Improvements in Safety Brakes applicable to Lifts or Elevators.
Year: 1898

page_text: [Communicated from abroad by THOMAS JEFFERSON VAIL, of Hartford, Connecticut,
United States of North America, Gentleman.]
Improvements in Safety Brakes applicable to Lifts or Elevators.
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:-
This invention is supplemental to that patented by me on the 5th May 1896
No. 9551 and relates to improved mechanism for preventing the main operating lever
from returning to its normal position after the said lever has once been either partially
or wholly actuated and the brake has been set.
The object of this invention is to provide a simple, efficient and powerful brake
mechanism for arresting the downward movement of the elevator car upon the
breaking of the main cable which supports the said car upon its travels, and to provide
an automatically acting block or stop which prevents the brake mechanism after it
has once been set from being released until the operator desires that the same be
released, no matter what position the main operating lever may be in at the time the
brake mechanism set.
The invention consists in the novel features of construction hereinafter set forth
and described, and more particularly pointed out in the claims hereto appended.
Referring to the drawings:
Fig. 1 is a side view of my improvements.
Fig. 2 is a bottom plan view.
Fig. 3 is a view of a section taken on the line 3-3, Fig. 1, and
Fig. 4 is a view showing a preferred form of the cam.
Like letters refer to like parts throughout the several views.
The inventor has not illustrated the mechanism which in case of accident actuates
the main operating lever, for it is to be understood that in such event the said lever
will be operated by substantially the same means as that set forth and described in
said Letters Patent No. 9551 of 1896, above referred to, that is to say, by 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 inventor does not, however, intend to limit his invention for use in connection
with the last described mechanism for actuating the said lever in case of accident, for
it is obvious that any suitable mechanism may be employed without departing from
the spirit of his invention.
B denotes a portion of the elevator car, to the bottom timber (A) of which the
operating parts of the 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, Fig. 2.

page_text: G G¹ are levers pivoted at h within the head blocks, and e e¹ are clamping levers,
the levers e being pivoted within the said head blocks, and the clamping levers el
being made integral with the levers G G¹. ff are the shoes constituting the brake
carried by the clamping levers e and the short arms e¹ of the levers G G¹, and pivoted
thereto. These brake shoes engage the vertical guide runners C¹ C¹ on the guide
posts C C and are adapted to operate on said guide runners simultaneously, and
compress the same between their faces when the safety device is called into operation:
The faces of the brake shoes may be grooved or roughened to promote adhesion if
desired, and by the pivotal connection between the brake shoes and their respective
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.
f¹ denotes a spring, the purpose of which is to keep the outer ends of the adjacent
levers away from each other and from the guide runners when the lever J, which is
firmly secured by a pivot bolt to the timber A at j, is in the normal position.
The function of this lever (J) is to act upon and operate the long arms of the
levers G G¹ when itself operated upon by the rope r, which connects its long arm q
with the governor and trip and clamping mechanism above referred to. This action
is conveyed through the medium of the short arms, m, n, which may be provided
with anti-friction rollers k, k, as shown, for the purpose of reducing friction. S S are
two guide plates provided with slots not shown, through which suitable securing bolts
pass into webs & formed on each head block. This enables them to be adjusted.
vware springs to prevent the lever J from being accidentally operated by the check
rope r, and to retain the levers in their normal position.
When the travel of the rope r is suddenly arrested by the action of the governor
and trip and clamp mechanism above referred to, a strong pull is communicated to
the lever arm g of the lever J, to which the said rope r is attached, and this instantly
moves the said lever arm outwards against the tension of the springs v and w. Motion
is thereby transmitted through the chain of compound levers to the brake shoes ƒ ƒ,
which are simultaneously constricted towards each other, embracing the guide runners
in their jaws, and thus arresting the downward movement of the car.
a¹ denotes a shaft passing upward through a metallic bushing b¹ passing downward
through the part B. a² denotes a covering for the shaft a¹. This bushing, however,
is not essential, as obviously the shaft may rotate in a hold in the part B instead of
the bushing. The lower end of this shaft is provided with a spirally formed cam c¹,
and rests upon a bearing on the yoke d¹ attached to the metal plate e², which latter
is securely fastened to the under side of the timber A.
