By on November 26, 2015

 

Gear arrangement for a 10 speed automatic from Patent # 8,834,310

Gear arrangement for a 10 speed automatic from Patent # 8,834,310

Editor’s note: This was probably the most comprehensive look at Ford’s 10-speed automatic when it was originally published back on December 1st, 2014. It’s also one of the top 10 most read articles published in the last 12 months. It’s time to geek out again on all those gears.

Lately there has been a lot of speculation on what the Ford Motor Company has been up to with their 10 speed transmission design. All we know is that there is a joint venture between Ford and GM to develop the next generation 10 speed transmission for next generation RWD trucks and cars. This article pieces together the information available from the invention disclosures from Ford, and makes  educated guesses about the actual design. While the author sincerely hopes that these guesses are educated in nature,  there is a possibility that the guesses are completely off base. With that disclaimer out of the way, let us look at what facts are at our disposal, and what the Ford 10 speed automatic transmission design is likely to look like when it is sees the light of day. If you are interested, read on.

US Patent number 8,834,310 is one of the many many patents granted to Ford for the design or design elements of a 10 speed automatic transmission. This same basic power flow was first disclosed in US patent number 8,545,362 but clearly it has been refined as the project has progressed. In September 2014, the annual Henry Ford Technology Awards winners were announced. Every year a maximum of ten awards are given out by Ford to recognize and honor technical achievements in the fields of Product Development, Manufacturing, and Research. One of the awards was

 

“For the design and development of the Next Generation 10-Speed RWD Automatic Transmission Family; advanced automatic transmission technology is critical to meet stringent government fuel economy regulations and customer expectations for increased performance.”

 

A major auto company like Ford applies for and receives hundreds of patents every year. Looking for what will actually make it to production can be like looking for the proverbial needle in a haystack. The names of the award recipients is an important bit of information that can be used to narrow the search down. But the recipient of such an award is likely to be a prolific inventor who has dozens of disclosed inventions to his or her credit. Thus even with this information, it is not a trivial task to filter out the noise.  In a modern automatic transmission, there are dozens of relatively minor but innovative things that are invented as the design is fleshed out. Typically the overall power flow is disclosed in one patent, the finer details are disclosed in subsequent patent applications as the design turns from a doodle to actual drawings that can be manufactured on a mass scale and work reliably over the expected life of a vehicle. An absence of such supporting patent disclosures can mean that the design concept is not being taken much further than a disclosed invention. Another clue is if the patent applications are being filed with international patent offices (EU, China, etc). International patent applications are not cheap, and typically inventions that are headed for production will turn into international patent applications as well to protect the intellectual property in jurisdictions besides NAFTA.

After reading through dozens of issued patents and patent applications, I have concluded that the design concept disclosed in part in Patent #8,834,310 is the concept going forward to production. A photochop of the likely cross section put together from the various supporting patents and applications is shown below. I am not sure if I got the width of the fourth planetary gear set and/or the width of clutch pack E correctly, but this should be pretty close to the finished product. The planetary gear set elements and the shafts connecting them are color coded along with the intermediate shaft which is connected to 3 of the shift elements but not to any of the planetary gear sets directly.

Ford ten speed transmission cross section design pieced together from various patent disclosures

Ford 10 speed transmission cross section design pieced together from various patent disclosures

Summary of design features of the Ford 10 speed transmission

The salient features of the design are as follows:

  • There are a total of 10 forward ratios (of course) and 1 reverse ratio
    • There are six forward under drive ratios (i.e. the input turns faster than the output)
    • There is a direct drive ratio where the input and the output shafts spin at the same speed
    • There are three overdrive ratios (i.e. the output turns spins faster that the input)
  • There are 4 simple planetary gear sets, just like the ZF 8HP and the GM 8L transmission families
  • There are six shift elements (as compared to 5 for theZF8HP and the GM8L)
    • 2  brakes (A and B)  that are nested (one shift element is packaged inside the other)
    • 4 clutches (B, C, D, and E), two of the clutches (D and F) are nested as well
  • For any of the 10 gear ratios, 4 shift elements are closed and two are open. Consequently the frictional losses are likely to be no worse than the 8 speed transmission designs
  • The nesting of shift elements means that the overall package size will be pretty similar to the 8 speed transmission designs
  • All shifts up and down need one shift element to be opened, and another one to be closed simultaneously. This is identical to how the ZF 8HP and the GM 8L transmissions work. The shift performance should therefore be very good.

