Lego 10277 - Crocodile Locomotive

[bogieman]

Does anyone know where the effective pivot point for the bogies relative to the center cabin is on the real locomotive? I'm thinking it must be very near the wall of the center cabin since there is very little clearance between the hood over the motors on the bogie and cutout in the wall. I've searched but didn't find anything that was clear. A picture of just the bogies would help to understand the arrangement. Tractive and braking forces appear to be transmitted directly between the bogies at the center of the loco and don't involve involve the center cabin, similar to other electric locos like the GG1.

[samsz_3]

10 hours ago, bogieman said:

Does anyone know where the effective pivot point for the bogies relative to the center cabin is on the real locomotive? I'm thinking it must be very near the wall of the center cabin since there is very little clearance between the hood over the motors on the bogie and cutout in the wall. I've searched but didn't find anything that was clear. A picture of just the bogies would help to understand the arrangement. Tractive and braking forces appear to be transmitted directly between the bogies at the center of the loco and don't involve involve the center cabin, similar to other electric locos like the GG1.

I asked this question - they are under the cabs at either end - if you look a few pages back you'll see links to videos of the Marklin models showing how they work

[Merlict]

Finally got round to running it on a track.. not impressed. Runs very rough on a basic loop of RC (whatever you call the latest tracks) and it feels like there is a lot of friction in the curves, and some unpleasant noises. 

[bogieman]

2 hours ago, samsz_3 said:

I asked this question - they are under the cabs at either end - if you look a few pages back you'll see links to videos of the Marklin models showing how they work

Thanks, I missed that.

[samsz_3]

16 minutes ago, Merlict said:

Finally got round to running it on a track.. not impressed. Runs very rough on a basic loop of RC (whatever you call the latest tracks) and it feels like there is a lot of friction in the curves, and some unpleasant noises. 

Have you done the various mods people have suggested such as removing the rubber bands on the non driven wheels?

[zephyr1934]

1 hour ago, Merlict said:

Finally got round to running it on a track.. not impressed. Runs very rough on a basic loop of RC (whatever you call the latest tracks) and it feels like there is a lot of friction in the curves, and some unpleasant noises. 

Yes, remove one band from each of the non-powered axles with the large train wheels, as per this post.

[Duq]

10 hours ago, samsz_3 said:

I asked this question - they are under the cabs at either end - if you look a few pages back you'll see links to videos of the Marklin models showing how they work

That's the Marklin model. On the real engine the two bogies are coupled in the centre of the locomotive with the centre cab module resting on the bogies. No pulling or pushing forces are transferred through the cab section.

Rememer, even very wide Lego curves are still tight in the real world. If you go with 1:40 scale the widest 3rd part curves are R102 which translates to a radius of around 32 meter. That's subway territory. The Grande Curve (made of straights, see Holger Matthes' website) translates to 80 meter in the real world which is still half of the minimum radius for mainlines.

[samsz_3]

Finally built my croc, using @SamLeCount power functions mod and a combination of various gap fixes that have been posted. Such a beautiful model, my 2nd favourite LEGO train after Emerald Night.

When I first ran it I only had the rubber bands on the driven wheels. It ran well on straights but seemed to struggle on corners, because the wheels were at the limit of LEGO radius track and the rubber bands made it slightly bigger. I found that it runs best with no rubber bands at all, if you aren't pulling lots (I've built 2 simple European ish coaches). There is some noticeable wheel slip, and it's pulling power is less, but before it's speed significantly fluctuated around corners. I think the weight of the battery and the motor as well as how dense the middle car build is give it enough traction.

[zephyr1934]

13 hours ago, samsz_3 said:

I found that it runs best with no rubber bands at all

If you don't mind a slight tilt, maybe try bands on all wheels on one side and no bands on the other side

[samsz_3]

5 hours ago, zephyr1934 said:

If you don't mind a slight tilt, maybe try bands on all wheels on one side and no bands on the other side

I tried bands on opersite sides, and it goes well clockwise and poorly anti clockwise (or vice versa depending on the sides). I'd be interested to hear from people who've motorised it using both PF and PU to see what issues you guys have had, and how you are running it (nose wheel rubber bands are already off)

[Mr Hobbles]

2 hours ago, samsz_3 said:

I tried bands on opersite sides, and it goes well clockwise and poorly anti clockwise (or vice versa depending on the sides). I'd be interested to hear from people who've motorised it using both PF and PU to see what issues you guys have had, and how you are running it (nose wheel rubber bands are already off)

I've removed the rubber bands from leading and trailing wheels (both sides), leading them only on the powered wheels in the middle only (both sides). It runs very well for me on both 9v and plastic track, straight and curved. :)

[samsz_3]

9 hours ago, Mr Hobbles said:

I've removed the rubber bands from leading and trailing wheels (both sides), leading them only on the powered wheels in the middle only (both sides). It runs very well for me on both 9v and plastic track, straight and curved. :)

When I do that, rubber bands only on the driving wheels, I still have a significant amount of slow down going through curves.

