< 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.