other occasions so he didn't look too quick.

 

Interestingly Stewart and Prost were two of the smoothest drivers ever.



#21 Ray Bell

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Posted 02 December 2015 - 10:46

A couple of points here...

First, with regard to braking with assistance from progressive downchanges and just using the brakes, the 1.5-litre era was the beginning of the time when brakes were up to the job without much assistance from the gears. It was also the beginning of the time when braking distances shrank and so the time for downchanges was reduced.

Second, comparing Stewart and Hill I would draw attention to the 1966 Australian Grand Prix, where Stewart was pretty determined to show he was able to leave Hill behind. But he shattered his gearbox in his efforts, so maybe his 'smoothness' was yet to be refined?

#22 f1steveuk

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Posted 02 December 2015 - 12:57

"Can of worms"!!

 

I can understand the joy of seeing/hearing a driver go through the gears, with each blip of the throttle and a smooth, precise change. That Hailwood did this is no surprise, as a motorcyclist, that's how I took downward changes with me to racing. A near miss braking like stink, while trying to go through ALL the gears, and nearly demonstrating my high speed parking skills, lead me to the "brake and go from 5th to 2nd" option, though it took some self education.  Again, in my early years my engineers mantra was always, "brakes are cheaper than gearboxes, which are cheaper than engines".

 

I am sure I read that the 312 of 1968 had this "down change interlock", and it appears to still be on the 312T, so I wonder from when, until when it was fitted.

 

As for Ermanno Cuoghi's comments, they sound like they come from his Brabham era, when Niki was teamed up with Wattie?



#23 nmansellfan

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Posted 02 December 2015 - 12:59

Skipping gears while downshifting would give less benefit from engine breaking I assume, as the clutch is pressed down from the point you go to push the shifter out of the gear you're in to the time you slot into the gear you want to be in for the corner, rather than drive being re-engaged every time you shift to the next lower gear.

 

Someone on TNF years ago posted their own audio from trackside of a '76 GP, where you could hear Lauda shifting straight into the gear he wanted, and Hunt going down through every gear.  It could have been the other way round though, i'll have to see if I downloaded a copy at the time!

 

I remember as a kid during the '86 Detroit GP on TV hearing certain drivers skipping gears downshifting in to some of the slow corners - I assume that by the mid 80's everyone had a 6 speed H-pattern and the closing speed / braking distances meant that to certain drivers there was a real benefit to skipping gears, especially with the reduced engine braking effect with a turbo powered car? (correct me if I'm wrong!)

 

Any mid / late 80's or early 90's GP onboard clip where the car still has a H-pattern box is great to watch; I can see why Ferrari developed the semi-automatic box as a time /  mechanical saver - the speed at which drivers had to downchange was incredible.  As many have said before, manually shifting is a lost art.



#24 f1steveuk

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Posted 02 December 2015 - 14:06

There is one other advantage to skipping gears, which is why we now have paddle shift gears. John Barnard, while telling me how he came up with the semi auto changes on the 640, calculated that each time a driver dipped the clutch, operted the gear lever and let the clutch up, he lost in the region of 15mph through mechanical drag, though going down, that might be an advantage!



#25 nmansellfan

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Posted 02 December 2015 - 16:55

15 mph?!  Surely if two cars following close behind were changing gear at slightly different times the car behind would have collided with the car in front?  Then again the most powerful machine I've ever driven on a track with any form of gearbox was a Silverstone school car with about 130bhp...



#26 Spa65

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Posted 02 December 2015 - 17:31

There is one other advantage to skipping gears, which is why we now have paddle shift gears. John Barnard, while telling me how he came up with the semi auto changes on the 640, calculated that each time a driver dipped the clutch, operted the gear lever and let the clutch up, he lost in the region of 15mph through mechanical drag, though going down, that might be an advantage!

I wonder about these figures. Assuming the power was off then on again after half a second, that would still equate to a decceleration of 1.3g during the coasting phase, which seems a bit high. Still, what do I know compared to John Barnard, assuming he really did say it. Maybe these cars really do slow down that quickly when power is taken off, but maybe only at full tilt.

