Corner Clearance for Lego Monorail

[bsupnik]

Hi Y'all,

I am working on a digital MoC that uses the lego 4-wide monorail. From this picture, we can see that (like all lego trains) when the monorail goes around a turn, the front of the train is outside the bounds of the 4-wide track.

http://cd8ba0b44a15c10065fd-24461f391e20b7336331d5789078af53.r23.cf1.rackcdn.com/brickset.vanillaforums.com/editor/le/6m0gj5dlrmdz.jpg

I was hoping someone who has physical access to the monorail could tell me how many studs worth of straight track I need to have the train fully within the 4-wide track.

In my current design, platforms are on the outside edge of turns, too close to the turn; I believe the train front will crash into the platform, but I do not know how far I have to move each platform to fix the problem.

Thanks!

Ben

[Artanis I]

It depends on the length (and width) of the train (see below). How much overhang is there? If you are only using that red train not much. I think it's 50 studs in length (including 1 overhang each end) with no side overhang. If you are using the space trains or a custom build then it's a different answer.

If you take a look at the base, you can see that the bogey stays completely over the track, and the train pivots over that. The train is never really completely & exclusively over the track until the bogey & middle section are both on the straight.

1/4 length straights are 8 studs long (full length straights being 32), most trains are @ 6 or 7 of those, at roughly 50-60 studs for the entire train. So you are looking at around 30-35 studs from the front of the train to the other end of the middle section. 4 or 5 1/4 length straights.

Does that answer your question / make sense?

Monorail train comparison

[bsupnik]

Hi Artanis,

Thanks for the fast reply!

The train is never really completely & exclusively over the track until the bogey & middle section are both on the straight.

That's what I was wondering. It seemed possible from LDraw that the front car might be straight while the motor is still slightly turned over the corner - I've tried to model that situation as best I can, but the LDraw part doesn't show the exact pivot point of the cars.

Do you know if, in real life, the car can fit without too much friction next to a platform, or does it tend to wobble side to side too much?

Thanks

Ben

[Artanis I]

Actually I hadn't properly considered the angle of the coupling, so once the coupling pivot point is on the straight then the train should be sitting straight. So that's 3 or 4 1/4 length straights, depending on your train.

The speed these things tend to fly along at (with a decent battery), if you have a wall on only one side then the train might bump off if it hits. If you have both sides with walls you would likely get stuck. Be aware that the walls will trigger the motor switch. If the platform has a hard edge right up against the track then the train will likely hit the platform corner on approach and derail, as it does wobble a little bit. But if it eased onto the edge I imagine it would be happy.

Someone else may be able to test it to be sure, I have mine packed away for now and nowhere to put it otherwise.

[marook]

Is offsetting the platform with 1/2 knob enough? I.e. with jumpers..

[Artanis I]

Is offsetting the platform with 1/2 knob enough? I.e. with jumpers..

I wondered if he might want to do that, it would surely fix any problems caused by being flush against the track. "Mind the gap" and all that

[_Ben_]

If you know track radius, body length and bogie centre dimension well then you could calculate the End Throw of the train.

Do everything in mm then convert your final answer to studs.

BTW: ET=(L^2-B^2)/8R

L = body length

B = bogie centre dimension

R = track radius

If you need help determining the track radius, you can do it from measuring the versine.

Good luck! :)

Edited April 14, 2016 by _Ben_

[Breakdown]

I can take some measurements tonight or this weekend with all three monorails.

There's a couple of factors here.

6990 has rockets or some junk on the outside of the cab and a hose on the front. that extends out.

6991 has a protruding nose, but minimal in the way of extra width except at window height and there's lots as this monorail car is designed to leave the train.

6399 has minimal of anything extending it.

Shorter or longer couplings on the motor itself could potentially influence extension on a turn as well.

[bsupnik]

Hi Y'all,

First, thanks to everyone for the input and information!

My preference is to -not- offset the track by a half-stud, although I could see picking up a small 1/2 plate gap by building the last stud of the platform by a SNOT plate and tile. (E.g. my goal is to keep the gap very narrow for realism.) I was planning to use rounded plates on the the platform end to provide guidance for the train into the platform.

I am currently using 1x2x2 reinforced panels to form the wall of the platform, and it appears these provide clearance for the direction switches protruding from the motor.

Breakdown, if you are able to measure 6399, it's almost exactly the same metrics as my custom train; my nose extends half a plate further (but has no forward-facing studs).

My sister-in-law owned the monorail back in the day, but so far she has only located the track; if I can get access to the train and experiment I'll post results here.

Cheers

Ben

[Breakdown]

Sorry so late, here's what I have. The white piece is directly struck in both pics. The pics on the left are slightly less further along on the turn. Looks like you'll need at least two studs clearance.

[bsupnik]

Breakdown -- thanks for posting these pics! I'll plan to have two studs of clearance all the way along the straight until the first car is fully on the straight part...I'm hoping 24 bricks is enough straight length.