[MOC] 1:8.3 Ram Rebel TRX

[2GodBDGlory]

This massive model was built last fall over a period of about three months, which is extremely long for me. It was intended to be a rough successor to my enormously complex 1:7 Bugatti Chiron, and although it is at a smaller scale, a pickup truck like this has a lot more internal volume than a supercar, so all things considered, it has about the same volume.

 

I chose to build this particular truck because I was fed up with spending so much time trying to replicate swoopy supercar bodies, so I figured I would just stuff similar functionality into a boxy truck with easy bodywork, and have a much more enjoyable building process (I wish I didn't have to build bodies. I know I could just forget it, but then I would have no space constraints for my mechanics, making the mechanics much less challenging). So, I chose the Ram 1500 pickup truck in Rebel trim, because I wanted to replicate an air suspension on an off-road focused model. Before I had gotten too far on the model, though, the ridiculous 702-hp desert-running TRX version of the truck was revealed, and I knew I had to replicate it, even though its fender flares messed up its boxy attributes, and the air suspension, barn-door tailgate, and transfer case would no longer be accurate to real life.

This model was also designed to integrate both PU and PF into the same model, using PU for drive, steering, and a semi-automatic gearbox, and all eight PF channels for other functions (well, two of them were on an auxiliary model). To do so, I put my little lithium-ion camera battery inside the hub, connected it to the contacts, while running a PF extension wire off of the same battery. I could surely have found room for a small PF battery box in the truck, but my only rechargeable battery was used on the auxiliary model.

This auxiliary model was a to-scale Suzuki LT500R quad bike, and there was also a trailer to allow the truck to tow the quad. Adding the extra models was rather interesting, and impressive to behold.

Perhaps most astonishing of all was that this massive model used literally every single friction pin I own! The trailer, which was built last, was forced to use 3L pins or frictionless 2L ones in many areas!

Functions:

-Drive with V8 piston engine-2x PU XL motor

-Steering with working wheel, Ackermann geometry, kingpin inclination, and castor angle-PU L motor

-8-speed sequential gearbox-PU L motor

-Pneumatic compressor with automatic control (small pneumatic cylinder and PF switch)-RC Buggy motor

-V8 piston engine with idle mode-PF M-motor (Engine is controlled with an adder between a constantly running M-motor and the two drive motors, causing it to rev up when the truck drives)

-Transfer case with 2H/4H/4L-PF M motor

-Rear differential lock-PF M motor

-Windshield wipers-PF M motor

-Front anti-roll bar disconnect-PF M motor

-Disc brakes-PF L motor

-Opening hood-PF L motor

-Distribution gearbox motor controlled by switch-PF L motor

-Synchronized opening of both right doors while running board deploys-distribution gearbox

-Synchronized opening of both left doors while running board deploys-distribution gearbox

-Raising/lowering tailgate-distribution gearbox

-"Barn door" opening tailgate (didn't work, needed more gear reduction)-distribution gearbox

-Trailer landing leg-distribution gearbox (from truck)

-Trailer ramp deploying-distribution gearbox (from truck)

-Independent front suspension with pneumatic shocks-pneumatic

-5-link live rear axle with pneumatic shocks-pneumatic

-Opening rear window-pneumatic

-Leaf-spring live axle suspension on the trailer

-Sliding front seats fore and aft-knobs and worm gears

-Tilting front seats-knobs and worm gears

-Folding rear bench

-Opening glove box

-Opening center console (Reveals manometer)

-Tilting steering wheel

-Manual pneumatic pump

-Front and rear anti-roll bars

-LED headlights, fog lights, hood scoop lights, and taillights

On Suzuki LT500R

-Steering with moving handlebars-PF Servo motor

-Rear-wheel drive-RC Buggy motor

-Front independent suspension

-Rear trailing arm suspension

 

 

Now I will add some details, where it is not already self-evident. Most images are hidden.

Aesthetic:

I was pleased with the aesthetic, but I know my standards are low. The boxy profile was certainly easier to model, though!

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Interior:

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The interior was quite detailed, with a tilting steering wheel, opening glove box, opening center console, and multi-way adjustable seats.

Drive:

The two PU XL motors could move the extremely heavy truck in most gears without too much drama, but it was certainly not fast enough to drive around for fun. 

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Here you can see the PU XL motors for drive, which are hard-coupled with bevel gears. The M-motor in the foreground is the one that allows the engine to idle, and the 24T end of the differential is attached to the drive motors through a 24T gear in the input of the gearbox. The V8 engine is also visible.

Steering:

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The lower L-motor visible is the one used for steering. The worm gear drives an 8T gear, which drives a rack for steering, and the bevel gear housing on the same axle drives the chain, which runs the steering wheel. The tan 20T gear is an idler, and does not mesh with the chain. Its only purpose is to prevent the 16T gear from being pulled up and to the right by the chain.

