MOC Review - 8x8 Dump Truck by Lucio Switch




Lucio Switch's "Bat Truck" is the biggest vehicle I have ever built. Strictly speaking it does not have the most parts, but with ~5600 it is pretty close. Using 13 Unimog tires, this thing is truly massive. But with all that size and weight does it work? Read on to find out. [I](Note that there are additional images and larger versions of all images at my [url=]Bricksafe[/url].)[/I] [img][/img] This is not made to be a scale model, but it is certainly inspired by the Iveco Trakker, their off road heavy duty truck, and it is a very good likeness. Although they offer a 4 axle variant, it is 8x4 with only the rear axles powered. The model, on the other hand, is a full 8x8 with all the axles driven. [img][/img]


[I]Instructions are available at xxxx.[/I] Lucio has done a lot of work on the instructions and it shows. The instructions are broken into 9 books to keep the file size reasonable. I appreciate this as it makes them more usable on my iPad. After the spectacularly rendered cover, the instructions continue with some electrical and pneumatic diagrams which can be used for easy reference later and are very helpful. [img][/img] [img][/img] [img][/img] To those people who complain about official LEGO instructions being too simple, you don't have to worry about that here. Sometimes hundreds of parts can be added on a single page. But with all the callouts and substeps, everything is still easy to follow. [img][/img]


As you can see in this cutaway view, this model is packed with functions. As stated previously, all 4 axles are driven for a total of 12 driven wheels. The front and rear pairs of axles are each powered by a pair of XL motors (4 total). There is no mechanical connection between the front and rear axles. This works out well because it allows the motors to share the load based on the torque required in the situation. The straight 6 engine under the cab rotates with the front axle motors. Both front axles are steered with a servo at different rates. There is a motorized winch behind the bumper which uses an L motor and a worm gear. There is also a 2 pump compressor driven by another L motor. The compressor powers the lifting of the bed through 3 new long actuators and a servo driven remote switch. There are also two manually switched pneumatic functions including cab tilt and a PPTO at the rear for a trailer. There are LED lights at front and rear, and an AUX connection at the back which will allow any trailer lights to be linked to the tractor. All of this is routed through a pair of Li-Po rechargeable batteries and 2 SBricks. [img][/img] One note on the parts is that the inner wheels on the dual rear axles must be the 6 hole variant. I originally thought it didn't matter and tried to use older 3 wheels I happened to have but it won't work. So you need at least 4 of the 6 hole wheels. The rest of the wheels can be either the old or new variety.


This image shows the pile of parts on my table (sans Power Functions which had not arrived yet at the time of the photo). The mass of liftarms and panels is incredible. This makes for a fairly slow build because a LOT of time is spent hunting for the right part. Sorting the parts at least to the level that I have shown in highly recommended. [img][/img]


The first thing that is built is the rear suspension and axle assemblies. The live axles pivot on suspension ball joints and are stabilized by 6L links. The rear suspension uses an unusual configuration representing leaf springs. The black and gray cross axles above the drive axles bend as the suspension is compressed. This might make purists nervous, but so far as I can tell it works great and has not damaged the parts. Although portal axle hubs are used, the drive axles actually run straight through with no reduction. This means there is quite a bit of torque being carried by the drive shafts here. In fact, all the torque for 2! XL motors runs through a single 8 tooth gear. Lucio has thought ahead and made it easy to remove and replace this gear if necessary. [img][/img] At the end of Book 1, the batteries, Bricks, and rear Xl motors have been added to the rear axle assembly. It is perfectly possible to test out the motors at this point and even to drive it around although there will be no steering. There is ample room for wiring so you hardly notice it in the image, but there is already a lot here. The wires for the rear tail lights and the aux trailer light extension are already present. [img][/img] At the end of Book 2, more of the forward chassis has been built, the front XL motors have been added, and the engine has been installed (although it is hanging precariously). Some of the pneumatic routing is also visible. The two L motors are barely visible just behind and under the engine. One is used to power to compressor, and the other is for the winch. The power of an L motor is probably not needed for the winch, but the pin holes are used as a structural part of the chassis so an M wouldn't work. [img][/img] Book 3 builds the front of the chassis including the headlights, the winch, and the pneumatic actuators for tilting the cab. This is a really solid assembly. [img][/img] By the end of Book 3 the front end has been joined to the chassis. The process of joining is a bit tricky because a bunch of axles and gears need to line up since the motors are in the aft section. Given the size, it is remarkable how rigid the chassis is. It can easily be picked up with one hand at almost any location with minimal flex. I really like that the straight 6 has some filters and other engine details which can be seen when the cab is open. [img][/img] The front axles are quite different from the rear. You can see that the portal axles are actually used for gearing down 3:1 this time. The XL motors do not have the upstream 3:1 reduction like those for the rear axles. In both cases, final reduction at the wheels is 3:1. The servo handles the steering. The 1st and 2nd axles are not quite the same. Besides a difference in the length of the steering control arms for a different steering lock, the 1st axle also has an anti-roll bar. Both axles are very similar though and are supported by a ball joint, some 6L links, and 2 hard shock absorbers. Servos are used for steering. [img][/img] Book 4 ends with the front axles joined to the chassis. Although the instructions do not call for it at this point, I could not resist installing the tires and driving the naked chassis around the house. There is still one more motor to add which is the servo for the pneumatic switch. [img][/img] At the end of Book 5, the exhaust stack has been added as has the mechanism for pneumatically tipping the bed. A servo is used to control the pneumatic switch. The fenders, fuel tanks, and other chassis details have also been added. The rear fenders are particularly massive assemblies and use more parts than some entire LEGO models. [img][/img] Next up is the cab. Although it does not contain any wiring or motors, there are gears here for the operational steering wheel. The dash is nicely detailed, and there is even a fire extinguisher inside. The light bar on the top is not functional. The "bat grille" is in full display here and looks just awesome. [img][/img] The final part of the assembly is the bed which uses 30+ LBG 5x11 panels. I like that it incorporates a slope at the front and rear so it doesn't just look like a rectangular box. [img][/img] When just looking at a picture of the bed without any context, it is hard to appreciate how big it is. With that in mind, here's a picture with the "tiny" 42043. Incidentally, 42043 is a pretty similar model of an 8x8 white dumping truck. [img][/img]


The model is finally complete! This is a really good model, whether you consider the scale or not. Almost everything is done with Technic; there are only a few System parts here in the grille and light bar. [img][/img] [img][/img] The model drives perfectly fine and with reasonable speed, although if you try to run over obstacles or do any off road driving you can expect some broken gears. The mechanism to tip the bed is at the limit of the LEGO pneumatic system. Using my manometer, I found that about 25 psi is required. The pumps are capable of 40 psi, but I found that several of my switches started leaking at about 15 psi. I had to try several switches before I got it to work. Even then, it takes quite some time for the compressor to tip the bed, but it does work. [img][/img] The cab tipping happens much more easily. It is controlled by a manual switch on the left. The right hand switch is for the unused PPTO. I found that a hand pump can be connected to the PPTO if you want to drive the pneumatics manually without the compressor. [img][/img] This model is not cheap to build, but it is well designed and functional and will really stand out in any collection. Even mine!


I thought I would end with this render of the truck next to some other large 8x8 dump trucks. Pictured are Designer Han's truck, M_longer's MAN TGS, and LasseD's cement truck. I could not take an actual photo because the truck barely fits on my photo table even by itself. [img][/img]

Discussion about this set can be found here.