Improved Apparatus for Automatically Taking Up or Giving Slack in Brake Mechanisms.
Year: 1897

page_text: Date of Application, 9th Nov., 1897-Accepted, 20th Aug., 1898
COMPLETE SPECIFICATION.
Improved Apparatus for Automatically Taking Up or Giving Slack in
Brake Mechanisms.
We, THOMAS ERNEST NICHOLSON, Car Builder, and JOSEPH NICHOLSON, Coach-
man, both of 1296, Topping Street, St. Paul, Minnesota, United States of America,
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 follow-
ing statement:-
The invention relates to improvements in slack adjusters, its object being to
provide an apparatus designed to automatically take up all the slack in the brake
mechanism caused by wear of the brake shoes, and also to automatically give slack
when the shoes become too tight, so as to maintain a substantially uniform travel
of the piston in the brake cylinder.
Other improved features of construction are also provided, which are herein-
after more particularly described and claimed.
In the accompanying drawings forming part of this specification;
Fig. 1 is a side elevation of the improvement, shown applied to a car truck;
Fig. 2 is a partial side elevation of the same, detached;
Fig. 3 is a sectional end view of Fig. 2;
Figs. 4 and 5 are details of a form of coupling used in connection with the
invention, and
Fig. 6 is a detail of the rack actuating dog.
In the drawings B represents the ordinary brake rod connected at one end with
the piston in the brake cylinder, and at its other end with the live brake lever 2,
which is connected by a link 3 with the dead brake lever 4. The brake levers 2
and 4 are connected by links 5 with the brake shoes 6. The upper end of the
dead brake lever 4 is pivotally connected by means of a rod 7 with the toothed
rack or bar 8, longitudinally slidable in the casing C, which is suitably attached
to the truck timbers A. The teeth 9 upon the under side of the bar 8 are engaged
by a gravity dog 10 and a spring controlled dog 11. The gravity dog 10 has the
fulcrum 12 in the casing, and is provided with the spur 13 projecting above the
top of the bar 8 for the purposes hereinafter more particularly described.
The dog 11 is provided with a spring 14, by means of which it is held in engage-
ment with the rack, and is adapted to control the rack when the gravity dog 10
has been released therefrom in the operation of the apparatus.
Having fulcrum connection 15 in the casing is the lever 16, the free end of
which is provided with a slot 17 through which the brake rod passes. The rack 8
is adapted to be moved forward in its bearings in the operation of the apparatus
by means of a dog 18 fulcrumed in the lever by a pin 19, passing through a
triangular opening 20 in the head of the dog, this opening being for the purpose
of giving the dog sufficient play in the actuating of the lever 16.
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page_text: The stem of the dog 18 slides through an opening 21 in the downwardly pro-
jecting end 22 of the casing, and is surrounded by a coil spring 23, by means of
which the lever 16 is held in the position shown in Fig. 2. 24 represents a pawl
engaging with the rack 8 in the rear of the lever 16, and actuated by the spring 23
bearing against it.
Arranged in an opening 25 through the lever 16 immediately above the top
of the casing is a pawl 26 held therein by means of the spurs 27 abutting against
the forward side of the lever, and by spurs 28 abutting against the wall of the
groove 29 in the rear of the opening 25. Secured in the end of the pawl is the
Tug 31 working in connection with a right angled trip 30 upon the top of the
casing.
In order to provide for the actuating of the lever by the travel of the brake
rod, we secure upon the rod the clamp collar 32, held in place thereon by bolts 33.
This collar is formed at one end with the lateral spurs 34, and at its other end
with the apertures 35, in one of which is adapted to be placed a pin 36 to engage
the lever in setting the brakes.
In Figs. 4 and 5 is shown a form of coupling used in connection with the in-
vention, the same being shown in Fig. 1 connecting the link 3 and the brake
rod B with the brake levers. This coupling consists of the members 37 and 38,
the brake or other rod B to be adjusted being secured in one end of the member 37.
The hinge member 38 is formed at one end with the gudgeon or pintle 40, adapted
to be placed in the notch 41 in the end of the member 37, the hinge member
when so secured being turned down as shown, with the catch 42 upon the opposite
end of the member 37, projecting through the opening 43 in the hinge member,
in which position the members may be held together by a key 44. The member 37
is provided with a pin 45 serving as a pivot for the end of the brake lever 2 or
similar part, the hinge member of the coupling being formed with an opening 46
to receive, when the members are closed, a pin on the opposite side of the lever 2,
or the pin 45 may be extended and its outer end enter the opening 46.
The operation of the invention is as follows. In the drawings the parts are
shown in normal position, with the brake shoes out of contact with the wheels.
When it is desired to apply the brakes, a pull is exerted on the brake rod in the
direction of the arrow. The parts are so adjusted that if no slack exists, the pull
upon the brake rod will actuate the lever 16 (by means of the engagement of
the pin 36 with the lever) sufficiently to carry the lug 31 underneath and
immediately to the rear of the trip 30.
The movement of the lever will not carry the dog 18 back a sufficient distance
to engage the rack, so that when the brakes are released the lever will return to
normal position without interfering with the position of the rack, the lug 31
sliding over the top of the trip 30, and thus not coming in contact with the
spur 13 of the gravity dog. When, however, by reason of wear of the brake
shoes, or by settling of the shoes by a heavy load upon the car, slack exists, the
piston in the brake cylinder will have to travel beyond its normal stroke, thus
pulling the brake rod greater distance to properly apply the brakes. This will
cause the lever 16 to be turned on its fulcrum a greater distance, by means of
the brake rod, and sufficiently to bring the dog 18 into engagement with the
teeth of the rack. As soon as the brakes are released the spring 23 upon the
dog 18 will force the lever 16 back into normal position, and also move the rack 8
forward by reason of the engagement of the dog with the rack teeth. This move-
ment of the rack will pull upon the dead brake lever 4 and take up any existing
slack.
As the lever 16 in this operation is returned to normal position on the releasing
of the brakes, the lug 31 will slide over the trip 30, preventing engagement of
the pawl with the spur 13 of the gravity dog 10.
When the brakes become too tight slack is automatically given as follows.
There will then be a shorter travel of the brake rod necessary to cause the brakes
to grip, so that the lever 16 will only be moved enough to carry the free end of

