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  1. #1
    Established Member Two Rings
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    Details about the Seven-speed dual-clutch gearbox 0B5/S tronic (DL501)

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    Here's a short article on the S-tronic gearbox.

    there is a older related article posted on AudiZine here:
    - Details of the Clutch Release Systems of Audi (Manual Gearboxes)
    Click here:
    http://www.audizine.com/forum/showth...ystems-of-Audi

    ==============================================

    This is the new 7 Speed S-Tronic Double clutch gearbox found in the A4 B8 and Q5 series. It is also found in the S5 Cabriolet/S4.

    The information presented here is for the high torque DL501 model. The gearbox code for this box in Audi is called "OB5". The general principals of operation and many other details are covered

    Enjoy the contents and hopefully gives drivers a better understanding on how this S-tronic gearbox actually works.





    Seven-speed dual-clutch gearbox 0B5/S tronic



    Following the great success of the six-speed S tronic on the Audi A3 and Audi TT models, a seven-speed dual-clutch gearbox, combined with the quattro powertrain, is now used for the first time, in a longitudinal configuration, on the Audi Q5/A4/A5.

    In combining the plus-points of the automatic gearbox (ride comfort and gear shifting without any interruption in tractive power) and the manual gearbox (sportiness and efficiency) in combination with extremely short shift times and "direct power transmission", the dual-clutch gearbox 0B5 provides a special driving experience.


    Specifications of Gearbox

    **The 7th gear is configured as an overdrive (6 + E). Top speed is in 6th gear. At present, the petrol engines have a ratio spread of approx. 6 : 1 and the diesel engines approx. 8 : 1.





    Exterior View of the Gearbox





    Partial Cut Away View of the Gearbox



    The advantages of having seven gear ratios
    Seven gear ratios enable a wide ratio spread to be realised, resulting in highly dynamic starting performance and allowing 7th gear to be used as an overdrive (E-gear). Low fuel consumption figures are thus achievable.

    In addition to the many other innovative detail solutions, which have been incorporated into the 0B5 gearbox, the seven gear ratios are a key factor enabling the Audi vehicle to combine sportiness and efficiency.



    Sectional view of gearbox overview of the component parts



    Gearbox mechanism design function
    Drive is transmitted to the dual-mass flywheel through the transmission plate. From here, torque is transmitted to the electro-hydraulically controlled dual clutch, which selectively operates the even or odd numbered gears.

    The gearbox is thus subdivided into two sub-gearboxes.

    Sub-gearbox 1
    The odd numbered gears (1, 3, 5, 7) can be driven
    through the central input shaft 1 by clutch K1.

    Sub-gearbox 2
    The even numbered gears (2, 4, 6) and the reverse gear can be driven through input shaft 2 (a hollow shaft) by clutch K2.

    Power is output through the common output shaft, from where the torque is transmitted directly to the centre differential. Torque is distributed approx. 60 % to the flange shaft connecting to the rear axle and approx. 40 % to the spur pinion and through the side shaft connecting to the front axle drive.





    Design features of the dual clutch

    The dual clutch serves two tasks:
    To engage the engine at driveaway and to disengage the engine when stopping
    To shift the gears (= changeover to sub-gearbox)

    The dual clutch was designed in such a way that clutch K1 is located on the outside, and therefore has the larger diameter. This meets the higher demands placed on K1 as the starting clutch (in first gear).

    Small pressure cylinders and coil spring assemblies on both clutches provide good controllability at driveaway and when changing gear. Hydraulic pressure equalisation is no longer required. The clutch control corrects the dynamic pressure build-up caused by centrifugal forces at high engine speeds. A pressure characteristic allows the dynamic pressure build-up to be compensated for in any situation.



    Gearshift sequence

    Driveaway:
    In selector lever position P or N, only 1st gear and reverse are engaged. This allows immediate driveaway from a standing stop. Depending on whether the driver decides to drive in reverse or forwards, the correct gears are already preselected.


