Improvements in and relating to Davits for Raising and Lowering Ships' Boats
Year: 1888

page_text: Date of Application, 14th Aug., 1888
Complete Specification Left, 11th May, 1889-Accepted, 29th June, 1889
PROVISIONAL SPECIFICATION.
Improvements in and relating to Davits for Raising and Lowering
Ships' Boats.
I; WILLIAM VINCENT SHAW of Stonefield Cottage, Hawick, do hereby declare the
nature of this invention to be as follows:-
This invention is a development of the improvements relating to davits for
suspending ships' boats described in the Specification of Letters Patent number 8673
of 1886 granted to me; and it comprises improvements in the construction of the
davits and in means for locking or securing them with the boats suspended either
on board or outside of the ships' bulwarks.
The davits which are preferably straight are keyed or fixed upon a shaft carried
longitudinally within the bulwarks so that both davits may be swung simultaneously
through an arc carrying the boats with them from over the deck to a point at
some distance outwards from the ships' side. On the side of each davit is secured
parallel with the davit a spindle having on it a toothed pinion in gear with a
segmental rack formed on an upright or support to which is or may be connected
blocks and tackle for raising and lowering or swinging the davits and when the
davits are swung the pinion on each davit engaging the rack may be locked to
prevent it turning and thus secure the davits in a vertical position or at any
inclination, by means of a sliding bolt fitted on the side of the davit and adapted
to enter between the teeth of the pinion or of a separate pinion on the same
spindle:
Over the upper end of each davit is fitted a tubular piece on which is fitted or
formed a bracket carrying a series of sheaves over which pass the ropes of the boat
raising and lowering tackle, the said ropes being carried round guide pulleys within
the davits, which are tubular, to the winding drums which may be arranged as
described in the Specification before referred to; and the tubular end piecès carrying
the sheaves are free to turn on their axes to the extent of about a semi-revolution
so that the boats may hang fairly from the davits both when the latter are swung
outwards and inboard.
To provide for more or less rapidly lowering the boats from the davits each
pair of the winding drums is provided with a double brake consisting of a strap
or straps extending over the spindles of the drums and passing under or attached
to a block which is acted on by a nút on a screw shaft carried vertically between
the drum spindles. Each nut is or inay be made in the form of a hand wheel so
that it may be freely turned by hand to bring more or less pressure on the brake
strap block and permit the more or less rapid unwinding of the suspension ropës
from the drums when the retaining pawl or catch is released.
Dated this Thirteenth day of August 1888.
CRUIKSHANK & FAIRWEATHER,
62, Saint Vincent Street, Glasgow, Agents.
COMPLETE SPECIFICATION.
1 Improvements in and relating to Davits for Raising and Lowering
Ships' Boats.
I; WILLIAM VINCENT SHAW of Stonefield Cottage, Hawick, do hereby declaré
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 is a development of the improvements relating to davits for
suspending ships' boats described in the Specification of Letters Patent number 8673
ID 1

page_text: of 1886 granted to me and it comprises improvements in the construction of the
davits and in means for locking or securing them with the boats suspended either on
oard or outside of the ships bulwarks, and brake mechanism in conjunction with
the said davits.
On the accompanying drawings Figure 1 is longitudinal elevation and figure 2
an end elevation of the improved davits constructed in accordance with my present
invention, figures 3, 4 and 5 being detailed views of parts of the apparatus drawn to
a larger scale and hereinafter more particularly referred to.
As shewn by these figures the davits A which are preferably straight and circular
in cross section excepting at their lower ends are so keyed or fixed upon a shaft B
carried longitudinally in bearings C within the bulwarks that both davits are swung
simultaneously through an arc thereby carrying the boats evenly with them from
over the deck to a point at some distance outwards from the ship's side. The
keying of the davits to the shaft B is or may be effected by grooving the shaft
and the inner parts of the lower ends of the davits and inserting a feather or key
in the said grooves as indicated at D figure 3. The shaft B may be made in one
piece or as indicated at E figure 1 it may be made in two or more pieces coupled
together for greater convenience in withdrawing it from its bearings when necessary.
Where it passes through the lower ends of the davits A the shaft has a series of
pulleys F, fig. 3, strung loosely upon it these pulleys acting as bearing pulleys for
the boat hoisting and lowering chains or ropes when the davits are vertical or
swung outboard. In close proximity to the pulleys F a like series of pulleys are
centred loosely on a short shaft carried in the lower part of each davit as seen at F
acting as bearers for the hoisting and lowering ropes or chains P when the davits
are swung inboard. The opposite or outer cheek of the lower end of each davit to
that keyed to the shaft B has formed on or secured to it a toothed segment as indicated
at G figure 4 in conjunction with which there is provided a clutch H having two or
three teeth at its inner end. The said clutches slide in a recess in the brackets G¹,
Figure 1, and they are connected to screws I on whose outer ends hand wheels J are
keyed and by turning which the teeth of the clutches are entered or withdrawn from
between the teeth of the segments G. The upright columns G¹ have connected to
them blocks K, L, the blocks L being hooked to the davits A and by hauling on or
paying out the tackle M provided with the said blocks the davits are raised or
lowered the davits being secured in any desired position by entering the clutches H
into the segments G and by making the tackle M fast. The clutch mechanism being
intended as auxiliary to the said tackle.
Over the upper end of each davit A is fitted a tubular piece A¹ on which is
formed or secured a bracket N carrying a series of sheaves 0 over which pass the
ropes P, of the boat raising and lowering tackle, the said ropes being carried round
guide pulleys within the davits, which are tubular, as under my said previous patent
and also round pulleys S, Fig. 1. to winding drums T, Fig. 2. which may also be
arranged as described in the Specification before referred to. The tubular end pieces
or heads A' carrying the sheaves O are braced together by a tie rod Q and they are
free to turn on their axes to the extent of about a semi-revolution so that the boats
may hang fairly from the davits both when the latter are swung outwards and
vertically or inboard.
To provide for more or less rapidly lowering the boats from the davits each pair of
the winding drums T is provided with a double brake consisting as seen at figure 5
of straps U extending over the spindles R of the drums and passing under or attached
to a block V which is loose upon a screw W but is acted on by a nut a on the said
.screw. The screw is carried vertically between the drum spindles R, and each nut
is or may be made in the form of a wheel so that it may be freely turned by hand
to bring more or less pressure on the brake strap block V and permit the more or
less rapid unwinding of the suspension ropes P from the drums T when the retaining
pawl or catch Y is released. To prevent the blocks V from turning with the nuts ✗
the screw W has or may have a vertical slot into which a pin fixed in each block V
enters.

page_text: Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
1. The general arrangement and combination of parts constituting the improved
davits hereinbefore described and shewn on the accompanying drawings.
2. In ship's davits connecting each davit of a pair to a shaft at its lower end and
providing the outer ends with swivelling or movable heads braced together substantially
as and for the purposes hereinbefore described with reference to the drawings
annexed.
3. In conjunction with ship's davits the improved locking mechanism for retaining
the davits in any desired position substantially as set forth with reference to the
appended drawings.
4. In conjunction with winding apparatus for ships' davits the improved brake
mechanism hereinbefore described with reference to the accompanying drawings.
Dated the Tenth day of May 1889
CRUIKSHANK & FAIRWEATHER,
62, Saint Vincent Street, Glasgow, Agents.