We illustrate a high speed engine and dynamo constructed by Easton &
Anderson, London. This plant was used at the Royal Agricultural
Society's show at Doncaster in testing the machinery in the dairy, and
constituted a distinct innovation, as well as an improvement, on the
appliances previously employed for the purpose. The separator, or
whatever might be the machine under trial, was driven by an electric
motor fed by a current from the dynamo we illustrate. A record was
made of the volts and amperes used, and from this the power expended
was deduced, the motor having been previously carefully calibrated by
means of a brake. So delicate was the test that the observers could
detect the presence of a warm bearing in the separator from the change
in the readings of the ammeter.
[Illustration: IMPROVED HIGH SPEED ENGINE AND DYNAMO.]
The engine is carefully balanced to enable it to run at the very high
speed of 500 revolutions per minute. The cranks are opposite each
other, and the moving parts connected with the two pistons are of the
same weight. The result is complete absence of vibration, and
exceedingly quiet running. Very liberal lubricating arrangements are
fitted to provide for long runs, while uniformity of speed is provided
for by a Pickering governor. The high pressure cylinder is 4 in. in
diameter, and the low pressure cylinder is 7 in. in diameter. The
stroke in each case is 4 in.
[Illustration: Fig. 2.]
The dynamo is designed to feed sixty lamps of 16 candle power each,
the current being 60 amperes at 50 volts. The armature is of the drum
type. The peculiar feature of it is that grooves are planed in the
laminated core from end to end, and in these grooves the conductors,
which are of ribbon section, are laid. Slips of insulating material
are laid between the coils and the dovetailed mouths of the grooves
are closed with bone or vulcanized fiber, or other dielectric. At each
end of the core there are fitted non-magnetic covers. At the
commutator end the cover is like a truncated cone, and incloses the
connections completely. One end of the cone is supported on the end
plate of the armature and the other end on a ring on the commutator. A
bell-shaped cover incloses the conductors at the other end of the
armature. The result is that the conductors are completely incased,
protected from all mechanical injury, and positively driven. They can
neither be displaced nor abraded. The conductors on the magnet coils
are likewise carefully protected from harm by metal coverings. These
dynamos are made in sixteen sizes, of which seven sizes are designed
to feed more than 100 lamps, the largest serving for 600 lamps.
[Illustration: Fig. 3.]
Messrs. Easton & Anderson are showing machinery of this type at the
Crystal Palace Electrical Exhibition now open in
London.--_Engineering_.
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