Improvements in Steam Derrick Cranes and Excavating Apparatus.
Year: 1898

page_text: PROVISIONAL SPECIFICATION.
Improvements in Steam Derrick Cranes and Excavating Apparatus.
I, THOMAS WHITAKER, of Horsforth, near Leeds, in the County of York,
Contractor, do hereby declare the nature of this invention to be as follows:-
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This invention relates to that class of crane known as steam derrick cranes
and navvies and is designed to provide improved gear for same by which the
heavy strain upon the gear will be reduced or equalized.
As hitherto constructed these cranes have been slewed or turned about their
vertical axes by cog wheels or gear and in consequence of the length of the jib
and the momentum thereof when the engines are stopped suddenly a very great
strain is suddenly thrown upon the cogs or teeth of the wheels which are in gear.
By my present invention I dispense with the cog gear and substitute therefore
rope gearing with a spring or buffer to equalize the strain.
At the foot of the jib or mast I provide a plain race wheel or pulley and on
the slewing motion shaft I place a corresponding plain wheel or pulley and
these I connect with a wire rope or chain passed one, two or three time round
each. At the connection or attachment of the wire rope or chain I interpose a
spring buffer so that when the engine is pulled up suddenly the momentum
of the apparatus will be taken up to some extent by the spring, and less shock
or strain will be transmitted to the gear.
The wire rope or chain may be passed round the small pulley and the two
ends separately attached to the race wheel or they may be connected in any
other suitable manner.
30
T
1
1000
WM. P. THOMPSON & Co.,
6, Bank Street, Manchester, Patent Agents.
I, THOMAS WHITAKER, of Horsforth, near Leeds, in the County of York,
Contractor, do hereby declare the nature of this invention and in what manner
the same is to be performed, to be particularly described and ascertained in and
by the following statement:
-
This invention relates to that class of crane known as steam derrick cranes
and navvies and is designed to provide improved gear for same by which the
heavy strain upon the gear will be reduced or equalized.
As hitherto constructed these cranes have been slewed or turned about their
vertical axes by cog wheels or gear and in consequence of the length of the jib

page_text: and the momentum thereof when the engines are stopped suddenly a very great
strain is suddenly thrown upon the cogs or teeth of the wheels which are in gear.
By my present invention I dispense with the cog gear and substitute therefor
rope or chain gearing with a spring or buffer to equalize the strain.
It will be fully described with reference to the accompanying drawings in
which sufficient of a crane is shown to illustrate the invention.
Fig. 1. Side elevation of part of base of crane (partly in section).
Fig. 2. Sectional plan of race wheel or pulley for slewing the crane.
Fig. 3. Side elevation of modified arrangement of race wheel or pulley.
Fig. 4. Sectional elevation of same.
Fig. 5. Plan of same.
At the foot of the jib A or mast of the crane or navvy I place a plain race wheel
or pulley B and on the slewing motion shaft C I place a corresponding plain
wheel or pulley D.
The race wheel or pulley B I drive by a steel wire or other rope or chain E
from the pulley D on the slewing motion shaft C. I at present prefer to employ
one or two steel wire ropes for the purpose.
The rope E is passed or lapped two or three times round the pulley D being
secured thereto it is preferably divided into two lengths the two ends being
separately attached as shown and the ropes wound in opposite directions so that
as the wheel or pulley D is rotated in one direction or the other one part is
unwound therefrom as the other is being wound up.
The free ends of the rope E are passed around the wheel or pulley at the foot
of the jib A and are attached thereto. At the point of attachment I interpose a
spring or springs F or spring buffer or its equivalent to take up the momentum
of the apparatus when the engine is pulled up suddenly and thereby lessen the
shock or strain on the slewing motion.
It will be evident that any arrangement of springs or buffers may be applied
for the purpose of preventing or relieving the shocks caused by stopping and
starting and such may be also supplied to the driving wheel D if found desirable.
A similar construction or arrangement of apparatus may be applied to other
motions of the crane such as for raising and lowering the jib.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed I declare that what
I claim is:
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1. Cranes or excavating apparatus constructed with apparatus for slewing or
turning them about their vertical axes comprising plain wheels or pulleys on
the foot of the jib and on the slewing motion and rope or chain and spring
buffers for conveying movement from one to the other substantially as described.
2. In a crane or excavating apparatus mechanism for slewing or turning it
about its vertical axis constructed and arranged substantially as described and
shown.
D
1011 1
2000