Shay Main Frame
Nelson Riedel Nelson@NelsonsLocomotive.com
Initial: 4/01/03 Last Revised06/05/2004:
Let's start with a bit of
history: Lima used two types of frames on the Class B (2
truck) and Class C (3 truck) shays. The sketch below
from a reprint of a Lima Service Department Instruction Booklet
shows the two types. Both these frames are for Class B
Shays. The Class C frames are nearly identical; the major
difference being that the part behind the rear truck is much
The upper frame is the later
Girder type introduced in the 1910 - 1920 period.
The lower frame is the I
Beam or Truss Rod type used from the beginning on the Class B and Class C
Shays and is the type Kenneth used in his design.
The main frame construction
easier than the tender frame because I'd developed some expertise doing
the tender frame. The following drawing is the 3-Truck
Main frame provided by Kenneth. There' a half dozen more
drawings for the main frame showing details such as coupler pockets, queen
posts, etc. ( These drawings are available from Kenneth.)
The sketch below is from
a reprint of a Lima Spare Parts Book . This main frame went with the
tender frame sketch shown in the tender frame note. My guess
is that it's from the 1900 - 1910 period. Excepting the
curved rear end, it's a nearly exact match for Kenneth's drawing above.
If one examines the frame drawing it will be obvious that the frame is not symmetrical around the
center line of the track or trucks. Recall that the
engine is on the right side of the locomotive. The boiler is off
center toward the left side of the locomotive to make room for the engine
and to balance the weight of the engine. The boiler is
centered on the side I
beams with the engine attached to the outside of the right I
I made my main frame is
exactly to Kenneth's drawing with the following exceptions:
The channels were screwed
together using button head cap screws (simulated rivets) rather
The triangle frame
brackets were used instead of the flat bar frame brackets.
Some cosmetic details were
added such as rivet detail for bolster supports and a front sill
The following construction sequence was
used on the main frame. This is a little different from the tender
frame since I knew where I was headed and had a pretty good idea of
how to get there.
Construct the pair of bolsters.
Make the side I
beams (two channels screwed together) and attach
Make and install I beam
truss rod details.
Make and install (triangle) frame
Make the end channels and attach to
|The bolsters shown on the right were
assembled first. All the parts except the angle
brackets were first screwed together and then silver
soldered. The angle brackets were then screwed into
the bolster but not silver soldered. The holes for the
screws between the I beams
and the bolster were drilled later using the holes in the I beams
as the drilling template. The truck pivot
pin holes illustrate the off center relationship between the frame
|Scale I beams
for the side frame pieces are not available so I beams
are made by fastening two channels back-to-back. Kenneth
welded his channels together. Because of nonexistent
welding skills I decided to screw the channels
together. Review of the Lima Drawings revealed braces
from the bolsters to the I beams.
I had no intention of installing those braces but the the rivets
on the I beam
end were used to hold the two channels of each I beam
together. A clearance hole was drilled in the outer channel
and the inner channel threaded for button head cap screws. There
are two like the one shown below on each side of the main
The truss rods looked to be a quick job until I counted up
all the required parts as shown in the photo below.
(When the truss rods were installed later it was discovered that 4
more of the brass nuts were required.) As
you'll see later, the truss rods add nice detail.
The frame brackets were made using the same technique as
described for the tender. If fact, the same fixture used on the
tender frame was used to fabricate the smaller
brackets. These brackets were made from 20 gauge
steel. The brackets and the truss rod details above took
over half the main frame effort.
|I reviewed the Lima drawing shown on
the right before
deciding how to fabricate the front sill and related brackets,
braces, etc. The bracket between the frame and the sill
channel is exactly like the bracket Kenneth shows in his
drawings. I made angle brackets for each side of each I beam
to attach to the upper part of the wooden sill.
There is a brace from the right I beam
to the back of the sill to support the sill that sticks out
quite a distance from the I beam.
This brace makes a nice detail to add.
The photo directly below the drawing shows one of these braces
on Cass No 5. The end that attaches to the I beam is
different from the drawing above. Also note that the bottom
of the triangle bracket is cut to provide clearance for the
brace. The brace seems to be bent a bit to make room
and to support the tool/storage box.
My model of this area is shown in the photo below. That is the
the under side of the right front. The frame was still under
construction at this point and only a few screws are used to
hold everything together. Button head screws
(simulated rivets) will be used everywhere except into the sill
where 4-40 hex head screws (simulated bolts) will be used.
Excepting the offset, the rear sill shown below is
essentially a mirror image of the tender front sill.
The following photos show completed frame after the 368
screws were installed.
|Update 2/20/2004: Careful measurement of the frame
revealed the the I beams bowed out about 1/4" midway between
the two bolsters. The photo on the right shows an
added cross brace to prevent the bowing. The photo is after the frame had been painted.
Note that the new channel is even with the top of the frame I
beams. I later found that it interfered with the bottom of
the boiler. A small amount of material was removed at
the top center to provide clearance. The brace could
have been aligned with the bottom of the I beams like the
bolsters and there would have been no problem. However, I
like the appearance with the cross brace in the upper
Some of the techniques used to fabricate some of the frame
parts are described in the accompanying note Main Frame Fabrication.
The next task is to construct the pivot blocks and rollers
that are the interface between the trucks and the frames. The
construction of the brake system will complete the trucks.