Here I am, quite late I'll admit

To execute the plan you outlined, I'd recommend the automatic drive the manual trans, not vice versa. You want the automatic's torque converter to improve launch torque, since it multiplies torque-- and a clutch cannot do that.

Then, you'd want that auto to shift into direct ASAP and then you just row through the gears on the manual. In certain circumstances, you could manipulate one tranny or the other to get certain benefits, either super low range with both in first gear, or mega OD with both in high gear.

To be worthwhile though, the gearing would have to be a lot closer together than either the 5600 or the 48re is. The splits on both are too wide to be used with each other-- resulting in a uselessly low double crawl gear (2.45 (auto) times 5.63 (nv5600) and a too-tall OD ratio (.69 (48re) times .71 (nv5600).)

With tighter gear splits, a combo-trans could be made to work.


Obviously, the cost/benefit analysis is pretty poor on this project, or we'd have OEM pickup trucks doing such a thing.

Conversely, OTR truck often have lots of gears because the different usage profile and lower-revving engine radically tilt the factors of the cost/benefit calculation.

Justin

 

So it would be more efficient if paired with an engine that redlines at 2600rpm? One torque monster could be made like that.

 

Or you could put them both in reverse , to go forwards

 

Double negative gearing! Genius!

I'm not uncertain that I'm unopposed to this. How could it never not malfunction?

And if you flipped the axles upside down, would it go forward in the reverse direction again?

 

I haven't thought of this manual-auto thing in a while, but at one point I considered something to make it work. Basically this whole idea is a whole lot of complication, just to have the convenience of a slush box. Since I had the dream, you guys gotta do it my way! The manual transmission is the master, the auto is the slave. If you want that torque multiplication of the auto, you'd still get it in any gear you put the manual in and leave it.

As for the gear spacing, you are right, it would provide such low gearing that you'd probably never use 1st manual, 1st auto ... much less 4-Lo, 1st, 1st. It might not even move. Actually 4-Lo, 1, 1 could be used for pulling wire through conduit.

To make it work, you'd have to use the manual as the master (remember, you gotta do it my way ), then the auto is connected to the output shaft of the manual via a (shift on the fly) transfer case. When the auto is put in gear, the transfer case automatically locks in.

What a crock of junk, weight, and expense just to add an auto. But it sure would be flexible to drive.

Just think, you have a big ole heavy trailer. You put the 6 speed manual in 4th and the auto in 'D' (3 of 4). When the light turns green, you have the gearing of less than 1st gear manual creeper. But who cares? Because the rig moves quick. The auto uses the torque multiplication and starts the load, and quickly shifts from 4 - 1, 4 - 2, 4 - 3. At the top of 4 - 3, you pop the auto in Neutral (the transfer case automatically unlocks) you get a bit of an up shift into 4 - 0 (which is manual 4th auto Neutral), then you manually shift to 5 - 0 and then 6 - 0.

Anybody who tows heavy knows that 4th, 5th, and 6th manual gears are very pleasant to use, but getting the load started is a lot of work in shifting and trying to make the drivetrain shift smooth is not nearly as easy in 1st, 2nd, and 3rd, as the higher gears.

So then you're cruising down the interstate 75 mph+, in 6 - 0 pulling a smaller open trailer, even with a car (for example) with 4.10 gears, or even maybe 3.73's. And the cummins has plenty of torque, but you're turning 2,300 - 2,500 rpm. You could drop the auto into 'OD' (6 - 4) and the rpms drop to like 1,800 rpm. The would be smoooooth.

 

How are you planning on having one transmission in neutral and have the other one going while still having the wheels turning? I want to see what the tranny hump on the floor will look like when we're done.

 

Shoot man ... I don't know. I'm just theorizing here. I've got an idea, but it would be way to complex ... I think. I'm sure there's a simpler way, but I'm not focusing on this pipe dream too much at this time.

 

Sure there's a simpler way:

 

If that's at automatic with push button shifters along with the floor shifter, I've never driven one that I thought was worth a plug. Granted that's a decent car OK it friggin awesome ... but give me a manual any day.

- JyRO

 

Just put a clutch in front of the auto. Infinite stall speeds and the efficiency of the standard when starting and stopping. Its not a new idea (I think Hurst made a version of the 727 TorqFlite in the 60's and called it a ClutchFlite).

 

I think they already make a version of what you want , in farm tractors, we have some fancy doo-dad's now.

In my uncles tractor , you can shift , or press a rocker switch , and it will shift for you. Fendt has the Vario transmission, and it is NICE to use IMO.

 

Just go CVT (Continually Variable Transmission), then you get the best of both words...Manual tranny efficiency, with Auto tranny convenience....just don't get it from John Deere, they can't make their's work correctly

Actually, a CVT would be a sweet deal...it takes ~8hp to run the thing, and it's nearly 100% efficient (would be 100% if there wasn't a small amount of internal hydraulic leakage in the pump/motors!) And with the right computer to control it, you could set your tranny to run at a certain "ratio" while the engine is at the best RPM range for fuel economy, or power, whichever you desire! And all it would take is the push of a button to bring RPM and tranny speed down to climb hills!!


But that is my dream...knowing how they operate in the AGCO tractors makes me want one in everything...they'll do anything you want, if you know how to make them do it. The only downside, in an automotive application is a cost effective, reliable tranny. The ones in the tractors are EXPENSIVE...but they are comparable in price to the other tractor trannies so it's cost effective!

Chris

 

In automotive applications, I've not seen a CVT that is as fuel efficient as a manual transmission. I work in the automotive industry, and have driven quite a few CVT's. The one's I've driven, I didn't like them. I find the continuous rpm change due to load (hills, speeds, wind, whatever) to be annoying.

 

The agricultural CVT transmissions are completely different.

AFAIK most of the automotive CVT trannys are very similar in design to snowmobile transmissions , two variable rate pulleys, that is old old OLD technology.

The Ag CVT's use a combination of powershift and hyrostatics ( I don't speak for all of them here , the ones i am familiar with use that setup) .

I drove a deere 7920 this summer with the IVT in it , and that thing was junk IMO , it doesn't hold a candle to the Vario used in fendt tractors.