So in effect, what this design provides is an additional over drive gear and an additional under drive gear at the cost of an added shift element. The packaging room is similar to the 8 speed designs, and the difference in weight for a given torque capacity should be minimal (within 5 lbs for a given torque capacity with equivalent levels of engineering diligence). The first 2 planetary gear sets and the fourth planetary gear sets are laid out pretty much exactly like the ZF 8HP transmission design. Therefore it is not surprising that first gear is achieved in a manner very similar to the ZF 8HP transmission, i.e. both the brakes are locked which grounds the ring gear, the sun gear, and consequently the planetary carrier of gear set 1. Since The planetary carrier of gear set 1 is connected to the ring gear of gear set 4, the ring gear of gear set 4 is therefore grounded. The engagement of clutch E connects the input shaft to the sun gear of gear set 1. Though not strictly necessary for the operation of first gear, clutch D is also engaged because clutch D needs to be connected for a shift to second gear or to reverse gear. Clutches C and F are the two open shift elements for first gear operation. This sets up an under drive ratio because the carrier of gear set 4 is the output shaft of the transmission, the ring gear is grounded, and the sun gear is connected the input shaft.

The ratio of first gear is therefore

1st   = S4+R4


S4

 

 

This equation is identical to the first gear ratio equation for the GM 8L90 transmission, as well as the ZF 8HP transmission. The GM design has a first gear ratio of 4.55:1, while the ZF design has a first gear ratio of 4.70:1. The second generation ZF 8HP transmission offers first gear ratio of 5.0:1, which is  the practical upper limit of the gear ratio such an arrangement can yield. Therefore, I do not expect that the Ford 10R family offers a much shorter ratio than 5.0:1 for the first gear. The 10th gear ratio is expected to be in the 0.6:1 to 0.64:1 range. For comparison, the GM 8L90 has a 0.65:1 ratio for the tallest gear, and the second generation ZF 8HP has a 0.64:1 ratio for the tallest gear. The calculations for all 10 gear ratios are detailed in the companion saturation dive.

Overall ratio spread and an example of design refinement

Therefore in terms of the overall ratio spread (ratio of the shortest gear to the tallest gear), this transmission design is not going to break new ground, and will likely be similar to the second generation ZF 8HP. I would project an over all ratio spread of around 7.5.  So while the ratio spread is similar to the 8 speed designs, the ratio spacing is going to be better because there are 10 steps between the numerically highest and the numerically lowest gear instead of 8.

Additionally this transmission design has many refinements that are not immediately obvious, e.g. the nested layout of the 2 brakes has a measurable advantage over the ZF or the GM friction element layout. The ZF 8HP design and the Ford 10R designs are compared in the figure below

Comparison of the brake arrangements for ZF 8HP and Ford 10R designs

Comparison of the brake arrangements for ZF 8HP and Ford 10R designs

With the ZF design, brake B is disengaged for 8th gear operation. At 3000 rpm transmission output speed (approximately 80 mph), brake B sees a relative speed of 4500 rpm. Therefore even a small amount of drag torque can translate to a substantial power loss and therefore a reduction in the fuel economy. The stationary plates are splined directly to the housing, which is smart because it saves a component but at the cost of added complexity to the transmission housing. But this design decision also has a downside, it limits the ability of transmission fluid to flow through the brake. It is customary to put holes in clutch drums to provide a path for the fluid to flow out of the clutch when it is open. With the transmission housing serving the role of the clutch drum, such holes are not possible because while you want the fluid to be able to leave the shift element, you do not want it to be able to leave the transmission housing (that leads to unhappy customers, warranty, etc). In the ZF 8HP design, the centripetal acceleration due to the angular velocity is slinging the fluid outwards, and that fluid has nowhere to go so it sits inside the brake and causes drag. Even a third of a lb-ft of additional drag torque is a quarter horsepower of power loss, i.e. approximately a quarter of an mpg loss in highway fuel economy.

The Ford 10 speed transmission design on the other hand moves the ground element of the brake to a nested clutch and hub design. Since the 2 brakes are now entirely  internal to the transmission, it is now possible to design in the appropriate passages for the fluid to leave. Therefore for the overdrive gears, when  brake A (outer brake) has to be open by design, the fluid has a way out of the clutch and therefore the plates spin in air instead of a bath of fluid. This leads to lower drag torques, and could easily account for a 0.1 mpg or more highway fuel economy enhancement over the ZF 8HP design. The original patent disclosure for the power flow had a brake arrangement very similar to the ZF 8HP, while the later invention disclosures go to the nested design. This is an example of the design being refined as the development progresses.

What is the competition doing?

