NG Road Engine – III


The first thing I wanted to do is see how widening the walkways would affect the design. Here .. I’ve sectioned the body. This is the HO body which is 1.425″ in width across the outside of the walkways and cab. The 0.260″ width as shown is the HO walkway width. The long hood is 0.905″ wide.
Soo .. here are three versions .. just to spark some discussion ..

  1. Original – this is the same as the section shown above .. just straight on.
  2. Narrow Walk – this version leaves the long hood width at 0.905″, overall width at 1.750″ (taken from the BVM cab width). The 0.162″ addition to the with gives us a 0.423″ walkway width. Full-size this would be 20.3″ wide.
  3. Standard Walk – this time the long hood is sectioned to 0.807″ wide. The walkways are widened with the 0.162″ addition. This gives a 0.471″ walkway width which full-size would be 22.6″ wide.
My conclusion – leaving the long hood along we end up only losing 2.3″ width which in my opinion is well worth not having to mess with the long hood width.
Added 0.162″ to either side of the walkway. The actual thickness etc. will of course depend on the model. I think there needs to be a overlay to cover the joint and strengthen the structure .. a diamond plate perhaps.
Looking at the chassis without the hood, cab etc. The sections ahead/behind the extensions (in red) will have to be sliced off and completely reworked of course.
I colored the step section in red so it stands out. This is HO .. which means the height will remain the same but will need to be wider. Since the height of each step will be larger it will probably be only two steps. It will also extend further out the make the walk wider. To figure out all of that we need some dimensions.
.. and so .. dimensions ..

  • 36-5/8″ – The walkway as it turns around the end of the hood. In O scale this is 0.763″
  • 49-5/8″ – This is the height of the step. The HO model scales to 0.57″. This in turn scales to 27.36″ in O scale. Trying to remember what numbers I am juggling here confuses me sometimes.
  • 35-3/8″ – In O scale this scales to 0.737″
  • Step heights – they vary all over the place .. 15-3/4″, 17-1/4″ and 15-3/8″. This averages out to 16-1/8″. In O scale this is 0.336″
  • Step offsets – again, all over the place. 5-1/2″, 6-7/8″ and 9-7-8″. This averages out to 7-7/16″.
This is like the third time I have worked on rescaling the step. The second one was way too long .. this time I added dimensions full-size/ .. and .. here we go. This is of course just a quick and dirty modification of the GP38-2 engine. The parts in red are those that are added/created. The cab was just enlarged without any other change other than the front windows which I enlarged.
Comment ..
The reason for all of this? Well. If we take a HO engine .. GP38-2, GP40 .. heck .. GP7 .. whatever .. and modify it to On30 there are various things that need doing –

  • The walkways have to be widened
  • New handrails need fabricating .. remember .. O scale is approx. 1.8 X HO.
  • New cab fabricated .. to the 7ft (1-3/4″) width for our O scale narrow gauge
  • New ends/pilot with appropriate sized steps and coupler pocket (2 of these of course)
  • The doors on the body are HO. Seems to me that one way to fix that is to simply sand off the current doors, clean up the sides and then glue on new, appropriately sized O scale doors.
  • Other features that are scaled to HO need also to be scaled to O scale .. any handgrips, lights for example

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