2 is an abutment or block for limiting the extent of rotation of the said cam made
integral with the plate e² and provided with a guide groove or channel g in which the
projection or ridge h¹ on the cam c¹ is adapted to travel. The periphery of the cam c¹
as shown in Fig. 4, is provided with a long flat surface c² and with a series of short
flattened surfaces each successively farther from the center than the preceding one.
These flat surfaces, however, are not essential, as the surface of the periphery of the
cam may be rounded without departing from the spirit of the invention. i denotes a
coiled spring encircling the shaft a³. The upper part of this spring is secured to the
shaft a and the lower part passes through the plate e² and is secured to the same by
means of a nut or rivet, the head of which is countersunk in said plate.
When the levers J, G and G¹ are in their normal position the cam is so arranged
that the flat surface c² thereof is parallel with and rests against the side of the lever G.
When the lever G is actuated and is being drawn in a direction away from the cam,
the coiled spring causes the came to be automatically revolved in synchronism with
the movement of said lever, so that no matter what position the lever G may assume,
there is always in direct contact with it some part of the periphery of said cam,
thereby preventing the said lever from springing back to its normal position in case
the rope should break after the lever J has been operated upon.
If for any reason the cam shaft a¹ should break, the abutment or block f2 would
still prevent the lever G and its connections from assuming their normal positions. It
is obvious that the cam may be used with either of the levers G or G¹, and even

page_text: directly with the main operating lever J without departing from the invention. By
turning the shaft in the opposite direction by any suitable means the lever G may be
gradually brought back to the position in which it originally was before being operated
upon.
By means of the mechanism last above described, the inventor is enabled to provide
a mechanism absolutely safe and reliable, whereby at all times after the brake
mechanism has been set, that is, after the lever J has been actuated, the posi-
tion of the lever J and its connections will become fixed and stationary, and be
prevented from returning to their normal positions if by any chance the roper should
break after the brake mechanism has been set.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed as communicated to me
by my foreign correspondent, I declare that what I claim is :-
1. In a safety device for elevators, the combination with the brake of the main
operating mechanism therefor, and means operating synchronously therewith consist-
ing of a spirally formed cam and co-operating elements whereby the brake is main-
tained in the position assumed after having been either partially or wholly set.
2. In a safety device for elevators, the combination with the brake of the main
operating mechanism therefor, and automatically acting mechanism consisting of a
spirally formed cam and co-operating elements acting synchronously therewith to
maintain the brake in the position assumed after having been either partially or
wholly set.
3. In a safety device for elevators, the combination with a clamping lever, a long
lever actuating said clamping lever, said levers being each provided with a brake
shoe, suitable supports for said levers and a main operating lever acting upon said
long lever, of cam mechanism operating in appropriate proximity to one of said levers
whereby the various parts are maintained in the position assumed after the brake has
been either partially or wholly set.
4. In a safety device for elevators, the combination with the brake of the main
operating mechanism therefor and an automatically rotated cam c¹ formed with
a bearing surface of continually increasing radius acting in synchronism therewith,
whereby the brake is maintained in the position assumed after it has been either
partially or wholly set.
5. In a safety device for elevators, the combination with the brake of the main
operating mechanism therefor and an automatically rotated cam c¹ provided with
a series of flattened surfaces, each successively farther from the center than the
preceding one, acting synchronously with the said main operating mechanism,
whereby the brake is maintained in the position assumed after it has been either
partially or wholly set.
6. In a safety device for elevators, the combination with the brake of the main
operating mechanism therefor and the automatically rotated cam c¹ formed with a
bearing surface of continually increasing radius, and means whereby the extent of the
rotation of said cam is limited.
