Measuring and testing – Testing of shock absorbing device – Railway draft gear
Reexamination Certificate
1998-12-16
2001-04-17
Fuller, Benjamin R. (Department: 2855)
Measuring and testing
Testing of shock absorbing device
Railway draft gear
Reexamination Certificate
active
06216525
ABSTRACT:
FIELD OF USE
This invention relates generally to retarders of the kind suitable for reducing the speed of a railcar traveling upon a set of tracks, and more particularly, pertains to a field testing device used to measure a resistive force in a retarder installed on the set of railway tracks.
BACKGROUND OF THE INVENTION
Railcar retarders are utilized in railway classification yards in conjunction with a “hump” over which a string of cars is pushed. The railcars are then individually, or in groups, allowed to accelerate down the hump and through appropriate switching networks to their ultimate destination. As the cars accelerate down the hump, it is necessary to maintain the speed of travel under certain limits in accordance with the railcars rolling resistance, distance to be traveled and various other factors. Because light railcars must usually be given the greatest acceleration to reach their most distant location in a classification yard, the hump is built high enough, or the yard is profiled, to cause light railcars to reach a sufficient velocity to carry them to their furthest point. Railcar retarders are then added to reduce the speed of the heavier cars, so that the railcars will not be damaged and will not be subject to excessive wheel lift and derailment.
One type of retarder exhibits a shock absorber-like construction which is mounted at various intervals to the rails in a yard. Such retarders are comprised of a hydraulic unit which exerts a variable resistive force upon deflection of a portion of the unit by the outer edge or flange of a wheel rolling over the rail. To ensure proper function of the retarders, it is necessary for the performance of the retarders to be periodically tested once the retarders have been installed on the tracks.
Heretofore, the most fundamental method of field testing retarders was effected by a maintenance person using his or her foot to compress the retarder and develop a “feel” to determine if the installed retarder has enough resistance. This method is unsafe, inaccurate, and unsanctioned in many classification yards.
A spring-loaded lever device exists for the purpose of measuring the resistive force in a retarder. The spring is compressed on a color-coded cylinder to give a rough measure of the resistive force left in the retarder. The existing tester requires that the user clear ballast under the base of the rail, slide a hinged lever arm under the base of the rail and rotate the device over the retarder and head of the rail. The user then pushes down on a handle and tries to read the color code located on the cylinder. All of this is done with the user crouching very close to ground level, approximately 7 inches thereabove. Normally there are hundreds of retarders to test on a single track in a classification yard. By using this existing method, this prior art device would take upward of two minutes to check one retarder.
Until this invention, no accurate method of checking the resistive force in an installed retarder was available. With the introduction of the spring-loaded lever device, an individual retarder could be checked. However, this method was cumbersome, inaccurate and impractical for checking a large population of retarders. This prior art device also could only check one brand of retarders, so that it had very limited application. Before the invention, the only way to find a “bad” retarder, or to check the condition of any retarder, was to remove the retarder from service and somehow push on it and then using an educated guess, determine whether the unit is acceptable or unacceptable.
Accordingly, it is desirable to provide an on-site testing device and method which allows for repeatable preventive maintenance by safely and accurately testing the amount of resistive force left in an installed retarder. It is also desirable to provide a testing device and method which will enable one to diagnose retarder performance within a short interval of time and without removing the retarder from the rail. Further, it is desirable to provide a testing device and method which permits a user to test a retarder in the field while standing in an upright position.
SUMMARY OF THE INVENTION
It is one object of the present invention to provide a testing tool which can quickly and accurately check any brand of retarder without a user bending down and crouching over the retarder and without stepping on the retarder.
It is also an object of the present invention to provide a lever-type testing apparatus which employs a load cell or transducer along with an easily readable gauge to measure and display the response of an installed retarder.
It is another object of the present invention to provide a testing device which allows an individual to effectively test a large population of installed retarders faster than any other previously known device.
In one aspect of the present invention, a testing device is provided for checking the resistive force of a retarder installed on a rail of a railway track for reducing the speed of a railcar rolling along the track. The retarder has a hydraulic unit and includes a housing, a cylinder slidably mounted in the housing, a piston rod fixed to the housing, a piston assembly fixed to the piston rod and dividing the cylinder into upper and lower chambers, and valve structure responsive to the flow of hydraulic fluid flowing between the upper chamber and the lower chamber. The testing device is constructed and arranged to allow a user to check the resistive force of the retarder installed upon the railway track while standing in an upright position. The testing device includes a rigid, hollow, center pipe having an upper end provided with a handle, and a lower end provided with a resistive force reading arrangement, such as a load cell, which is engageable with the cylinder. The test device further includes a gauge mounted on the center of the pipe in the vicinity of the handle, and electrically connected with the resistive force reading arrangement for displaying the resistive force of the retarder installed on the railway track. Wiring is disposed within the center pipe and connects the resistive force reading arrangement with the gauge. The lower end of the center pipe includes a stop bar which is engageable with the top portion of the rail. The lower end of the center pipe further includes a head portion for accommodating the resistive force reading arrangement in a recessed manner.
The invention also contemplates a method for checking the resistive force of a retarder installed on a rail of a railway track for reducing the speed of a railcar travelling along the tracks and having a hydraulic unit including a housing, a cylinder slidably mounted in the housing, a piston rod fixed to the housing, a piston assembly fixed to the piston rod and dividing the cylinder into upper and lower chambers, and a valve arrangement responsive to the flow of hydraulic fluid flowing between the upper and lower chambers. The method includes the steps of (a) providing a test device including a handle, a center pipe having an upper end connected to the handle, and a lower end formed with a device for reading the resistive force exerted by the retarder; (b) engaging the resistive force reading device with the cylinder while holding the handle and standing in an upright position over the installed retarder; (c) applying a downward force of the resistive force reading device against the cylinder while standing in the upright position; and (d) displaying the amount of resistive force exerted by the cylinder to the user while standing in the upright position.
In yet another aspect of the invention, there is provided a portable, on-site testing device for checking the resistive force of a retarder installed on a railway track for reducing the speed of a railcar rolling along the track. The retarder is a hydraulic unit including a housing, a cylinder slidably mounted in the housing, a piston rod fixed to the housing, a piston assembly fixed to the piston rod and dividing the cylinder into upper and lower chambers and a valve arran
Bernd John J.
Bohme Richard C.
AAA Sales & Engineering Inc.
Andrus Sceales Starke & Sawall LLP
Fuller Benjamin R.
Thompson Jewel V.
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