MOC: Custom building mechs.

[Locomotive Annie]

This evening I was working on putting together a mech for a loco project with the main criteria being slow running and the ability to haul two passenger coaches at the most. I was thinking back to pictures I've seen on the forum of mechs that folk have put together and the main thing I remember about them was the use of a lot of bevel gears. I can't remember anyone using worm gears to build a Lego loco mech, but I'm quite willing to be proved wrong.

Basic mech being test run on 3 volts, it runs very smoothly.

[bricks n bolts]

I can't remember anyone using worm gears to build a Lego loco mech, but I'm quite willing to be proved wrong.

No, neither can I, funny this is though I'm doing that also right now... It worked quite well as you have it there until I started adding weight (more friction on the worm gear eventually halting the motor)./

In the end I moved the worm gear down one level so the actual motor only has a normal (small) gear.

[Frank STENGEL]

I remember seeing a shunting loc by lego 12 volts that is using a worm gear to go very slowly... It is not the same gearing as yours, but in the end achieves the same purpose: low speed and high torque.

[Spitfire2865]

How do you attach the axle to the motor? I have that motor but I cant figure it out. Haha.

Sorry if it double posts. It seems my comment wasnt submitted.

[Locomotive Annie]

Spitfire, I used one of these to connect the motor to the worm gear.... http://www.bricklink.com/catalogItem.asp?P=32034 I guess I could have used one of these too .http://www.bricklink.com/catalogItem.asp?P=6538 , only for some reason I couldn't find one last night even though I know I've got dozens of the things.

B n B I found that setting up the worm gear was fairly critical to removing friction too which is why there is all those cigarette paper shims underneath the motor. I think I'm going to have to mess around with it a bit more yet before I'm completely happy with it.

Frank, thanks for the link to that shunting loco. There's some interesting ideas being used there and I may borrow some of them before I'm finished with building my own mech.

[Spitfire2865]

Umm isnt that a 4.5V motor? Or 12V or something. On my motor the end has a thin axle peg. Its about 1 mm thick or so. I would love to be able to use it but idk..Im probably just stupid and not seeing the obvious. Could you show me a picture of your motor disconnected from everything? If its already in the loco dont bother. I just dont know if My motor is missing something or not. I got it from a friend so I have no idea.

[bricks n bolts]

Umm isnt that a 4.5V motor? Or 12V or something.

Probably a 4.5v, I had one just like that in the '80s but it broke back then...were made in 12v but much rarer - I ordered a black 12v one from bricklink but it was broken too.

Still have the original battery box that came with the 4.5v motor though, from which I made an 'alternative' 4.5v battery wagon :

[Locomotive Annie]

Yes it is a 4.5volt motor Spitfire. It's this one http://www.bricklink...tem.asp?P=6216m All I did was plug the connector onto the motor peg, fit a 5 wide axle into the other end, slide on the worm gear and pop a retaining collar on to hold it in place.

I've got two of those battery boxes as well B n B and I was going to build tank cars around mine too. I was going to use the battery tank car plan on the 'L' Gauge website http://lgauge.com/ to build my tank cars, though your one looks very good as well.

I own several 4.5volt mechs and it's only right that they should be allowed to come out and play too.

Edited February 28, 2013 by Locomotive Annie

[Spitfire2865]

Ohhh I see my problem. My motor doesnt have that black axle bit at the end. Its just a 1mm thick peg. I guess its useless to me then. Haha.

[jmchisel]

Amazing - I was about to post some pics of my WIP shunter which uses a 4.5V motor and a worm drive!

Annie, I think your other post about "hybrid" loco drive mechs must have got us thinking along the same lines.

Here's the worm drive - I'm currently using a belt down to the drive axle for compactness, but it has hugely compromised the torque available!

I can't find the part number of the Technic gear block housing :-(

And here's the WIP shunter chassis with the 4.5V motor hooked up. The motor sits in the cab (it's a 6-wide and it's the only place wide enough) and the rotation goes through a Technic 6538 axle connector to a pair of 16-tooth gears which conveniently fit the end holes in the gearbox housing. I'll post more pictures in a separate thread once I'm happy with the performance:

I tested this with voltages from 3V-6V and while it's beautifully slow, the belt drive starts slipping once you ask it to do any sort of real work.

The problem is I have very limited space in which to get power down to where it's needed. Like literally the width of that Technic half-bush. Anyone have any ideas?

