A model of a generic Kenworth-style truck featuring an 8-speed transmission, full RC capabilities, and more.
About this creation
Propulsion: 2 x L motor Steering: Front wheel with 1 x M motor Drive Type: 2 driven rear axles Transmission: 8-speed triple-clutch sequential with 1 x M motor Weight: 1.78 kg (3.92 lbs, ~524 LEGO minifigs) Length: 62 studs (49.6 cm, 19.5 in) Width: 18 studs (14.4 cm, 5.7 in) Height: 24 studs (19.2 cm, 7.6 in) Power source: 8878 Li-Po Rechargeable battery box Estimated part count: 2800 pieces Suspension:
--------Front: dual-wishbone independent
--------Rear 1 & 2: live axle Build time: ~80 days Working Headlights Opening Roof, Doors, and Hood
A generic model of an American truck that ended up looking (at least to me...) like a Kenworth, this truck features an 8-speed transmission, full suspension, drive, steering, and several other functions.
Not really a lot to say here. There was no specific truck I had in mind while building this, so the bodywork was more sculpted by space constraints than anything else. To my untrained-truck-eye, it looks something like a Kenworth, so we'll go with that and call it good.
Yup, another 8-speed transmission. Same design as previously except I modified aspects of the switching mechanism so that it works a little more reliably. I'll probably post instructions eventually.
I wanted to go with XL motors for the propulsion on this one, but the space underneath the hood was too darn small, and there was nowhere else to put them. So L motors it was, hard-coupled and geared down before being fed into the transmission. After the transmission, it was all geared down again before the two rear axles. Both rear axles were driven through the same driveshaft; does that count as cheating?
The two L motors had enough torque to (barely) propel it on top gear, but at least the transmission held firm without any gear slip whatsoever. I wasn't fast, but then again it wasn't supposed to be.
Steering was simple as ever, with a single M motor geared down really really far before the steering system itself. The parts for the front steering and suspension were from the 9392 Quad Bike, which actually held up extremely well to a model of this size and weight.
Suspension and Chassis
As noted previously, the front suspension was a simple dual-wishbone using these suspension parts. The rear suspension was where thing got a little more interesting. I originally wanted to do separate live axles with shock absorbers for the two rear axles, but I quickly realized that there wasn't going to be anywhere near enough room for that. The solution? A rear-axle suspension system like that of the 42043 Arocs, except with a 19L flex axle on each side in substitute for the shock absorbers. It actually worked extremely well, and the setup can be seen in the photo above.
The chassis was slightly more difficult. Half-ish of the truck's weight had to rest on a ~25 stud long, 3 stud wide beam that held the rear axles, and studless pieces just weren't cutting it. So, I did the same thing that every other builder on the planet would have done from the outset, and used studded bricks and plates to produce a beam of sufficient rigidity. The rest of the truck was still composed of studless pieces.
It looks like a truck. At least, to me it does. The shape of the airfoil may not be quite right, but otherwise I think I did okay. I would have much preferred to have had a billion chromed pieces to works with, but the light bluish-gray seems to work okay.
This was my largest vehicle to date, as well as one of my longest builds. I'm happy with the end product, though: it looked good, functioned well, and was an interesting first foray into building truck trucks instead of pickup trucks. I do think XL motors would have worked much better here, and if I ever do this again I'll make more of an effort to fit them in.