    Shifting:
    To drive forwards, the driver shifts the selector lever into D and drives away in 1st gear. When a defined speed threshold of approx. 15 kph is exceeded, 2nd gear is engaged in sub-gearbox 2 (reverse was previously engaged).

    When the shift point for upshifting from 1st to 2nd gear is reached, the gearshift is made by lightningfast opening of clutch K1 and simultaneous rapid closing of clutch K2 without any interruption in tractive power. To enhance shift comfort and preserve the clutch, engine torque is reduced during the gearshift (overlap).

    The gear shifting process is completed within a few hundredths of a second. 3rd gear is now preselected in sub-gearbox 1. The process described
    above repeats itself alternately during the subsequent gearshifts from 2-3 up to 6-7.


    Synchromesh
    To achieve extremely short shift times, all synchromesh gearboxes have carbon-coated synchroniser rings.

    Gears one to three and reverse are also configured as triple-cone synchronisers, due to the high stresses to which the y are subjected.

    Gears four to seven use single-cone synchronisers.



    Gearbox oil system

    ATF oil system
    The 0B5 gearbox has two separate oil systems. The first oil system accommodates the dual clutch, the mechatronic syste m and the oil supply.
    These components use an ATF developed specially for the B5 gearbox.
    This ATF provides rapid response of the shift and clutch control mechanisms even at low temperatures, and serves to lubricate and cool the dual clutch.

    A basic requirement for the ATF is that it allows the dual clutch to be controlled in a precise fashion.


    Gear oil system
    The second oil system incorporates the manual gearbox, the transfer case (centre differential) and the front axle drive.

    Lubrication is by means of a hypoid gear oil with a special oil additive for the centre differential. By separating these oil chambers, it has been
    possible to design the individual component parts of the gearbox optimally. Thus, it was not necessary to make any compromises due to conflicting demands on the lubricant.

    ** compare this to the transverse mount 6 speed where a single ATF was used to lubricate the clutches and the gears.


    Sealing the oil systems
    The oil chambers must be reliably sealed off from one another at the transitions between the two oil systems. For instance, the ingress of gear oil into the ATF oil chamber (the ATF mixes with the gear oil) would adversely affect the performance of the dual clutch. To prevent this from occurring, special sealing elements are fitted in the relevant places.




    Input shafts 1 and 2 are sealed by a double oil seal ring (in total, four radial sealing rings are used). If a radial seal is leaking, the oil drain port allows the leaking oil to drain off and prevents it from entering the other oil chamber. The transverse bore in input shaft 2 establishes a connection between input shaft 1 and the oil drain port.


    ATF supply lubrication
    A sufficient supply of ATF is essential for the operation of the gearbox. An external gear pump driven by the dual clutch through a gear step provides the necessary oil flow and oil pressure.

    The ATF pump supplies the mechatronic system with the oil pressure it requires to perform the following functions:

    Control of the multi-plate clutch (engagement and disengagement)
    Cooling and lubrication of the multi-plate clutch
    Control of the gearbox hydraulics



    Gearbox control - Mechatronics
    The gearbox is controlled by a recently developed mechatronic system. Its control concept allows precision control of gear engagement speed and force when changing gear. Thus, depending on the driving situation, it is possible to achieve rapid gearshifting without compromising on comfort, e.g. while coasting.




    The mechatronic system acts as the central gearbox control unit. It combines the electro-hydraulic control unit (actuators), the electronic control unit and some of the sensors into a single unit. On account of the longitudinal configuration, the rpm sensors of both gearbox input shafts and the gear sensor are located on a separate mounting bracket.


    The mechatronic system controls, regulates and performs the following functions:

    Adaptation of oil pressure in the hydraulic system to requirements
    Dual clutch regulation
    Clutch cooling regulation
    Shift point selection
    Gearbox control and regulation
    Communication with other control units
    Limp-home programs
    Self-diagnostics




    Gearbox protection functions

    Control unit temperature monitoring
    High temperatures have a negative impact on the useful life and performance of electronic components. Due to the integration of the gearbox control unit into the gearbox (lubricated by ATF), it is very important to monitor the temperature of the electronics and, accordingly, the ATF.

