I'm not in O scale so I'm not voting, but I can offer some useful thoughts.
The G1, G2 and G5 were almost identical in many of their most important
dimensions. They all had driver axle spacing of 6' 6", 10 feet between rear
driver and trailing axle, and 4'7" from front driving axle to cylinder centre,
but the G5's pilot truck axles were 3 inches farther apart. The G1 and G2 had
33'7" wheelbases while the G5 had 33'8.5". G1 pilot wheels were 34 inch
diameter, G2 were 31 inch and G5 were 33 inch. G1s had 75 inch drivers, G2s
originally had 69 inch but were changed to 70 inch, and G5's had 70 inch. Since
they had the same heights (smokebox centreline was 9'4" above top or rail) the
frames must have been adjusted slightly higher upon the axles of the G2s and
G5s. The G1s and G2s received new boilers with slightly different dimensions in
the 1920s. A conspicuous difference was relocation of the sandbox from above
the second driver to above the first one. The shape of the smokestack was
changed on the new boiler. The G5 boiler had the same dimensions but lacked a
steam dome (I presume they used a dry pipe), and the pressure valves were moved
forward almost to the position of the G1 and G2 steam dome. Some received
Elesco feedwater heaters and others did not, in no pattern I'm aware of.
Tenders on the G1s and G2s were replaced along the way and I wouldn't presume
to categorize these as there were a number of variations. Changes to details
altered the appearance of the G1s and G2s over time, and some customization
would be needed to make an engine appropriate for the period modeled. So in
principle it should be possible to produce an engine that could represent any
of these classes with the necessary modifications, thanks to CPR's legendary
standardization policies. If the manufacturer doesn't offer different
variations, the intrepid modeler can try them at home.
There were 39 G1s with 75 inch drivers compared to 166 G2s and 102 G5s with 70
inch drivers.
What surprised me was that the same frame could serve as the base for G3 and G4
Pacifics as well. Of course these engines had substantially larger boilers.
They had driver spacings of 6'7", with driver diameters of 75 or 70 inches. The
rear truck axle was 10 feet behind the rear driver and the wheels had the same
45 inch diameter as the G1, G2 and G5. At the front end the G4s and early G3s
had their cylinders several inches ahead of those on the smaller engines, and
the pilot truck wheelbase was longer. The later (Bowen semi-streamlined) G3s
had slightly larger dimensions on these as well, as well as longer smokeboxes
(perhaps to accommodate the countersunk headlights?), and the sandbox was
slightly farther back. A manufacturer or scratchbuilder could use the frame of
the G1, G2 or G5, with modification of the front end, to create a G3 or G4.
Just my two cents worth, and if somebody wants to produce any of these fine
engines in N scale they will find me standing eagerly in line!
Don Thomas
----- Original Message -----
From: citadis
To: cpsig@xxxxxxxxxxxxxxx
Sent: Sunday, December 06, 2009 10:24 PM
Subject: [cpsig] G5
Hi Guys,
For those of you who are O scale steam fans (and who isn't??) there is a
company considering making a CP Pacific. They are thinking along the lines of
G5 1201.
My thoughts are that, whilst a nice locomotive, the most prolific, most
handsome and the quintasential CP locomotive were the G1 and G2 types (and
their various sub groups) They lasted longer, in most cases right to the end
and were used in virtually every corner of the great CP on every type of train
from branch line way frieghts to mainline pass. They speak Canadian Pacific!!
I would be interested to hear what you gents think but please, let's only
hear from O scale modellers as it really only concerns them.
Cheers
Greg King
