Posted August 7, 20195 yr Hello EB! 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. Specifications : - 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 Design: I opted for a design in the spirit of # 42009 and tried to add some details. The result suits me. Features: The chassis: Propulsion of the model is done manually. The turntable rests on the top of the chassis. The gearbox: 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 winch: 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 ! Edited August 8, 20195 yr by mathieulego
August 8, 20195 yr 14 hours ago, mathieulego said: The extending is done by cables I think, this is really optimal solution. Overall nice creation.
August 8, 20195 yr I like how you was able to match stickers from another set to show the functions. Adding a second LA wouldn't have increased the power, unless the single one was activating the safety clutch.
August 8, 20195 yr Author Thank to you two. 6 hours ago, Jurss said: I think, this is really optimal solution. I think the same. I find that it is better aesthetically. Furthermore, it is easier to implement than a rack when space is limited. 2 hours ago, allanp said: Adding a second LA wouldn't have increased the power, unless the single one was activating the safety clutch. The safety clutch doesn't activate. I thought that two LAs would divide the load. So, raising would require less force from each LA. I don't know ! Edited August 8, 20195 yr by mathieulego
August 8, 20195 yr 25 minutes ago, mathieulego said: The safety clutch doesn't activate. I thought that two LAs would divide the load. So, raising would require less force from each LA. I don't know ! The load is split between the two LAs, so each LA has half the load (which is only really useful if one LA can't cope and is therefore activating the safety clutch) however the motor now has to drive two LAs, so the load on the motor is the same, perhaps a bit more due to the extra friction of driving another component. This is not like pneumatics where adding another cylinder actually does double the lifting force at the cost of halving the speed of movement.
August 8, 20195 yr LTR's chassis (well, tracks actually) can be widened, have you considered that function? :)
August 11, 20195 yr Author @allanp I understand what you want to explain. I always thought that the engine would better drive the two LAs but finaly it makes sense : there is transfer of charges. On 8/8/2019 at 4:19 PM, M_longer said: LTR's chassis (well, tracks actually) can be widened, have you considered that function? :) Yes ! I worked on this system. After several tries, I finally gave up because the crane lose stability : (the chassis (with widening system) was no longer rigid and bent under the weight. I think it would be possible to get something more rigid in studfull. I have to test. Edited August 11, 20195 yr by mathieulego
August 12, 20195 yr 17 hours ago, mathieulego said: : (the chassis (with widening system) was no longer rigid and bent under the weight. I think it would be possible to get something more rigid in studfull. I have to test. Sounds familiar:
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.