LEGO Technic Excavator

I’ve been a LEGO fan since I was a kid, and my LEGO paid for my first PC when I was 14/15 (and by my first PC, I mean the first one I had exclusive access to in my bedroom, I’ve had PC’s since I was 7 in the family). So recently I’ve taken to playing with LEGO again, more for the challenge of it. And when I say LEGO, I’m actually referring to LEGO Technic which in the last 5 years or more has developed into more of an independent product with studless beams and such.

My first purchase was the 8241 Mobile Crane (featured here) which was modified slightly as the pneumatic cylinders weren’t up to much and now features dual double cylinders. I’ve also experimented with various concepts with the motors but have never gotten round to turning it into a true RC crane. Construction time was around two days for this.

Next up came the 8275 RC Bulldozer (featured here) and took me about 2 days to build also. Value for money wise, this is the best set purchased to date, and has in fact gone up in value now due to it’s rarity! This set is stock, as frankly LEGO got it right!

My next purchase was a disappointment, the 8258 mobile crane (featured here) for the following reasons:
1.) Front wheels foul upon the steps to the cab when on full lock.
2.) Rotation of the mast occurs when engaging and disengaging a function.
3.) The rubber restraint piece holding the crane rope in/out from moving doesn’t work very well, often when you twist it, the stud comes out of the rubber and has to be pushed back in.
4.) The extending jib isn’t motorised, which is a bit of a let down.
5.) If you’re picking up a heavy load the jib just rolls in under the weight.
6.) The crane doesn’t tuck away neatly, it seems like it needs adjustment to sit neatly without being under tension.
7.) When you roll the legs out initially, you then have to switch motor direction to un-tuck the arm.
8.) No RC functions! For what is a very expensive model (£130!) this is a big let down.
9.) Confusion occurs when moving the arms and legs and turntable due to the single motor running everything. IMHO a pair of M motors running each linear actuator would be better suited to those operations, run from an IR block on the arm. A further pair of M motors on a IR block would then suffice for the slew and legs. The XL motor could then be used to drive the model, with an M motor for steering on a third IR block. A further pair of M motors and IR block could then sit on the last crane arm and provide the jib in/out and wind the string in/out also. A £200 price point wouldn’t be unreasonable for this amount of functions, and I’d certainly pay that. Looking at the RC Bulldozer, you get 2x XL and 2x M motors, 2 IR blocks and the battery box for around £100. This model is £130 and you get an XL Motor, Reverser Switch, and Battery box!
10.) While the engine is powered from the wheels as is typical, it would be nice if the engine ran while the motor was running, instead of from the wheels. After all, with the cab in place you can’t see the engine while you’re moving the unit.
11.) Getting to the battery box to change batteries is a real pain, and requires some disassembly, as well as rotating it at an odd angle to get it out.
12.) The linear actuators are nowhere near as powerful as hoped, though I admit that they are better than the pneumatic system.
13.) Proportion wise, I think it would have been better to build this model as a flatbed truck, rather than an artic tractor. The back of the unit is basically useless as the fifth wheel is non-functioning, it would be better if it was stretched slightly more and given a flat back.
14.) The stabiliser legs don’t really have any feel to them, and seem to catch slightly when moving the model over a surface.
15.) Packaging – Why did they bother to pack things in so many little bags, when they are all jumbled together! Why not package gears in one, studs in another, coloured parts together etc.
16.) Labels – I’m not normally one to use the labels provided but as they seemed a large part of the model I relented this time, and I’ve been disappointed. 2 Days after building and I have them peeling on several parts. The sheet came badly folded in the box, and I think this has had an effect on their durability.

Subsequent testing has shown it has a maximum 100g lift at it’s furthest reach, and can just manage 400g close in.

Don’t get me wrong, I love it for it’s technical complexity, building it was a wonderful time, slowly assembling one of the most complex gearboxes I’ve ever seen, but this same gearbox is also this models biggest weakness and folly. It tries to do too much! And for the money, I wouldn’t recommend this model.

The latest addition to my “fleet” is the 8294 Excavator (featured here) arrived at Christmas from my Sister (no doubt to keep me quiet for a few hours while she prepared the meal). Great little set for the money, but sorely needed the 8293 Power Functions set adding to it. It’s designed for this to be added, which is just as well as winding the little cog on the back was a real pain! Wish they’d just sell the two together! So with that added fairly quickly it took on a whole new life. I added an IR brick I had in stock and that gave it a bit more to play with. Routing the LED’s into the model also worked well, but the best bit came when I grabbed a second M motor and managed to fit it on the opposite side, removing the sliding switch to select one arm or the other. Now it happily moves it’s arm via IR, and I did plan upon making it fully IR like the bulldozer (as other people have done) but a new excavator is on the horizon for late 2010 – the 8043 (image here) so modifying this one seems a little pointless, and I’ll probably build it into the B model when the new one arrives.

I’ll leave you with an image of the 8294 I took after completion at Xmas, and a link to the video of the completed RC version on YouTube here.

8294 Excavator

8294 Excavator

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