IMPROVEMENTS IN SAFETY APPARATUS FOR LIFTS OR ELEVATORS.
Year: 1882

page_text: LETTERS PATENT to Alexander Melville Clark of 53, Chancery Lane, in the
county of Middlesex, Patent Agent, for an Invention of IMPROVEMENTS
IN SAFETY APPARATUS FOR LIFTS OR ELEVATORS. A communication from
abroad by James McCarroll, of the city county and state of New York,
United States of America.
PROVISIONAL SPECIFICATION left by the said Alexander Melville Clark at
the Office of the Commissioners of Patents on the 21st February 1882.
ALEXANDER MELVILLE CLARK of 53 Chancery Lane in the County of Middlesex,
Patent Agent.
"IMPROVEMENTS IN SAFETY APPARATUS FOR LIFTS OR ELEVATORS
[A communication from abroad by James McCarroll, of the City County and
State of New York, United States of America.]
"
The object of this Invention is to prevent the falling of the cages of lifts or
elevators in the event of breakage or other accident to the ropes or chains by
which the cages are suspended, and the Invention consists in self acting stop
mechanisin held out of action by the rope until the latter being slackened from any
cause, the mechanism is released and arrests the cage.
According to this Invention, the rope by which the cage is suspended passes over
guide pulleys set in a cross beam at the top of the well and off in a nearly
horizontal direction at one side to the winding drum passing through an aperture
in a box which is suspended by a spring from a fixed support and fitted with a
pulley for the rope to run over. Dogs or latches are pivoted upon or within
recesses in the side posts or guides for the cage, and are connected together nt
their outer ends by ropes or chains that pass over guide rollers to the box with
which the ropes or chains are connected, and the cage is furnished with lugs or
projections at each side forming a rack in front of the dogs.
:-
The parts described constitute the automatic safety stop operating as follows:-
By the tension of the rope by which the cage is suspended, the box is retained in
its lowest position with its spring distended and the ropes or chains of the dogs
being thus slackened, the dogs fall by gravity to their norinal position, that is to

page_text: say, their inner ends are withdrawn from the path of the lugs on the cage. If the
suspension rope breaks or is slackened, the box is released and is instantly drawn
upward by its spring, thereby drawing up the chains and throwing the inner ends
of the dogs into the path of the lugs on the cage and at once arresting the cage.
This occurs at any point in the travel of the cage at which it may be. Springs
may be interposed in the chains or ropes of the dogs to prevent undue strain and
consequent risk of snapping the ropes should the dogs drop directly against the
lugs. The dogs when in operative position take against shoulders on the uprights
or guides so that the strain is taken from the pivots of the dogs.
As an additional safeguard, I provide for bringing the dogs into operative
position by means on the cage at the hands of the passengers. To this end the
cage is fitted with a vertical tube through which passes a rope or chain that
extends from top to bottom of the elevator well. At the top the rope is connected
to the ropes of the dogs at suitable points-and the tube is fitted with an eccentric
lever whose outer end is in position for being grasped by a person in the cage to
force the eccentric against the rope in the tube and thus clamp the rope. The ropo
being thus drawn on as the cage moves down the dogs are moved into position for
engaging the lugs on the cage.
The dogs may be connected by a rigid bar or rod, and the ropes or chains
connected to the bar and the lugs on the cage instead of being placed at intervals,
may be arranged as a continuous rack.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Alexander Melville Clark in the Great Seal Patent Office on the
21st August 1882.
"
ALEXANDER MELVILLE CLARK of 53 Chancery Lane in the County of Middlesex,
Patent Agent "IMPROVEMENTS IN SAFETY APPARATUS FOR LIFTS OR ELEVATORS.”
A cominunication from abroad by James McCarroll of the City, County, and
State of New York, United States of America.
The object of this Invention is to prevent the falling of the cages of lifts or
elevators in the event of breakage or other accident to the ropes or chains by
which the cages are susponded, and the Invention consists in self acting stop
mechanism held out of action by the rope until on the latter being slackened
from any cause the mechanism is released and arrests the cage as hereinafter
described.
The Invention is illustrated in the accompanying drawing which is a sectional
elevation of a lift or elevator provided with the improved devices. A is the
elevator cage or carriage constructed in any usual form. B B are upright posts or
columns between which the cage moves and by which it is guided in the usual
manner. C is a cross beam at the top of posts B from which the cage is suspended
by a rope d. The rope d attached to the cage passes over guide pulleys e e
and off in a nearly horizontal direction at one side to the winding drum, being first
led through an aperture in a box E suspended by a spring f from a fixed support g
and fitted with a pulley k upon which the rope & travels. F F are dogs or latches
pivoted upon or within recesses in posts B and connected together at their outer
ends by ropes or chains i that pass over guide rollers k k to the box E with which
the ropes or chains are connected. G are lugs or projections on the cage A forming
a rack in front of the dogs F.
h
The parts described constitute the automatic safety stop operating as follows:-
By the tension of rope d the box E is retained in its lowest position with its
spring f stretched and the ropes or chains i being thus slackened, the dogs F fall
by gravity to their normal position, that is to say, their inner ends are withdrawn
from the path of lugs G on the cage. If however the suspension rope breaks or is
slackened from any cause, the box E is released and is instantly drawn upward by
the spring, thereby drawing up the chains and moving the inner ends of dogs F
into the path of lugs G so as to cause the latter to take upon the dogs F and at
once arrest the cage. This occurs at any point in the travel of the cage at which
it may be. Springs may be interposed in the ropes i as shown at 7 to prevent
undue strain and consequent risk of snapping the ropes, should the dogs F drop
directly against the lugs G. The dogs when in operative position take against
shoulders on the posts B as shown in dotted lines so that the strain is taken from
the pivots of the dogs. As an additional safeguard I provide for bringing the dogs
into operativo position by means on the cage at the disposition of the passengers.
To this end the cage is fitted with a vertical tube m through which passes a rope
or chain n that extends from top to bottom of the elevator well. At the top the
rope n is connected to the two ropes i at suitable points and the tube m is fitted
with an eccentric lever o whose outer end is in position for being grasped by a
person in the carriage to force the eccentric against the rope n in the tube and thus
clamp the rope. The rope being thus drawn on as the carriage moves down, the
dogs F are moved into position for engaging the lugs G. The dogs F may be
connected by a rigid bar or rod and the ropes or chains i be connected to the said
bar, and the lugs G instead of being placed at intervals as shown, may be arranged
as a continuous rack.

page_text: It is evident that the character and position of the safety spring and the method
of bringing the tension of the hoisting rope to bear, may be greatly varied without
departing from the Invention, and that many equivalent devices may be
substituted for the cam to obtain a grip on the safety rope.
Having described the nature of the said Invention and the manner of performing
the same, I declare that what I claim as the Invention to be protected by the
hereinbefore in part recited Letters Patent is.
1st. The arrangement of dogs or latches at the sides of an elevator shaft or
frame for engaging the cage or carriage and connections therefrom to a spring
actuated device for moving the dogs into their operative position, these being
combined with the main hoisting rope in such manner that the tension of the rope
by the weight of the suspended cage or carriage retains the dogs out of contact,
substantially as shown and described.
2nd. The combination of the auxiliary rope extending through the elevator
cage and a gripping device on the cage with the safety dogs or latches, substantially
as shown and described.
In witness whereof I the said Alexander Melville Clark have hereunto set
my hand and seal this twenty first day of August, A.D. 1882.