433D 3-Cylinder Express Passenger Locomotive
Designed by Frihdrik Tešlov
Built in 1950 by Henschel & Sohn, Kassel, Germany
the RSR was still pondering where to order the new 2-10-2s Tešlov had
designed, work had already started on their passenger counterparts, the
class 433D 4-8-2s. Henschel, of Kassel, who had free capacity where
order (from Portugal, evidently) had been cancelled, were able to fit
RSR job in. A total of 60 of these superb engines, which were to
the RSR's passenger traffic as the 533As would later do with the goods
services, was delivered during 1950 and 1951. Unfortunately, owing to a
misunderstanding in the drawing office, which led to the assumption
that the loading gauge could accommodate the extra height of the
chimney extension common in German practice, the 433Ds were too tall as
built and had to be confined to major routes in the northern plains.
After the embarrassments of the 434A and 474A, the RSR knew better than
to complain to Henschel.
in 1955, most of the class received new tapered boilers, which despite
a slightly reduced heating surface were thermodynamically superior,
becoming class 433DD. Their height was also reduced to fit within the
general RSR loading gauge.
positive experience the RSR was achieving with poppet valves led also
to their application to the 433DDs. As they passed through the works
from 1957 onwards, all engines were fitted with the new valve gear,
greatly enhancing their performance and efficiency.
In 2000, all
(no. 433DD.034 was badly damaged in an accident
Nestavor in 1957 and had to scrapped - without having received its
poppet valves) were still in service and making a
contribution to the RSR's passenger moving efforts, sharing the top
with the later 4-8-4s. Withdrawals began in 2002 and proceeded at a steady
pace, leaving just nine engines in service as of January 2008. No. 433DD.017 had
already been set aside for preservation in working order. In their time the
433DDs were, it seems, more popular with the enginemen than later designs, owing
to their easy steaming and roomy (although admittedly draughtier) cabs.
Text and graphics © Norman Clubb 2012