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JLiu15

[MOC] MCI D4500CT Commuter Coach (INSTRUCTIONS AVAILABLE)

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Posted (edited)

LEGO Technic MCI D4500CT Commuter Coach

Model of a New Jersey Transit 2020 MCI D4500CT commuter coach. Features motorized drive, steering, full suspension, working passenger door, removable Cummins engine model, and changeable destination signs.

Functions/features:

  • Drive
  • Steering
  • Full suspension
  • Working passenger door
  • Removable Cummins engine model with moving pistons
  • Changeable destination signs

Instructions available on Rebrickable: https://rebrickable.com/mocs/MOC-186023/JLiu15/mci-d4500ct-commuter-coach/#details

In 2016, a new order of MCI D4500CT commuter coaches began slowly being introduced to the New Jersey Transit fleet to replace the aging D4000 and D4500 coaches built in the early 2000s. Deliveries would occur until 2022, and over 1200 buses were ordered for New Jersey Transit as well as private carriers. The buses saw a number of minor changes throughout the delivery years, most notably a change from the Cummins ISX-12 to the X12 engine around 2020. They are largely used on routes to and from New York City, as well as long-distance routes in southern New Jersey. My model depicts bus 20052, a 2020 model year unit assigned to Wayne Garage.

I began working on this model in August 2022, starting with the Stud.io model. I wanted to build this model in traditional NJT colors, which includes silver stainless steel panels on the sides and a black upper rear section. I wanted to build at the same scale as my New Flyer XD60 model (roughly 1:20), and thankfully the rims for the 62.4x20 tires are available in metallic silver to match the silversides. I also ensured the seating layout is identical to the real-life NJT MCI D4500CT, with 57 seats on non-lavatory units (30 units equipped with lavatories from the 2018 and 2019 model years have two fewer seats). The model uses the Control+ system for electronics - the drive axle is driven by a Control+ XL motor and steering is controlled by a Control+ Large motor. Initially I planned to use a Control+ Large motor for the bi-parting passenger door as well, located in the roof support frame, but the two door panels would not open evenly since the drive from the motor is first transferred to only one of the panels. I eventually placed the entire door mechanism under the passenger entry in the front, and a WeDo 2.0 Medium motor is used to power the doors as its shorter length allows it to easily fit in the limited space. My initial design also sought to include a functioning wheelchair lift with its functions (extending/retracting, elevating/lowering and wheelchair lift door) along with the passenger door controlled by a 4-output distribution gearbox.

Work on the physical model did not begin until November 2022, at which point I already had the chassis and axles largely modeled in Stud.io. After building the wheelchair lift mechanism I found it to be ineffective in practice - because the lift slides in and out from the side of the model and needs to elevate and lower in a limited space, the mechanism eventually had so much friction that the motor powering it stalls when the extension and elevation functions are selected and the elevation mechanism has so much backlash that the lift would not lower even after rotating the input of the mechanism until it eventually drops all of a sudden. I eventually decided to abandon the wheelchair lift mechanism (the 4-output distribution gearbox was saved for my Mack Granite Boom Truck model which also helped test the suspension design for this MOC). In the end the lower part of the model where the luggage compartments are normally located only contain the Control+ hub and Technic frames for rigidity. Because the underside is largely covered with Technic panels, I used the newer Control+ hub with screws as there is no need to leave open space around the hub for access to the battery door latches. In the end removing the wheelchair lift mechanism was a good call, as even without it the model is very heavy at over 6100 pieces.

