Improvements in Safety Brakes for Elevator Cars.
Year: 1896

page_text: Date of Application, 5th May, 1896-Accepted, 13th June, 1896
COMI DEIE NIEUITICATION
[Communicated from abroad by THOMAS JEFFERSON VAIL, of Hartford, in
the County of Hartford, State of Connecticut, United States of America,
Gentleman.]
Improvements in Safety Brakes for Elevator Cars.
I, WILLIAM PHILLIPS THOMPSON, F.C.S., M.I.M.E., of The Agency for
Foreign Patent Solicitors, 322, High Holborn, in the County of Middlesex,
6, Lord Street, Liverpool, and 6, Bank Street, Manchester, both in the County of
Lancaster, and Lower Temple Street, Birmingham, in the County of Warwick, Civil
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 :-
My invention relates to improvements in safety brakes for elevator cars, and
consists in a novel combination of brake mechanism and compound levers for
operating the same on occasion and clamping the brake shoes powerfully to the
guide rails on which the car traverses, in conjunction with a rope, cord or chain
ordinarily moving with the car but controlled by a governor and trip and clamp
mechanism which only operates when an accident occurs to greatly accelerate the
motion of the car. The said governor and stationary trip and clamp mechanism
I have illustrated and described for the sake of perspicuity, but my claims to
invention are herein confined to the brake mechanism borne on the traversing car.
In the accompanying drawings forming a part of this Specification, I have
shown in
Figure 1 a side view of my improvement.
Figure 2 is a plan view partly in section, and Figure 3 is an end view.
Figure 4 is a front view of the elevator car with the vertical guide posts and
guide rails or runners, showing my device secured beneath the car to the bottom
timbers thereof; also the running rope by which the safety device is operated.
Figure 4 is a view of a governor, trip and clamping device by which the safety
mechanism may be brought into action.
Figure 5 is a detail view of a convenient form of governor which may be
employed for the purpose.
Referring to Figures 1, 2, and 3 which illustrate my specific improvement,
B represents a portion of the elevator car, to the bottom timber A of which the
operating parts of my safety brake attachment are securely bolted on the under
side thereof. D, D are hollow head blocks firmly secured to the timber A, one at
each end, shown in section. e, el illustrate members of the compound clamping
levers, pivoted within the head blocks. G G', are the long lever members of the
compound clamping levers, also pivoted within the head blocks. f, f, are the brake
shoes, carried by the clamping plates e, e' and pivoted thereto. These brake shoes
engage with the vertical guide runners, and compress the same between their faces
when the safety device is called into operation. The faces may be grooved or
roughened to promote adhesion if desired. By the pivotal connection between the
brake shoes and the clamping members or short levers, the former are enabled to
adjust themselves in position to the vertical surface of the guide runners, so as to
secure contact of the entire surface.
f denotes a spring, the purpose of which is to keep the outer ends of the
clamping plates e e¹ away from each other when the lever J is in its normal
position.

