STATIONARY ENGINES.
109
hauling engines can run. Such engines should be of suffi-
ciently large dimensions to be capable of hauling, in case of
need, a loaded cage with one cable. As they are, more-
over, generally built with an ultimate view to haul from
increasing depths, the dimensions of their steam cylinders
The reversing and the expansion gear, governed by two
eccentrics and a Gooch link, are worked by the same lever,
this being an essential condition. The réduction of dead
spaces is obtained by the division in two parts of the
distribution slide valves, the separate slides being placed
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. 288. Express Passenger Locomotive for State Railways of France.
are iound excessive for ail normal work. This unfavourable
state of tliings renders a low degree of expansion and a low
initial steam pressure necessary, especially as the engines
are non-condensing, and considering also the loss of effective
power that would arise through the pressure at the end of
each stroke being below the counter-pressure at the exhaust.
at the ends of the cylinder. The free inlet of steam and
a low counter-pressure at the exhaust, are insured by the
large sections of the steam ports. The valves are worked
through ß, servo-motor. The maximum admission, corre-
sponding to the dimensions of the link, is .78 ; this is
sufficient for starting with safety, whatever be the various