Hi all,
First large-scale MOC-WIP, this is the first iteration of my design exercise.
This project started a while ago with my fascination with 3 section booms; how they worked and their capacities etc... With some research around the interwebs and after a couple of trial builds found out that most of them are gravity "retracted" using strings. I tried to find an another way to make a 3 section boom using a "loop" of chain links ( Brickshelf ). With that not-so-easy project, one of the by-product I found out that a 3 section boom has tension extending and retracting. On the same day I saw one of those flatbed with a piggy back forklift. There you go, here's the result.
note: i cheated on this pic, forklift is held up by a liftarm at the back; more explanation further down.
Flatbed is inspired by the 8264-B but supersized. Geometry for the tilting platform was a real pain, a lot of trials and errors.
Flatbed:
Length : 69 studs
Width : 27 studs
Platform : 45L x 27W
1 PF-XL (drive)
2 PF-M (platform + steering)
Picture of the coupling system
Forklift:
Length : 26studs (+11 Forks)
Width : 23studs
Height : 27->43
Forks reach : -2 -> 32
3 PF-M
1 PF-XL
Basically it's the 3 section lifting geometry of the 8416, modified to use lego chains to achieve "self-lifting" on the back of the flatbed. It works in theory, and in practice, it needs a little help. But there's way too much flexing and tolerances in the boom to work really nicely.
Conclusion:
Not very pretty, but the principles work,
Upcoming design upgrades:
Flatbed:
1- double LAs and motors to tilt the platform
2- gearing down of the direction
3- widening of the "tracks" for the coupling system
4- truck cab
5- adding winch on platform
Forklift:
1- reducing weight
2- change PF-M to XL on lifting mechanism
3- double the chainlinks
4- reducing flex in boom mechanism
5- moving the tilting LAs 2 studs back
6- improve steering mechanism
Other Pics: Brickshelf Folder
-Nick