Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
20~4974 67487-432
PROTECTIVE COVER FOR EMPTY/LOAD VALVE ACTUATOR
Field of the Invention
This invention relates to the actuating mechanism for what
is known in the art as an "empty/load valve" and which is used
on vehicles, such as railway freight cars, to control the
braking pressure on the wheels of a vehicle in accordance with
the load on the vehicle.
Background of the Invention
Empty/load valves are well known in the art. See, for
example, U.S. Patents Nos. 4,648,661: 4,826,259; 4,844,554 and
4,824,179. In general, the valve includes a reciprocable rod
extending from the valve housing which actuates a changeover
valve within the housing and which is actuated by pivotable
measuring arm mounted on, but externally of, the valve housing.
The position of the arm, and hence, the rod and the braking
pressure, is determined by the load on the vehicle. Generally
speaking, the length dimension of the arm and the pivot point of
the arm are selected 80 that the length dimension of the arm
intersects the axis of said rod.
One of the problems with the prior art devices is that the
valves usually are located where they are subject to dust, dirt,
other particulates, rust and moisture. Such foreign substances
can interfere with the movement of the arm and actuation of
said rod and hence, the operation of the valve.
It has been proposed to protect the rod and the arm where
it engages the rod by an accordian pleated rubber boot. See,
for example, U.S. Patent No. 4,824,179. While such a boot is
reasonably satisfactory when initially installed, it
deteriorates relatively rapidly under the conditions of use and
develops cracks or becomes torn thereby losing its effectiveness
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a3 protection for the arm and the actuating rod.
Brief Description of the Invention
In accordance with the preferred embodiment of the inven-
tion, the pivotally mounted arm which measure~ the load extends
from a pivotable shaft mounted on bearings carried by a rigid
cover secured to the valve housing. The pivotable shaft is
interconnected with the reciprocable rod which operates the
changeover valve by a linkage. The cover covers the end of the
rod extending from the valve housing, the linkage and most of
10 the shaft in a dust-free manner. Furthermore, the actuating
arm is offset from the axis of the rod and is disposed out-
wardly from the valve housing so that dirt or other foreign
objects cannot intervene between the arm and the housing and
interfere with the movement of the arm. ~referably, stops
extend outwardly from the cover to limit the pivotal movement
of the arm.
The invention may be summarized, according to a f irst
aspect, as in an empty/load valve having a housing, said
housing comprising a first air port for receiving air under
20 pressure above atmospheric pressure and a second air port
outlet for supplying air to a brake cylinder, air received at
said first air port being supplied to said second air port
outlet, a control valve within said housing for controlling the
pressure of the air supplied to said second air port outlet
and control means mounted on the within said housing for
operating said control valve, the improvement comprising:
a rigid cover mounted on said housing in dust-free
relation thereto, said cover overlying said control means;
a pivotable shaft pivotally mounted on said cover with at
30 least a first portion thereof within said cover and a second
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portion thereof externally of said cover and having a pivot
axis:
a relatively long and narrow load measuring arm mounted on
said second portion of said shaft externally of said cover and
with its length extending transversely to said pivot axis; and
interconnecting means within said cover and interconnecting
said shaft and said control means for causing movement of said
control means with pivoting of said shaft, said interconnecting
means comprising a linkage pivotally secured to said shaft and
10 said control means whereby movement of said control means in
either of two directions causes pivoting of said shaft.
According to another aspect, the invention provides in an
empty/load valve having a housing, said housing comprising a
first air port for receiving air under pressure above atmos-
pheric pressure and a second air port outlet for supplying air
to a brake cylinder, air received at said first air port being
supplied to said second air port outlet, a control valve
within said housing for controlling the pressure of the air
supplied to said second air port outlet and control means
20 mounted on and within said housing for operating said control
valve, the improvement comprising:
a rigid cover mounted on said housing in dust--free
relation thereto, said cover overlying said control means;
a pivotable ~haft pivotally mounted on said cover with
at least a f irst portion thereof within said cover and a
second portion thereof externally of said cover and having
a pivot axis; said cover having a pair of spaced side walls
extending transversely to said pivot axis, and a spacer
mounted on and secured to said. first portion of said shaft
30 and engageable with said side walls for maintaining said
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shaft in a predetermined axial position;
a relatively long and narrow load measuring arm mounted
on said second portion of said shaft and with its length
extending transversely to said pivot axis; and
interconnecting means within said cover and inter-
connecting said shaft and said control means for causing move-
ment of said control means with pivoting of said shaft.
Brief Description of the Drawin~s
Other objects and advantages of the present invention
will be apparent from the following detailed description o~
the presently preferred embodiments thereof, which
description should be considered in conjunction with the
accompanying drawings in which:
Fig. 1 is a plan view of an empty/load valve modified
in accordance with the invention and with the cap forming part
of the cover removed;
Fig. 2 is a side elevation view of the embodiment shown
in Fig. 1 with the cap in place;
Figs. 3 and 4 are side elevation views, partly in cross-
3ection, taken along the line 3-3 indicated in Fig. 1 with
the measuring arm omitted and respectively show the normal
positions of the parts and the positions of the parts when a car
i 8 emp ty .
Detailed Description of Preferred
Embodiments of the Invention
~lthough the invention has application to other empty/load
valves, the invention will be described in connection with
the empty/load valve shown and described in U . S . Patent No.
5,039,174.
The empty/load valve illustrated in Figs. 1-4 comprises
3a
_ 3B
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a housing 1 with a tank or canister 2 for receiving air from
the housing 1 in a known manner. The tank 2 has an indicator
3 thereon for indicating the pressure of the air in the tank 2.
