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2GodBDGlory

[MOC] Ford Raptor Drivetrain Model

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I'm back with the third installment in my drivetrain model series, in which I build interesting drivetrains, without the annoyance of putting bodies around them!

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For this one, I modeled the drivetrain of the Ford Raptor pickup truck, which allowed me to do a few interesting things. For one, this truck has a ten-speed transmission, which would be a challenge to replicate. Additionally, it has an unusual 4WD transfer case, allowing for RWD, AWD, and 4WD modes, with the AWD allowing some slip to the front half despite lacking a central differential, and with the 4WD locking it up completely. Finally, it has a Torsen limited-slip central differential, which I've been wanting to put in a model for a while. In the end, my model has these features:

  • V6 piston engine, with an unusual build to allow for a 60 degree cylinder bank, and driven by a PF L-motor
Spoiler

I really wanted to make this as realistic as possible, so I aimed for a 60 degree bank and 120 degree intervals between pistons, but I was sadly unable to get the 120 degrees I aimed for. The 60 degrees is still cool, though, and makes it distinctive in a world of identical engines.

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  • 12+4R sequential transmission. There's several gears more than necessary, but you can always ignore those and pretend it's a 10+R like the real truck. Strangely, it's actually easier to build it with the extra gears.
Spoiler

This is a variation of an old 12-speed I made a long time ago. I rebuilt it from the instruction video I made here: 

, and then started thinking about how I could add a reverse gear to it. The original gearbox was in the form of a close-ratio four-speed multiplied by a wide-ratio three-speed that would shift every time the four-speed got through a cycle. I tried a bunch of complex things to try to get the reverse in, and then found one so laughably easy to work in that it should have been there from the beginning. All I had to do was add a 20T clutch gear on a string of three driving ring extenders (the new low-backlash ones were great here!), and it worked perfectly!

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^Gearbox

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^Here you can see the 20T I added for reverse, meshing with the 24T side of the differential housing. It's likely going to be a weak connection were this an RC MOC, but it works perfect here!

The transmission was controlled by the knob in the lower left of that picture, through a worm drive. A stepper mechanism caused the 3+R gearbox to cycle once each time the 4-speed cycled, making this a 12+4R transmission! Ignore two forward speeds and three reverse ones, and we've got a realistic 10+R

  • Hi-Lo transfer case
Spoiler

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This was extremely simple, and can be seen on the left side here. It was independently controlled by the knob below it.

  • RWD/AWD/4WD transfer case
Spoiler

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I learned about this transfer case from an Engineering Explained YouTube video (Basically the only non-Lego guy I watch much of), which, as I understand it, has three modes. RWD, AWD with the front axle connected by a fluid coupling, so that it can slip a little bit to avoid the binding that would normally occur without a central differential, and 4WD, with the fluid coupling locked up. I simulated it as you can see in the image. One side of the driving ring drives the front wheels through the 24T clutch gear to simulate that fluid coupling; the other side locks it up for 4WD, and the middle is simple RWD. You can also see my simulated half universal joint on the back as my rear-wheel output.

  • Torsen front differential
Spoiler

The differential is driven by a universal joint shaft from the transfer case. I've been intrigued by Torsen limited-slip differentials for a while now, but it was the design I used here, from Lego Technic Embodiment on YouTube, that got me to finally understand how they worked (Engineering Explained also helped). This design is surprisingly compact, and seems like it could possibly have legitimate use cases in RC vehicles. Come to think of it, it'd be an interesting swap into the Top Gear Rally car or PU Buggy... Anybody want to test that? Here it allows for one front wheel (or rather universal joint half) to rotate slower than the other side, as when steering, but will not allow it to stop moving, as in a slip situation. It's really cool, and I'm glad I've finally put one in a finished model, even if it has no practical use at all.

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Images at: https://bricksafe.com/pages/2GodBDGlory/ford-raptor-drivetrain-model

Let me know how you like the new format I'm trying here, with a bullet-point outline with more details and images in spoiler boxes. It seems neat and simple to me, so it might be what I do going forward.

Overall, I was happy that everything worked nicely, and it was overall a pretty painless build that allowed me to try out some fun mechanical concepts!

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I absolutely love this idea and am glad to be able to study it further, this is stuff I need to understand better. Thanks a ton.

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