[U47]

Originally Posted by Bill Hanlon

Dual-Range Hydra-Matic (last used in '56 Pontiacs, '62 GMC trucks and '66 Rolls Royce) was "locked up" in 3rd and 4th gear.

__________________________________________________ ________________________

Bill, In "D" type Hydra-Matic when shifting to third, the forward gear assy. goes back into reduction and the gear assembly locked. because of the way the gear assy. is arranged, the coupling went from handling 100% of engine torque to around 40%, the rest was handled by the gear train 60% ( mechanical).
The shift from 3rd into 4th gear locks the forward gear assy. which produces 1.00:1 transmission. Now the fluid coupling only handles 25% of the engine torque. Although not completely a mechanical connection, it's pretty darn close at 75%. Quite unlike a T-350 & 400 where all engine power goes through the converter.
I think Super and Roto do the same thing in top gear, but since the Roto is completely locked in 2nd gear 100% to the engine it is the only that one can say is truly locked at one time or another. The real difference between "D" type and "P" type is the interposing of a secondary fluid coupling and a pair of sprag clutches in place of the former friction clutch and brake bands. Power flow however is the same.

A correction on the thread below, My friends dragster was a AA/Fuel dragster.

D.

[pontiacpark]

hey bill, did you sort out your own transmission problem you had recently

[Bill Hanlon]

Originally Posted by U47

Bill, In "D" type Hydra-Matic when shifting to third, the forward gear assy. goes back into reduction and the gear assembly locked. because of the way the gear assy. is arranged, the coupling went from handling 100% of engine torque to around 40%, the rest was handled by the gear train 60% ( mechanical).
The shift from 3rd into 4th gear locks the forward gear assy. which produces 1.00:1 transmission. Now the fluid coupling only handles 25% of the engine torque. Although not completely a mechanical connection, it's pretty darn close at 75%. Quite unlike a T-350 & 400 where all engine power goes through the converter.
D.

First, my knowledge here is all book learning, not practical experience, so maybe I have a reading comprehension problem.

The way I read the Dual Range Hydra-Matic manuals, when the rear unit is in "clutch on" mode (happens in both 3rd and 4th gear) the driving and driven elements in the torus are mechanically locked together at a 1:1 ratio. Here is my logic:

The driving unit of the torus is mechanically attached to the clutch hub of the rear unit. The driven unit of the torus is mechanically attached to the sun gear of the rear unit. Because the rear unit clutches are applied, I think that means that both the driving and driven torus elements must turn at the same speed therefore no slippage.

I agree that the front unit (operating in "band applied" mode in 3rd gear) is still providing a reduction of about 1.5:1 (varies depending on transmission model).

[U47]

Originally Posted by stevep

The Roto started it's short lived life in 1961 and ended in the 1964 model year.

BTW, it was Oldsmobile's design.

A 1960 Pontiac trans is 1960 only.

__________________________________________________ __________________________ The design brief and later blueprints for Roto Hydra-Matic was developed by Jack Qualman assistant general manager Detroit Transmission at the time of the design. A little history on Jack, who was also on the design team of Detroit Transmission for the original Hydra-Matic.
Jack Qualman:
Age 90, passed away on November 8, 2005. He was born July 2, 1915 in Saginaw, MI. Jack secured sponsorship to General Motors Institute in 1933, enabling him to fund his college education during the depth of the Depression. He graduated in 1937 with high honors as a mechanical engineer and began a 44-year career with General Motors. He was soon involved with the design of the Hydra-Matic, the world�s first automatic transmission. Jack designed automatic transmissions for military vehicles during WWII and went on to specialize in transmission design receiving several patents for his innovations. He retired as chief engineer of Hydra-Matic Division, in 1977.

D.

[stevep]

Don,

Please keep posting whatever you can!! This is all great info. There are not many people around today who know or care about this stuff.

[U47]

Stevep, Not taking anything away from people like Jim Wangers, or John Sawruk, but automotive historians/journalist should have been paying some attention to some of the unsung hero's of the automotive world before they quietly slipped away. We can read history about them, but once they are gone there is no more question/answer dialog. I read a Q&A article in HPP featuring Bunkie Knudsen, and John DeLorean which were good, but lacking any real depth & just a few pages at best. HPP should have known that Pontiac people would have loved a whole issue featuring each guy possibly with some historical pictures. Sadly they are gone too. I never saw a article from any Pontiac magazine interviewing Pete Estes....without Pete the GTO would have never been. I mean Pete worked with Kettering on the Olds V-8 and oversaw it's development. For goodness sake he was also the fifteenth president of GM.

[Jack Gifford]

Ditto to Bill Hanlon, on the fluid coupling being "along for the ride" in 3rd and 4th gear of a Dual-Range.

[Safari Larry]

Originally Posted by pontiac jack

Ditto to Bill Hanlon, on the fluid coupling being "along for the ride" in 3rd and 4th gear of a Dual-Range.

Agree, the torus does not transmit power in 3rd and 4th, the driven torus is mechanically driven same speed as the drive torus. Power transmission is purely mechanical in those gears.