Similar to my previous bus models, this model features a System finish with Technic inners. Much of the chassis between the front and rear axles is quite empty, with the only electronic components being the Control+ hub and the drive motor (the steering motor is integrated in the suspended front axle). There is a Technic roof support frame as well, but because all electronic components are placed in the chassis, the frame is kept simple (consisting of mostly 11x15 Technic frames) and the lack of exposed wires in the interior is another advantage. However, there is a vertical axle in the interior allowing for pressing the power button of the Control+ hub from the roof. Reinforcing the roof support frame was a challenge though, as the real-life bus has the left and right side seats slightly offset from each other. This meant a vertical support beam on the left side may not work on the right side, as the beams must sit directly behind the window pillars to remain unobtrusive. Another challenge was the rear of the chassis, as it had to be kept largely open with no transverse reinforcements for the removable Cummins engine model connected to the drivetrain. The sections of the chassis directly above the front and rear axles also had to be kept open yet reinforced for the suspension - I also had to change the front suspension to two shock absorbers per wheel as the model got heavier which required rebuilding a significant portion of the front chassis section. The front of the chassis would still experience some bending even with the roof frame in place, but after the bodywork was added the issue was largely mitigated. As for the passenger seats, my initial design had them as System builds finished with dark blue tiles and slopes (the real-life NJT MCI D4500CT has two-tone blue vinyl covered seats), but because ordering so many dark blue pieces for an interior feature would be expensive yet still not capturing the two-tone blue finish, I decided to use Technic panels for the seats (part 24116 with 2L liftarms to slightly increase their height). While they are slightly less realistic, they offered a much more rigid connection to the Technic inner floor and likely helped reduce the weight of the model.

The bodywork consists of a largely seamless white finish made using System pieces. Like my MTA New Flyer XD40 model, I made sure all connections to the Technic core are made using white Technic axle pieces into Technic bricks with axle holes to prevent exposed Technic pins. The roof however is still made using Technic panels, and a section of the roof also contains the power "button" which pushes the vertical axle for the hub power button mechanism. One of my goals when I started working on this model is for the silversides to actually be silver, not light bluish gray. Because the LEGO metallic silver palette is limited, I had to make sure all the parts I need exist and can be acquired in the numbers I need. LEGO's Pick A Brick came in handy here, as I was able to order over 70 2x4 tiles in metallic silver and several other metallic silver tiles, and acquiring the metallic silver pieces alone cost over $80. The passenger door was more of a challenge as the door panels are made using Technic pieces and some pieces I need (such as a 1x4 thin liftarm) do not exist in metallic silver, so unfortunately there is still some light bluish gray in the doors. The New Jersey Transit livery is done using custom stickers, mostly on transparent glossy sticker paper but also some on white sticker paper for those that do not sit on a white section (e.g. the silverside panels). I also included a mechanism for easily removing the front destination sign which allows for changing the destination displayed on the sign. The side destination sign is connected using only two pins which also allows for easy removal. Finally, because the run sign (the number display at the lower right hand corner of the front windshield) is only attached using two half pins, the number displayed on the run sign can also be easily changed.

Overall, I'm satisfied with how my third motorized bus model turned out. At over 6100 pieces, it has nearly 1000 more pieces than my New Flyer XD60 model from two years ago. The System finish for the bodywork allows for a largely seamless look and the metallic silver for the stainless steel panels really make the silversides stand out. However, the heavy weight of the model also means the drive speed is quite slow, and I also noticed the front wheels would struggle to stay upright after driving it for a while. This could be mitigated by adding a second drive motor and Technic wheel hubs for future bus models of this size. Despite these issues, the other functions worked flawlessly, and I'm especially satisfied with how the bi-parting door mechanism came together. It's been a very rewarding two years working on this model, and I still have many more motorized bus models planned for the future.

Video:

Photos:

LEGO Technic MCI D4500CT Commuter Coach - 1

 

LEGO Technic MCI D4500CT Commuter Coach - 2

 

LEGO Technic MCI D4500CT Commuter Coach - 3

 

LEGO Technic MCI D4500CT Commuter Coach - 4

 

LEGO Technic MCI D4500CT Commuter Coach - 5

 

LEGO Technic MCI D4500CT Commuter Coach - 6

 

LEGO Technic MCI D4500CT Commuter Coach - 7

 

LEGO Technic MCI D4500CT Commuter Coach - 8

Brickworld Chicago Photos:

LEGO Motorized MCI D4500CT Commuter Coach - Brickworld Chicago 2024 - 1

 

LEGO Motorized MCI D4500CT Commuter Coach - Brickworld Chicago 2024 - 2

 

LEGO Motorized MCI D4500CT Commuter Coach - Brickworld Chicago 2024 - 3

 

LEGO Motorized MCI D4500CT Commuter Coach - Brickworld Chicago 2024 - 4

 

