RAILWAY CAR TRUCK FRICTION SHOE SPRING GROUP
A friction shoe for a railway car truck is provided. The railway truck comprises two parallel side frames, a suspension spring assembly supported by the side frames, and a bolster transversely mounted between the side frames and supported by the suspension spring assembly. Each side frame has at least one vertical support face, and the bolster has at least one sloped support face. The friction shoe comprises a sloped wall engaging the sloped support face of the bolster, a vertical wall engaging the side frame vertical support face, and a bottom base engaging and supported by a suspension control spring group which comprises three concentrically nested coil springs which provide a normal force on the column wear plate of between 3000 and 5000 pounds in the static empty railway car truck condition and between 7,500 and 12,000 pounds force under the static loaded railway car truck condition.
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The invention relates generally to railway car truck friction damping arrangements, and more particularly to a railway car truck friction shoe spring group.
The present invention is directed to a friction shoe suspension control spring group for a railroad car truck and in particular to a suspension control spring group having three concentrically nested coil springs and to a friction shoe including a body having a sloped face and a vertical face. The suspension control spring group applies force to the friction shoe which dissipates energy throughout the range of suspension travel thereby controlling the relative motion between the side frames and bolster as the railway car travels down the track.
Railroad car trucks of a design known as a three piece railway car truck include a pair of spaced apart side frames and a bolster that extends transversely between the side frames. The bolster is resiliently supported at each end on a respective side frame by a plurality of suspension springs. Wedge shaped friction shoes are used in such railroad car trucks to dampen movement of the bolster with respect to the side frame of the railroad car truck. Friction shoes are usually generally triangular wedge shaped such that two laterally spaced sloped faces are each in contact with one of two laterally spaced sloped faces of the bolster. The friction shoe is also comprised of a vertical face that is in contact with a corresponding wear plate mounted on a vertical face of a side frame column. The wear plate on the vertical column of the side frame is usually comprised of steel. Accordingly, the friction shoe acts as a motion damping wedge between the bolster and the wear plate on a vertical column of the side frame.
The friction shoe also is comprised of a bottom section that joins the vertical face and the two laterally sloped face. The bottom section includes a spring lug in the form of a hollow protrusion extending form the bottom section. Such design spring lug saves weight as it has a hollow core. Further, the bottom of the spring lug is open which allows water or other debris to pass out of the friction shoe.
The friction shoe is wedged into engagement between the sloped faces of the bolster and the vertical column of the side frame by a suspension control spring group. Such spring group typically comprises one or two concentrically grouped coil springs, or an elastomeric solid or hollow spring may comprise one or more of the springs in the spring group. Resistance to sliding movement of the friction shoe with respect to the side frame, which in turn provides dampening of vertical bolster movement, is provided by the frictional forces generated between the friction shoe vertical face and a wear plate on the side frame vertical column. This also provides improved truck squaring capability and warp stiffness.
It is an object of the present invention to provide an improved railway car truck suspension control spring group and friction shoe that is comprised of three concentrically nested springs wherein the damping frictional force on the vertical movement of the bolster is better controlled with greater energy dissipation.
Referring now to
Railway wheels 4 are mounted on axles 3. Axle bearings 5 are mounted on the ends of axles 3. Bearing adaptor 6 and pad 7 are provided to receive axle bearings in side frame pedestal openings 2A. Center bowl 11 on the top surface of bolster 1 is provided to help support the railway freight car on the truck.
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Referring now to
Outer coil spring 42, middle coil spring 43, and inner coil spring 44 may be comprised of steel coil springs or solid or hollow elastomeric springs. Middle coil spring 43 is seen to surround the outer cylindrical surface of spring lug 37. Inner coil spring 44 is seen to contact bottom surface 41 of spring lug 37 upon sufficient compressive force downward onto spring group 9. Under empty or lightly loaded railcar conditions, spring group 9 may be uncompressed 110 and not in contact the friction shoe bottom surface 34 or spring lug bottom surface 41.
The damping force by the friction shoe 8 can vary as may be selected from the various materials for friction shoe body 17 and the force with which the front face 19 is impinged against side frame column wear plate 15 which is directly related to the vertical force applied to the bottom of the friction shoe 8 by the suspension control spring group 9.