[U47]

Originally Posted by Safari Larry

Agree, the torus does not transmit power in 3rd and 4th, the driven torus is mechanically driven same speed as the drive torus. Power transmission is purely mechanical in those gears.

__________________________________________________ ________________________
Larry, thanks for getting back to me when I called and left a message on your answering machine to you about a low mileage 57 StarChief's reverse flow cooling tubes that a friend had just opened up for the first time in the cars life...just thought you would have been interested.
Back to HydraMatic. Instead of stating my case I will read and summarize both manuals for D & P types. Just a FYI have and of you ever heard of the 61-63 Tempest automatic?? Although Tempestorque is a version of a Chevy Powerglide, it's main difference is something called Split Torque. Split torque is not something new to HydraMatic, and D & P types have it also.
4th gear-Power flows mechanically from the flywheel to the torus cover and to the internal gear attached to the torus cover. At the internal gear mechanical power divides. This is called Split Torque and unlike Tempestorque which is 50/50, HydraMatic is 25% coupling and 75% gear train. In the flow chart it clearly shows the split. Just look at the flow chart for 4th gear.

D.

[Jack Gifford]

No "split torque" in a Dual-Range. Give it up U47- you'll just confuse innocent readers.

[Safari Larry]

Jack, we are wrong! U47 is correct and we are confusing innocent readers. See new thread that explains it.

[Jack Gifford]

You need to spend more time hands-on with epicyclic (planetary) drives. It won't take you long to realize that locking any two elements of the unit together makes it a direct-drive.

I'm getting impatient with all this nonsense, since I've spent much more time "inside" a Dual-Range than any of you:

I've built/rebuilt/modified Hydro-Stick versions of it since 1965- and driven them many thousands of miles.
I built various derivations of a Dual-Range as my mini-rod pulling tractor evolved over seventeen years:
... a two-speed (1st & 2nd) that retained the fluid coupling and valve body.
... a single-speed (2nd only) that retained the fluid coupling but eliminated hydraulic control, employing a manual band-apply lever to facilitate a 'neutral'.
... a fluid-coupling-only unit driving an in/out box and my own design top-loading quick-change box.

Do you really think I don't know how the thing works?

[Safari Larry]

Jack, hang in there and try to find some patience to help educate us when we go astray. I seek enlightenment -- and guidance from a master is most valuable. You have the credentials to qualify as a master of the Hydro. I appreciate that and I will listen. However, I don't always accept what the master tells me without questioning the underlying principles.

My practical experience is from way back when I was the transmission guy in a Pontiac/Buick/Cadillac dealership. But the last dual range Hydro I had apart was in 1963 when I was 20 years old. Getting headaches from exhaust gasses in an enclosed garage caused me to find another profession. I have enough experience to know that I can't take a dual range apart and understand it by looking at the parts -- like I can with a standard transmission. Understanding an automatic transmission takes more than practical experience.

I understand well the principles and operation of a planetary gearset. I have studied the principles of operation of the dual range Hydro. I have studied the parts in the Hydro planetary gearsets using the Master Parts Catalog. So my experience is primary book learning and I have the mathematics and physics background to understand principles and design. I appreciate and listen to those who have the practical experience.

I had previously accepted that the dual range was "locked" in third/fourth. But when the disagreement came up, I studied the operation of the trans to validate that we were correct. The problem is that in that study, I could find no way possible that any two gears in the rear planetary gearset could be locked together without going through the fluid coupling. I did find how the ring gear and sun gear were "locked" but the sun gear was attached through the fluid coupling. I explained it in a document available over on the new thread and I invite you to go over there, read my explanation, and tell me where I am wrong -- which I may be. Or just tell us how you believe two elements of the rear planetary are locked together in third/fourth.

I suggest further discussion be done over on the other thread where it can be found later by our ancestors wishing to learn about the dual range Hydro. It will get lost here in this thread.

[Jack Gifford]

The rear clutch. Duh...
My post from yesterday WAS a response to your other thread- which I hope well eventually get deleted.

[Safari Larry]

Jack, the rear clutch locks the rear Internal Gear (Ring Gear) to the intermediate shaft -- which is connected to the front unit planet carrier. The engaged rear unit clutch causes the front unit to planet carrier to turn the rear Internal Gear only. It does not lock any two gears together. Please explain how two gears are locked together in the rear unit.

I submit to your superior knowledge but need assistance in understanding.

Was I wrong in my explanation in the other thread?

[Jack Gifford]

Larry-

My apology won't mean much, on the heels of so much arrogance on my part. Nevertheless, I offer my apology. Even after taking some parts in-hand, I couldn't find a means for the rear clutch to lock up the rear planetary- just as you said.

As I get to it, I'll try to search out my old erroneous posts and update them with a "correction".

My misunderstanding may come back to bite me, in a very real way. The HydroStick I'm putting in my GMC will mark the first time I've used torus members cut for higher stall speed in a road-going vehicle- I was thinking the coupling would have no influence in 3rd and 4th gear. But it might turn out to be "looser" than desired when at-speed on the highway.

Now... for my excuse- I'll [wish I could] push the blame onto John Paul Rank. These images are out of his "The Hydro" book which, in 1965, was my first real introduction to the workings of a Dual-Range.