    When the temperature reaches approx. 135 C ( measured by one of the two temperature sensors in the gearbox control unit), the gearbox electronics must be protected against a further rise in temperature.

    When this threshold value is exceeded, the gearbox control unit initiates a reduction in engine torque in order to reduce heat input. Up to a temperature of approx. 145 C, engine torque can be reduced gradually until the engine is at idle.

    When the engine is at idle, the clutches are open and there is no power transmission from the engine to the drive wheels.

    When the protective function is activated, an entry is made in the fault memory and the following text message is displayed in the dash panel insert: "You can continue driving to a limited extent".



    Clutch protection
    If the clutch cooling oil temperature exceeds a value of approx. 160 C , the clutch is within a critical temperature range which can damage it. These temperatures occur, for example, when driving away on extreme gradients (possibly when towing a trailer) or when the vehicle is held stationary on an uphill slope using the accelerator and the clutch (without using the brake).


    As a safety precaution, en gine torque is reduced when the cooling oil temperature exceeds 160 C. If the cooling oil temperature continues to rise, engine torque is gradually reduced; this can be to the extent that the engine is only idling. When the engine is at idle, the clutches are open and there is no power transmission from the engine to the drive wheels.

    When the protective function is initiated, an entry is made in the fault memory and the following text message is displayed in the dash panel insert: "You can continue driving to a limited extent".

    As an additional safety precaution, the clutch temperature is determined using a computer model.

    If the computed temperature exceeds a pre-defined value, the above-mentioned precautions are taken.



    All you need to know about the

    gearbox control unit
    In the B8 series, a new data and diagnostic log is used for the engine control units, the gearbox control units and the airbag control unit.

    The previous data blocks and numberings are no longer used. In return, individual measured data is now available and listed as full text in alphabetical order. The required measured data can then be specifically
    selected.


    Clearing the fault memory
    The fault memories of the engine and gearbox control unit are always cleared jointly. If the fault memory of the gearbox control unit is cleared, then the fault memory in the engine control unit will automatically be cleared as well. The converse also applies if the event memory in the engine control unit is cleared.


    towing
    If a vehicle with S tronic needs towing, the conventional restrictions on automatic gearboxes apply:

    Selector lever in position "N"
    A max. towing speed of 50 kph must not be exceeded.
    A max. towing dis tance of 50 km must not be exceeded.


    Explanation:
    When the engine is at standstill, the oil pump is not driven and certain parts of the gearbox are no longer lubricated. Exceeding a speed of 50 kph results in unacceptably high rotational speeds within the gearbox and dual clutch, because one gear is always engaged in both sub-gearboxes.

    If the towing conditions are not observed, serious gearbox damage can occur.

  2. #2
    Veteran Member Four Rings JimmyBones's Avatar
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    Some one copied and pasted from the SSP about this gearbox. Bad Bad Bad and watch out for the copyright police!

  3. #3
    Veteran Member Four Rings NWS4Guy's Avatar
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    Thanks Deck, always great info. Some questions for you:

    Since thepumps areworking when the engine is working, would it harm the car to coast in neutral down a long hill for example? Assuming that the mechatronics know what is happening, and don't attempt to place 1st gear as the next option when you are going say 100km/hr.

    Additionally, do you know of a posted maintenance inteval for the DSG? Someone did a EU delivery and said that there, they have a 40K maintenance where the oil is changed like the 6 speed DSG's in the TT and A3, but there has not been one psoted for the US. The best answer I have gotten to day is that unless something major changes, there will be no service for thsi newer DSG, which seems wrong to me - we all know hydrolic fiuld breaks down with age and heat and pressure, so it has to be changed at *some* point.

    *** Edit - Deck pays a lot out of pocket to have the access to the Audi manuals and guides, he never posts these as his own info, and rarely posts the things in them at all. We appreciate the sharing and understand that this is a special and limited access to Audi.
    Like a surgeon with a scalpel, my S4 is a precision instrument, with which I carve and dissect my way through traffic.

