A Self-acting Derrick.
Year: 1892

page_text: Date of Application, 13th Sept., 1892
Complete Specification Left, 23rd Sept., 1892-Accepted, 29th Oct., 1892
PROVISIONAL SPECIFICATION.
A Self-acting Derrick.
"5
I, ALEXANDER MCKINLAY, Master 8.9. Rajpootana" of the British India
Steam Navigation Company Limited, Calcutta, do hereby declare the nature of
this invention to be as follows:-
The object of my invention is to enable the boom or jib of a derrick to be
wung outboard and inboard by means of a travelling span and guy, as hereafter
described.
The travelling span is a rope fastened to the mast head (or rove through a block
at the mast head) and the one end either made fast to the end of the derrick or on
leck, said rope being led through a block at the head of the derrick and made
fast on the deck at a distance from the gangway and steamer's side, regulated
according to the length of the derrick used, the breadth of the vessel, and the
distance of the mast from hatch, so that a sling of cargo can be lowered clear
outside of the steamer. The end of the travelling guy is fastened to the opposite
It is led through a
side of the steamer to that at which the span is fastened.
block at the derrick head, through another block at the mast head, and thence
down to a winch on deck. The winch chain for hoisting the cargo sling out of the
hold and lowering it over the side passes over a sheave at the foot and over another
sheave at the head of the derrick boom as usual. The head of the derrick boom is
supported by being slung in the bights of the travelling guy and span as above
described, so that if one be slackened more than the other, the boom will tend to
move away from the one which is so slackened. The operation of slewing the
boom will therefore be effected as follows:-' When a sling of cargo has been hove
up above the hatch combings by the winch chain, it can be at once slewed clear of
the steamer's side by simply slackening the travelling guy. This slewing of the
derrick boom is effected automatically by the weight of the load as by slackening
the guy the head of the derrick travels downwards along the span and is conse-
quently caused by the tension of said span to slew outboard to whatever distance
the sling of cargo is required to go, in order to clear the steamer's side. Conversely
by tightening the guy the derrick is caused to move upwards and inboard. In the
event of discharging cargo, when the steamer is rolling, the derrick is prevented
from swinging about by reason of its being hung in the bights of the span and
guy, the ends of which are made fast respectively at opposite sides of the steamer
so as at all times to control the position and motion of the derrick.
As above stated, when the guy is slackened, the weight of the sling of cargo on
the derrick will slew it out clear of the steamer's side and when the sling of cargo
is landed over the side of the steamer, the guy can be attached to the winch and as
the winch chain, which is slackened out with the sling of cargo, is being hove in,
it will heave in the guy, at the same time causing the derrick to rise and slew
inboard until it is in the required position over the hatch.
Dated this 13th day of September 1892.
ALEXR. MCKINLAY,
By A. M. & Wm. Clark,
53, Chancery Lane, London, Chartered Patent Agents.

page_text: COMPLETE SPECIFICATION.
A Self-acting Derrick.
1, ALEXANDER MCKINLAY Master s.s. "Rajpootana" of the British India
Steam Navigation Company Limited, Calcutta, 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:-
The object of my invention is to enable the boom or jib of a derrick to be
swung outboard and inboard by means of a travelling span and guy as hereafter
described.
It
In the accompanying drawing, forming part of this Specification, E is what I
term a travelling span being a rope fastened to the mast head A or rove through
a block at the mast head and the one end either made fast to the end of the derrick
or on deck, said rope being led through a block e at the head of the derrick B and
made fast on the deck at E' at a distance from the gangway and steamer's side
regulated according to the length of the derrick used, the breadth of the vessel,
and the distance of the mast from hatch, so that a sling of cargo can be lowered
clear outside of the steamer. F is the travelling guy, the end of which is fastened
at F to the opposite side of the steamer to that at which the span is fastened.
is led through a block at the derrick head, through another block f' at the
mast head A and thence down to a winch on deck. B is the boom or jib of the
derrick; C is the winch chain for hoisting the cargo sling out of the hold and
lowering it over the side. It passes over a sheave G at the foot and over another
sheave H at the head of the derrick boom as usual. The head of the derrick
boom is supported by being slung in the bights of the travelling guy and span as
above described, so that if one be slackened more than the other the boom will
tend to move away from the one which is so slackened. The operation of slewing
the boom will therefore be effected as follows; When a sling of cargo has been
hove up above the hatch combings by the winch chain C, it can be at once slewed
clear of the steamer's side by simply slackening the travelling guy F. This
slewing of the derrick boom is effected automatically by the weight of the load as
by slackening the guy F the head of the derrick B travels downwards along the
span E and is consequently caused by the tension of said span to slew outboard to
whatever distance the sling of cargo is required to go, in order to clear the
steamer's side. This slewing of the derrick boom by the effect of the span E
under the control of guy F is indicated in dotted lines in the drawing; conversely,
by tightening the guy the derrick is caused to move upwards and inboard.
Iu
the event of discharging cargo when the steamer is rolling, the derrick Bis
prevented from swinging about by reason of its being hung in the bights of the
travelling span E and travelling guy F the ends of which are made fast respectively
at opposite sides of the steamer so as at all times to control the position and motion
of the derrick.
As above stated when the guy is slackened the weight of the sling of cargo on
the derrick will slew it out clear of the steamer's side and when the sling of cargo
is landed over the side of the steamer, the guy can be attached to the winch and as
the winch chain, which is slackened out with the sling of cargo, is being hove in,
it will heave in the guy, at the same time causing the derrick to rise and slew
inboard until it is in the required position over the hatch. With the ordinary
derrick as at present in use (which is hung by a stationary span from the mast
head) considerable labor is required to slew it outboard and it is to supersede this
that the invention is chiefly designed.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
Supporting a derrick boom or iih in the highto of
onan

page_text: the mast head running through sheaves on the derrick and diverging to fixed
points, the guy being capable of being slackened or tightened for the purpose
of permitting or causing the slewing motion of the derrick, substantially as
specified.
Dh: 02-1 dow of Santember 1892
A. MKINLAI,
By A. M. & Wm. Clark,
53, Chancery Lane, London, Chartered Patent Agents.