This image shows some of a front, steered hub, but the picture was originally taken to illustrate the brakes, so it isn't the clearest.

Gearbox:

The gearbox was my oft-used 8-speed sequential design, with certain reinforcements necessary for such a big model. Shifting was done by a PU L motor through a worm gear. I did some fairly complicated programming in the Powered Up app to make a semi-automatic gearbox. There were both manual and automatic modes that were triggered by pressing a button to turn it on and off. In manual mode, speeds could be cycled by pressing a + button to go up a speed, or a - button to go down a speed. There was also a virtual speed indicator. In the automatic mode, the speed of the drive motors was constantly monitored, and if the average speed over six intervals of a fraction of a second each was above or below a certain parameter, the gear would shift up or down. In practice, this didn't work when the truck was driving, likely because of the inefficient drivetrain, but I would like to try the PU semiautomatic gearbox with a smaller, more efficient model with a simpler 4-speed gearbox. If anyone is interested in the details of the program, I could provide more details.

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The PU L-motor in this image drives the 8T gear through a worm gear, which then shifts the gearbox. There was a subtle way in which I could insert an axle from the outside to the motor's output so, by backdriving the motor, I could resynchronize the motor.

Compressor:

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The automatic control for the compressor is in the rear of the image, where the underside of a PF switch and the small cylinder are visible.

 

Transfer case:

This transfer case had a separate 2-speed gearbox and a disconnect for the front axle. Both were controlled by shift levers through a PF M-motor. In order to make them shift sequentially, the system worked as follows: The motor (after gear reduction) rotated a short connector (with the towball on the end), which pulled a rubber band, which pulled a 2L beam, which engaged 4WD. When the M-motor continued rotating, this rubber band stretched more, but did not affect anything. This continued rotation caused the towball to bump two 4L black half-beams which were held back by more rubber bands. These half-beams, when pushed, shifted through the speeds of the transfer case.

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Here you can see the PF M-motor for shifting, along with its gear reduction.

The next three images show what happens as it shifts through 2H, 4H, and 4L

Differential lock: Because I desired a small, realistic-looking rear axle, and also because I cannot figure out a way to drive a HD differential perpendicularly while locking it, with enough strength for my needs (even 7x11 frames allow the gears to skip under torque), I housed only a number of knob wheels in the rear axle, with two half-shafts making their way to the chassis and an inboard HD differential, with the lock. 

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Here you can see the differential and the transmission driving ring. The LG changeover catch is driven through a worm gear by a M motor above.

Here is the rear axle. No differential in sight!

Wipers: This used a similar design to ones I have used in the past, with a number of linkages allowing the wipers to cycle back and forth, though not as far as they should have.

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I can't find any pictures of the mechanics; you can see examples of how it worked in some of my older models.

Front anti-roll bar disconnect: This feature, present on some real Rams and Jeeps, allows the front anti-roll bar to be disconnected remotely to increase axle articulation off-road. My solution split the anti-roll bar into two halves, which were normally only connected by a Lego bar, allowing them to rotate freely relative to each other. However, when an M-motor with a simple friction clutch moved a linkage, an old transmission driving ring slid along one half of the anti-roll bar and meshed its inner profile with the second half, strongly and efficiently locking them together. This made no performance difference whatsoever on the model, but was an interesting, and, I believe, unique in Technic, function to include.

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Disc Brakes:

The disc brake system was driven by a PF L-motor, which split into a number of different axles using bevel gears. These eventually ran four small linear actuators, one for each wheel, which pressed rubber axle joiners against rubber track inserts on the brake discs. The front LAs were atop the upper wishbones, and proved to be minimally effective, but the rear ones on the solid axle were extremely strong.

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This underbody shot is the best image I have to show how the drive from the L motor in the lower right of the image connects to all four wheels.

The small linear actuators pull linkages to work the brakes.

Rear brake

Front brake images

Opening hood:

The hood could be opened by a PF L-motor which drove a worm gear, drive, which eventually drove a rack to push the hood up. The rack-based solution fit the space well, and seemed rather retro. Originally the rack was fixed to the hood, but then I realized that I would never be able to open the hood to turn the truck on or off, because if the model was off, I couldn't open the hood, and I couldn't shut the hood if the model was off. I then modified it so the rack merely pushed the hood up, allowing it to be manually opened as well.

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Distribution gearbox:

Doors and running boards:

This mechanism used large linear actuators and many linkages to allow both doors on a single side to open together. At the same time, a long black running board slid about one stud out of the side of the truck, providing a step up into the high cab.

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Hopefully you can make something of these linkages. If not, my YouTube video may shed some light on it.

Tailgate raising/lowering:

This used worm gears and levers to lower each side of the tailgate independently (because of the barn-door style opening, they could not be connected)

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By the way, the rear suspension is sagged in this picture. The anti-roll bar shouldn't be so low.