[bricks n bolts]

Ohhh I see my problem. My motor doesnt have that black axle bit at the end. Its just a 1mm thick peg. I guess its useless to me then. Haha.

If it's more like 2mm you could maybe fix it with this : http://www.pololu.com/catalog/product/1001 ?

I tested this with voltages from 3V-6V and while it's beautifully slow, the belt drive starts slipping once you ask it to do any sort of real work.

The problem is I have very limited space in which to get power down to where it's needed. Like literally the width of that Technic half-bush. Anyone have any ideas?

Interesting, did you try a very large gear (such as http://www.bricklink.com/catalogItem.asp?P=3649) where you have the top of the belt / half bush and a small gear on the actual wheel axle (maybe http://www.bricklink.com/catalogItem.asp?P=32270 would be better than http://www.bricklink.com/catalogItem.asp?P=3647 ) ?

[Spitfire2865]

Hmm..if I really wanted to use the motor I may be able to make my own adapter with a 2L cross peg and a small drill. Ok then...thats another thing on my long hobby to-do list. Haha

[bricks n bolts]

I may be able to make my own adapter with a 2L cross peg and a small drill.

Hmm, and then you'd need glue next to all that motor heat. The pololu rubber seals on the other hand just don't budge..

[Spitfire2865]

Glue? No I was thinking I could just use friction by drilling a slightly smaller hole.

What rubber seals?

[bricks n bolts]

Glue? No I was thinking I could just use friction by drilling a slightly smaller hole.

What rubber seals?

OK, if you think. I would mess that up for sure at 1-2mm.

The adapter at http://www.pololu.com/catalog/product/1001 is made of rubber and just seals itself onto the metal shaft. I'm running one of them off a 12v motor, they just don't shift at all once they're on.

[Locomotive Annie]

The adapter at http://www.pololu.co...og/product/1001 is made of rubber and just seals itself onto the metal shaft. I'm running one of them off a 12v motor, they just don't shift at all once they're on.

They look to be seriously useful B n B. I think I will have to get some for research purposes

[Locomotive Annie]

Amazing - I was about to post some pics of my WIP shunter which uses a 4.5V motor and a worm drive!

Annie, I think your other post about "hybrid" loco drive mechs must have got us thinking along the same lines.

Here's the worm drive - I'm currently using a belt down to the drive axle for compactness, but it has hugely compromised the torque available!

I can't find the part number of the Technic gear block housing :-(

And here's the WIP shunter chassis with the 4.5V motor hooked up. The motor sits in the cab (it's a 6-wide and it's the only place wide enough) and the rotation goes through a Technic 6538 axle connector to a pair of 16-tooth gears which conveniently fit the end holes in the gearbox housing. I'll post more pictures in a separate thread once I'm happy with the performance:

I tested this with voltages from 3V-6V and while it's beautifully slow, the belt drive starts slipping once you ask it to do any sort of real work.

The problem is I have very limited space in which to get power down to where it's needed. Like literally the width of that Technic half-bush. Anyone have any ideas?

Interesting setup with your shunter JM, but I don't think a plain belt will transmit enough torque for your loco to be useful. It would really need to be a chain drive, only you don't have room to fit a Technic chain between the back of the wheel and the gearbox casing.

By the way is this the gear casing part you were looking for? http://www.bricklink.com/catalogItem.asp?P=6588 I have this one and I've been trying to think of a way to use it to drive a loco http://www.bricklink.com/catalogItem.asp?P=768

I think if you were to try fitting a chain drive onto an extended axle shaft on the outside of the wheel you might have more success. The only problem might be fitting the extra width a drive like this would have on a 6 wide loco.

[Werlu Ulcur]

The problem with belt drives is slipage or lack of tension and/or pliability?

[jmchisel]

The problem with belt drives is slipage or lack of tension and/or pliability?

The problem I'm having is one of slippage, primarily due to lack of tension. I've now freed up a tiny bit of extra space in my "engine bay" and changed the half-bush to a wedge belt wheel (http://www.bricklink...Item.asp?P=4185) and this has helped a lot with this aspect.

Interesting setup with your shunter JM, but I don't think a plain belt will transmit enough torque for your loco to be useful. It would really need to be a chain drive, only you don't have room to fit a Technic chain between the back of the wheel and the gearbox casing.