page_text: the pawl 26 to the rear of the projecting end 13 of the gravity dog, with the
lug 31 of the pawl 26 standing underneath the trip 30. When the brakes are
released, and the spring 23 forces the lever 16 back into its normal position, the
free end of the pawl will be carried into engagement with the end 13 of the
gravity dog, freeing said dog from the rack. If the brakes have been so tight
that the above described act of releasing has not sufficed to thoroughly disengage
them, there will be of course still some pull upon the brake levers, and this will
cause the rack to be pulled to the rear, as illustrated by the dot and dash line
position of the dog 11 in Fig. 2. As the pawl 26 is freed from the gravity dog 13
said dog will return to engaging position with the teeth of the rack. It will be
evident by referring to Fig. 2 that the dog 11 limits the rearward movement of
the rack. Said dog is held in engagement with the rack by the spring 14, said
dog being so pivoted that it is allowed movement only between the full line
position and the dot and dash line position, and thus when the rack has been
carried sufficiently to the rear to bring the dog 11 into the dot and dash line
position, further movement of the rack is prevented by means of said dog. If
this movement of the rack should happen to give too much slack, the next setting
of the brakes will take up as many notches as necessary in the manner described.
The bar 8 is provided with a sufficient number of teeth to take up all of the
slack until the brake shoes are completely worn out, and in order to avoid
further movement of the rack, so as to break any of the parts, the end of the rack
bar 8, which is connected with the dead brake lever, is formed with a plane sur-
faced portion 47, which serves as a stop, and thus when such an amount of slack
is taken up as to bring the dog 18 to the portion 47, the lever 16 will be actuated
without further moving the rack.
It will thus be evident that the invention will not only take up any existing
slack, but will also give out slack when the brake shoes are too tight, avoiding
the necessity of any personal attention until the shoes are worn out. If it i
desired, however, to give any slack without applying the brakes, this may be
done by hand by turning the gravity dog 10 to release the rack, and also slack
may be similarly taken up by means of the adjustable connections between the
rods B and 3 and the brake levers.
In Fig. 2 the lever 16 is shown composed of two parts connected by a bolt 48,
constituting a transverse joint in the lever. The purpose of this is to allow out-
ward turning of the end of the lever, rendered necessary where the wheels are
going around curves.
Having now particularly described and ascertained the nature of the said
invention, and in what manner the same is to be performed, we declare that what
we claim is:-
1. In combination with the brake rod and shoes, and the slack take up mechan-
ism connected with said shoes and operated from the brake rod, of the means
actuated from said brake rod when the brake shoes are too tight to release said
slack take up mechanism and give a predetermined amount of slack.
2. A device of the class described, comprising a toothed bar sliding in suitable
bearings, and adjustably connected with the dead brake lever, the lever controlled
from the brake rod, and adapted to actuate said bar to take up any existing slack,
and also adapted to be actuated from the brake rod when the brake shoes are too
tight to release the bar and give a predetermined amount of slack.
3. In combination, the rack slidable in suitable supports and connected with
the brake levers, the dog for holding the rack in position, the lever actuated from
the brake rod and adapted when moved beyond a certain limit to engage and
cause the travel of the rack in one direction, and the means actuated by said
lever when the same is moved through a predetermined limit to release said rack,
and allow it to travel in the opposite direction.
4. In combination, the rack slidable in suitable supports and connected with
the brake levers, the dog for holding the rack in position, the lever actuated from

page_text: the brake rod and adapted when moved beyond a certain limit to engage and
cause the travel of the rack to take up slack, said lever being formed with a
transverse joint to allow outward turning of the ends of the lever.
Dated this 9th day of November 1897.
F. WISE HOWORTH,
46, Lincoln's Inn Fields, London, W.C., Agent for the Applicants.