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?