Claims
1. A railway car truck comprising:
- two parallel side frames,
- a suspension spring assembly supported by the side frames,
- a bolster transversely mounted between the side frames and supported by the suspension spring assembly,
- each side frame having at least one vertical support face,
- the bolster having at least one sloped support face,
- and a friction shoe comprising
- a bottom base engaging and supported by a support spring group,
- the bottom base including a cylindrical spring lug extending downwardly therefrom,
- at least one sloped wall engaging the sloped support face of the bolster,
- and a vertical wall engaging the vertical support face of the side frame,
- and a suspension control spring group having an outer coil spring, a middle coil spring concentric within and inside the outer coil spring,
- and an inner spring located concentric with and inside the middle coil spring.
2. The railway car truck of claim 1 wherein
- the inner coil spring is shorter than the middle coil spring and the outer coil spring such that the inner coil spring is compressed only when the railway car truck is loaded.
3. The railway truck of claim 1 wherein
- the proportion of combined spring rates of the suspension control spring group engaging with the friction shoes to the combined spring rates of the suspension springs engaging with the bolster is between 12 and 18 percent in the empty railway car truck condition and between 20 and 27 percent in the loaded railway car truck condition.
4. The railway car truck of claim 1 wherein the inner coil spring interfaces with the bottom surface of the friction shoe spring lug.
5. The railway car truck of claim 1 wherein a composite facing is bonded to the friction shoe vertical support face.
6. The railway car truck of claim 1 wherein a polymer wear liner is bonded to the friction shoe sloped support.
7. The railway car truck of claim 1 wherein
- a single friction shoe inner, middle and outer coil spring provide a normal force on the column wear plate of between 3000 and 5000 pounds in the static empty railway car truck condition and between 7,500 and 12,000 pounds force under the static loaded railway car truck condition.
8. The railway car truck of claim 1 wherein
- the friction shoe is comprised of cast iron.
9. The railway car truck of claim 1 wherein
- the friction shoe is comprised of cast steel.
10. The railway car truck of claim 1 wherein
- the sloped wall of the friction shoe extends to direct contact with the bottom base.
11. The railway car truck of claim 1 wherein
- the sloped wall of the friction shoe is comprised of two laterally spaced surfaces with a spacing wall located between the two laterally spaced surfaces.
12. A friction shoe for a railway car truck,
- the railway car truck comprising
- two parallel side frames, a suspension spring assembly supported by the side frames, and a bolster transversely mounted between the side frames and supported by the suspension spring assembly,
- each side frame having at least one vertical support face,
- the bolster having at least one sloped support face,
- the friction shoe comprising:
- a bottom base engaging and supported by a support spring group,
- the bottom base including a generally cylindrical spring lug extending downwardly therefrom,
- a sloped wall engaging the sloped support face of the bolster,
- and a vertical wall engaging the vertical support face of the side frame, and wherein the friction shoe support spring group is comprised of an outer coil spring, a middle coil spring and an inner coil spring.
13. The friction shoe of claim 13 wherein
- the bottom base spring lug includes a hollow opening extending vertically through the spring lug.
14. The friction shoe of claim 13 wherein
- the friction shoe support spring group is comprised of an outer coil spring, a middle coil spring located concentric with and inside the outer coil spring, and an inner coil spring located concentric with and inside the middle coil spring.
15. The friction shoe of claim 13 wherein
- the friction shoe support spring group is comprised of an outer coil spring, a middle coil spring located concentric with and inside the outer coil spring, and an inner solid elastomer spring located concentric with and inside the middle coil spring.
16. The friction shoe of claim 13 wherein
- the friction shoe provides a damping force of between 7500 and 16,250 pounds when the friction shoe is moving at a velocity of between 0 and 19 inches per second.
17. The friction shoe of claim 13 wherein
- the friction shoe provides a normal force of between 2000 and 12,000 pounds.
18. The friction shoe of claim 13 wherein
- the friction shoe is comprised of cast iron.
19. The friction liner of claim 13 wherein
- the friction shoe is comprised of cast steel.
20. The friction shoe of claim 13 wherein
- the sloped wall extends to direct contact with the bottom base.
21. The friction shoe of claim 13 wherein
- the sloped wall is comprised of two laterally spaced surfaces with a spacing wall located between the two laterally spaced surfaces.
Type: Application
Filed: Mar 8, 2017
Publication Date: Sep 13, 2018
Applicant: Amsted Rail Company, Inc. (Chicago, IL)
Inventors: John Coseglia (Edwardsville, IL), Aleynikov Igor Arkadyevich (St. Louis, MO), Ralph H. Schorr, PE (Edwardsville, IL)
Application Number: 15/453,546