This picture shows the underside of the bed. The long, black axle on the left comes from the gearbox, and then drives the brightly colored worm gears (I was out of LBG ones), which turn the linkages seen in the next image.

Tailgate "Barn Door" opening:

This function also used worm gears to rotate the two parts of the tailgate outwards, through universal joints along their tilting axis. Unfortunately, I made the mistake of not gearing the function down enough, so it only worked with great coaxing.

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The heavy duty CV joint in the upper right of the image drives the tan bevel gears, which then go transversely, where they drive worm gears, which drive 8T gears, which were meant to turn the sides of the tailgate out.

Also note the trailer hitch in the center, with the easily removable hitch.

Trailer landing leg:

This simple function on the trailer was driven from the truck through a universal joint, and worked using a worm gear.

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Trailer ramp deploying:

The ramps on the trailer which would theoretically allow the quad bike to drive up onto it would slide out of the rear of the trailer, and were driven by small tires that forced them to slide. This was also driven from the truck through a universal joint.

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That 1x4 brick is not meant to be up like that!

Front suspension:

The suspension on the truck was pneumatic, which allowed for long travel, great stiffness, and some damping, but leaked air incessantly, forcing me to pump it back up all the time, which was very annoying. There was technically adjustable hardness, because there was a valve controlling it. If it was left in the extend position, all of the air in the airtank would be part of the system, causing the overall pressure to increase less for a given compression of cylinders than it would if the valve were closed. Closing the valve really just caused air to leak if the suspension was pressed all the way, though. The front used XL cylinders.

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The 6L link visible was intended to prevent the long (for long-travel) wishbones from moving fore and aft.

Rear suspension:

The rear suspension was a 5-link live axle, with four longitudinal links and the fifth transverse one, the Panhard rod. It used medium cylinders.

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Opening rear window:

A long, thin V2 pneumatic cylinder hidden under the roof slid a square, System window piece sideways, as if the central rear window on the real truck were being opened. It was quite a smooth function, and impressive to look at, but it used up my stored air, so using it meant a lot of pumping.

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Trailer suspension:

The trailer had an extremely basic live axle, with flex axles serving as leaf springs. The trailer appeared to have a lift relative to a regular trailer, a not unheard of practice in the world of towing with lifted trucks.

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Anti-roll bars:

There were two anti-roll bars, a disconnect-able one in the front, and a fixed one in the back, which had curves similar to those evident to anyone looking at the rear axle of a modern Ram, helping it to avoid the simulated differential housing.

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Suzuki LT500R Quad Bike

This extra little model was a model of one of the most extreme Quad Bikes ever, which packed a 500cc two-stroke engine, for an amazing power-to-weight ratio. I believe it was (perhaps still is) the world's fastest production quad bike, with speeds, if I remember correctly, approaching 80 mph (130 km/h, or so). Mine had an interesting lime-and-purple aesthetic, which I consider decent for my first attempt at a quad bike, particularly since I was very limited in what lime and purple pieces I could use. Performance would have been acceptable were it not for an issue with my V2 receiver which cuts power to drive motors under even minimal stress, emitting a squealing sound. (I couldn't replace it, because I only had four receivers, and I couldn't swap it with one in the truck because of my V2's other idiosyncrasy,  namely that the red channel only works with servo motors and LEDs, and there were no servos in the truck to power off of it).

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Trailer images:

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I hope I have made this very long post legible enough, but it is rather hard. I believe image quality may be up since I started taking pictures with my phone rather than my digital camera, and my video now has a much less obnoxious watermark. More images can be seen at: https://bricksafe.com/pages/2GodBDGlory/ram-rebel-trx, and the video is here: 

Overall, I think the model was a success, with a greater percentage of working functions than usual, a greater number of functions than usual, and an exterior that isn't a disaster!

 

[Maaboo the Witch]

All very, very nice. 

[Bartybum]

Well that's bloody scary lol, great work

[Aleh]

This is just a bench of functions, wrapped in RAM body! So complex, so cool! 

Working window cleaners is a brilliant solution!

I was able to watch a 1/3 of the video. I observed the brakes on each wheel, but were they shown in work?

 

I promise i will read the full article. 

[Aleh]

I don't understand are those wheels are wrangler ones or Xerion???

[Milan]

1 hour ago, Aleh said:

I don't understand are those wheels are wrangler ones or Xerion???

Xerion. The big ones.

[Aleh]

1 hour ago, Milan said:

Xerion. The big ones.

aha, I've noticed defender wheels. Even Xerion tyres looks too small for me here, indeed.

Edited January 17, 2021 by Aleh

[2GodBDGlory]

4 hours ago, Aleh said:

I was able to watch a 1/3 of the video. I observed the brakes on each wheel, but were they shown in work.

I think they were shown; I tried to go through all the functions, but it has been a few months since I filmed it, so I am not sure.

Thanks for the comments, guys!