page_text: J is another lever, firmly secured by a pivot bolt to the timber A at j. Its office
is to act upon and operate the long arms of the levers G G when itself operated
upon the rope r, which connects its long arm g with the governor and trip and clamp
mechanism. This action is conveyed through the medium of the short lever
arms m, n, which may be provided with anti-friction rollers kk, as shown, for the
purpose of reducing friction. S, S are two guide plates provided with slots as
shown in Figure 3, through which suitable securing bolts pass into webs s formed
on each head block. This enables them to be adjusted. v, w, are springs employed
to prevent the lever J from being accidentally operated by the check rope, and to
retain the levers in their normal position.
6 denotes a pin or bolt which drops down after the lever .J is drawn out as shown
in dotted lines Figure 2; the object of this construction is to prevent the lever J
from returning to its normal condition, if by any chance the rope r should
break after the operating lever J has been drawn out, as shown in said dotted
lines.
Referring to Figures 4 and 5, which are introduced merely for purposes of
illustration, to show an operative device, B is a front view of the elevator car,
showing my device attached to its bottom timbers. C, C are the vertical guide
posts, and C'C' the guide runners on which the brake shoes simultaneously operate
when in action. r is the running rope made fast to the car at one end, as at O,
Figure 4, passing downward over the tension sheave F and upward over the
governor pulley, and thence over pulley r to the long arm q of lever J, as shown
in Figure 2. The rope is thus seen to travel with the car under ordinary
circumstances, and has no special function until arrested in case of accident by the
operation of the clamp M. E is the upper framework of the building, supporting
the governor H and pulley attached, over which the rope r traverses. N is a
standard carrying a rocking trip 4, which may be of any convenient form, its office
being to sustain the rod L supporting the lever arm P and weight K until tripped
by the action of the governor H.
The operation of this portion of the mechanism, to which I lay no claim in this
application, is as follows: Upon the breaking of the main cable which supports
the elevator in its travels, the rope r, which travels with the elevator car, accelerates
the motion of the governor, which is so arranged that its accelerated movement
springs the trip 4, which in turn lets drop the rod Land with it the lever arm p and
weight K. This operates the clamp M, arresting the movement of the rope r, and
thereby causing a sudden pull with a force proportioned to the weight and momentum
of the car upon the lever J to which it is attached. This is communicated through
the compound lever system to the brake shoes f, to produce the desired effect.
The governor may be arranged to produce the trip in any well known manner to
cause the desired result. As I have shown it, for the purpose of illustration merely,
the weighted arms 2, 2, shown in Figure 5, are forcibly thrown outward against
the tension of the springs 3, 3 by the centrifugal force due to the increased
velocity, and in their expansion come into contact with the lever arm of the
trip 4, but this may be varied ad infinitum to suit the pleasure of the designer.
The specific operation of my device will now be described. When the travel of
the roper is suddenly arrested by the action of the governor and trip mechanism
as aforesaid, a strong pull is communicated to lever army of the lever J, to which
the said roper passing over pulley is attached, and this instantly moves the said
lever arm outwards against the tension of the spring v. Motion is thereby trans-
mitted through the chain of compound levers to the brake shoes f, f which are
simultaneously constricted towards each other, embracing the guide runners in
their jaws, and thus arresting the downward movement of the car.
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. In a safety brake for elevators, in combination with a running rope r,

page_text: controlled by a governor, trip and clamping mechanism, a compound lever system
comprising lever J having long arm g and short arms as m, n, levers G, G, clamping
levers e, e and pivoted brake shoes f, f, acting upon the guide runners C¹ C¹ to
clamp the same when operated by unusual stress upon the rope », substantially
as specified.
2. In a safety brake for elevators, the head blocks D, D, the clamping leverse, e¹,
pivoted within the said head blocks, brake shoes f, f, pivoted to the said clamping
levers, one on each side of the guide runners, lever J, having arms m, n, and q,
levers G, G¹, pivoted within the head blocks, having short arms acting in opposite
directions on the arms of the clamping levers e, e, long arms P, P, acted on in
opposite directions by the short arms m, n, of the lever J, and rope r, substantially
as specified.
3. In a safety brake for elevators, a pair of clamping levers as e, e', pivoted in
head blocks D, D, carrying brake shoes as f, f, pivoted thereto, which engage
with the guide runner, and compound levers acting upon the said clamping levers
to compress the brake shoes through the medium of a rope, cord or chain r, when
an unusual strain occurs upon the latter through the accelerated motion of the car
downwards, substantially as specified.
4. In a safety brake for elevators, the combination of head block D, adjustable
guide plates S, held to webs s, clamping levers e, e¹, carrying pivoted brake
shoes ff, lever G acting upon the said clamping levers simultaneously to compress
the brake shoes, and pivoted lever J, having short arm m acting on the long arm
of lever G, and long arm 9 acted upon by the rope or chain r, when strain occurs
in the said rope or chain, all substantially as specified.
5. In a safety brake for elevators, the combination of the head-block D, guide-
plates S, clamping levers e, e, brake-shoes f, f, lever G acting upon the said
clamping lever simultaneously to operate the brake-shoes, lever J, having arm m,
acting upon long arm lever G, and arm q acted upon by the rope or chain r, when
strain occurs in the said rope or chain, substantially as specified.
6. In a safety brake for elevators, the clamping levers e, e', pivoted in head
block D, carrying pivoted brake-shoes f, f, which engage with the guide runner,
in combination with double acting lever G, operating simultaneously in opposite
directions on the clamping levers; levers J, and rope r, substantially as specified.
Dated this 5th day of May 1896.
W. P. THOMPSON & Co.,
322, High Holborn, London, W.C., Patent Agents for the Applicant.