Class
434F 3-Cylinder Compound General Purpose Tank Locomotive
Designed
by Jochann Ketterik
Built
in 1986 (under the auspices of Artur Gorote)
by RSR Works, Bevice-Akohniçe, Ruhnia
Several
times during the history of the RSR related locomotives have shared a
common fate. So it was also with the 423Ds and 423Es. By the early
1980s their boilers were feeling (and showing) their age. Ketterik
clearly felt that these engines had not yet had their day and decided
to bring them into line with current practice. The
most drastic aspect of the rebuild was the conversion to
3-cylinder compound drive. The outside cylinders retained their
quartering and received low-pressure steam and a new, high-pressure
inside cylinder was installed, its crank being set at 135° to each
of the outside ones. All three cylinders drive the second coupled axle.
The leading coupled axle is cranked to clear the inside
connecting rod. Steam is fed saturated to the
high-pressure cylinder and resuperheated for the low-pressure
cylinders. In this way, an excessively high temperature of superheat is
avoided, simplifying the lubrication of the high-pressure cylinder. In
addition, the rebuild involved poppet valves,
boxpok wheels and
a new, tapered boiler, with a similar firebox to that used earlier on
the 323FFs and 533BBs, the difference being the installation of a gas
producer combustion system. All 83 of the engines still surviving in
1986 were rebuilt; work proceeded quite slowly, the last rebuilt
locomotive emerging from the works in 1994. In the final analysis, not
much was left of the original design except the mainframes (suitably
modified) and the cabs, water tanks and coal bunkers.
Text and graphics © Norman Clubb 2012