[Safari Larry]

Thanks Jack, we are on the same page now. I understand the confusion, I was also relying on documentation to tell me how it worked. The Pontiac dual range Shop Manual says about 4th gear "... the fluid coupling is relieved of engine power which results in a more efficient drive." That seems pretty clear but it is wrong and has led me to assume for several years that 4th gear was purely mechanical drive!

When this issue came up, I talked to U47 on the phone and we continued to disagree. I have considerable respect for his Pontiac knowledge and I hesitate to disagree with him. So I decided to study the power flow and set him straight by explaining how it worked. That's when I discovered U47 was correct -- but not entirely. Where he said "This is called Split Torque and unlike Tempestorque which is 50/50, HydraMatic is 25% coupling and 75% gear train." is not correct. The dual range Hydramatic is also 50/50 split, contrary to the Wikipedia article where I think U47 got his information.

So it seems misinformation is rampant about how the dual range operates in third/fourth. It even seems the authors of the Pontiac Shop Manual didn't understand it -- if they did, they did a poor job of explaining it. Of course this assumes my understanding of the power flow and physics of the planetary gearset is correct, and I have little doubt about it. I have an open mind though and welcome anyone to correct me.

A little more about the fluid coupling in third/fourth. You would usually like 100% efficiency (no slippage) in the fluid coupling. But in third/fourth when you get slippage in the coupling, you will get some gear reduction which could be a good thing but probably not in a high performance application. The gear reduction comes about because the Center Gear (driven by the coupling) will be turning slower than the Inner Gear (driven mechanically). The slippage will result in some loss of power (energy) in the form of heat in the transmission oil. That's how I see it.

[U47]

[QUOTE=Safari Larry;4569553]
When this issue came up, I talked to U47 on the phone and we continued to disagree. I have considerable respect for his Pontiac knowledge and I hesitate to disagree with him. So I decided to study the power flow and set him straight by explaining how it worked. That's when I discovered U47 was correct -- but not entirely. Where he said "This is called Split Torque and unlike Tempestorque which is 50/50, HydraMatic is 25% coupling and 75% gear train." is not correct. The dual range Hydramatic is also 50/50 split, contrary to the Wikipedia article where I think U47 got his information.
__________________________________________________ ________________________

Larry, I got the information from a Crouse book on dual range. In that book it has a power flow by the number ( 1-17) from beginning (engine) to the end (tailshaft) for each range. In this book it says that in fourth power divides, and it says due to the manner in which the rear gear assy. was arranged, the coupling went from handling 100% of engine torque to 25%. Possibly this is where the Wikipedia get's it's information-I don't know. I think the key to what the Crouse book says is this gear arrangement. I'm still trying to get around and figure that one, but as we know for sure the Hydramatic book says a division of power between the coupling and the gear train. This same division of power/torque (whatever percentage ) also happens in TempesTorque at 50%-50% only this time the Tempest Hydramatic manual calls it Split-Torque.
Sorry to you all for getting everyone bent up, I was only seeking understanding the truth.



D.

[Safari Larry]

So the Crouse book may be the source for the original Wikipedia information. There is no doubt in my mind that the percentages they give for the power split is wrong. The first clue to that is that they give a different percentage split for third and fourth gears. But the split works exactly the same in third and fourth. The difference in third/fourth is in the front unit, before power is split. Here's how the split torque in the dual range works.

Power is split after the front planetary unit and the split occurs only in third/fourth gears. The front unit outputs power through the planetary carrier with partial power going to the rear unit ring gear and partial power going to the drive torus, to the driven torus, and finally to the rear unit sun gear. So partial power is turning the rear unit ring gear and partial power is turning the rear unit sun gear. Output power is through the planetary carrier to the tail shaft. If the rear unit is to operate in direct drive then the ring gear and sun gear must turn at the same speed -- which has the same effect as locking the two gears together and produces 1:1 drive. If there is no slippage in the fluid coupling, they will turn at the same speed. For both the ring gear and the sun gear to rotate at the same speed, the same torque (power) must be applied to each and requires that the split torque be 50/50. That's the physics of it. The only possibility for anything other than 50/50 power split would be if there was slippage in the coupling -- that would result in loss of power in the fluid coupling and the ring gear carrying a higher percentage of the power (it would also result in gear reduction).

Yea Don, you did stir things up a bit (I wouldn't say "bent up") but that's a good thing. A few of us learned something and I think the truth was revealed. I call that "progress"... Unless I'm wrong about all of this

[wheneaglesfly]

I have a 1964 Pontiac Super Hydramatic 315 Dual Coupling Transmission.
Its complete and just missing the external Throttle arm to the Carburator(s).
Its a Massive Trans with an an all aluminum case and seperate bolt on bellhousing.
I picked it up back in 2006 and was attached to a 1964 389 engine I still have.

I knew it was unique .
I am into Street Performance and Drag Racing and used to the Turbo 400.

I read through this thread.
I have been educated.

Code is PBS. And the Hydramatic aluminum Tag still intact.
I believe from a 1964 Bonneville 4-bbl.