BaulkTorque=

Discussion in 'Car Modding' started by lordpantsington, Nov 11, 2019.

  1. lordpantsington

    lordpantsington Registered

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    I understand what this is being used for (penalty for not clutching in an H pattern), and it is obvious that what it does (reduces the maximum torque through the gears while a shift is being made).
    The question I have is why does this entry exist?
    More specifically, what mechanic exists in a gearbox such that the maximum output is limited while a shift is being made?
    I have an idea, looking for an objective second opinion.
     
  2. davehenrie

    davehenrie Registered

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    I was always under the impression that Brake Torque was used to represent the mechanical drag the engine itself creates. This prevents the engine from producing electric power. the Torque, before it can produce HP, must overcome the BT. That is why you see negative values at zero rpm.
     
  3. lordpantsington

    lordpantsington Registered

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    Baulktorque, it is under the [Driveline] section of the HDV.
     
  4. Slamfunk3

    Slamfunk3 Registered

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    I have always thought of it as purely the willingness of the engine to stall while taking off from a standing stop. The higher the baulk torque the more revs/more clutch slip necessary. I guess it could also come into play when up shifting at too low of an RPM, making the engine "baulk" before accelerating smoothly. Have never considered it's impact on the gearbox.

    TK
     
  5. Emery

    Emery Registered

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  6. Emery

    Emery Registered

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  7. lordpantsington

    lordpantsington Registered

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    Hmm thinking through Slamfunk's reply.
    Engines stall N>1st, because of the additional inertial load from the drivetrain. If the engine output is not sufficient enough to maintain rpm, it will stall. I know that inertia of wheels, axles, and the like, are defined in rf. I don't remember if inertia values in the pm include half the gearbox load per drive wheel (in a 2WD). I find no other entry for the inertia of the transmission parts, so there might be something there.
     
  8. lordpantsington

    lordpantsington Registered

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    Emery, that is what I was also thinking. Like there exists a capacity at which the friction from a synchro can do it's job to equalize rotational speeds and allow a gear change. Over a certain input torque, and the output is limited.

    Regardless of how it is being used to penalize for non-clutch use, is that the reason why the entry even exists (to simulate the torque transferring capacity of synchros).
     
  9. lordpantsington

    lordpantsington Registered

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    Rather than just editing a number and seeing how the car reacts, ultimately the goal here is to calculate better estimates for this value. If it as 'simple' as the torque capacity of a cone clutch, those equations are known.
     
    Last edited: Nov 12, 2019
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  10. Slamfunk3

    Slamfunk3 Registered

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    So the original rFactor .hdv file explanation is "BaulkTorque=360 How much torque clutch can handle before slipping. Should roughly equal max engine torque, and probably always greater, except possibly some modified road cars without upgraded clutches..."

    Sounds more like how much torque a clutch can handle before you start to loose the 1:1 engine-gearbox connection. Looking through catalogs of several clutch manufacturers they usually state a "Torque Capacity" of each clutch model. I know that's probably not the full explanation you're looking for but as far as making an educated guess it's something.

    TK
     
  11. Lazza

    Lazza Registered

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    @Slamfunk3 there's a separate entry for what the clutch can handle when in gear. Baulk is for the time during engagement.

    In the absence of better drivetrain modelling I use this to punish bad shifting (lack of throttle lift, really), in the current state I don't think it's worth worrying about aiming for realistic values.
     
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  12. lordpantsington

    lordpantsington Registered

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    These are from the skippy in moddev:

    BaulkTorque=320 // Maximum torque transferred through gears while engaging them
    ClutchTorque=230 // Maximum torque that can be transferred through clutch

    Reading back through the forum, it was stated that once your are done with the gear change, BaulkTorque doesn't matter.
     
  13. Deadpedal

    Deadpedal Registered

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    The line in the RF HDV files "BaulkTorque= x// maximum torque transferred through gears while engaging them" might have better been expressed as the "maximum torque that can be applied through gears in the process of changing gears". There are a few mods where the value is less than the engine’s torque, notably the S397 Howston G4 & G6 (a Lola T70-like car) and Pixsim’s Lola T280. If the value expressed in the BaulkTorque line is exceeded (by applying too much throttle or compression braking), then a shift cannot be completed. This forces the driver to lift, blip or declutch when shifting gears. Conversely, when this value is more than the torque that the engine can produce, this allows foot-to-the-floor flat-shifting.

    So that then begs the question, what is baulk? The literal definition of baulk is resistance, reluctance or unwillingness to accept or act but is usually used in relation to human attitude or action. Unfortunately, I can’t say definitively what it means with regard to mechanics because I can’t find enough references. When searching Google for the term “baulk”, about the only thing that comes up in mechanics does indeed have to do with to gearboxes: a “baulk ring” is a component of a cone synchronizer in a synchromesh gearbox. A cone synchronizer is a kind of clutch and as such uses mechanical lock caused by force and friction to function. (To be clear, I don’t believe that “baulk” in the case of this particular line in the HDV file is in relation to the synchronizers). But mechanical lock is the key to understanding why torque on a gearbox needs to be reduced when shifting gears.

