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By
DAVID PIKE
The name Daimler and the British royal family had a long association
during the 1920s and 1930s. At every state occasion there would be a
line of Daimler Double-Sixes each adorned with either a flag - the Royal
Standard - or the Royal Crest above each expansive windscreen. These
cars featured the unorthodox `Silent Knight' double-sleeve-valve engine
in use throughout the Edwardian years but when there was a change in
chief engineer at Daimler, Laurence Pomeroy, the new man set about an
engine redesign.
Since he had never favoured the use of low
powered engines no matter how refined they were, in 1926 he
introduced the Daimler Double-Six engine. This was considered by
many to be the most complex power unit ever made for a private
car. Pomeroy started off using two of the 25-85 Daimler
six-cylinder blocks which he mounted at 60 degrees to each other.
To this arrangement he added a cast aluminium crankcase. Each of
the engine blocks was split into two groups of three cylinders so
there was, in effect, four cylinder heads. Because the cylinder
banks were not offset, all the right hand connecting rods had
forked big ends, and shared their crankpins with the left side
rods.
From this description it is not hard to imagine
this 7.0-litre 112kW engine was quite massive, weighing in at
around 2268kg and this made chassis design quite a problem. As it
was the chassis had a wheelbase of 4140mm and a track of 1520mm.
England's King George V never bought a full
112kW Double-Six, initially having two earlier model Daimlers
converted for the V12 engine; two of the smaller 3.7-litre models
were added to the Royal fleet late in the 1920s, while three 40-50
limousines and two 30-40s were acquired in an exchange deal in
1930.
At the end of the 1920s Daimler catalogues
listed seven different Double-Six chassis and with Daimler
coachwork, 15 variations were possible including a good-looking
Corsica cabriolet. The sporting models had tuned engines and light
bodywork on a short chassis. Pomeroy improved the Daimler range
for 1931 by combining a fluid flywheel with an epicyclic
pre-selector gearbox to produce something akin to an automatic
transmission system. Ultimately the engines were revised in
detail, using more aluminium to reduce overall weight.
By 1933 the 30-40 and 40-50 Double-Sixes had
been redesignated `40' and `50' respectively. Also all other
Daimler models had poppet valve engines. The new poppet valve
straight eight that was introduced in 1934 did not immediately
supersede the Double-Six, as a few V12s were built with poppet
valves, including the last ceremonial limousine built by Daimler,
expressly for the 1935 Silver Jubilee celebrations.
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