Empty-load device with brake cylinder test port

An empty-load device with an additional brake cylinder test port which is at the same pressure as the brake cylinder port of the empty-load device. The empty-load device includes a housing and pipe bracket having a brake cylinder, a control valve and brake cylinder test ports. The brake cylinder port and the brake cylinder test port are on one side of the valve seat of the load responsive valve and the control valve port is on an opposite side of the valve seat. A check valve is provided in the brake cylinder test port which is opened when a connector is mated with a brake cylinder test port.

BACKGROUND AND SUMMARY OF THE INVENTION
 The present invention relates to empty-load device and more specifically,
 to an empty-load device with a brake cylinder test port and the brake
 system in which is incorporated.
 An empty-load changeover apparatus is a device which senses the load of the
 car to which it is connected and modifies the braking signal received from
 a control valve to the brake cylinder. One example is shown in U.S. Pat.
 No. 4,884,544 to Rojecki as well as an improved version in U.S. Pat. No.
 5,211,450 to Gayfer et al. These typical devices have an inlet to receive
 the brake signal from the control valve and an outlet to be connected to
 the brake cylinder. An additional port is provided for an equalization
 reservoir.
 There are many situations where it is desirable to measure the brake
 cylinder pressure. This generally requires special taps put in the line
 prior to the brake cylinder. If it is placed at the exit of the braking
 signal from the control valve, it would not take into account those
 systems which have an empty-load device. If it is between the empty-load
 device and the control valve, it would not provide an accurate measurement
 of the brake cylinder pressure. More recently, test ports have been added
 to the manifold of the control valve. Again, this would be upstream of the
 empty-load device and not provide an accurate indication of the brake
 cylinder pressure downstream from the empty-load device.
 The present invention provides an empty-load device with an additional
 brake cylinder test port which is at the same pressure as the brake
 cylinder port of the empty-load device. The empty-load device includes a
 housing having a brake cylinder, a control valve and brake cylinder test
 ports. A valve structure in the housing limits fluid pressure at the brake
 cylinder port and brake cylinder test port from the control valve port in
 response to a load force on the rail car. The valve structure includes a
 valving element and a valve seat. The brake cylinder port and the brake
 cylinder test port are on one side of the valve seat and the control valve
 port is on an opposite side of the valve seat. A check valve is provided
 in the brake cylinder test port which is opened when a connector is mated
 with a brake cylinder test port. The brake cylinder test port may be
 provided on the housing itself or on the pipe bracket which includes the
 brake cylinder port and the control valve port. An equalization reservoir
 port is also provided on the pipe bracket.
 A railroad system which incorporates the empty-load device just described
 includes a control valve having an outlet providing a brake signal. The
 outlet of the brake control valve is connected to an inlet, which is the
 control valve port of the empty-load device. The brake cylinder port is an
 outlet and the brake cylinder test port is a test port. A valve structure
 limits the fluid at the device outlet and test port from the device inlet
 in response to a load force on the rail car. A brake cylinder is connected
 to the device outlet.

