< Rear Pony Truck 2 >
Axle of the rear pony truck is turned with
'traveling steady', same as the other axles.
Rear wheels are glued onto it with Loctite
603. Incidentally, shelf life of the Loctite
is specified 2 years. We had better keep
away from too old one.
The axle with wheels is mounted between the
axleboxes. I was frustrated by this operation
because I had to screw a lot of nuts in narrow
opening with tweezers. Full scale axlebox
has cut bottom so as to put axle without
dismantling chassis.
Cast oil pod is onto the axlebox, laser-cut
door flange is onto the oil pod, then laser-cut
door is onto the flange. The flange and the
door have projections for hinge. They are
cut from thick plate. For clamping, they
were temporary soft soldered on a steel plate.
When a thin hole for the hinge is opened
with a drill, a thin paper is sandwiched
between the plates as a spacer.
Top and bottom faces of the oil pod are trued
up in four-jaw. Note the two faces are not
parallel.
Holes for bolts are opened vertically to
the bottom face, not to the top face. First
a larger stop hole is cut with end mill,
and then a smaller hole is drilled through.
This step is for sinking bolt head.
The photo shows oil pod with flange and door.
The phosphor bronze band on the door is a
spring to stop the door at opened and closed
positions. It was fixed with brass rivets
and soft soldered. The hinge shaft was made
from brass nail.
All of parts are once disassembled. Oil pod,
flange and door are put onto the axlebox
one after another.
The photo shows gunmetal casting of side
control cylinder and laser cut plate of cylinder
heads.
In advance, bolting face of the cylinder
is cut. Then the face is push up against
the angle on the face plate. Then the bore
and a side face are finished. After that,
whole job was reversed and another side face
is finished to a desired length.
Cutting 'step' on the cylinder head for fitting
to the cylinder bore.
The cylinder holds two pistons with coned
projections. They are turned from brass round
rod.
Coil spring set between the pistons consists
of inner and outer springs for reinforcement.
Each one is coiled in the lathe. Note they
are dextral and sinistral pair, so as to
avoid entangler.
Assembled side control system is mounted
at the end of the back frames.
Pivot pin of the truck has plane round head.
It has a small key just under the head. The
key is made from hard stainless steel wire
and glued into a cross hole of the shaft.
One of the main frame stretchers has a hole
for the pivot pin. There is a sharp groove
in the hole cut by a fine rectangle file,
so as to prevent the pivot pin rotating.
The opposite end of the pivot pin is closed
with a nut and a cotter pin.
The rear pony truck is mounted under the
rear frame. Note the axle weight is loaded
through the equalizing arms.
