A fully rc-ed wheel loader from three sets: bulldozer, offroader and excavator, that imo beats the new LEGO loader set, judge for yourself
About this creation
Even before the LEGO loader set was announced, I wanted to use the new linear actuators from the excavator set in a remote controlled model, and decided to combine the excavator and the bulldozer sets.
After deciding for a front loader i acquired a full size bucket with the old pneumatic front loader set. I did some research and ended up by "copying" a Liebherr while blending Liebherr and Volvo color schemes. To get wheels that fit with the bucket, i had to use the offroader set too, for its wheels, differential and other parts.
I ran into many problems when creating this model. Just about when it started to work out well, i was informed about the new LEGO loader set!
Of course i had to get one too, and i assembled one in the summer holidays 2009. The LEGO model is really nice, but there are a number of technical points i do not like. The central hinge is not centered, for instance. The wheels are wider (sideways) than the bucket. The front and rear axles are far apart. Furthermore, i see that the LEGO designers struggled with the looong linear actuators, just like i did. The cylinders are actually too bulky on this scale, and the lift/tilt mechanism is not as it could be.
I tried to solve this by putting the base end of both cylinders pretty high and close to the driver, and devising a whole new tilt/lift mechanism . The drawback is that the cabin ends up a bit high and behind. However, i like the end result better!
This vid shows the model in action and a bit of the process to come to it.
Please let me know with a comment which one of the three loaders in the line-up you like best!
The bucket has a pretty high reach.
The front piece has two motors that drive gear trains. On the right side is the one driving the top cylinder for tilting the bucket, on the left side are the gears that drive the lower cylinder for lifting the bucket.
The model has articulated steering that mimicks the hydraulic cylinders from reality. On one side it has stairs to get in the cabin.
Front wheel drive with a differential and gearing down inside the wheels. This reduces wear of the drive train, including the crosscoupler centered between front and rear axles.
Putting the model on its side and removing the right rear wheel allows us a peek at the oscillating rigid rear axle. This one is not driven as the three sets have just one differential all together.
Here is how the steering works: the two cylindrical springs are just an embellishment as they both act as rigid rods. These rods pull the front part backwards, simultaneously on the left and right sides of the main central hinge. The other ends of the rods are mounted between triangular plates as shown in the photo. These plates are rotated by a gear driven by a worm wheel, see the photo below.
This is the XL motor that drives the steering worm wheel via some other gears.
In the end i squeezed out a cabin with typical curved window line, adjustable chair and dasboard with steer. From the remaining parts i covered the back of the loader with plates, tiles and grilles, disguishing up the IR receivers as airco inlet. Finally i added the wheel guards and back bumper.
Notably the excavator is still just the excavator, but robbed from its linear actuators.
Some more stats: the model weighs 1.5 kilograms, batteries and driver :) included.
Here you see it carrying 1 kilograms. It can CARRY this, but not lift. The new official LEGO loader set 8265 fails to carry 1 kilograms because the bucket tips over.
The lifting capacity is determined by battery power and friction. I got as far as lifting 200 grams of batteries in the bucket. Strangely, both up and down speeds decrease when increasing the load, so friction limits the load. I suspect lubricating here or there may drastically increase the lifting capacity.
Thanks both of you for your comments.
The rebuilding will have to wait until i upload pictures from taking it apart, i guess.
Although admittedly anyone can have a go at it now... :)
4 WD is in principle possible, but without the new rectangular frames the new differential will be hard to mount solidly. The model is actually very narrow in view of the oscillating big wheels so it is another challenge. Maybe another time. I already had other plans for a full-size excavator with this big bucket and off course fully rc-ed, from the bulldozer and loader sets, with three LA's to control 2 segments and the bucket. And then it happened again! The same device is supposed to become the LEGO Technic flagship model in 2010 according to leaks...
Currently i work on a Power Function version of the NXTruck.
Hi Liftboy, WOW! You managed it again: a vehicle loaded with excellent RC technolgy which can be rebuild by other Legofans! I especially like the steering mechanism and the front wheel driveline (coming from the back going through the rotating steering center and with a gear set inside the wheels)! And that with a limited number of parts/sets. Would it be possible to realize 4WD in your loader, assuming that a 2nd differential is available?