[Mr Hobbles]

16 hours ago, samsz_3 said:

When I do that, rubber bands only on the driving wheels, I still have a significant amount of slow down going through curves.

That is strange, I don't experience that. Maybe a 5-10% speed drop at best. Here is a video of my Crocodile running on both 9v and plastic track.
 

 

[Phoxtane]

Mine finally arrived today! I love the look and the size, it feels just right.

I’m  thinking that it would be awesome to build one in dark green, or even dark blue or dark red if the parts availability exists. I’m probably going to end up doing the gap-closing mods as well as converting it to Power Functions.

[Merlict]

5 hours ago, Phoxtane said:

t would be awesome to build one in dark green, or even dark blue or dark red if the parts availability exists.

Sadly the windscreen is only out in black, white and plain blue. Most of the other parts are common or can be worked around but replacing the windows and keeping it neat is beyond my skills

 

[Toastie]

22 hours ago, Phoxtane said:

converting it to Power Functions

Do the conversion to PoweredUp (i.e., 2I/O Hub + Pup L motor). Here's my reasoning:

I changed my custom PuP control program (VB6 + nsoftware BLE stack) today to use "speed" instead of "power" for LEGO motors providing that feature (L and maybe XL PuP motors - for sure I know the L PuP motors advertised for this model can do). Set the speed (not power) to "5%" and the maximum power to be applied to maintaining that speed to 100%, your crocodile will negotiate whatever track geometry is present at constant speed - 5%is really slow. It just continues to plow through whatever track geometry. The PID algorithm in the Hub's firmware is really powerful. It may be worthwhile to investigate what the "max power" parameter does with regard to maintaining the speed (I believe it goes into the PID algorithm) but nevertheless: This is one >major< advantage of PuP vs PF for controlling trains, as far as I am concerned.

And you can do that with the Pup app right away.

Best
Thorsten

Edited July 28, 2020 by Toastie

[Phoxtane]

 

1 hour ago, Toastie said:

Do the conversion to PoweredUp (i.e., 2I/O Hub + Pup L motor). Here's my reasoning:

[reasoning]

My reasoning for not doing this - at least not immediately - is that I don’t have a PU L-motor. I did take delivery of the green PU cargo train last week though, so I do have the hub.

Also, it seems you’ve already built some of the functionality I had planned for a project of my own that keeps getting pushed back - a sensor package built into  a LEGO train to do, among other interesting things, exactly that (except using accelerometer data).

[Marinho]

Hi all! Small question... I am thinking to buy a second set to mod, as I would like to have an "original" one to display, and one to have fun and run on the tracks. On the pictures I see from the real thing, all the parts that Lego did in DBG, seem to be all black! So did Lego did in purpose in order for the details to "come out" a bit more, or was this original grey and then later repainted to black?

Edited September 29, 2020 by Marinho

[firstofminifigs]

Sorry if this has been asked before... Has anyone tried using a PU simple medium motor instead of the large one?  I have the medium motor from the PU Batmobile and I'm wondering if I can throw that in the Crocodile Locomotive and save a little money.  TIA.  

[dr_spock]

3 hours ago, firstofminifigs said:

Sorry if this has been asked before... Has anyone tried using a PU simple medium motor instead of the large one?  I have the medium motor from the PU Batmobile and I'm wondering if I can throw that in the Crocodile Locomotive and save a little money.  TIA.  

I think you'll have to create your own controls in the Power UP app to drive it.

[zephyr1934]

17 hours ago, firstofminifigs said:

Sorry if this has been asked before... Has anyone tried using a PU simple medium motor instead of the large one?  I have the medium motor from the PU Batmobile and I'm wondering if I can throw that in the Crocodile Locomotive and save a little money.  TIA.  

If you know you are going to get the locomotive (or you have it already), why not give it a try. It probably will not cost any more in shipping to order the locomotive now and the motor later. However, with all of the tecnic axle wheels on the locomotive, my hunch is that you'll need the L

[ejayb]

Do the running issues from from the main body and the driven axles or from the two articulated sections? 

Has anything tried running the body by itself?

I'm thinking of buying the croc and building something with just the body for slow, shunting in an R40 yard. Taking inspiration from Ge 2/2 and a local tram among others.

 

 

[ejayb]

A quick knock up. The front end and the height makes it look a bit silly.

 

[zephyr1934]

I haven't tried it running, but generally you have to take the hoods off when you pick up the crocodile and whenever I do I can't help thinking it looks like a box cab locomotive just like that. If I were planning to run it as a box cab I would probably make a few modifications, e.g., extend the center unit a little bit and either get a third set of (non-flange) driver wheels in the middle or a pair of smaller wheels on either end.

[Merlict]

Not going to link it as I'm not sure of the rules for posting paid instructions, but there's an awesome alt build for this set on Rebrickable into a steam train!