    2010 S4 Prem+, Quartz Gray, S-tronic, Sport Diff, B&O, Nav, Gray Birch
    StopTech ST-60 BBK - Stratmosphere intake - APR v2.2 Stage 2 w/pulley + exhaust, v2 Coolant System
    Alu-Kreuz, Apikol rear diff mount, 034 transmission mount

  4. #4
    Established Member Two Rings
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    for the audi tech guys, this new concept of DL501 gearbox now uses 2 different fluids and is an advancement over a single oil used in the 02E Stronic (audi TT):
    (1) ATF for the clutches and another (2) hypoid gear oil for the lubrication of the gears and mechanicals.

    the reason why the factory engineers split this now is because they have more freedom in the properties of the respective oils in design.
    if you use a single ATF for clutch and gear lubrication, there would be a point where the properties of the single lubricant prevent you from designing a more efficient and higher torque gearbox. there is no longer a need to make compromises due to the conflicting demands of the lubricants.

    there is no mention for coasting mode, but analyzing the SSP
    the hypoid gear oil is not the issue as the gear chamber is soaked in the stuff.
    the issue is with the supply of ATF for the clutches at idle/coast - the pump is rotating port pump with 2 pressure lines K1 & K2.
    the feed of ATF (not the hypoid gear oil) is via a suction pump jet principal based on venturi effect to draw ATF from the sump.
    the reason this is used is because it doubles the cooling rate without increasing the oil pump capacity. smaller pump = greater efficiency of gearbox.

    in any event, i doubt there is a stretch of road for 50km when you can continually coast in neutral?????


    A interesting question and a very valid point re the oil intervals for the ATF.
    if you look at the technical "marketing" literature from the factory there will always be a line that says "lifetime" filling!
    same for BMW...but as we all know oil is wear and tear item even ATF.

    there is no mention of ATF/Gear oil interval for the DL500 series of gearboxes in the SSP literature for this particular gearbox.

    perhaps we can draw similar learnign experiences from other Audi gearboxes:
    in the tropics we do a CVT (01J gearbox) ATF change every 60,000km.
    (some owners do it as often as 20,000km or 30,000km for CVT)

    for the sister transverse S-tronic found in the A3/TT. we change the ATF at 60,000km also here.
    if you look at the SSP for the 02E S-tronic they never quote anything about the intervals and always refer to a line like
    "refer to service literature". *groan*

    My best educated guess is 60,000km ATF for the DL501 without referring to ELSAWIN service literature
    (its on another computer at home, am at work now)


    Perhaps the service question is best posed to other drivers in a more temperate/EU climate.
    Singapore (and Middle East) is a high heat climate. there is a lot of start stop driving here.
    so the service intervals are not programmed like other places (rest of world).

    for example with engine oil, we do not have the "longlife" or "Advance Maintainece concept" where the vehicle promps you for service depending on driving conditions.
    we have a fixed 15,000km interval here even on the S4 (and every other audi). Singapore is not the best reference actually cos the intervals for everything are not the same as rest of world. the gearboxes also operate under such conditions and the fastidious Audi drivers here will do an ATF change well in advance of the mandated factory intervals. the rule of thumb used locally here is either 1/2 or 1/3 the factory suggested interval.

    short of the gearbox having no ATF drain plug (other brands have this amazingly - truely lifetime LOL!).
    i'd personally change the ATF out every:
    20,000km for a CVT [the filter is dead expensive so its changed at 60,000km]
    30,000km for a DSG/Stronic
    30,000km for a manual.

    the issue further gets more complicated when you want to change the haldex oils and other 'differential' oils or the gear oil only for the transfer case of the S3 etc etc.
    the Audi dealer here sometimes is adverse to the work. there are audi drivers here that will drive a S3 into the official VW workshop and pay them to have the haldex oil changed - cos VW is willing to do the work on all the strange haldex/transfer case oil changes. strange but true!

