Improvements in Ships' Davits and Apparatus therefor.
Year: 1899

page_text: Date of Application, 23rd May, 1899-Accepted, 4th Nov., 1899
COMPLETE SPECIFICATION.
Improvements in Ships' Davits and Apparatus therefor.
I, JAMES WILSON MCKINNON, of 713, East 138th Street, in the City of New
York, County and State of New York, U.S.A., Inventor, do hereby declare the
nature of my 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 improvements in ship davits and apparatus therefor.
It is the purpose of the invention to provide simple and easily operated
mechanism to turn the davits, for carrying the boats outboard and inboard, and
for operating the drum which pays the boat-hoisting-tackles in and out. By
this invention the time for getting a life boat outboard and lowering it in case
of emergency is greatly reduced below what is required with present devices,
and the danger of capsizing the boat or dropping the passengers into the sea
is reduced to a minimum, because the drum always lowers the boat on an even
keel, and in no circumstances can the boat suddenly fall to the sea, the apparatus
being so designed, that if the sailors who are lowering away should cease their
attention to the apparatus the boat will hang suspended from the davits, until
some one manipulates the operating chains, which can be easily done by a
passenger without previous experience.
Referring to the drawings which accompany the specification to aid the
description;
Fig. 1 is a longitudinal elevation of the apparatus with life boat, and
Fig. 2 is an elevation of the left hand davit as seen from the right;
Fig. 3 is an elevation on large scale of the drum and clutches, the latter
being in the position for revolving the left davit and leaving the drum
stationary;
Fig. 4 is an elevation from the left of Fig. 3;
Fig. 5 is an elevation of the worm gear for revolving the right hand davit.
a and are the davits, the life boat, and d, e and f the framing. With
the worm gear i, which is keyed on davit a, meshes the worm j, fixed on
shaft, on which is the loose pinion 1, provided with the clutch face m and
meshing with pinion n, which is formed integral with or secured to the chain
wheel or sprocket p, which is loose on shaft g, o being a clutch face on pinion n.
Clutches, respectively sliding on and turning with shafts and g, are
connected in any usual manner with lever . When said clutches r, u, are in
the position of Fig. 3, the operation of sprocket wheel p, as hereinafter described,
will revolve worm j and turn davit a, but when lever w is thrown to the other
position, said sprocket wheel p will revolve shaft q and that the drum 29 which
operates the fall and tackle of the life boat, the gearing between shaft
said drum 29 being hereinafter described.
and
Bevel gear on said shaft 7 meshes with bevel geary on the shaft of the
worm 2, which worm meshes with worm gear 2 on drum 29. The periphery
of drum 29 is preferably grooved in the usual manner, and has wound on it two
tackles s, t, one for each end of the life boat, so that in raising or lowering
the boat both ends necessarily remain at the same level, and the capsizing of
Price 77

