Crawler crane and jerky power functions

[wemb]

I'm pretty new to lego (well, new since my childhood thirty years ago, any way) - and this is the second set I've built after the Merc Arocs 42043 truck (why not jump in a the deep end..) - while I'm enjoying the crawling crane a little less - I wish it was more of a modular build like the Merc was, some of the design choices means reversing the build or breaking it down is going to be tough to undo, I'm still looking forward to getting it going

However, I've got to stage of completing the meaning gearbox, tracks and turntable and am a little disappointed about how poorly it moves when I turn the power on - both the caterpillar motion and the rotation and very jerky, and I'm rather surprised how bad it is.  Hopefully I've missed something with the rotation gearing and can fix that - but after pulling the entire thing to pieces, I'm wondering if there's anything I can do to improve the motion of the caterpilar tracks.

Obviously, given the big teeth and large parts, there's a lot of friction and momentum to overcome, but I'm not sure the universal joint feeding power from the gearbox helps, and there seems to be a lot of lateral movement in some of the bevel gears.  Anyone with experience of dealing with catepilar drives in lego have any thoughts on anything that can be done to improve this? or am I just building the model poorly?  Or, perhaps, is this just how the model works and is a limitation of lego?

 

Thanks! Wemb.

[Imanol BB]

Hi Wemb, welcome to Eurobricks, i suppose that you are talking about the 42042, if that is case i tell you this: This crane was made to be slow, why?, because it is based in real life crawler cranes (which move really slow) and also because most of the customers of this model wouldn't want it to be running fast, it is not a real Lego limitation, and i am sure it can go much more faster, you would only need to change some gears in the gearbox, let me see the instructions in internet to find a way to make this easy to make for you.

[suffocation]

The jerky crawl is indeed due to the U-joint. The other functions should run smoothly, though - I built mine a year ago and it still works great. As a rule, you should take the time at every stage of the build to ensure all the gears and axles can spin freely.