Kozo K-27 Crossheads and Pistons
This construction segment will
concentrate on the pistons, piston rods and crossheads. The photo of
K-27 463 is provided for reference.
These six pieces will make up the main
portion of the crossheads. The thicker block will be sandwiched between
two plates and then the assembly will be soldered together. September
The components for the two crossheads
have been silver soldered with the one on the left still showing the
temporary retaining screws. The first cuts have been made on the piece
to the right which include the drilling and threading of the piston rod
hole along with a round shoulder. There will be many more cuts made to
get these to the final shape and mount the brass shoe at the top.
September 27, 2020.
The piston rods have been machined out
of stainless steel and threaded into the crossheads. Nuts for the
piston rods have also been machined out of 3/8" hex stock and are used
to lock the rod at the correct length when the piston position is
adjusted. The brass shoes have been cut and will be mounted in the top
of the crossheads with five screws. Once that is done the shoes will be
milled to the correct height using the rods as the reference point.
October 4, 2020.
The brass shoes have been machined to
be parallel to the piston shafts and milled to the correct thickness to
fit between the guides. October 11, 2020.
Holes for the main rod bolts have been
drilled and reamed. A short chamfer has also been milled at 45 degrees
on the lower edges near where the piston shaft threads in. The next
step will be machining two arcs on the rear of the crossheads to bring
them to the final shape. October 11, 2020.
This evening one of the crossheads was
milled to the final shape with three different arcs at the rear. The
length of this assembly is just over 5 1/2". Note that the hex socket
screws will be replaced with hex head fasteners in a future step.
October 11, 2020.
Both of the crosshead assemblies have been finished to the final shape. October 14, 2020.
The first piston has been machined
with a diameter of about 1.3". The o-ring is an AFLAS which is able to
stand up to higher temperatures, steam and oils. October 18, 2020.
The two pistons have been completed
and also pinned to the piston rods. A screwdriver slot was also cut
into the piston end of the rod to allow for length adjustment once
mounted in the cylinders. The next step will be the machining of the
crosshead arms that attach at the main rod hole and will attach to the
valve gear. October 24, 2020.
The crosshead arms have been machined
with the pin fitted and soldered to the arm. The next step will be to
accurately position the arms 10 degrees from vertical and then drill
the mounting holes in the crosshead. Here we see one of the arms
set on a temporary pin in one the crossheads to provide a visual of how
the pieces fit together. November 8, 2020.
This afternoon was spent making the
custom crosshead bolts that will replace the cap head screws in the
prior shot. On the right we have a sample of the first machining work
performed on the lathe. In the middle is the hex head formed by
machining in a hex collet block on the mill. At the far left is the
final machining on the lathe to provide the appearance of a bolt end
sticking out through a nut. November 15, 2020.
The ten custom crosshead shoe bolts
have been completed to appear like a bolt sticking through a nut as
seen above. One of the crosshead pins has also been machined that will
attach the main rod to the crosshead. A second will need to be machined
and then hardened to take the abuse. December 13, 2020.
Both crosshead pins and the custom
size nut have been machined and used to help locate the crosshead arms
on the assemblies. The crosshead arms are canted 10 degrees from
vertical and the mounting holes have been drilled and tapped. Now
I need eight custom bolts to get rid of those slotted screws. December
The eight custom bolts for the crosshead arms have been completed. December 23, 2020.
The piston and crosshead assembly have been completed and test fit on the locomotive. December 23, 2020.
The progress to date with pistons and crossheads fitted to the assembly. December 23, 2020.