Improvements in Hoists for Supplying Ammunition to Guns, and for other purposes.
Year: 1896

page_text: Date of Application, 12th Mar., 1896-Accepted, 25th Apr., 1896
COMPLETE SPECIFICATION.
Improvements in Hoists for Supplying Ammunition to Guns, and
for other purposes.
We, Lieutenant-Colonel Sir GEORGE SYDENHAM CLARKE K.C.M.G. and
GEORGE HENRY BANISTER, Civil Engineer, both of The Royal Arsenal,
Woolwich, in the County of Kent, 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 hoisting apparatus actuated by an electric motor,
which is utilized also as an automatic brake to control the action of the apparatus
in the lowering of the cage. The said hoisting apparatus may be constructed to
serve for hoisting ammunition to guns on ships or elsewhere or it may be adapted
for other purposes.
The accompanying drawings illustrate the application of the said invention for
the purpose of an ammunition hoist.
Figure 1 is a side elevation of the hoist.
Figure 2 is a rear elevation.
Figure 3 is a sectional plan of the same.
Figures 4 to 8 illustrate on an enlarged scale the switch connections and apparatus
by which the electric motor is made to serve as a brake when required. Figure 4
being a longitudinal section, Figure 5 a plan with the cover removed, Figure 6
a plan of the cover, Figure 7 a transverse section on the line 1. 1 Figure 4, and
Figure 8 an end view.
a is the hoisting barrel, which is provided with a helical groove about its
periphery for the reception of a wire rope f which passes from this groove
downward to a pulley c, then ascends the trunk A of the hoist and passes
over another pulley to the cage or carrier which is suspended from the wire
rope.
The hoisting barrel a is carried on a shaft d to which it is normally made fast
by an arrangement of friction plates such as that shewn at e Figure 3. An
ordinary clutch is fitted to slide freely on the shaft d but is compelled to rotate
with the latter; b is a worm-wheel and is a spur wheel both being loose on the
shaft d but, by means of the hand-lever m mounted on the shaft m¹ carrying a
fork m², the clutch / may be at any time caused to gear with the worm wheel b
or the spur wheel 1, so as to bring either of these wheels into rotative connection
with the shaft d and the hoisting barrel a.
When the spur wheel 1, is thus coupled to the barrel a it forms with the
pinion g and winch-handle k a system of gearing for working the hoist by hand.
For electric driving the worm-wbeel b is coupled by the clutch h with the
shaft d so that it will rotate with the barrel ar The worm wheel b is also geared
by the worms and bevel wheels with the clectric motor p which is included in
the circuit (which we term the main circuit) of any suitable source of electricity.
The armature of the motor is rotated by the electric current in the main circuit
and rotates the hoisting barrel a thereby winding the wire rope f into the helical
groove on the barrel and raising the cage or carrier. When the hoisting of the
cage is completed the main current is automatically cut out by an ordinary switch
not shewn in the drawings.

page_text: The worms is preferably supported on a ring of balls forming a ball bearing;
the said worm is therefore capable of turning very freely about its axis and the
weight of the cage with or without its load, when pendent by the wire rope f
from the hoisting barrel a, is sufficient to turn the barrel backward and so cause
the worm wheel b to rotate the worm and thereby reverse the action of the electric
motor p.
In order to prevent the premature lowering of the cage we provide the following
means, that is to say the shaft t of the worm s is prolonged at t and at its upper
end is geared by bevel wheels t2 to a transverse shaft which is provided with an
automatic retaining clutch handle r. This shaft is carried in a bearing o in
which the said shaft rotates; this bearing is provided on one side with a neck or
prolongation which is screw-threaded externally and on which the clutch handle r
has its boss fitted as a screw-nut on its bolt. The clutch handle r is so arranged
relatively to the screw-threads that the said handle, tending always by its weight
to move in a downward direction from the position shewn in Figure 1, is thereby
tightened against the adjacent face of the collar ' fixed on the shaft b', the said
shaft being thereby locked and held fast to its bearing. The clutch handle is so
arranged that when the barrel a is rotating in the hoisting direction there is a
tendency to raise the said handle and release the shaft from the clutch, while
when the barrel a is reversed in direction, for lowering the cage, there is a
tendency to turn the clutch handle downward thereby keeping the gearing locked.
The gearing can however, be immediately released by raising the clutch handle
by hand, when it is desired to lower the cage, the handle being then retained in
its raised position by a spring catch. The above described retaining clutch is the
device we prefer to use, but a ratchet wheel and pawl or other convenient means
may alternatively be used for the same purpose.
The arrangement by which the armature of the electric motor p is rapidly
rotated in the reverse direction during the lowering of the cage, allows us to
utilize the said motor as a dynamo-electric brake for bringing the cage safely to
rest at the bottom of the hoist. For this purpose the terminals of the electric
motor are connected in a short circuit, with or without means for increasing or
diminishing the electric resistance therein, so that the energy of the descending
cage is absorbed in the work of generating electricity.
If so desired the electric motor p may remain short-circuited as above described
during the whole period of the descent of the lift, but preferably, in order to
reduce the time of lowering the cage, an automatic switch such as that shewn in
Figures 4 to 8 is inserted in the short circuit between the terminals.
The object of the introduction of this switch is to permit the armature to be
freely rotated by the descending cage and allow the latter to freely fall until near
the end of its descent, when the short circuit is closed and starts the brake action
of the electric motor by permitting the said motor to work as a dynamo-electric
machine, the short circuit being finally re-opened by the switch as the cage comes
to rest.
The said switch is constructed and arranged as follows, that is to say, it has a
stationary spring-plate w connected to the frame of the hoist, and a box z, with
a slider v. The box is capable of moving freely along the shaft y, this
movement being imparted to it during the rotation of the barrel a by means of a
bara which projects from the box z towards the hoisting barrel and is so
arranged that its curved portion lies in the helical groove about the said hoisting
barrel.
Electric communication can be established between the slider v, the contact
piece 9 on the box 3 and the terminals of the aforesaid electric motor.
In the descent of the cage or carrier the bar a is moved by the helical groove,
across the periphery of the hoisting barrel a, thereby causing the switch box z to
travel toward the left side of Figure 4, the cage falling freely until a projection or
projections p, on the slider v meet a projection or projections won the spring-
plate w. The movement of the slider v to the left is then arrested, while by the