By the way is this the gear casing part you were looking for? http://www.bricklink...Item.asp?P=6588 I have this one and I've been trying to think of a way to use it to drive a loco http://www.bricklink...gItem.asp?P=768

I think if you were to try fitting a chain drive onto an extended axle shaft on the outside of the wheel you might have more success. The only problem might be fitting the extra width a drive like this would have on a 6 wide loco.

Thanks for those links Annie - I've never had that gearbox part so I'd struggle to think of application too! I'm really enjoying seeing new possibilities for my Technic collection though, it's revitalised my interest in that stuff. Totally agree that a chain drive would be the way to get loads of torque to the wheels, and while I have seen shunters with such an arrangement, the prototype I'm trying to stay faithful(ish) to is not quite that agricultural! :-)

Interesting, did you try a very large gear (such as http://www.bricklink...Item.asp?P=3649) where you have the top of the belt / half bush and a small gear on the actual wheel axle (maybe http://www.bricklink...tem.asp?P=32270 would be better than http://www.bricklink...Item.asp?P=3647 ) ?

I would have loved to use an "all gear" solution B n B, but I am trying to keep the mechanicals of this shunter into a very tight space. Basically, with the SNOTery I'm doing for the engine compartment, I have 1 plate + 2 studs + 1 plate of width in order to get the axial rotation from the motor geared down (these 4.5V motors are not strong at all), rotated through 90 degrees (in line with the axle(s)), and brought down to the axle level.

I like using the 6588 gear housing because it holds the worm gear at the exact right distance to the gear wheel (as you can see in Locomotive Annie's original picture, it can be tricky to maintain this!) and it has handy holes for putting extra axles into that wouldn't exist in a brick-built solution. So that uses 2 studs of width in the centreline of the loco, and I only get one plate worth of space (each side) to get the drive down to the wheels! Hence the belt drive. But as I mentioned, using a larger wedge belt wheel has helped get some better tension on the belt, and I'm also using a belt on each side, which helps even out the forces on the axles and frees them up a little.

I'm actually quite growing to like the belt drive + worm gear combination! The worm drive makes a tremendous grumbling noise, perfect for a dirty little workhorse diesel shunter. And the fact that it stops DEAD when you kill the power, combined with the stretchyness of the elastic bands, makes the loco do this little back-and-forth rock when you stop it - it's really cute and sorta-kinda prototypical, maybe! :-)

Edited March 1, 2013 by jmchisel

[bricks n bolts]

I've got two of those battery boxes as well B n B and I was going to build tank cars around mine too. I was going to use the battery tank car plan on the 'L' Gauge website http://lgauge.com/ to build my tank cars, though your one looks very good as well.

Swapped out the picture of the tank wagon (and the one on 'Horse Scandal') as I've only got a camera phone at the moment and I can't get enough light on the layout. Also note I built these a while ago and bits have fallen off here and there, so this is the good side...

I like using the 6588 gear housing because it holds the worm gear at the exact right distance to the gear wheel (as you can see in Locomotive Annie's original picture, it can be tricky to maintain this!) and it has handy holes for putting extra axles into that wouldn't exist in a brick-built solution. So that uses 2 studs of width in the centreline of the loco, and I only get one plate worth of space (each side) to get the drive down to the wheels! Hence the belt drive. But as I mentioned, using a larger wedge belt wheel has helped get some better tension on the belt, and I'm also using a belt on each side, which helps even out the forces on the axles and frees them up a little.

I'm actually quite growing to like the belt drive + worm gear combination! The worm drive makes a tremendous grumbling noise, perfect for a dirty little workhorse diesel shunter. And the fact that it stops DEAD when you kill the power, combined with the stretchyness of the elastic bands, makes the loco do this little back-and-forth rock when you stop it - it's really cute and sorta-kinda prototypical, maybe! :-)

Sounds cool jmchisel. Do you think you can get it to do the full work of a shunter yet? I have the http://www.bricklink.com/catalogItem.asp?P=46220 gearbox where the worm is sealed, always get close to using it for something, haven't done yet though.

[Luke_likes_Lego]

Sorry that I'm not contributing to the tech usefulness of this thread, but.....

I just wanted to compliment Annie on the first picture.....it's topical and attractive with the addition of the mini-doll, cat, toolbox etc., but serves its purpose to show the gears and setup.

LLL