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Intro
I have always wanted to build an excavator such as this but I was usually restrained by lack of pieces or lack of skill. Lately I have been purchasing more Lego sets and parts in bulk so I decided that it was about time that I built one of my own. This was probably my most challenging model to make so far, because it required me to use mechanism that I had never used before. |
| Drive train
The drive train was a very tricky part to design, mostly because of lack of space in the undercarriage. I didn't have room to place the turntable motor, the drive motors between the tracks, and include the necessary reduction, so that meant that they would be located in the superstructure. The problem with this is that I would need to have two concentric axles going through the turntable to reach the tracks in the undercarriage. Luckily for me, I had seen a solution to this problem on Jennifer Clark's site in the propulsion section. Using this method I put a differential through the opening in the turntable and had the differential axle turn one track and had the gear that makes up the actual differential turn the other track. Below the turntable the axles fed into the last reduction stage that would eventually drive the excavator. Overall I was satisfied at how this part of the model looked and functioned. |
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Superstructure
The body of the excavator makes up a majority of the overall weight of the excavator. Inside are the drive motors, the counterweight, and the pneumatic pump. The counter weight is two battery packs and is located at the far rear of the superstructure. The first one supplies power to the remote control unit which is also housed in this part of the model. The other battery pack is used to run the pump for the pneumatics. I gave it a separate battery pack so I would not have to hold down the button on my remote control, instead I would simply have to turn on the battery pack and then be able to keep my hands free. The pump itself is made up of two small compressors, run by a mini motor. |
The Excavator Arm The arm that is used for digging on an excavator is made up of three parts: the boom, the dipper, and the bucket. The boom is the section that is attached to the superstructure, the dipper is the part that has the bucket on one end, and the bucket is what actually comes in contact with the digging surface. The arm is probably the most structurally sound part of my entire model. It has vertical bracing in many spots, mostly because I wanted to make sure that it would not fall apart during use. When looking for a suitable bucket for my excavator, I came to the realization that I did not have one that was the proper size for my model. So I decided to make one of my own. I had never done this before, but I didn't think it would be too hard. I looked at a Lego bucket that was a little too small for this application and then upscaled it using some leftover pieces. The result turned out a tiny bit larger than the scale of the rest of the model, but it had a large volume so I decided to keep it.
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| Control Unit
As I have done before I used my remote control and receiver for controlling my excavator. There is a white 4 by 6 box which is the plug for all the electrical wires. Power is supplied to that via a batter pack located in the rear of the superstructure. I can access the battery packs by opening a hatch. This is hinged door which can fold up to blend in with the body work of the rest of the model. In the picture it can be seen open. As I mentioned before the only function not controlled by my remote control system is the pneumatic pump. I like this setup and I plan on making most if not all of my future models remote controlled. |
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