[HELP] Gear Grinding

[Sir_Samsalot]

Hello all. It's been quite a while since I last posted anything here (got too busy for legos, sadly).

However, recently I have been working on an MOC for a train (Correct me if I'm wrong, but this seems like the correct forum since I'm just asking about gear issues), and have run into a few problems:

Here we have the train, without its cover. Nothing pretty here, just something thrown together to see if my ideas were even possible.

The train is powered by one XL motor (attached by rubber bands to hold it in place), which is fed into Sariel's lovely 4-speed linear gearbox (http://sariel.pl/201...linear-gearbox/), after which power is geared up into the wheels.

The main problem is the evident flimsiness of the whole setup (don't worry, it's still a WIP). The front wheels are not attached on well, the front needs more weight (though pushing down on the front doesn't entirely solve the problem), the middle needs more support (shouldn't be a problem after the case is finished), and despite my attempts to fix these problems, the gears constantly lock up and the train can only seem to move a few inches at a time before I shut it off in fear of motor damage.

Evidently, gears are not my forte. So before I attempt to dive into this mess again and screw something up, I wanted to get suggestions from all of you people on where my problem area is and what I should do to fix it. But first, here are a few more pictures:

A close-up on the rubber-banded motor. The bands aren't completely tight, so the motor probably pops out a little when everything locks up.

Likely problem spot #1: The bevel connecting to the front wheels. The way it's set up, the entire front wheel assembly ends up spinning with the wheels. Not a good sign.

Likely problem spot #2: The actual front wheel assembly. I tried to make it as efficient with my limited collection of parts, and this was the best I could make.

Well, there you go. Hopefully I can get a suggestion on where to start with this thing, so I can get to actually finishing it

Thank you!

EDIT: I have narrowed down the issue to being the bevel gear, which was far too weak to handle the power I was giving it. Also, the motor seems to require stronger rubber bands, as it's really starting to slip now on the higher gears. Guess I should've done more experimentation before making this post . Oh well, I'm still open to suggestions for how to improve this thing's stability and reliability, not to mention its strength. Any ideas?

Edited December 30, 2014 by Sir_Samsalot

[nicjasno]

Your construction is not very good.

What happens is that the bricks just give and when the gears are under stress, a gap forms.

This construction can be made with a lot less material and very much better with technic stuff instead of bricks. This way you will not get gear grind.

And on the last pic with the bogey, you have to support the gears on the 5 stud axle like on the left side, if you don't have parts, at least reverse the setup and have the brick supported gear on the right side, with a thin 12 tooth gear on both sides.

Otherwise it will not work. The gears you use to transfer the power from the motor to the wheels are also very inefficient and take up way too much space. This can be achieved simply by an axle that connects both bogeys with 12 tooth gears on both ends and one bigger gear that connects to the motor. Without any other gears or bricks.

[Epic Technic]

Yeah nicjasno is right and also instead of using rubber bands try to use technic beams.

such as these rubber bands:

Try to lower the top black bevel gear down by half a stud.

Hope that helps

[Sir_Samsalot]

@nicjasno

Ah, I hadn't even considered that the bricks were a cause of stress. I'll try using liftarms instead.

As for the bogey, I did unfortunately run out of the right parts (I suppose I could try to buy some online or something).

And yeah, I know the setup takes up tons of unnecessary space (like I said, WIP), but most of the gears are there because of the 4-speed gearbox, where I still have yet to build the parts that actually control the gears (I'm thinking about a setup similar to this

, but have yet to figure out the logistics). Also, only one of the bogies is controlled by the gears; the other is a PF train motor. I'm trying to gear it in a way that the two motor speeds can be as close as possible. I might just have to scrap that idea though, and do the two bogies thing you suggested.

Thank you for your input.

@Epic Technic

Well, looks like I'll probably have to scrap most or all of my bricks in favor of liftarms. Maybe I'll just do a full redesign, so I can work on better weight distribution. And that bevel is completely gone now. It was just too loose to work with. Thanks for the advice.

Edited December 30, 2014 by Sir_Samsalot

[nicjasno]

Liftarms and connectors will be far more efficient.