DETAILED DESCRIPTION OF THE EMBODIMENT
 In a rail brake system, emergency and auxiliary reservoirs are charged from
 a brake pipe through a control valve. In a charged system, no fluid
 pressure is present in a brake cylinder. The control valve monitors the
 brake pipe and supplies pressure from the reservoir to or removes pressure
 from the brake cylinder in response to change of pressure in the brake
 pipe. Brake pipe systems are well known as described in the patents
 discussed above.
 An empty-load device 10 shown in FIGS. 1-6 includes a housing 12 having
 first housing portion 14 joined to a second housing portion 16 by
 fasteners 15. A pipe bracket 17 is connected to the housing portion 16 by
 fastener 19. The empty-load device 10 includes a brake cylinder test port
 18, a control valve port or inlet 20, a brake cylinder port or outlet 22,
 an equalizing volume port 24, and exhaust port 26.
 The brake cylinder test port 18 is illustrated in FIG. 1 as being connected
 to the housing portion 16 of housing 12. The control valve port 20 and the
 brake cylinder port 22 are connected to the pipe bracket 17 at face 21 of
 the pipe bracket. The equalization valve port 24 may either be on the left
 side face 23 as illustrated in FIG. 3 or on the right side face 25, as
 illustrated on FIG. 6. The exhaust port 26 is in the body portion 16 of
 the housing 12. The right side face 25 in FIGS. 2 and 5 includes a plug 27
 received in a passage in the face which leads to the interior of the
 housing portion 16. This provides an alternative brake cylinder test port
 as illustrated in phantom FIG. 5. The additional test port is indicated as
 18'.
 For a left handed model where the equalization reservoir is mounted to face
 23, the right face 25 could include the additional test port 18'. Plug 27
 would be removed and a connector would be inserted. For a right handed
 model, the equalization reservoir port 24' would be on the right face 25
 as illustrated in FIG. 6. The alternative brake cylinder test port 18'
 would not be provided in that face. The left handed face 23 would not have
 the equalization reservoir port 24 as shown in FIG. 3. The brake cylinder
 test ports 18 and 18' preferably have a quick disconnect nipple and a
 check valve (not shown) which is opened when mated with a connector of a
 test device.
 A control valve 28 is connected to control valve port 20; brake cylinder 30
 is connected to brake cylinder port 22; and an equalizing volume 32 is
 mounted to the housing portion 16 and connected to equalizing volume port
 24.
 A load-sensing lever 34 is pivotally connected at 36 to the housing portion
 14 and is also pivotally connected at 38 to a push rod 40 extending from
 the housing portion 14. The sensing lever 34 contacts a portion of an
 unloaded structure of a railroad car track to sense the load force of the
 car.
 A sensing piston 42 includes a pair of members which are connected to the
 body 12 by a diaphragm. The sensing piston 42 is secured to the push rod
 40 between a shoulder 41 on the push rod and a threaded fastener 43. A
 spring 44 extends between the housing portion 14 and a face of the sensing
 piston 42 and biases the sensing piston 42 to the right in the figures. It
 should be noted that the housing portion 14, the sensing lever 34, the
 push rod 40, the spring 44, and a sensing piston 42 is substantially as
 that shown in the Scott patent 3,671,086 and is the valve known as SC-1.
 The push rod 40 includes an actuator 46 threadably received therein and
 extending through a ratio piston 48. The ratio piston 48 includes a first
 surface 50 facing a surface of the sensing piston 42 with the brake
 cylinder port 22 therebetween. A second surface 52 of the ratio portion 48
 is smaller than the first surface 50. A ratio valve, which bypasses the
 ratio piston when open, is mounted on and travels with the ratio piston
 48. The ratio valve includes a valve seat 54 in the smaller surface 52 of
 the ratio piston 48, a valving member 56, a biasing spring 58, a spring
 cage 60, and retainer 62. The ratio valve as illustrated is a check valve
 which is responsive to the position of the actuator portion 46 of the push
 rod 40 as well as the differential pressure there across.
 The brake cylinder test ports 18 and 18' and brake cylinder port 22 are on
 one side of the ratio valve seat 54 and the control valve port 20 is on an
 opposite side of the ratio valve seat 54. Thus, the cylinder test ports 18
 and 18' accurately reflects the brake cylinder pressure and not the
 desired brake cylinder pressure from the control valve 28 at port 20.
 The housing portion 16 includes a first bore 64 and a second smaller bore
 66 to receive the ratio piston 48. The end wall of bore 66 acts as a stop
 for the ratio piston 48 in its release or loaded position. A stop ring 68
 is provided in the larger bore 64 as a stop adjacent to the empty-load
 position. The exterior surface of the ratio piston 48 is separated from
 the internal bores 64 and 66 to create a space 71 therebetween which is
 sealed by seals 71 and 72. With the ratio piston 48 in the release or the
 loaded load position, the internal space 71 connects the equalizing volume
 port 24 with the exhaust port 26 and disconnects the equalizing port 24
 from the control valve port 20. When the ratio piston 48 is moved to its
 empty-load position, the internal space 71 is connected only to the
 exhaust port 26 and the equalization volume port 24 is disconnected from
 the exhaust port 26 and is connected to the control valve port 20.
 It should be noted that the specifics of the changeover valve of FIG. 4 is
 just an example of a changeover valve which may be used. The critical
 point is that the brake cylinder port or outlet 22 of the empty-load
 device and the brake cylinder test port 18 are on the same side of the
 valve seat 54. This provides an accurate reading of the brake cylinder
 pressure versus the desired brake cylinder pressure from the control valve
 28 at the inlet or control valve port 20. For the specific operation of
 the empty-load device illustrated in FIG. 4, reference is made to U.S.
 Pat. No. 5,211,450 which is incorporated herein by reference.
 Although the present invention has been described and illustrated in
 detail, it is to be clearly understood that the same is by way of
 illustration and example only, and is not to be taken by way of
 limitation. The spirit and scope of the present invention are to be
 limited only by the terms of the appended claims.