Today I present you my first MOC on the forum. This is not my first try but it's the first one I finished and I'm proud enough to share it.
This is a telescopic crawler crane. It is not a reproduction but I was inspired by the Liebherr LTR1100 crane. Indeed, I prefer to adapt the reality to the Lego rather than accurately reproduce a model at risk of losing playability.
- Length : 58 studs
- Width : 21 studs
- Height : 18 studs
- Maximum height under hook: 60cm
- Maximum range: 40cm
- A 3 sections boom
- Three motorized functions: boom raising, boom extending and winch
- M motor for the motorization
I opted for a design in the spirit of # 42009 and tried to add some details. The result suits me.
Propulsion of the model is done manually. The turntable rests on the top of the chassis.
The M motor drives a gearbox after two 12t/20t reductions. It is "unidirectional": there is a driving ring by function and each side corresponds to a direction of rotation.
The boom raising :
The left driving ring controls this function. When activated, the motor drives 3 16t which then drive an LA. The raising is quite fast (about 15 seconds) but the engine barely a bit under the weight of the boom. I can hardly reduce the number of gears because the driving ring is higher than the LA. Another solution would be to add a second LA but it does not correspond to the spirit of the crane that I want to reproduce. However, this is not a problem with the use, the engine only stalls when I want to raise the arm with a load.
I tried to bring the boom as close as possible to the center of the structure so that the BB was sufficient as a counterweight.
Boom extending :
The extending is done by cables: the mechanism takes less space than the usually configuration The assembly is simple: one drum allows the go and the other the return. I could have used gravity for the return but the construction of the second section (in grid) makes it tends to hang the main section: with the return cable, there is no problem.
The central driving ring controls this function. When activated, the motor drives a VSF/20t. The 20t is mounted between the two drums.
Extending works well and it takes about 30 seconds to deploy the two inner sections.
The right driving ring controls this function. When activated, the motor drives a 20t/12t then a VSF/20t/Drum. The speed of winding/unwinding of the cable is rather slow but the lack of space prevents me from using a smaller gear on the VSF. The crane manages to lift loads of about 150-200g.
Cabin in working position:
A wheel connected to a 20t/12t allows to drive a mini-LA and tilt the cabin.
Thanks for reading !