7. In a safety device for elevators, the combination with the brake of the main
operating mechanism therefor and the automatically rotated cam c¹ formed with a
bearing surface of continually increasing radius acting in synchronism therewith,
and having a fin or ridge h¹ adapted by contact with an abutment f2 to limit the
rotation of the said cam, said cam being arranged as described in relation to said
main operating mechanism whereby the brake is maintained in the position assumed
after it has been either partially or wholly set.
8. In a safety device for elevators, the combination with the brake of the main
operating mechanism therefor and the automatically rotated cam c¹ formed with a
bearing surface of continually increasing radius acting in synchronism therewith
and provided with a ridge or fin h¹ adapted to limit the rotation of said cam by
contact with an abutment f2 provided with a guide groove g, said cam being arranged
as described in relation to said main operating mechanism whereby the brake is

page_text: maintained in the position assumed after it has been either partially or wholly
set.
9. In a safety device for elevators, the combination with the brake of the main
operating mechanism therefor and the cam c¹ formed with a bearing surface of
continually increasing radius rigidly mounted upon the shaft a¹ in appropriate
proximity to said mechanism, said shaft being submitted to an unremitting torsional
strain, whereby when said actuating mechanism is put in operation, said cam is
rotated synchronously therewith to maintain the various parts in the position assumed
after the brake mechanism has been either partially or wholly set.
10. In a safety device for elevators, the combination with the brake of the main
operating mechanism therefor, and a cam c¹ formed with a bearing surface of
continually increasing radius, rigidly mounted on a shaft a¹ in such proximity to said
main operating mechanism as to remain in constant contact therewith, and a coiled
spring operating on said shaft, whereby when said main operating mechanism is
actuated said cam is rotated in synchronism therewith.
11. In a safety device for elevators, the combination with the brake of the main
operating mechanism therefor and a cam c¹ formed with a bearing surface of
continually increasing radius, automatically rotated, acting synchronously with said
main operating mechanism, and in such proximity thereto as to prevent the brake
from assuming its normal position after it has been either partially or wholly set, and
ineans whereby said cam may be so rotated as to allow the various parts to assume
such position.
12. In a safety device for elevators, the combination with the brake of the main
operating mechanism therefor, and the cam c¹, formed with a bearing surface of
continually increasing radius, rigidly mounted upon a shaft in proximity to said
mechanism, said shaft being subjected to an unremitting torsional strain whereby
when said actuating mechanism is put into operation said cam is rotated synchronously
therewith to maintain the various parts in the position assumed after the brake has
been either partially or wholly set, said shaft being constructed and arranged as
described so as to be capable of rotation to return the various parts to their normal
position.
13. In a safety device for elevators, the combination consisting substantially of
brake shoes adapted to engage the guide runners and a compound lever system for
compressing the same against the said runners, and cam mechanism comprising a
spirally formed cam and co-operating elements operating in conjunction with one of
said levers in said system and in synchronism with the operation of the same to
maintain the brake in the position assumed after the brake has been either partially
or wholly set.
14. In a safety device for elevators, the combination consisting substantially of
brake shoes adapted to engage the guide runners, and pivoted respectively to a
clamping lever and jaw acted upon by a long lever, actuated by the main operating
lever, and mechanism applied to one of said levers and acting synchronously with the
operation of said main operating lever to maintain the brake in the position assumed
after the brake has been either partially or wholly set.
15. In a safety device for elevators, the combination consisting substantially of
brake shoes adapted to engage the guide runners, and pivoted respectively to a
clamping lever or jaw, acted upon by a long lever, actuated by the main operating
lever, a spirally formed cam c¹ rigidly mounted on a shaft a¹ in such proximity to one
of said levers as to remain in constant contact therewith, and a coiled spring i
operating on said shaft whereby when said inain operating mechanism is actuated said
cam is rotated in synchronism therewith.
W. P. THOMPSON & Co.,
322, High Holborn, London, W.C., Patent Agents for the Applicant.