The Daimler 9G-Tronic 9 speed gear box also had 4 simple planetary gear sets and 6 shift elements. But it only accomplishes 9 speeds from the layout as compared to the 10 from the Ford 10R design. At the expense of 1 gear ratio, the Daimler 9G-Tronic design gains a wider ratio spread of 9.16 (first gear ratio of 5.5:1, 9th gear ratio of 0.6:1). On the flip side however 3 of the 6 shift elements are disengaged/open for any given gear, as compared to 2 for the Ford 10R design thereby giving Ford the slight edge in parasitic frictional losses.  You win some, you lose some.

ZF CEO has emphatically stated that his company is not going after 10 speed designs for now. Therefore the long list of clients ZF has are presumably happy with the 8HP and the forward evolution of the design. But ZF engineers do have a few disclosures with 10 speed power flows similar to this one (6 shift elements, 4 planetary gear sets, 2 open shift elements in any gear) going back to 2007-9 time frame.

Hyundai and Kia also have invention disclosures with a power flow that is in effect very similar. So it is possible that  10 speed transmissions are also on the horizon for the luxury offerings from the 2 brands.

General Motors has officially partnered up with Ford to use this design in the future. Ford appears to be leading this design effort, and in return GM appears to be leading the design effort for the 9 speed FWD transmissions. Though the GM 8L family is an excellent design in its own right, but perhaps the economies of scale inherent in a partnership are attractive enough for them to adopt this design after a relatively short time with the 8L family.

Conclusions 

The rumor has it the first prototypes were installed in test vehicles late last year, and the controller software development is in full swing right now. Unless the software team is working extra fast, 2015 CY is unlikely. Likewise for the production tooling, I doubt that it is possible to tool up this transmission within 18 months  of first vehicles level prototypes. While it is possible that this transmission shows up for 2016 model year in late 2015, it seems more likely that it actually does not show up till the middle of 2016  for 2017 model year vehicles.

This is a good solid design, kudos to the design engineers at Ford for making this happen. A project of this kind is not a trivial undertaking, and I am sure there is a tale of blood, sweat, and tears behind this design. While the mechanical design seems fairly complete, the Tresmonos of the world are probably slaving away to get the tooling all set up as this article is run. At the same time the code monkeys are likely working just as hard on the software to make sure that this transmission shifts like the best. It is safe to say that there are more missed anniversaries and birthdays ahead for a large team at Ford and GM.

Forward progress seldom comes without an effort. This is forward progress.

The first commentator to say CVTs are better shall find coal in his or her stockings. A CVT design with this much torque capacity is yet to be seen. Physics, it can be a pesky thing.

For all 10 gear ratios, and details of the operation of the transmission, please refer to the saturation dive.

The author would like to stress again that all information presented in this article is from publicly available sources, mostly the USPTO website. Internet, it can be a wonderful source of information.

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19 Comments on “Giving Thanks: Exclusive: An Inside Look At Ford’s New 10 Speed Transmission...”


  • avatar
    Big Al from Oz

    Before we get to wrapped up in the technical wizardry of these marvelous transmissions lets look and see if they are really a necessity. When I state a necessity, I’m stating that regulatory controls are forcing these upon us. I’m also questioning their requirement? Do the majority really want them, not just TTAC car enthusiasts?

    What are the pros and cons of these fabulous gear bags?

    1. Pro, better FE, yes, but negligible,

    2. Pro, better performance, yes, again negligible,

    3. Pro/Con less driver input, ie, more computer control,

    4. Con, more expensive to manufacture, thus increasing the possibility of off shoring production,

    5. Con, more expensive to repair,

    6. Con, increase probability of failure, ie, more moving parts increase this, and

    7. Con, less driver involvement in vehicle operation.

    Are they worth the investment?

    I not stating not to use these transmissions, but I do think we are not utilising our technology the best. Irrespective of the final cost, it will be far cheaper to construct and maintain and use a 6spd auto or better still a 6sped manual, with little loss in FE and performance.

    I’d bet if these transmissions were made options when purchasing and the “base” transmission was a 6sped auto or manual, we would see most vehicles with the 6spd in lieu of a 10spd. If this was not the case how do Toyota’s bread and butter vehicles offer 5spds, and less tech and remained near the top?

    The money wasted on developing these could be used to reduce the cost of buying a vehicle, and still being able to get from point A to point B, with the same levels of comfort and speed.

    Arent’ EVs going to replace the ICE in a decade or two?

    • 0 avatar
      DenverMike

      If midsize pickups were the 1st to get 10-speeds instead of fullsize, you’d be falling all over yourself with praise.