    The mechanical lock to which I refer is caused by the gears and/or dog clutches being meshed in the presence of the force of engine torque and the inertia of the car. Under such a load, the friction between these transmission components, even in the presence of lubricants, causes a mechanical lock that is very difficult, if not impossible, to overcome with a gear lever. This kind of resistance to movement is what I believe the term baulk in BaulkTorque refers to.

    Unfortunately, the use of low BaulkTorque values in the HDV to force drivers to lift or declutch when shifting has never been satisfactorily implemented for me. Any mod that uses a low BaulkTorque value results in requiring one to shift far too slow than one would for a racing dog box like the Hewlands that the aforementioned Lolas would have had.
     
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  14. Lazza

    Lazza Registered

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    @Deadpedal I think you've got some of that sideways.

    I don't think BaulkTorque is really a real thing; it's a simple way to limit how much power you can apply while the gear change completes, and therefore is a sort of substitution for a proper transmission model. I assume the Baulk name is because you need to wait to apply power, like you do when the baulk (blocker) ring is beginning to engage.

    It's true that many mods have a BaulkTorque just as high as the ClutchTorque, which means there's no reason to lift the throttle when shifting. However, how they work when it's lower depends a lot on the shift time, which is also defined in the vehicle. If the shift is completed faster than you (can) complete the movement, it won't cause any issues.

    Unfortunately, even if you fall foul of the BaulkTorque it doesn't stop you going into gear. In fact the one thing the game always does is respect your shifter position, and put you into gear no matter what. A 'medium' BaulkTorque value will limit your applied power, hopefully less than you'd get from the engine at post-shift RPM (*1), so even though you don't miss the gear entirely (*2) you still need to lift for a little time in order for the gear to engage properly.


    *1 The distinction between peak engine power and post-shift RPM power is important. You can have BaulkTorque lower than the stated peak engine power, but benefit from a bad shift because the engine power at below-peak revs (as you get, generally, after a proper upshift) can be lower than the BaulkTorque. So someone completing a shift properly, having a fully engaged drivetrain, can produce less effective power than someone with a high-revving engine still forcing through the BaulkTorque value. The only detriment is fuel use and potentially engine wear.

    *2 The game doesn't make you miss the gear, but for anyone not happy with that I highly recommend the Realistic Gearshift plugin/program.
     
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  15. lordpantsington

    lordpantsington Registered

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    Is there any reason to specify a baulktorque= value, lower than what is produced at post-shift RPM, for a sequential?
     
  16. Lazza

    Lazza Registered

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    Depends whether the sequential system has throttle cut I suppose. If you can flat-shift in the real car it should be set that way in game, then you can probably up the baulk torque to make sure nothing goes wrong. But if you have to lift the throttle for the sequential to change gear, you can use a low baulk to make rF2 drivers do the same.

    Need to be mindful of what happens on downshifts too, though. That's why I don't see this parameter as an accurate representation, even putting aside the game's shortcomings with gear selection. Best to just tune the baulk until it 'feels' right across different scenarios. Later when rF2 does things properly go back and adjust mods to suit.
     
  17. lordpantsington

    lordpantsington Registered

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    So the question in post #15 was asked because there are no baulk/ synchrorings in a sequential. If the entry is negated by setting it high (relative to the torque at post shift rpm), would that not support the theory that its inclusion and design intent is to simulate the torque capacity of the baulk/synchro ring friction interface?
     
  18. lordpantsington

    lordpantsington Registered

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    Using formula and data in this: https://www.hoerbiger.com/upload/file/2013_basicsofsynchronizers.pdf
    Found my 1st gear synchro to have an estimated capacity of 64.21 Nm, new. This is assuming a shifting force of 1000N, and a CoF of 0.1. With a 4.0 Final Drive acting as a multiplier that is a baulktorque of 256.84Nm. FWIW my engine has Peak Torque of 405 Nm.
     
  19. Emery

    Emery Registered

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    How does that compare with what you expected and/or what values are being used by modders?
     
  20. lordpantsington

    lordpantsington Registered

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    It seems lower than I expected for my application, but this H pattern could previously be hammered like a flappy paddle sequential. So I suspected the previous values were massively incorrect. I remember driving into T2 at laguna and dropping 6th to 2nd with such ease that I was thinking, 'this can't be correct.' It was previously set to 600Nm.

    As far as other mods are concerned, I haven't looked, as I don't want to taint objectivity.
     
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