[MOC] Hot Trot - RC Trial Pickup w/ Diagonal AWD (42129 B model)

[pleegwat]

6 hours ago, Void_S said:

The H-Drive scheme is even simpler (and allows easy extend it up to 6x6 or even 8x8 wheels) and also needs the central diff lock. However, for the on-road use it has a slight disadvantage of fixes rotation speeds per side. So, it should be better to have all the wheels steered at the same angle to keep the same speed. Best for military slow-speeded vehicles, not so dynamically stable for fast on-road regular cars.

This was used by Dutch DAF YA-328 military vehicles. They would only use six-wheel drive while off-road; for on-road use the drive to the front wheels would be disconnected.

[Void_S]

1 hour ago, pleegwat said:

This was used by Dutch DAF YA-328 military vehicles. They would only use six-wheel drive while off-road; for on-road use the drive to the front wheels would be disconnected.

Yeah, and Brittish Alvis APC family as well. 

[Didumos69]

Thanks for your analysis @Void_S!

9 hours ago, Void_S said:

it smoothly operates in on-road conditions, as has approximately the same speed for diagonal wheels in average, and works better than H-Drive for forward-only steered vehicles. As for the off-road use, the lack of the differential locks may be taken as a disadvantage but actually, it is comparable with a regular scheme with locked central differentials (but still turns better).

Another advantage I see over a regular scheme with locked center differential is that the regular scheme will fail when a diagonal pair loses grip like in a diagonal test. My setup will fail when both front wheels or both rear wheels lose grip.

2 hours ago, pleegwat said:

This was used by Dutch DAF YA-328 military vehicles. They would only use six-wheel drive while off-road; for on-road use the drive to the front wheels would be disconnected.

I read somewhere that people driving these military vehicles with H-Drive (I should call the diagonal setup X-drive) drove into the roadside every now and then (with one side) to release windup.

Edited November 19, 2021 by Didumos69

[westphald]

7 hours ago, Didumos69 said:

I read somewhere that people driving these military vehicles with H-Drive (I should call the diagonal setup X-drive) drove into the roadside every now and then (with one side) to release windup.

I do similar with my truck when the automatic locker kicks in. If I'm going around a turn and the outside wheel slips, kicking in the locker, tension builds up in the axle. Going straight doesn't relieve it very fast.

[Didumos69]

@Void_S, @pleegwat, @westphald, @2GodBDGlory, in the final video you can see what I mean with the diagonal test. At 2:23 you can see how the model moves back and forward over a hat shelf from a car. Every time when it returns (twice), you can see how one diagonal pair loses grip. It struggles a little, but it keeps on going, because the other diagonal pair still has traction.

Edited November 21, 2021 by Didumos69

[Didumos69]

Instructions are ready: https://rebrickable.com/mocs/MOC-93255/Didumos/42129-b-model-hot-trot/

Edited November 22, 2021 by Didumos69

[Didumos69]

I got seconds thoughts on the price for the instructions, which I set to 20 euro. I dropped the price from 20 euro to 15 euro. I also refunded the payments that were already made for this MOC, because I don't want to disadvantage anyone.

Edited November 21, 2021 by Didumos69

[Jay Psi]

I hope the price drop works out. It does seem that €15 has become a "soft ceiling" for instructions of alternate models.

FWIW, I was happy to pay €20, the implementation of diagonal drive in Lego is one worth studying.

[Didumos69]

Just did a slope test. I was not disappointed.

Also shot some footage of it on CLAAS tires. When it gets steep, it underperforms the Zetros tires, but other than that it rides smoothly.

Edited November 22, 2021 by Didumos69

[ord]

Really cool concept and impressive that you achieved it as a B model .

[MY1]

wtf thats a lot of torque 

[Didumos69]

On 11/23/2021 at 4:54 AM, ord said:

Really cool concept and impressive that you achieved it as a B model .

On 11/23/2021 at 6:12 PM, MY1 said:

wtf thats a lot of torque 

Thanks! I had a lot of fun building it!