Improvements in Cranes of
Year: 1895

page_text: I, NATHANIEL SHEPARD KEITH of The Sandycroft Foundry and Engine
Works, Hawarden in the County of Chester, Electrical Engineer, do hereby declare
the nature of this invention to be as follows:-
In lifting and moving masses of iron and steel such as billets, bars, rails, girders
plates and the like much time and labour is expended in raising the article
sufficiently to pass a chain around it in order to attach it to the lifting hook.
According to this invention this difficulty is overcome by utilising the well known
attractive force of a magnet.
For this purpose the hook at the end of the lifting chain is replaced by an
electro-magnet. The current is supplied to the coils of the magnet from any
convenient source of electricity by means of wires which support a pulley and
weight so that they are always kept tight. Or the wires may be wound on a drum
or drums after well known ways.
Two switches are preferably provided one within reach of the man in charge of
the crane or hoist and the other near the magnet.
1002
Improvements in Cranes of
1, NATHANIEL SHEPARD KEITH, of The Sandycroft Foundry and Engine
Works, Hawarden, in the County of Chester, Electrical 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:
In lifting and moving masses of iron and steel such as billets, bars, rails, girders,
plates and the like much time and labour is expended in raising the article
sufficiently to pass a chain around it in order to attach it to the lifting hook.
According to this invention this difficulty is overcome by utilising the well known
attractive force of a magnet.
For this purpose the hook at the end of the lifting chain is replaced by an electro
magnet. The current is supplied to the coils of the magnet from any convenient
source of electricity by means of wires which support a pulley and weight so that
they are always kept tight. Or the wires may be wound on a drum or drums after
well known ways.
Two switches are preferably provided one within reach of the man in charge of
the crane or hoist and the other near the magnet.

page_text: DESCRIPTION OF THE DRAWINGS.
Figure 1 is a side elevation and Figure 2 a front elevation of a crane constructed
according to my invention. This crane is an electric crane but it will be understood
that the invention is equally applicable to other cranes and hoists.
Figure 3 is a section showing the lifting gear.
A is an electric motor driving the loose spur wheel B and also the worm wheel D
by means of a pinion and worm respectively, fixed on the motor shaft.
B is a spur wheel gearing into the pinion fixed on the shaft of the motor A, and
running loosely on shaft a Figure 3 and having a suitable bearing surface d on the
shaft of a non-magnetic substance such as brass, Babbitt's metal or the like.
The wheel B is made of a magnetic metal such as cast iron, wrought iron or steel,
and on C becoming magnetised will instantly form a magnetic armature to C.
C is an electro-magnetic clutch.made of a magnetic metal, keyed on the shaft a
having a coil of insulated copper wire b, the ends terminating and being electrically
connected with rings c, el of some suitable metal, such as brass, copper, etc.
The metal rings are insulated from one another and from C, but are accessible
to electric conducting sliding contact brushes e, which have a current conveyed
to them from the switchboard H by suitably insulated copper wires, and so
through to coil b. On a current of electricity being passed through coil b, C will
become an electro-magnet having poles e and f. C becoming magnetised, B will
revolve by having a magnetic contact with C through the driving cones at e and
will continue to revolve until a strain, something under the breaking strain of the
teeth, causes the friction surfaces to slide. The angle of the cone at e is such,
that the surfaces will readily disengage on C becoming de-magnetised.
D is a worm wheel, geared into the worm fixed on shaft of the motor A,
attached to a double sided electro-magnetic clutch of same construction as C but
duplicated, having armatures E and F running loosely.
EF are armatures to D attached to any suitable mechanical arrangement having
for its object the slewing of the crane, or if E and F have hubs around which a
chain may pass and also passes around the pillar of crane, and attached to it
in such a manner that if E, side of clutch D be worked the chain winding on
the hub of E will turn the crane in one direction and unwind chain on F but if F
be worked, the chain winding on hub of F will turn the crane in the opposite
direction and unwind chain on E.
These details form no part of the present invention.
G is the lifting electro-magnet for lifting magnetic substances, and consists of two
pole pieces and a yoke of soft iron, also a suitable bow for fixing it to the crane chain.
A hook may be fixed underneath the bow so that the magnet need not be
removed when required to work with slings &c. The cores of magnet are wound
with insulated copper wire g the whole being suitably insulated and protected.
A suitable switch may be fixed on the maguet G itself and at the crane switch-
board H or any convenient place.
k is a flexible twin insulated wire to connect G with H, k being completely
insulated from the framework by wheels of some insulating substance such as wood,
porcelain, etc., and kept taut by the loose pulley and weight m.
H is the crane electric switchbbard of some high resistance material such as slate,
marble wood, etc. It contains a main switch, resistance switch for resistance coils K
governing motor A, lifting switch that works C, 2 way slewing switch which may
work either E or F, also it may contain a switch to work G if desired.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed 1 declare that what I
claim is :-
1. In cranes or hoists the combination with the lifting chain or rope, of an
electro-magnet for taking hold of the load.

page_text: 2. In cranes or hoists the combination of the lifting chain or rope, an electro-
magnet for taking hold of the load, a wire passing from the source of electricity
to the magnet over pulleys on the frame and means for taking up slack in
the wire.