As I understand it, the CVT doesn't actually have any gears at all and the shifter is nothing more than a drive-by-wire system for telling the computer what direction to run the motors. That said, what exactly is "park" then? If there is no gear like a typical transmission, what does "park" do to insure that your vehicle doesn't roll? I find myself using the parking brake all the time now even on fairly level surfaces...is this wise or overkill?

 

You should ALWAYS use the emergency/parking brake when you park ANY vehicle regardless of whether you have an automatic or manual transmission.

 

I happen to agree with you completely, so will most mechanics and the "Car Talk" guys (who could be more authoritative ). However, you'll find you just opened a can of worms because of all the people that are going to tell you its going to 1) Freeze up your brakes 2) warp your rotors and what not or half a dozen other issues.

Truth is, "P" isn't as secure as most people think and a backup is a great idea especially on a hill. On level ground it probably doesn't matter, but if you don't use it regularly the cable will rust and will freeze up so you won't have it when you do park on a hill.

But you aren't going to convince half the world of that....

 

If anyone posted those things, they would be wrong. I'm certain they would thoroughly research the issue first.

 

Since I haven't had one apart (yet) I am not 100% sure how the rear disc brakes on the FEH work as far as the parking brake goes.

On earlier cars that had the rear disc brakes, brake adjustment was made by use of the parking brake. I got in the habit of using the parking brake when I used to drive a '77 Fleetwood Cadillac. Until then I never used the parking brake on a car with an automatic transmission.

As to the original question, I think the eCVT in the FEH has to work the same way as any other "automatic" transmission out there - it has to have a mechanical means of stopping the car from rolling. I wouldn't trust it on a steep hill but I wouldn't trust park in any other care either.

 

Well, I guess my real question is "What exactly does putting the 'transmission' in Park do on a vehicle with the CVT the Hybrid has?" Is there some type of locking or braking mechanism? Does putting a normal automatic transmission in "park" lock the gears or something like that? I realize that the parking brake is always a good idea, but I was wondering what the "Park" setting does on this particular vehicle.

 

they certainly didn't on the other forum where I tried to suggest the parking brake was a good idea

 

Its a good question. In a normal automatic transmission putting the tranmission in "Park" engages a pin into the gears to prevent them from moving. The pin is called the "Parking Pawl". Its not as robust as most people think.

For one thing delivery people are sometimes are in a hurry and they slam the tranny into Park while still rolling a bit. This eventually causes the Pawl to fail. I've seen it happen. While attenting at college in the UP of MI, I ordered pizza from such a person. He parked on a particular street in Houghton, MI called Garnet Street and came inside. Wwhile giving me my pizza I watched over his shoulder as his car shuddered twice and then slipped out of park rolling down the hill onto some tennis courts (through a chain link fence). Yes I tried to warn him it was about to go... but was too late.

As to your original question..... I'm not entirely sure whats in there, but I'd guess its very similiar to a parking pawl and is just a pin sticking into the gears to stop them. The tranny still has gears, they are just configured completely different than a normal transmission. From the one cutaway diagram I saw its a planetary arrangement but I'll be ****ed if I know how it works, I'm an EE not an ME.

 

Quote:

Originally Posted by Tim K

As I understand it, the CVT doesn't actually have any gears at all and the shifter is nothing more than a drive-by-wire system for telling the computer what direction to run the motors.

I could be wrong but it seem the eCVT does use gears. First check out '2005 MY OBD System Operation' pdf - page 5 and then page 7. The graphics show the 'Planetary Gear Set' between the ICE and Generator & Traction Motors. Well just what is a 'Planetary Gear System' and how does it work? Check out 'Planetary Gearing' on Wikipedia.

But I could be totally wrong and the FEH uses a version of the 'Hybrid Synergy Drive system', actually if you read on down in the article it says -

Ford Motor Company has independently developed their own hybrid technology which works basically identically to HSD.

Also look at Electronically-controlled CVT at Wikipedia.

I would say the 'Power Split Device' as shown at Graham's Toyota Prius is actually the 'Planetary Gear System' as shown on page 7 of the '2005 MY OBD System Operation' pdf on the FEH. Could be a Hybrid version of both - guess it is.

As far as how the mechanics of the 'Park' works I can't find - guess someone with a shop manual will have to give the answer to that. Anyone ever mistakenly pushed the shifter into 'P' while moving? I have - If I remember correctly, there was the sound of something grinding. Yes, the gear shift lever (as well as the gas pedal) is 'Fly by Wire' and the PCM along with the TCM controls gearing/torque etc.

Could be wrong - Probably am - Heck I just Love to Drive my FEH!!

 

It is an eCVT meaning its electronically controlled. HOWEVER, nothing about that says it can't have gears. The electronics can control the hydraulic valves that move the gear system around. Many automatic transmissions do this now and shifting is electronic. The CVT implies that there is a smooth transistion from one ratio to another, but that appears in the FEH to be done with a gear system... and it appears to be planetary.

From the few times I've parked on a hill and forgot to use the brake before shifing into park (which is bad) The parking system FEELS just like a normal automatic transmission, you feel the car roll slightly until it hits on what I assume is the Parking Pawl.