The steam engine model renders in about 1.5 minutes on my nvidia 3050Ti notebook graphics adapter (depending on scene content). Peak memory is about 2.5 GB. It contains about 1.6 million faces. 

Information pertaining to the "..._b4.blend" (updated for Blender 4) file:

Main Collection is "Engine52Series". With the "Empty52" the model can be moved. The Collection "HelperObjects&Cameras" includes what it is named after and is not necessary for importing into your scene.

The cameras are included as well, which have been used to create the images of the engine. These are named accordingly.

The textures are packed into the blend file. I suggest to unpack them to reduce loading and saving time when you use the file.

All steam engine parts are grouped by Empties. These do not have any other functionality. Exceptions are the objects, whose names start with "CrossSection...". These are used for the Bezier Curves of pipes and wires.

Information pertaining to the "..._v1.blend" file:

The model is structured on five layers:

Layer 1 contains the carriage (aka "the red parts").

Layer 2 contains the fuselage of the locomotive.

Layer 3 contains the fuselage of the tender.

Layer 4 contains cross sections of wires and pipes.

Layer 11 contains the studio (background, lights, etc.)

Empties are used to structure the model. All objects are consistently named. Objects unrelated to the locomotive (like ground, lights, etc.) have names starting with "_". 

There are cameras included (named "Camera...") for any of the images presented. 

In order to use the model, simply append all objects not starting with "_" and not "Camera".

(This file renders without issues in Blender 4 as well.)