< Tender Chassis 3 >
There is no casting at the back end of the frames. Instead, there are two reinforcement plates parallel to the frames. Front ends of them are bolted onto a stretcher casting and back ends of them are fixed to the frames through rectangle packings.
The rear buffer is reinforced by two triangle plates. The plates are laser-cut parts and drilled holes for screws.
In order to mount the triangle plates, drill and tap screw holes on the bottom edge of the frames. Care must be taken to place holes precisely on thickness center line.
Mount laser-cut rear buffer plate. The left hand photo is a view from top and the right hand photo is a view from bottom. The triangle plates are secured onto the buffer with brass angles and screwed down to the frames.
The photo shows a view from back side. In order to keep appearance of the prototype, any screws that should be hidden are screwed from the inner side and filed flush on the outer face.
In case of the prototype, two air cylinders are hidden between the frames and they are connected to a thick driving axle held by two casting brackets. And the axle drives the bogies' brake. In case of the model the brake is driven by driver's foot, so I will make only the axle and the brackets that will be connected to a foot brake pedal. The photo shows the casting brackets made of gunmetal.
Finish back face in four-jaw.
Hole for the driving axle is drilled and reamed. It is 13 mm dia.
Cut a necessary step by end mill at the upper bolting face.
The brackets will be held under the chassis with laser-cut baseplates. The photo shows tapping screw holes to a baseplate.
Mounted brackets with the baseplates. Note their side positions are different each other. The left hand brass plates are dummy baseplates for the imaginary air cylinders.
This is another link bracket fixed to the chassis. It is made from rectangle steel rod. Start with cutting a step by end mill.
The bracket's round end is cut in the rotary table. Round center is fixed with a small screw and another end is clamped firmly. Finally, cut a slit by end mill.
This is a similar item for a free link with two links at both ends. It is made here with the same process.
The bracket is also held under the chassis with a baseplate. Note relatively thick bolts are employed so as to against large braking stress.
The chassis was completed except the braking components.
