Infinitely Variable transmission

[JeremyClarksson]

http://www.torotrak.com/IVT/works/howworks.htm
I believe this would be a great bit of kit if it ever gets fitted to a tow car.

They sem to believe it can manage the torque requirement as they have talked off fitting it to buses.

It has to be better than conventional auto or stepped transmissions.

Any views?

 

[RogerL]

Correctly named Continously Variable Transmission (CVT). If it were infinitely variable the drop-down gear ratio would go right out to infinity, which is of course not possible.

The DAF 44,55 and 66 all had belt-driven CVT in the '60s. When DAF was taken over by Volvo one of them was given a Volvo number that I don't recall.

The recent MG TF had a CVT as an option, I believe the Ford Fiesta still does.

CVT is a good concept but drivers dont like it. The initial MG CVT was continous but later ones were given electronic steps to be more acceptable to drivers.

The main weakness of CVT is mechanical wear. It's not difficult technically to overcome using expensive materials but difficult to do within normal budgets.

 

[JeremyClarksson]

Roger

I was correct in referring to IVT not CVT, they are 2 totally different systems - you need to look at the link to understand the difference.

The IVT uses a full toroidal roller system rather than belts and pulleys and is rated to much higher torque levels than CVT.

The feel in operation would be similar to CVT but it is supposed to be more efficient than all present types of transmission, I think it would be particularly good for towing because it keeps the engine at its most efficient all the time.

 

[Guest]

Story as I remember it.

Volvo bought out Daf cars partly becasue of a new version of the original Daf gear box described as running on "rubber bands".

The newer lighter more compact version was to run on "steel bands" and the story was that Volvo thought they got the cars and the old and new design rights, but ended up without the new design being theirs to their shock as it was not part written into the deal and heads were said to have rolled!

 

[RogerL]

Roger

I was correct in referring to IVT not CVT, they are 2 totally different systems - you need to look at the link to understand the difference.

The IVT uses a full toroidal roller system rather than belts and pulleys and is rated to much higher torque levels than CVT.

The feel in operation would be similar to CVT but it is supposed to be more efficient than all present types of transmission, I think it would be particularly good for towing because it keeps the engine at its most efficient all the time.

The torodial roller is just an alternative to the "rubber" belt on DAFs or steel belt on MGTF/Fiesta.

It can't be infinite, the gear ratio WON'T go to infinity!

 

[Lutz]

The following website gives some reasons why the DAF transmission was never a breakthrough success:

DAF 66/VOLVO 340 CVT

 

[Guest]

That's how I remember it Lutz. I seem to remember being told that as Volvo had "been sold a Pup" ( not got what they expected ) they were developing their own steel belt CVT, along with someone else I think - another Gear box manufacturer ?

So are the current CVT drives a development from Volvo or the original owners of the DAF system?

Just interested !

 

[Pelyma1]

From what I've read hybrid technology will be a boon to. LR are working on a system that will use electric motors, these have maximum torque available instantly, great for offroading but presumably great for towing too?

 

[RogerL]

From what I've read hybrid technology will be a boon to. LR are working on a system that will use electric motors, these have maximum torque available instantly, great for offroading but presumably great for towing too?

GM already have this type of hybrid in pre-production development. If put into full production, they will be "cake and eat it" particularly for towers - almost unlimited torque at the bottom end and very high power at the top end, plus extra weight from the batteries. These engines would appear to make diesels obsolete, at a stroke!

 

[parker1158]

Hi All

Daf's (A short version of their original name 'Dafodil') that takes me back. When I left school and did a motor trade apprenticeship it was at a garage that specialised in Dafs. I must admit I had a fondness, and still do, for them.

Lutz's included item above is how I understood there demise to have come about. Certainly the transmission system was very bulky and took some squeezing in as it was under the rear of the car directly driving the rear wheels and the engine had to be removed to do most jobs, like repairs to the prop-shaft for instance, and parts were very expensive. Incidentally there were two bands one band driving each rear wheel independently, which meant you got true two wheel drive giving superb grip especially in mud and snow.

90% of the owners were very elderly and swore by them.

If you have never driven one you have missed out on a truly unique experience.

Strangely enough after I had completed my apprenticeship and went into motor sport they were enjoying more than their fair share of success on the rally circuit

I was always of the opinion that the system was ahead of its time and the general public not yet ready for it and it surprises me that it has taken this long to be re-invented.

 

[Guest]

Mid 70's I had a brief but exciting ride in a DAF rally car piloted by a crazy German or Italian / Swiss driver who shouted excitedly in a teutonic clipped style but with more of a French accent.

We weren't sure if he could speak in one complete language as he swapped between English, French, German and Italian and had rallied in Scandianavia and swore in Swedish. He threw the car side ways on gravel mountain roads as he kept his foot right foot buried to the floor as the transmission made horrible noises as he shouted risque lines about the car and an experience with some "Dutch Dykes" (double entendre!!!).

Great car that scared a few works cars until it broke prop shaft joints 1/3 of the way into an event.

 

[JeremyClarksson]

RogerL

IVT could be loosely bracketed as being in the CVT group of transmissions but it is nothing like the Cones and rubber band CVT of the Daf, MG or any CVTs fitted to other vehicles on the road of which hydraulic seem to be the main ones fitted to tractors etc and cone and belt to cars.

The "infinitely" description is largely theoretical, on cone and belt systems the the cones have to rotate around a shaft so are definitely limited from being called infinite.

In hydraulic CVTs I believe the limitation is that the highest ratio is 1:1(straight through).

An IVT in theory not practice (phenomenal torque through a small area) can pivot right through the zero or neutral position to reverse - as it can do that in theory it is infinitely variable.

The diagrams I pointed you at do show this very clearly but I have found that they do not seem to open up.

This site also explains how it works quite well and you can also see how other types of IVT, CVT and dual clutch and conventional auto systems work by using the side arrows.

http://www.histomobile.com/histomob/tech/2/109.htm

 

[Mike_5041144]

RogerL

IVT could be loosely bracketed as being in the CVT group of transmissions but it is nothing like the Cones and rubber band CVT of the Daf, MG or any CVTs fitted to other vehicles on the road of which hydraulic seem to be the main ones fitted to tractors etc and cone and belt to cars.

The "infinitely" description is largely theoretical, on cone and belt systems the the cones have to rotate around a shaft so are definitely limited from being called infinite.

In hydraulic CVTs I believe the limitation is that the highest ratio is 1:1(straight through).

An IVT in theory not practice (phenomenal torque through a small area) can pivot right through the zero or neutral position to reverse - as it can do that in theory it is infinitely variable.

The diagrams I pointed you at do show this very clearly but I have found that they do not seem to open up.

This site also explains how it works quite well and you can also see how other types of IVT, CVT and dual clutch and conventional auto systems work by using the side arrows.

]http://www.histomobile.com/histomob/tech/2/109.htm

http://www.histomobile.com/histomob/tech/2/109.htm[/quote
Try an Audi A4 with MULTITRONIC transmission - fantastic - so smooth.

Mike