    rule of thumb........ feed an engine/gearbox/transfer case good fresh oil frequently - it would be less likely to give you problems in the long run.
    that smooth fresh oil change feeling is a good thing :-)

  5. #5
    Veteran Member Four Rings JimmyBones's Avatar
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    Quote Originally Posted by NWS4Guy View Post
    *** Edit - Deck pays a lot out of pocket to have the access to the Audi manuals and guides, he never posts these as his own info, and rarely posts the things in them at all. We appreciate the sharing and understand that this is a special and limited access to Audi.
    Man you are no fun. But if he posted the information about this trans then also post the information for the sport rear differential because it is very similar and just as interesting to read about; along with inside the same book.

  6. #6
    Senior Member Three Rings Zed 2.0's Avatar
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    Interesting on the torque capacity of 500nm @ 9000 rpm. We've been hearing much more capacity from other sources. What are the figures at lower speed? Depending on what dyno you believe, the S4 is making around 500nm out of the box.

  7. #7
    Active Member Two Rings
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    Quote Originally Posted by Zed 2.0 View Post
    Interesting on the torque capacity of 500nm @ 9000 rpm. We've been hearing much more capacity from other sources. What are the figures at lower speed? Depending on what dyno you believe, the S4 is making around 500nm out of the box.
    I think you misread it, it says 550Nm (~406 ft-lbs) at 9000 RPM.

    If I had to guess it seems that at lower RPM, torque capacity would be higher if anything. But it seems like its implying up to 550 Nm at up to 9000 RPM

  8. #8
    Senior Member Three Rings Zed 2.0's Avatar
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    My bad, been a long day. Still, I thought we were hearing ~450 ft/lbs for capacity?

  9. #9
    Veteran Member Four Rings NWS4Guy's Avatar
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    Quote Originally Posted by JimmyBones View Post
    Man you are no fun. But if he posted the information about this trans then also post the information for the sport rear differential because it is very similar and just as interesting to read about; along with inside the same book.

    ok.
    Like a surgeon with a scalpel, my S4 is a precision instrument, with which I carve and dissect my way through traffic.

    2010 S4 Prem+, Quartz Gray, S-tronic, Sport Diff, B&O, Nav, Gray Birch
    StopTech ST-60 BBK - Stratmosphere intake - APR v2.2 Stage 2 w/pulley + exhaust, v2 Coolant System
    Alu-Kreuz, Apikol rear diff mount, 034 transmission mount

  10. #10
    Established Member Two Rings
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    ok chaps i went to look up the "black book" with the Intel chip at home.

    for the DL501:
    ATF is 6.7L for change-
    no interval number specified in the "inspection service" procedure but i take this to be 60,000km as per the rest of the gearboxes.
    the change volume is 6.7L, but when it comes out from the factory it is filled to 7.5L. thisoverfilling is done cos some of the ATF has to go into the volume space for the ATF cooler that is integated to the RHS of the front radiator.
    if u change ATF its 6.7L baically

    as for the gear oil in the DL501 its 4.35L - "lifetime" are the exact words from the factory source.

    FOr the S4 folks that have a manual gearbox (code KMR), its pretty straight fwd, 3.8L of SAE 75W90 manual tranny gearoil for a change.
    60,000km interval also.


    for a higher torque rating of this 7sp S-tronic gearbox....wait for the RS5, it has a DL700 series with reinforced internals that is based on the DL500 series.

    hope this helps

  11. #11
    Established Member Two Rings
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    double post deleted

  12. #12
    Senior Member Two Rings
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    S4 B8 SprintBlue S-tronic
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    Can anyone here specify the factory part number of the ATF oil for S-tronic of S4 B8?
    I'll be most grateful.
    I'm going to change the ATF fluid at 30000 km.
    Sorry for my English - I'm an ignorant Russian bear... just love Audis.

  13. #13
    Registered Member One Ring
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    please full this file "Seven-speed dual-clutch gearbox 0B5/S tronic"
    my email: dat_euro88@yahoo.com
    or: datckd07@yahoo.com.vn



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