      Trucks need all the gears and overdrives they can get. More aggressive overdrives means more aggressive final drives. That’s more work with less fuel consumption.

    • 0 avatar
      Lou_BC

      ………And Big Al has called some people Luddites!

      We don’t need this transmission since Ford is building it.

      Big Al has spoken.

      How many gears do transport trucks have?

      Why do they have so many?

      Ford is just compensating for a their aluminum bodies. That must be it.

      My 6 speed F150 is vastly inferior to my dad’s 1977 F250 3 speed.

      • 0 avatar
        JohnTaurus_3.0_AX4N

        A-men Mike & Lou.

        I remember thinking when reading that part about adding .1mpg with the improved design that some idiot would take that and assume that is ALL the gain this unit will have on fewer geared transmissions. I shouldve known who it would be.

        Not only that, but he has already built this transmission himself and tested it himself in order to learn that long list of cons that are totally fact (as his extensive data will prove, no doubt). Im sure glad he did his homework before talking out of his @$§. That couldve been embarassingly stupid otherwise.

        Why do we need more that a PowerGlide anyway? Noone shouldve tried to raise the bar. Our friend proves that doing so will be a horrible mistake, with too little an improvement to justify the cost and complexity of going beyond the current working design.

        I guess all the engineers can instead study seat cusions in an effort to make the car $0.85 cheaper for the consumer. Thats far more useful.

  • avatar
    65corvair

    Ten times the trouble! Fords still hasn’t figured out the powershift yet. There has to be a point of diminishing returns. I do wish my Corvair powerglide had three speeds instead of two.

    • 0 avatar
      JohnTaurus_3.0_AX4N

      Wow, you have built and tested this transmission yourseld, as [email protected]§$fromoz did? Or is your reaistance to change strong enough so as to cause you to assume new=trouble?

      And then you complain that your trans doesnt go far enough. Soooo…. “New sucks! Wish I had newer.”

    • 0 avatar
      bball40dtw

      The Powershift is a Ford Europe/Getrag jointly developed transmission. It will eventually be phased out for CVTs or other automatics (Possibly 9F). They need another transmission for the 1.0T engine because it is terrible with the Powershift DCT, and Raj Nair hates it.

      Ford’s best FWD transmissions were jointly developed with GM. The current 6R transmission that is on most RWD Fords at the moment is also a good transmission. The 10R has a robust design and was created with the North American truck owner in mind. I wouldn’t expect problems like you saw with the Powersh!t.

  • avatar
    WhiskeyRiver

    After studying the diagram shown at the top of the story, my question is: Why does this thing need a yagi antenna?

  • avatar
    Big Al from Oz

    I do believe the three who made comments or an attempt at a counter argument/retort should be able to comprehend and digest the intent of my comment.

    I do find it hard to understand the need to be affectionate towards a pile of metals, plastics, silicon, etc.

    My comment is not that of a Luddite, maybe Lois should understand what a Luddite represents.

    As a person in engineering I do find this quite interesting, but as a driver and an owner of quite an economical, heavy’ish vehicle I do find six forward gears are adequate (plus another gear that makes my pickup go backward;).

    Or does Ford need a way to improve the FE on their EcoSuck engines? The comments made against me do come from the dedicated Frod phan boi club.

    Guys, Fords are like any other form of transportation, they are not magical.

    Go back and re-read my comment, then respond, please, without the overstatements, or as I interpret, trolling. Maybe then we could exchange mature dialogue.

    Until then, thank you.

    • 0 avatar
      Big Al From 'Murica

      24 mpg on the drive from Augusta to Atlanta including the craziness on I75/85. My Frontier never beat 18 on that trip. More powerful, much larger truck beating the mpg of a stripped down little toy truck is pretty close to magicmagic and my kids knees weren’t in my back the whole trip. I anticipate doing better going home as it is downhill most of the way if the Atlanta traffic doesn’t bite me. Yes, if you use the pedal lime an on off switch ecoboost mileage sucks. Driving it normally nets great returns.

    • 0 avatar
      DenverMike

      @BAFO – You’re not an engineer, so don’t even throw that around. At most, the engineers let you on the floor to squeeze mop. And engineers can be as dumb as rocks, except great at memorizing and reciting back numbers and facts.

      Work trucks cannot have enough gears. Memorize that for future reference. When I’m just putting around town, 6 gears is more than enough. That’s one overdrive. Except it limits the ‘final drive’ to around 4.3:1 without a huge penalty in fuel economy. And the engine is revving hard at freeway speeds.

      Seven pulling gears and three overdrives is a great advancement, no matter how you slice it. Add enough ‘final drive’ and 8th is ‘direct drive’.

