Side haul railway dry docks
Ship transfer machinery
Chains, rollers and maintenance
Bridles roller system
Restoration & enlargement
Vertical lifting vs. inclined ways
Hauling machines for railway dry docks have been developed for
this particular use. A machine consists of a train of gears, now
operated by electric motors but earlier using steam, turning one
or more toothed chain wheels driving the hauling chain.
Each hauling chain is arranged, in conjunction with a smaller
"backing chain," in an endless system attached to the cradle.
The hauling chain passes around its chain wheel, and the backing
chain passes through a submerged sheave.
Enclosed oil-bath speed reducers are used to eliminate unnecessary
noise and the danger of open high-speed gears, and to insure adequate
lubrication with maximum cleanliness. Automatic brakes protect
against cradles running away because of human or electrical failure.
Interlocks are provided to prevent operating in reverse against
the stop pawl or forward with the cradle against a head wall;
their function is extremely important, since gear damage could
result that would put the railway out of operation for several
Sometimes a railway dry dock cradle will surge during the hauling
operation. Assuming a roller system in good condition and proper
support for hauling chain, the surging can usually be eliminated
by a moderate increase of the hauling speed. Naturally the increased
speed will require greater horsepower, but it will also reduce
the hauling and lowering times.
Years ago steam served as motive power, offering the advantages
of true autonomy and a wide range of speeds. The switch to electricity
- for new installations and by conversion of old ones - permitted
the use of electric brakes, limit switches, and overload protection,
and eliminated the need to fire boilers prior to operation.
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