Improvements in Cranes and other Hoisting Machinery.
Year: 1896

page_text: Date of Application, 1 th Mar., 1896
Complete Specification Left, 29th July, 1896-Accepted, 12th Sept., 1896
PROVISIONAL SPECIFICATION.
Improvements in Cranes and other Hoisting Machinery.
I BENJAMIN BAINES DADLEY of The Thames Iron Works & Shipbuilding
Company Orchard Yard Blackwall London E. Civil Engineer, do hereby declare
the nature of this invention to be as follows:-
Whereas with the hoisting machinery as at present in use, it frequently occurs
in suddenly checking the lifting or lowering of a load, or from its surging especially
with high speed cranes & such like hoisting machinery, that the crane or machinery
& particularly the chain or its equivalent (for simplicity hereinafter called the
chain) is subjected to severe shock, and consequently dangerous strains are
frequently set up in the materia! of the chain; also in the case of automatically
closing grabs or skeps a sudden closing of the jaws will sometimes take place while
the load is suspended, which causes the grab or skeps to fall almost freely until it
is arrested or pulled up by the chain, now if a suspended load fell freely through a
distance of but a few inches, it would when suddenly arrested in its descent by the
chain, exert a stress on the chain of several times its weight, it is therefore
manifest that a very severe strain would be set up in the chain to the great risk of
its breaking, & consequent danger to the men working under it; as is shewn by
the numerous accidents which occur from this & such like causes.
Now by this invention I attach a spring buffer or other suitable elastic medium
to the crane jib, or its equivalent, or adjacent to it, or to the chain itself, in such a
position that a large proportion of the shock or strain due to to the beforementioned
& such like causes, is taken up & absorbed by the action of the spring buffer or
other suitable elastic medium, to such an extent as to considerably reduce the
strain otherwise set up in the chain, & keep it within a safe limit by this means
I increase considerably the working life or durability of the chain, & conduce
greatly to the safety of the men working under it.
Dated this 14th day of March 1896.
BENJAMIN BAINES DADLEY.
COMPLETE SPECIFICATION.
Improvements in Cranes and other Hoisting Machinery.
I, BENJAMIN BAINES DADLEY, of The Thames Iron Works & Shipbuilding
Company, Orchard Yard, Black wall, in the County of London, Civil Engineer,
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:-
My invention relates to cranes and similar hoisting machinery and has for its
object to provide improved means for minimizing the undue strains upon the chain
which frequently occur in suddenly checking the lowering or lifting of a load and
also when using automatically closing grabs or skeps by reason of the sudden
closing of the jaws whilst the load is suspended.
According to my invention I arrange the wheel or pulley at the end of the crane
jib and over which the lifting rope or chain passes to slide in longitudinal guides

page_text: in the jib, and in connection with the said pulley I arrange a spring-buffer, the
spring being of such strength that under any normal stress or strain upon the
chain it will be compressed very little, if at all, but so that in case of any
abnormal strain such as would occur under the circumstances before indicated
it would be compressed and take up a large portion of the shock or strain
produced.
To enable my invention to be fully understood I will describe the same by
reference to the accompanying drawing, in which :-
Figure 1 is a sectional side elevation of the upper portion of a crane jib; and,
Figure 2 is a sectional plan of the same.
a is the crane jib which as represented is of the trussed girder type; and 6 is the
pulley over which the chain c passes. The said pulley, instead of being mounted
rigidly in the head of the jib, is mounted in a frame or fork d which is capable of
sliding in suitable guides e, e arranged lengthwise of the said jib.
Between the fork d and a cross brace fof the jib is arranged a volute spring g
which as herein before stated is adjusted so that normal loads will not affect it but
so that it will be compressed under abnormal strains. To permit of adjusting this
spring in the desired manner, a rod his fixed to the sliding fork d and extends
through the spring and through the cross brace f, below which brace the said rod
is provided with a nut or nuts as shewn. To prevent any hammering between the
said nut and the cross brace when the spring is re-acting after compression,
I arrange a cushion i between a washer on the regulating nut and the said cross
brace as shewn.
Although I have described my invention as applied to the jib of a crane, it is to
be understood that it may be applied in any other convenient position between the
barrel upon which the chain is wound and the free end of the chain.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what
1 claim is :--
1. The improvement in cranes and similar hoisting machinery consisting in the
use of a pulley mounted in a sliding fork arranged in combination with a spring in
such a manner that, when a chain or rope passing over the said pulley is subjected
to abnormal strains, the said spring will be compressed, substantially as, and for
the purpose, described.
2. The combination with the jib of a crane, of a pulley arranged in conjunction
with a spring substantially in the manner hereinbefore described and illustrated in
the accompanying drawing for the purpose specified.
Dated this 20th day of Lule 1896
G. F. REDFERN & Co.,
4, South Street, Finsbury, London, Agents for the Applicant.