The housing l has an air port 5 for supplying air to a
brake cylinder, such as by way of a hose (not shown) and an
air port 4 for receiving braking air under a pressure above
atmospheric pressure from a conventional source. The housing
1 is secured to a support in a conventional manner such as by
bolts 6.
The valve mechanisms and air passageways within the
housing 1 Eor controlling the pressure of the air supplied
to a brake cylinder may be of any conventional type, but the
valve illustrated in the drawings is of the type described in
said U.S. Patent No. 5,039,174 and operates in the manner
described therein. As described therein, the housing 1
contains a changeover spool 7 (see Figs. 3 and 4) which is
positioned in accordance with load on a car and which causes
the braking air
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pressure supplied to the brake cylinder to be high when the car
load i8 high and to be lower when the car is empty. Pigs. 3 and
4 respectively show the positions of the spool 7 and the
associated parts after braking air is supplied and when the car
load is high and when the car is empty.
The control means for the spool 7 comprises a shoulder screw
rod 8 threaded into a piston 9 and encircled by a spring 10 which
bears against the shoulder of the screw 8 and against a washer
12. The spring 10 normally maintains the parts in the positions
shown in Fig. 3. The piston g is, in effect, an extension of the
rod 8 and is slidably received in a sleeve 11 secured to the
housing 1. The head of the piston 9 is pivotally connected to
a link 13, and the opposite end of the link 13 is pivotally
connected to a yoke or hinge 14.
A rigid cover 15, e.g. made of aluminum or steel, or other
rigid material which can withstand the operating conditions, is
secured to the housing 1, such as by bolts 16, and includes a cap
17 (see Figs. 2, 3 and 4) which is held against the cover 15 by
the bolts 16. A sealing gasket 18 is interposed, between the
main body of the cover 15 and the housing 1 and if desired, may
be interposed between the cap 17 and the main body.
Preferably, the main body of the cover 15 and the housing 1
have holes therein for receiving four roll pins 37 (only two of
which are shown in Fig. 2) for the purpose of properly aligning
the main body with the housing 1.
A shaft 20 is pivotally mounted on the cover 15 and is
encircled near the end which extends from the cover 15 by an O-
ring 21 (Fig. 1) to seal it with respect to entrance of moisture,
etc. into the interior of the cover 15. The opposite end of the
shaft 20 is received in a blind hole in the wall 25 of the cover
15. Although the yoke or hinge 14 may be otherwise secured to
the shaft 20, the portion of the shaft 20 internally of the cover
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has an axial slot 22 (see Figs. 3 and 4) which receives theyoke or hinge 14. The shaft 20 also has a flat portLon 23
against which a spacer 24 made, for example, of Delrin, bears.
The spacer 24 is engageable with the walls 25 and 26 of the cover
15 to maintain the proper axial position of the shaft 20. The
spacer 24 and the yoke 14 are secured to the shaf t 20 by bolts
27 .
Although a measuring arm 29 may be otherwise secured to the
shaft 20, the portion of the shaft 20 which extends externally of
the cover 15 also has a slot 28 which receives the measur lng arm
29 which is held by bolts 30. The length of the arm 29 extends
transversely to the pivot axis of the shaft 20 and portions 29a
and 29b of the arm 29 extend outwardly, on opposite sides, of the
shaft 20. The longer portion 29a has, at the free end thereof
remote from the shaft 20, a contact screw 31, e.g. of nylon,
threaded into a tapped hole on the portion 29a. A jam nut 32 is
used to prevent rotation of the screw 31 after it has been
adjusted to the position in which it properly contacts the
portion of the car which varies in position with respect to the
housing 1 in accordance with the load on the car.
The shorter portion 29b of the measuring arm 29 is
engageable with a pair of stops 33 and 34 which can be bolts
screwed into the cover 15 and which extend into the path of
movement of the portion 29b to limit the movement of the measuring
arm 29. Since the stops 33 and 34 are relatively small, it is
unlikely that any foreign matter or objects of significant size
will become lodged thereon and interfere with the proper movement
of the measur ing arm 29 .
It will be observed that the measuring arm 29 is displaced
in the direction of the pivot axis of the shaft 20 from the
housing 1 and does not overlie the control means for the
changeover spool 7. Since the measuring arm 29 is so dlsplaced,
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interfering matter or Qbjects cannot intervene between the arm 29
and the housing 1 and prevent proper movement of the arm 29.
In addition, ~t will be observed that the control means for
the spool 7 and all the movable parts which actuate it, except
for a small portion of the shaft 20 and for the measuring arm
29, are covered and protected in a dust-free manner by a long
lasting, rigid cover 15.
Fig. 3 illustrates the normal positions of the parts before
braking air is supplied to the air port 4. When braking air is
supplied to the port 4, the spool 7 is urged to the left as
viewed in Fig. 3, and by way of the screw 8, the piston 9, the
link 13 and the yoke 1~ urges the shaft 20 counterclockwise, as
viewed in Fig. 3, which, in turn, urges the measuring arm 29 in
the direction of the arrow 36 in Fig. 2. If the car is heavily
loaded, there will be little, if any, movement of the arm 29, and
hence, of the spool 7, and full braking air pressure will be
supplied to the brake cylinder by way of the air outlet 5 .
On the other hand, if the car is empty, the arm 29 will move
in the direction of the arrow 36 permitting the shaf t 20 to
partially rotate around its axis and permitting the parts,
including the spool 7, to assume the positions shown in Fig. 4.
When this occurs, the braking air pressure at the air outlet 5
will be reduced, and the braking pressure applied to the car or
truck brakes will be reduced.
Although preferred embodiments of the present invention have
been described and illustrated, it will be apparent to those
skilled in the art that various modifications may be made without
departing from the pri ciples of the invention.
