< Equalizing System 1 >
The drawing shows equalizing system of the
loco. Three driving wheels and trailing wheels
are linked together in each side.
Each equalizer beam between driving wheels swings in a cutout of the main frames. It can tilt until its end touch the upper frame of the window. That is to say it determines limit of the equalizing motion. I calculated the maximum gradient that the equalizer can pursue. The chart shows equalizer motion when the middle driving wheel passes a sharp valley. Red point shows each wheel's position, from left, leading - three driving - trailing wheels. The blue lines show equalizer motion and the green line shows tilt of the loco body. If you reverse the chart vertically, you can get a motion when the loco passes a sharp summit.
From calculation, the maximum gradient is about 6.5 per million (13 per million from downhill to uphill) in both at valley and summit. As actual gradient always changes smoothly, the equalizer can follow typical ground level track layout with maximum 10 per million slopes. Incidentally, even if the gradient reaches to the limit, any wheel does not rise from the track, because the axlebox can drop independently. Only the axle weights become uneven.
I started with the spring shafts. There are two types, eye bolt type and fork end type. The former is made from 5 mm and 10 mm silver steel round rods screwed together and silver soldered. It is difficult to pour solder into the thread, so I cut a groove crossing the thread by a fine triangle file.
The fork end type was made from laser cut square rod. Note the rod was enough long to chuck in a vise while cutting the slit. After that the chucking part was cut off and threaded to connect the shaft.
The parts were degreased with spirits, screwed together with flux. Silver solder rings were prepared by coiling a fine silver solder wire and cutting by wire cutter. The rings were put around the shafts, then whole job was heated by propane torch. Surplus solder melted down into the hole was removed with a leamer.
There is a kind of spring shafts that will be fixed to the leaf spring with a cotter, instead of double nuts. I cut a long hole in the side of the rod by 2 mm end mill. The cotter was made from 2 mm steel plate. Cotter and shaft have small holes to bind with a pin.
There are 24 shafts for the engine including 4 for the leading truck.
Each equalizer beam for driving wheels was laser cut from 9 mm steel plate. A phosphor bronze bush was press fit. The bush is not vital for such kind of parts. But it can space the beam from inside faces of a bracket.
The picture shows driving wheel spring with a saddle. The saddle rides the main frame astride and pushes the driving axlebox by its feet. The saddle is cast irons with large bottom slits and small rectangle windows. In case of full size locomotive, the leaf springs and the saddles are individual parts. But I combined them so as not to let them fall apart when carrying the locomotive. Top of the casting was cut to a width of the spring holder, and a screw hole to secure the spring was opened.
The saddle will be swung according to the equalizer motion. So its bottom line should be curved. I cut it on a rotary table. Incidentally, center of the radius corresponds to a middle point of the spring top face. It is to balance fall down force and stabilizing force.
The trailing equalizer is cast iron made. The three holes for the fulcrum are same as prototype. They are for adjusting axle weight of the trailing wheel. Incidentally, if you change the trailing axle weight by this fulcrum, the leading axle weight is also changed automatically.
I temporary assembled the trailing equalizer. Swing washers are missing between the spring and the nut. I will introduce in the next issue.