      Yes there’ll likely be teething problems, but read the article. It’s not as complicated as you think.

      Sorry midsize trucks won’t be getting 10-speeds anytime soon. Just suck it up, big guy… Engineers don’t cry!!!

      • 0 avatar
        Big Al From 'Murica

        But Al’s only needs 6 gears to carry 14000 lbs in the bed while getting 53 mpg. It will be even better when he adds the trifecta tune.

        • 0 avatar
          Big Al from Oz

          Big Al from Sudan,
          If you remove your overstatements that are an attempt of a troll what you speak of is available in pickup form and has been for a number of years.

          The pickups obtain 55mpg(Imp) and can carry around 2 500lbs.

          http://www.carsireland.ie/913263

          • 0 avatar
            DenverMike

            @BAFO – That’s just laughable! Not just the 55 mpg, Imperial, Royal or Mystical Gallons, but the 2,500 lbs payload on basically a subcompact fwd car with a tray???

            Ridiculous even for you.

          • 0 avatar
            Big Al From 'Murica

            I can carry 2200 pounds, tow over 8, get around 25 and get to drive something comfortable in which I don’t look like a true jackwagon. So to sir, can SHOVE IT and take your little trifecta tuned crapwagons and drive em where the sun don’t shine.

    • 0 avatar
      Lou_BC

      Big Al – how many gears are too many?

      I drove a V6 Pentastar Ram with the new transmission. it pulled nicely and always appeared to be in the right gear. The only real negative was an intermittent very harsh downshift from 2nd to 1st when one rolled to a stop at a light or stop sign.

      My 6 speed F150 will gear hunt around 60kph on fairly flat ground due to the programming wanting to stay in as high a gear as possible.

      All of my brother’s 6.0 V8 Chevy work trucks will rev to redline then upshift then drop rpm and bog then do it all over again when pulling heavy trailers.

      TFL truck got to go with Nissan engineers when they ran the Cummins XD against a 5.0 Ford. Apparently the F150 would redline then shift then loose power and keep repeating the process.

      In all of those situations a transmission with more gears would be beneficial.

      There can be a point where we have too many gears. 10 speeds will most likely be max unless we get durable high torque load CVT’s or HD’s with 2 speed differentials.

      • 0 avatar
        Big Al from Oz

        Lou,
        I don’t disagree with your comment, my comment was in relation to current requirements, as these requirements are artificial, similar to the EV/hybrid situation. I don’t condone this style of “free market” consumerism.

        My comment is, “can we make better improvements easier and cheaper?”

        First up using heavy vehicles as a comparison is a overstating the usefulness of more gears. Heavy diesel engines are a different beast to the multi cam’ed, VVT and fuel delivery systems on a light duty gas engine. These modern light duty gas engines are very flexible with a much broader power band than a heavy diesel. So of course the requirement for many more gears is necessary. Even more so when you take into consideration the power to weight ratio of a heavy truck to a light duty vehicle, even a pickup.

        The best, cheapest option is to improve aerodynamics if you want FE gains.

        I have a light diesel pickup, it has a narrow power band compared to the Pentastar Ram you drove and look at my FE in comparison. I’m talking real life not the goofy EPA numbers. A Ram 1500 with a Pentastar is averaging just under 18mpg in real life, combined. I’m averaging 26mpg, that is a significant difference.

        Energy choice and aerodynamics will play a larger role than number of gears in obtaining the best FE. Because irrespective of energy the more gears you have will improve your FE performance, especially if you “glide” through the air.

        So, finally, my comment again points towards ensuring the consumer is not short changed. Why should the consumer not have the choice? I would buy a 6spd manual any day over a 10spd auto in a light vehicle.

        The costs alone make the 10spd a waste of resources that could be better spent. Have the 10spd for those who want it, but don’t regulate them, which is the case.

        • 0 avatar
          DenverMike

          I can see why you’re so scared of progress, but all cars will eventually have 10-speeds. Last of which will be midsize pickups, Corollas and such.

          Except you see it as midsize trucks losing more buyers to fullsize pickups, because of those DAMN DARN 10-speeds.

          By the time 10-speed trannies are mainstream, fullsize pickup will be pushing 15 to 20-speed transmissions. It’s just the way it is.

          Meaning truck owners will no longer have to chose between towing or econo final-drive ratios (ring and pinion gear sets). Just set the selector to squeeze all the power it can from the engine, or cruise along empty, with the flow of traffic.

          Kind of like simi-trucks skipping every other gear, when empty and or slightly downhill.

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