Wheel connector leading to friction

[evancelt]

Hi all - I am working on a Thomas TTE MOC based on @ScotNick's design. As I was building out some passenger cars for it yesterday I decided to try running the Thomas MOC on some 9V track.

I positioned the trains as such: Thomas --> Passenger --> Passenger --> 9v motor (caboose location)

When the technic flex wheel connectors are in place, it bogs down in the corners of a R40 loop. With the wheel connectors removed it makes it through.

I tried with the passenger cars removed and it happens in that case as well.

The wheel connectors are offset 90 degrees on the two sides of the train as I've read that would help.

I can just remove the technic flex cable at shows to run the MOC, but is there a way to keep it on the train and have it successfully make the corners?

Would a more rigid wheel connector function better?

Thanks!

[SD100]

Either a more rigid rod might help, or you may want to allow some more slippage. On my 3 axle locomotives I only have the center axle solid. The wheels are on 1/2 pin/1/2 axles and held in by the rods and that has alleviated a lot of friction. It also allows slightly more side to side movement in curves and switches.

SD

[ScotNick]

Hi @evancelt!

Wow, flattering to see a replica of my model!

I've run into a similar problem quite some time ago, albeit not with my Thomas model. It seems that some of those flex rods (not all though) are a bit too short, while others are fine.
Not sure about the reason, but I'd suspect that during the cooling process some rods might have shrunken a bit more than they should have.

I had the problem with my 4L long flex tubes as can be seen here:

This is inacceptable! by ScotNick1, auf Flickr

I "fixed" this by replacing the flex cables with metal rods cut to length and putting them in some Lego hoses. Sadly I don't have a good pic anywhere, but it works.
I can only show this video where you can see one of those metal rods exposed - the others are coverd by the hoses. You might have to try a little bit at first hand, but it works, is MUCH cheaper than buying flex cables, and you can also have odd lengths ;)

valve gear testing by ScotNick1, auf Flickr

Hope this helps!

Cheers, Nick

 

Edited January 17, 2023 by ScotNick

[evancelt]

Thanks guys! I'll give your suggestions a try later this week and report back what works!

Some other thoughts I had were: 1) adding rubber bands to one side's wheels to allow the other side to slide more freely or 2) swapping the flanged wheels from the back or front with the middle blind wheels to shorten the wheelbase that is in catching on the track corners.

[evancelt]

Thanks @ScotNick and @SD100 - I tried a few more things this evening to get it to work

First, I tried replacing the full axles with half-axles to allow the wheels to spin independently. This helped a little, but it still didn't make the curves.

Next, I tried replacing the technic flex with a pair of 13L liftarms and it still didn't make the curves. So I tried taking the outer piston rod off, and it made the curve.

So then I tried adding back the technic flex on one side only using 3/4 pins to connect it, and it didn't make the curve.

However, once I replaced the 3/4 pins I was using with full pins, it did make it (using the technic flex). I believe the 3/4 pins weren't allowing for enough lateral movement.

So currently I only have the piston rod on one side and only the blind driver is a full axle, but that will be good enough for a show!

Thanks