page_text: continued movement of box the slider is brought into metallic connection with
the contact piece q thus closing the short circuit through which an electric current,
generated by the rapidly rotating armature of the electric motor, then passes and
canses the required brake action of the motor for stopping the descent of the cage.
The above described relative movement of the box and the slider v will then
have compressed the spring between the end of the slider and the block =
which is fixed to the switch box =.
The continued movement of the switch box to the left further compresses the
spring until the end of the spring plate w coming into contact with an incline
or sloping rib on the contact piece y and riding up the same, releases the-
projections won the spring plate to from contact with the projections p on the
slider e; the latter, therefore, being no longer held, immediately resumes its normal-
position in the switch box z, under the action of the spring and electrical
connection between the terminals of the electric motor is instantly and automatically
interrupted as the cage comes to rest.
The above described switch is very advantageous for our purpose but as an
alternative method the switch box may be actuated by a screw or other device
coupled to the hoisting barrel a; or the arrangement in either of the above.
described methods may be reversed, the switch box being held at rest and the-
spring plate forming the moving part.
Moreover as an alternative arrangement for controlling the movement of the
enge in its descent, the aforesaid friction plate clutch (Figure 3) may be so
arranged that the barrel a can be coupled to or released from the shaft d at will,
by means of the hand wheel e' which is screw threaded and acts as a nut on a
screw-threaded portion of the shaft d. A slight movement of the wheel in the
required direction will put on or take off the pressure of the friction plate clutch e
so that at any time the same may be readily adjusted to release the birrel thereby
leaving it free to rotate by the weight and descent of the cage. Ordinarily the-
wheel is used for tightening the above described clutch e and is not afterwards
interfered with,
The trunk A is provided with doors at its upper and lower ends, throngh the
former of which doors the ammunition is removed from the cage, and through the
latter is inserted into the cage. The lower door is furnished with a fastening
device which is so arranged in connection with the main circuit that when this door
is opened the circuit is broken, but made again when the door is closed.
The cover illustrated in Figure 6 has a longitudinal slot e therein in which a
projection on the spring arin w works. This projection may have a pointer
thereon which, in conjunction with a scale adjacent to the said slot, will by its
movements indicate the position of the cage in the trunk.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed, we declare that what we
claim is :-
1. In a hoist such as that herein described the employment of a dynamo or
magneto electric-apparatus arranged to serve alternately as a motor and as a brake
for the purposes specified.
2. In the said hoist the electric motor supplied with current from any suitable
source of electricity for operating the hoisting barrel to raise the cage and so
arranged in connection with the said barrel and with a short circuit including a
switch that its action will be automatically reversed in the descent of the cage for
the purpose specified.
3. In combination with the gearing whereby the barrel is connected with the
motor, the clutch constructed substantially as described so that it acts automatically
to lock the gearing and thereby prevent the premature descent of the cage.
4. The automatic switch constructed substantially as described with reference to
Figures 4, 5, 6, 7 and 8 and arranged to be operated by devices in connection with
the hoisting barrel substantially as and for the purpose specified.

page_text: 5. A hoist comprising the mechanical apparatus and the electrical arrangements
combined and arranged substantially as described with reference to the accom-
panying drawings and operating as set forth for the purposes specified.
Dated this 12th day of March 1896.
HASELTINE, LAKE & Co.,
45 Southampton Buildings, London, W.C., Agents for the Applicants.