Return to the BUILD

In this issue, we will install the gearbox and test the operation of the engines using the motor and USB power.




Materials: The Turbine Shaft is metal and the other non-electronic parts are plastic.


  • Giant of the Sea – Britannia and Her Sisters
  • 20th Century – Titanic the ‘Blockbuster’ (Part II)
  • Step-by-Step Instructions


Installing the Motor/Gearbox

Step 1

Retrieve your Engine Room Deck assembly from Issue 36 and your Gearbox assembly from the previous stage. Feed the plug of the Motor wiring down through this square hole of the Engine Room Floor Section (Rear), as shown:

As you feed the wiring down through the hole, position the Gearbox so the Turbine Shaft slides into this rear slot of the Turbine Base:

Rotate the External Propeller Shaft from each Engine until they can slide into the D-shaped Cog E on each side of the Gearbox.

Take care not to dislodge the Propeller Shafts from the engine Flywheels as you position this Gearbox:

Fit the four rounded tabs of the gearbox Base onto the matching short posts at this location of the Engine Room Floor Section (Stern).

On my model, this was kind of a tight fit. The two External Propeller Shafts need to be firmly seated in both the engine Flywheels and the two Cog E gears for the Base to line up correctly:

Loosely secure the Gearbox assembly to the Engine Room Floor with four (4) AP screws:

Step 2

Check the position of the Connecting Shafts/Link Sections on each Engine. These rectangular valvetrain ‘links’ should alternate their positions. For example, you can see in the picture below that from left to right, links 1 and 3 are withdrawn into the Columns while links 2 and 4 are extended out over the Gangway. This is the correct orientation.

If you need to reposition any of these links, gently press them into the proper orientation. None of them should be farther inside the Columns than the inside edge of the Gangway. Here is a view of my port engine with the links in the correct places:

And, here is a picture of my starboard engine with links 1 and 3 retracted. As long as the links alternate positions, you should be good to go:

Testing the Motor

Step 3

The Printed Circuit Board for Motor (PCB) has a small sliding switch on it. When the switch is in the center, it is OFF. When we slide the switch towards the motor (MOT) socket, this should turn the Gearbox in the ahead (forward) direction. Sliding the switch towards the USB socket should turn the Gearbox in the astern (backwards) direction.

I used small drops of green and red paint to mark the ends of my switch for future reference – green for ahead and red for astern:

Step 4

Connect the plug of the Motor wiring to the MOT socket of the PCB. Then, connect the USB-C to USB-A Cable to the other socket.

The MOT socket is keyed so make sure this is connected correctly. You may also want to make sure the PCB switch is in the center (OFF) position:

Connect the USB-A end of the Cable to a 5V power supply that can supply 1A or 2A (amps) of current, such as a phone charger (not a computer port).

Slide the PCB switch to the ‘ahead’ position and let it run for about 30 seconds.

  • Both Engines and External Propeller Shafts should turn (in opposite directions) and the center Turbine Shaft should rotate as well.

Then, slide the PCB switch to the ‘astern’ position and check for proper operation.

  • In this mode, the Gearbox should only turn the Engines/External Shafts and the center Turbine Shaft should remain motionless.

When you are satisfied with the Motor/Gearbox operation, slide the PCB switch to center (OFF) and disconnect the cables.

Finally, fully tighten the AP screws from Step 1.

Here is a quick video of my Titanic Engines churning along in the ahead (forward) direction:


  • If you find the Motor does not turn the engines/gearbox at all, check all of your wiring and your power supply. Also check the Engines and Thrust Blocks are fully secured to the Engine Room Deck.
  • If you find the center Turbine Shaft either doesn’t turn or turns in both modes, you may need to check the Gearbox internals.
  • If an External Propeller Shaft is turning but the connected Engine is not, check that the Shaft is fully seated into the Flywheel.


OK, there is some truly special about watching all of our hard work on this engine room in motion! Everything is working perfectly and our Gearbox is not nearly as noisy as I thought it would be. Keep the PCB and Cable stored just in case we need it again later. As this assembly is now quite long and heavy at the Engine end, take extra care storing it to prevent any damage to the small details.

Next Up

Issue 39 – Shaft Plate, Steam Pipes, Pump Details, Control Handwheels, Central Walkway, Grips

3 thoughts on “ISSUE 38”

  1. Todd,
    Wow! Great Job. Looks Spectacular. I followed your instructions to the letter and my engines are functioning properly. However, they do seem just a little “labored”. Would you suggest adding any lubricant to any of the visible pieces? I don’t want to risk any of my paint coming off. Thanks for all of your tips. Quick question: Do you have a Holy Grail partwork that you hope to be released?

    1. Thanks Brad! I did go back and add drops of 3-in-One oil to the joints of the engine components, but it did not make much difference. The plastic floor of the engine room flexes too much at this point in the build to really gauge final operation. Once we install it into the hull, I am hoping it smooths things out. As for my holy grail of partworks, that would be to build a large-scale motorized Johnny 5 from the Short Circuit movie!

  2. I really appreciate the insight you have given me into this build. I am incorporating alot into my build that I have seen through here. I really thought the frosted window part was a very good idea and am doing something similar using different materials because my local hobby shop didn’t have the acrylic sheets you used. I told the guy what I wanted to do and how you did it and he gave me materials to create the same affect using thin clear plastic sheets cut to size and sanded the same way you did. I trust him because his shop does R/C builds and repairs and they even are going to install a dcc sound decoder into a locomotive for me since I also do madel railroading.

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