 

Just a thought: a human body in free fall has a terminal speed of about 120 mph, at which speed the force will equal 1g. If such a body were somehow to be immersed in the same density of airstream at 200 mph, the instantaneous force on the body would be about 2.8g. So maybe a racing car is about twice as slippery as a human body. Seems plausible to me. Perhaps Masten Gregory theorised likewise during his numerous high speed exits.

 

Reminds me of when Chapman brought out the Lotus 76. It had a little button on top of the gearstick, that could be used to operate the clutch instead of using a cumbersome foot pedal. That also allowed the left foot to be used for braking. In effect it had four pedals, the two brake pedals being connected. The biggest surprise to me was that Chapman claimed this set up would save 2 secs a lap. I thought that was extremely unlikely and it may have owed a lot to Chapman swagger. Again, what do I know compared to the great man. The 76 was a lemon, but probably for unrelated reasons. I guess the electronic shifting and left foot braking have come to pass, but 2 secs a lap gain for a 1970's car? I believe the gear lever still had to be manually moved. Maybe on the Nurburgring,

 

First time I've ever written any pseudo-technical ravings like this while still sober. Early stages of senility perhaps. Going to the pub tonight to reflect.



#27 nmansellfan

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Posted 02 December 2015 - 18:01

I think Audi had a similar setup to the Lotus 76 on some of the Quattro (or is it lower case 'q'?) E2's, I remember seeing a film demonstrating it where the clutch pedal would physically move when the button on top of the gearstick was pressed.  It looked pretty 'robust' in its movement, I wouldn't liked to have left my foot under the clutch pedal accidentally if you were using the button for up-shifting!


Edited by nmansellfan, 02 December 2015 - 18:01.


#28 JtP2

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Posted 02 December 2015 - 18:19

nmansellfan. Porsche triptronic



#29 f1steveuk

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Posted 03 December 2015 - 10:44

I interviewed John Barnard some years ago, but I am sure it was around 15 mph, drag within the gearbox, shafts, rolling resisitance of the tyres etc etc. I don't think I have misqouted, but possibly. I do know that he got quite irate if anyone suggested the idea came about so that a driver could keep his hands on the steering wheel!



#30 Charlieman

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Posted 03 December 2015 - 13:05

Much respect to those who rode the late 1960s Suzuki 125 with 35 bhp and a 10 speed gearbox.



#31 Peter Morley

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Posted 04 December 2015 - 09:42

Reminds me of when Chapman brought out the Lotus 76. It had a little button on top of the gearstick, that could be used to operate the clutch instead of using a cumbersome foot pedal. That also allowed the left foot to be used for braking. In effect it had four pedals, the two brake pedals being connected. The biggest surprise to me was that Chapman claimed this set up would save 2 secs a lap. I thought that was extremely unlikely and it may have owed a lot to Chapman swagger. Again, what do I know compared to the great man. The 76 was a lemon, but probably for unrelated reasons. I guess the electronic shifting and left foot braking have come to pass, but 2 secs a lap gain for a 1970's car? I believe the gear lever still had to be manually moved. Maybe on the Nurburgring,

 

I just happen to have the Lotus 76 pedal lying around...

Lotuspedal.JPG



#32 Spa65

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Posted 05 December 2015 - 00:48

I just happen to have the Lotus 76 pedal lying around...

Lotuspedal.JPG

Peter,

 

Please tell us more.



#33 DampMongoose

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Posted 05 December 2015 - 12:57

I just happen to have the Lotus 76 pedal lying around...
Lotuspedal.JPG

Did the car actually have a clutch pedal too as well as the button? I wonder, as the space between the double brake pedal is greater than I would have expected.

Edit: is a bit unaturally missing from the pedal or has it been removed deliberately to make room?

Edited by DampMongoose, 05 December 2015 - 12:59.


#34 Peter Morley

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Posted 05 December 2015 - 23:01

The pedal came with a load of Lotus parts that were 'rescued' from a scrapyard!

 

The left side of the pedal has been deliberately cut away, presumably to give clearance either when pressing the clutch pedal or resting the left foot if a switch was used.

 

The wear on the pad surface is rather surprising and I don't think entirely due to corrosion.



#35 DampMongoose

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Posted 06 December 2015 - 10:21

Thanks Peter, the wear was my other thought...