definition of 4wd?

[DavesTractor]

Looks a lot like the F215 I just sold. Are you sure the model number is FF205? Nice tractor by the way!

 

[jimstractors]

Great Info!!! How many days did it take to type all that?

 

[MJB]

That may be true, but not because it is "All Wheel Drive". The Audi must have some type of traction control or limited slip differentials in order to still move when only one wheel has traction.

 

[MJB]

I would agree with most of that but change the terminology sligtly. To my thinking if a system is "Full time 4wd" then, as the name implies, there is no option of two wheel drive. I would call your option number 2 "Part time 4wd with automatic engagement" and option 3 would be "Full time 4wd". With the trucks I am familiar with a single stick part-time transfer case would have 4 options: 4 low, neutral, 2 high, and 4 high. The full-time 'case would offer low lock, neutral, high, and high lock. Low and high lock positions lock up the center differential in the transfer case, making it just like part-time 4wd, where the high position leaves the differential unlocked but the vehicle is still in four wheel drive.

 

[BrettW]

Dave, Yep it is FF205. I got it in a direct shipment that a group of guys did here in Md. I came out pretty sweet at 1,500 bucks!!!! Just kidding guys and dealers. It is a good machine and I got lucky. Could have been a dog that was sight unseen. By the way did the F215 have any ROPS attached or did you add one? The FF205 is 20 hp at the PTO.

 

[SteveM]

Most 'all wheel drive' cars have a viscous (sp?) coupling which literally gets less viscous when the primary drive axle begins to spin. In most cases these vehicles are front wheel drive with the back powering only when needed. The differentials on these vehicles are definately 'open' with some limited slip functionality. What is interesting is some SUVs have a 'full-time/part time' system like my jeep. You can run 2wd, 4 fulltime (any pavement surface) 4 part time, or 4 low. The latter 2 settings lock the front differential, so slippery surface only. It is the best system for all uses. My wife's bravada, on the other hand, has no levers or knobs - automatic all wheel drive via the viscous coupling.

 

[Trev]

All I can say about Quattro is that it's awesome to drive. I routinely have fun taking off from red lights and leaving 4wd trucks sitting there spinning. It's full time power to all four wheels.. until a wheel loses traction; then the power distribution shifts to the wheels which still have some traction.


Here's a brief blurb about how Quattro works that I found on

<A target="_blank" HREF=http://www.audiworld.com/news/00/geneva/quattro.shtml>http://www.audiworld.com/news/00/geneva/quattro.shtml</A>

Quote:

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In the Audi quattro all four wheels are driven permanently. The advantage: in the ideal case each wheel needs no more than half the propulsive power required in a conventional single-axle driveline. Because the total force transmitted by each wheel - the aggregate of propulsive and lateral locating force - is limited, an Audi quattro can transfer a correspondingly greater lateral locating force to the road surface: a necessity for guaranteeing excellent cornering stability and outstanding straight-line running on both wet and dry surfaces.

Of course, an Audi quattro is particularly capable of demonstrating its traction advantage on wet roads, gravel and snow, on slippery surfaces or on partially iced roads. Conventional cars fitted with purely electronic control systems can also prevent the driven wheels from spinning. However, this method works only be reducing the propulsive force.

Not so in the Audi quattro, where the self-locking Torsen centre differential ensures that the engine's power is distributed uniformly to front and rear wheels. Any sudden differences in speed - for example if only the front axle hits a patch of black ice - sees the system responding like lightning: up to 75 percent of torque is then redirected to the wheels turning more slowly - in this case, the rear wheels. Torsen is a purely mechanical system.

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I gather it also does this not only front to rear but side to side.. you pay a price in extra weight for all the differentials, so they add a turbo and some nice stuff for added ooomph.. but I can still get over 30mpg on the highway. I can't say enough about how good this system is.. and I've tried the ones like Subaru, etc. There is a noticeable lag time in those that simply isn't there with Quattro.

 

[DavesTractor]

Brett, no ROPS on the F215/235 etc's that I have imported. Some have canopies, but they are not ROPS. The newest Yanmar's have ROPS, but I haven't got my hands on any of them yet.

 

[Soundguy]

<font color=red>SUVs have a 'full-time/part time' system

<font color=black>My Yukon XL has these options for the xfercase, and are electronically actuated.. no gear shift.

2wd, 4 low, 4 high, and 4wautomatic.. which is explained in the book as " engages when needed based on tire slippage', etc.

Soundguy