page_text: the boat or the dropping of the passengers into the sea through the sudden
descent of one end, is averted. Said tackles s, t, are guided by suitable sheaves,
as 3, 4, 5, 6, 7, to and partly around blocks 10, 10, respectively on davits a, b,
and to the ends of the boat, where they are secured in the usual manner.
On davit is the worm gear 11, with which meshes worm 12, fixed on the
shaft 13, on which is also fixed the chain or sprocket wheel 14. Sheaves 7, 7,
are preferably arranged to slide on their shafts as seen in Fig. 3.
Endless sprocket chains 15, 16, respectively going partly around said sprocket
wheels and 14 are guided by suitable sheaves 17, 18 up to and partly around
sprocket wheels 19, 20, respectively fixed on the outer ends of shafts 21, 22,
which are respectively carried by davits a, b. Respectively fixed on the inner
ends of said shafts 21, 22 are sprocket wheels 23, 24, provided respectively with
endless chains 25, 26, which descend into the boat, and chain 25 is long enough
to admit of being operated from the boat when at the level of the sea. Chain 26
need, however, only be long enough to reach down into the boat, as it is used only
in turning davit b. Said shafts 21, 22, are preferably carried in boxes which
are respectively pivoted on the davits at 27, 28, so that the strain of chains 25, 26
will raise the outer ends of said shafts, and tighten chains 15, 16, on sprockets 1,
and 14.
The operation is as follows:
Suppose it is desired to lower the boats from the position of Fig. 1, all the
passengers and crew except one sailor for each pair of davits go into the boats.
Now the sailors left on the ship throw levers w to the position of Fig. 1,
(if indeed the apparatus is not normally left in that position), and the sailors in
the end of the boat which is suspended from davit 6 begin pulling on chain 26
in the direction for moving davit 6 outboard. Shaft 22 with sprocket 20 being
thus revolved, sprocket 14 and worm 12 are also revolved causing davit b
to turn outboard. At the same time the sailors in the other end of the boat may
pull sprocket chain 25 to turn davit a a little to the left to case the strain on
the boat tackles. When davit is at the quarter the sailors at said other end
of the boat reverse their pull on chain 25, thereby ultimately revolving sprocket p,
pinions n, 1, worm j and davit, a in the reversed direction. Both davits are
now continued to be revolved until davit & comes full outboard, when the sailors
at chain 26 cease pulling and davit b stops at the outboard position. The sailors
at chain 25 continue pulling until davit a is outboard. At this position the
sailor on the ship throws lever so as to engage clutch with clutch face n,
and then gets into the boat. Now the sailors continue pulling chain 25 as
before, and drum 29 revolves in such direction as to lower the boat evenly to
the water. When at the sea level the tackles are disconnected in the usual
manner.
To raise the boat, lever wis first thrown to the same position by sailors on
the ship as for lowering away, and then sailors, by pulling chain 25 in the
reverse direction to that for lowering, revolve drum 29 so as to wind up the
tackles and raise the boat steadily and evenly to the position of Fig. 1. Now
a sailor on the ship throws clutch lever w to the position of Fig. 1, disconnecting
the drum and connecting worm j, and the sailors, at chain 25 pulling as for
raising the boat, revolve davit a back to the inboard position. When davit a
is at the quarter, the sailors at chain 26 begin pulling the reverse of what they
did before and revolve davit 6 inboard, returning the boat to the position of
Fig. 1.
The pitch of worm z is so flat that the loaded boat will hang without revolving
the drum 29, so that there is no danger of the boat's falling suddenly to
the water, and the friction between the gear 2 and the worm is increased by
making the threads of the worm and teeth of the gear very deep, thereby increasing
the frictional surface.
The aforesaid frames d, e, which carry the drum, worms, gears, clutches and
other parts for raising and lowering the boat and operating the left hand davit

page_text: are preferably formed as one or so fastened together to constitute one frame,
and the base g, thereof, is of such size and shape and so provided with a flange h
that it will fit against the ship's sides,' above the channels v, and be readily
bolted to said sides, and the frame f for worm and other parts which operate
the right hand davit is similarly provided with base and Hange to fit against
the ship's sides above the channel v. This construction, by which all the
mechanism for each davit is arranged on a single frame adapted to the ship,
has great practical advantages, in that it allows all the parts to be assembled on
the frames in the shop, brought to the ship ready and put up with the minimum
of work at the ship.
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
I claim is:―
1. The combination in a ship's davit apparatus, of the davits and boat tackles,
a drum for operating said tackles, and means operated from a life boat for
actuating said drum, substantially as and for the purpose described.
2. The combination in a ship's davit apparatus, of a davit, worm gearing for
turning the davit, a drum for operating the boat tackles, a sprocket wheel adapted
to be operated from the life boat, and clutches adapted to put either said worm
gearing or said drum in operative connection with said wheel, substantially as
described.
3. The combination in a ship's davit apparatus, of a davit, a shaft carrying a
sprocket adapted to be operated by a chain from the life boat, and also a sprocket
adapted to drive a chain leading to the ship, a sprocket driven by said last
named chain, worm gearing for turning the davit, a drum for the boat tackles,
worm gearing for driving the drum, and clutches for placing the worm gearing
for the davit or the worm gearing for the drum in operative connection with
said last named sprocket, substantially as described.
4. In a ship's davit apparatus, the combination with a drum for operating boat
tackles, a gear thereon, and a worm meshing with said gear and having such low
pitch and deep thread that the weight of the loaded boat will not cause the
drum to revolve, substantially as and for the purpose described.
5. The combination in ship's davit apparatus, of a sprocket adapted to be
driven by chains from the boat, a sprocket adapted to drive a chain for actuating
davit-turning and boat-raising devices, and a shaft on which said sprockets are
fixed arranged to oscillate about a point between said sprockets, substantially as
and for the
purpose described.
6. In ship's davit apparatus, framing carrying devices for turning a davit and
raising and lowering a boat and adapted to be fixed to a ship adjacent to the
davits, substantially as described.
1 1
1000
CRUIKSHANK & FAIRWEATHER,
Chartered Patent Agents,
62, Saint Vincent Street, Glasgow, Agents for the Applicant.