LEGO Motorized MCI D4500CT Commuter Coach - Brickworld Chicago 2024 - 5

 

LEGO Motorized MCI D4500CT Commuter Coach - Brickworld Chicago 2024 - 6

 

LEGO Motorized MCI D4500CT Commuter Coach - Brickworld Chicago 2024 - 7

 

LEGO Motorized MCI D4500CT Commuter Coach - Brickworld Chicago 2024 - 8

 

Edited by JLiu15

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First of all your model looks extraordinary good; level of details, smooth lines, all great and wheels from 8285 set are perfect on your bus. Looking at your video, you should use hubs on wheels because they are much stronger. To use 2 motors for drive would be better if you need more torque, or to have a bit less reduction (for similar torque); easiest way is to use 20 to 28 gear gray differential instead of red (or 28 tooyh double bevel gear with red differential) or differential from Ferrari Daytona.

For my mocs torque / speed calculation I often use this

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This build is incredible, almost diecast level. Very well done! It deserves to be front paged.

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7 hours ago, 1gor said:

First of all your model looks extraordinary good; level of details, smooth lines, all great and wheels from 8285 set are perfect on your bus. Looking at your video, you should use hubs on wheels because they are much stronger. To use 2 motors for drive would be better if you need more torque, or to have a bit less reduction (for similar torque); easiest way is to use 20 to 28 gear gray differential instead of red (or 28 tooyh double bevel gear with red differential) or differential from Ferrari Daytona.

For my mocs torque / speed calculation I often use this

Thanks! I'm definitely thinking of using hubs for my next bus model of this size since the weight of the model really added up. I'll probably use two drive motors too. My initial design actually had the yellow differential from the Ferrari Daytona set, but as the weight of the model increased I had to find gearing down somewhere and changing the gear reduction at the differential from 14:22 to 12:28 seemed to be a good choice.

6 hours ago, Alex Ilea said:

This build is incredible, almost diecast level. Very well done! It deserves to be front paged.

Thank you! I'm really satisfied with how the looks of the model turned out in the end. Using System pieces for the bodywork really helps to capture all the details.

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2 hours ago, JLiu15 said:

Thanks! I'm definitely thinking of using hubs for my next bus model of this size since the weight of the model really added up. I'll probably use two drive motors too. My initial design actually had the yellow differential from the Ferrari Daytona set, but as the weight of the model increased I had to find gearing down somewhere and changing the gear reduction at the differential from 14:22 to 12:28 seemed to be a good choice.

 

Perhaps you can use planetary hub reduction but have to upgear directly from motors...

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This is beautifully built, I like the mix of functional technic chassis with studded finish. The door mechanism is especially cool and seems smooth. I admire people who take so much time and parts to build a single model in such detail. Great work!

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Studless and very realistic! I like the engine to be removable too.

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13 hours ago, 1gor said:

Perhaps you can use planetary hub reduction but have to upgear directly from motors...

I've considered that but realism is a major consideration for my bus models so if the real bus doesn't use planetary hubs I probably won't use them either, although they really do provide a huge amount of gear reduction (over 5:1 I think).

9 hours ago, gyenesvi said:

This is beautifully built, I like the mix of functional technic chassis with studded finish. The door mechanism is especially cool and seems smooth. I admire people who take so much time and parts to build a single model in such detail. Great work!

Thanks! I like this approach as it allows for all the Technic functions while giving it a detailed finish with System pieces. It took me a while to get the right geometry for the door mechanism, but in the end it worked flawlessly and is one of my favorite parts about this MOC.

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Posted (edited)

Only upgrade I would make to this, would be custom real working screens for the bus number and information thingy. That would elevate this beautiful MOC to the next level!

Edited by Alex Ilea

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Yes, reduction hubs use 5,4:1 reduction. There are some axles with reduction or inverted portal axles made by Metitor for busses, but I don't know if there is the case with 4500 model.

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2 hours ago, Alex Ilea said:

Only upgrade I would make to this, would be custom real working screens for the bus number and information thingy. That would elevate this beautiful MOC to the next level!

I've considered using something custom like BrickScreens by Brickstuff, but I don't think they make any in the dimensions of a typical bus destination sign (unless maybe I put a bunch of smaller ones next to each other).

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