DTE Seminar

Constant Contact Side Bearings

Paul Aspengren

Key Terms and Concepts• Constant Contact Side Bearing – CCSB• Preload• Setup height• Gap• Hunting• Long Travel• L/V Ratio

Railcar

Railcar Truck

Introduction

Roller

Non Constant ContactNon Constant Contact

Side Bearing Types

Block

Constant ContactConstant Contact

Metal Cap

Non Metal Cap

Linear CageLinear Cage Telescoping CylindersTelescoping Cylinders

Side Bearing Types

Truck Bolster

Car Body Wear Plate

Preload

Setup HeightTravel

Basic Terminology

Constant Contact

•Standard

•5/16”

•Long

•5/8”

• Setup Height is the distance between the wear plate and bolster pad

• Rule 62 has condemning limits for different models• Important to measure on empty cars on reasonably

level track• Shims added or removed to adjust setup height

Setup Height

Long Travel

Roller Assist

Standard Travel

Side Bearing Types

Functions of a Side Bearing

• Improve curve negotiation

• Help in controlling car body roll

• Increase hunting threshold

•Long Travel (LT) equalizes vertical wheel loads entering and exiting curves.

V V

Curve Negotiation

Pad absorbs energy on each

compression

Area within curve is equal to

absorbed energy

Helps to dampen car body roll

Vertical Hysterisis

TCC-III-60 Enhanced

0

1

2

3

4

5

6

7

8

9

10

4.44.64.855.25.45.65.866.2

Set-Up Height (in)

Load

(kip

s)

• At higher speeds, the steering forces will cause the wheel set to over compensate and diverge from equilibrium.

What is Hunting?

What Is Hunting?

Hunting Control

-150%

-100%

-50%

0%

50%

100%

150%

-0.3 -0.2 -0.1 0 0.1 0.2 0.3

Displacement

Sh

ea

r F

orc

e

84%

-150%

-100%

-50%

0%

50%

100%

150%

-0.3 -0.2 -0.1 0 0.1 0.2 0.3

Displacement

Sh

ear

Fo

rce

46%

Side Frame - Pedestal Roof

Side Frame - Adapter LugsBolster- Inner Column

Gibs

Side Frame -

Anti Rotation Lugs

Bolster - Column Gibs

Bolster - Shoe Pocket

Why Hunting Control is Important to Car Owners – Reduces Excessive Wear!

AAR Circular C-9560 on December 10, 2002

Rule 88.C.3.(18)(m) – Truck Components All units must be equipped with …….

Long-travel Constant-Contact Side Bearings …… conforming to AAR Specification M-948.

Effective December 31, 2002.

(1) New Cars(2) Rebuilt Cars (3) Extended Service Status Cars(4) Increased Gross Rail Load Cars

Long Travel Mandate for New Cars

AAR Circular C-10068 on March 24, 2005

Rule 88.A.15.f – Tank Cars

The approved revision to the rule becomes effective on April 1, 2005.

AAR Circular C-10271 on February 9, 2006

Rule 90.B.5.i – Flat Cars

The approved revision to the rule becomes effective on April 1, 2006 as was suggested in c-10250.

Recent Long Travel Mandates

AAR Side Bearing Mandate• TTCI Side Bearing Testing

- Comprehensive CCSB and Car Type Matrix

• Rule 62 - New Side Bearing Maintenance and Billing Requirement

• M-948 - Side Bearing Specification Rewrite

AAR Field Manual Rule 62

• Wear limits

• Setup height criteria

• Correct repair practices

• General information

• Billing and Job codes

• Incorrect fasteners can lead to broken housings

Yard Inspection

Setup Height Issues

•Rule 62 has replacement criteria

•Pocket Guides have free height criteria

Pad Condition

Wrap Up• Intro to side bearings

• Function of side bearings

• Rules governing side bearings

• Common failures related to side bearings

Questions?