Performance Characteristics
for Freight Car Bogies
What the Industry is Looking for
to Improve Rail and Wheel Life
Jay P. Monaco
Vice President Global Engineering
Amsted Rail Company, Inc.
1
Demand for Productivity
Capacity increases through…
• Longer trains
• Heavier axle loads
25.0 t
27.5 t
30.0 t
32.5 t
37.5 t
• Increased train velocity
• More lading capacity, lighter railcars
Increase sensitivity to…
• Load balance and vehicle stability
• Speed and track conditions
• Railcar construction
Increasingly demanding operating environment
2
40 +
Component Attributes
Long life / low maintenance / reduced wear…and…
Quality / integrity / reliability • Reduced incidence of in‐service failures ‒ Safety / security / service reliability
‒ System capacity and efficiency • Maximum uptime
‒ Asset utilization / train velocity
‒ Productivity
Component performance is critical to wheel and rail life
3
Key Running Gear Components
Bogie and Braking Systems
End of Car Systems
Optimize the systems!
Railcar running gear components work together as a system
4
Wheel / Rail Interaction
Suspension, vehicle and track are a system
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Demands on Bogie System
Make wheels last longer
Eliminate bearing failures
Reduce system maintenance
Reduce system weight
… but service loads are increasing !
6
Bogie System Weight Variation
Bogie Castings, Stabilizers, Load Coils for 286,000 lb. GRL
Average Carset weight
across all designs
= 7,857 lbs.
800 lbs. difference
Lower weight components = more carrying capacity
7
Dynamic Performance
Yaw & Sway
Car / Suspension Specific
Twist & Roll 15‐25, 50‐60 mph
Pitch & Bounce
50‐70 mph
Truck Hunting
Truck Warp, Truck Rotation, Wheelset Movement
40+ mph
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Bogie Performance Evolution
More demanding environment
Bogie system performance
AAR Specification M‐976
Steering
Curve negotiation without compromising high speed stability
Suspension
M‐976 Bogie System
Reduced wheel and track wear
Damping of vertical and lateral inputs; bogie squaring
Reduced impact of loading conditions
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M-976 Test Regimes
Loaded Short Car 4427 cu. ft.
Empty Short Car 4427 cu. ft
Test Regime
Covered Hoppers:
• Empty / Loaded
• Short / Long
Hunting
Empty - Short
Steady State Curving
Empty - Short
Loaded - Short
Curve Resistance
Loaded – Short
Spiral
Empty - Short
Loaded - Short
Empty - Long
Twist / Roll
Empty - Short
Loaded - Short
Pitch / Bounce
Empty - Short
Loaded - Short
Yaw / Sway
Loaded - Short
Dynamic Curving
Loaded - Short
Major_modes_qt.mov
Empty Long Car 6000 cu. ft.
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M-976 Test Regimes
Hunting Criteria
•
•
Maximum Lateral Acceleration: 1.5 g’s peak to peak
Standard Deviation: 0.13 g’s rms
Steady State Curving
•
•
95th percentile Maximum Wheel L/V:
0.8
95th percentile Maximum Axle Sum L/V:
1.5
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M-976 Test Regimes
Curving Resistance
•
•
•
•
•
Average Pounds \ Ton \ Degree: 0.4 maximum
1.5 Degree Curve
4.0 Degree Curve
7.5 Degree Curve
10 Degree Curve
Pitch / Bounce
• Minimum Vertical load: 10% • Dynamic Acceleration:
1.0 g
• Spring Capacity Maximum: 95%
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M-976 Test Regimes
Twist / Roll
•
•
•
•
Max. Axle Sum L/V: 1.5
Min. Vertical Load: 10% Dynamic Acceleration:
1.0 g
Spring Capacity Maximum: 95%
Yaw / Sway
•
•
Maximum Truck Side L/V:
Maximum Axle Sum L/V:
0.7
1.5
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M-976 Test Regimes
Dynamic Curving
•
•
•
Minimum Vertical load: 10% Maximum Wheel L/V:
1.0
Maximum Axle Sum L/V: 1.5
And if that wasn’t enough…
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SRI 2A – Integrated FC Truck
New test regimes being considered
• Loaded Car Hunting
‒ Same criteria as empty car hunting
‒ Using loaded 5160 c.f. grain car
‒ > 75 mph
• Curving Resistance ‐ Low Rail Traction Ratio (T/N) ‒ Vertical, lateral and longitudinal forces at contact patch
‒ Using instrumented wheel set measurements ‒ T/N < 0.37
Traction Ratio < 0.37 = magic number to alleviate RCF
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Low Rail Traction Ratio
vectored longitudinal force (taking tread taper into account)
T/N = vectored lateral force (taking tread taper into account) at the contact patch
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Key Bogie Components
Stability / hunting control • Friction wedges; squaring; dimension control
• Center bowl liner (loaded car) – rotational resistance / friction damping (too low = stability issues)
• Side bearings (light car) – rotational resistance / friction damping; railcar roll control
Reduced rolling resistance
• Low torque bearings
• Passive steering components
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Steering and Stability
Steering = axle movement to negotiate curves
• Elastomeric pad and special adapter enable steering • Pad deflects in shear with controlled stiffness (too stiff = harder on wheel; too soft = hunting / stability issues)
• Stored pad energy restores axle on tangent track
• Standard metal adapters can stick due to friction, causing wheel / flange scrubbing
Curving vs. Stability… • Passive mechanical system is a compromise
• Balance curving resistance and high speed stability
…and remember vertical performance
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Lateral and Longitudinal Motions
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Lateral and Longitudinal Motions
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Lateral and Longitudinal Motions
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Findings
Softer pad material = higher deflections
Stiffer pad material = lower deflections
• Less energy input
• Less movement per unit of force
• Increase in hunting threshold
Alternatives exist to mitigate hunting and associated wheel tread scrubbing
Squaring mechanism such as transom, spring plank or bracing helps with curving and stability, but adds cost and maintenance issues
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High Speed Stability
3‐piece truck vs. alternative truck
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Next Generation M-976 (?)
AAR/TTCI (with supplier input) determining next level of achievable performance through SRI 2A
• New specification to implement lessons learned
• Test values expected to be tightened
• Cost / benefit analysis to be undertaken before implementation; may be 3 + years out
“One size fits all” philosophy to deal with any encountered conditions and car types forces design optimized for test conditions
24
High-mileage Tank Cars – Crude Oil
Production surge required rail transport
•
•
•
Largest source = Bakken Shale reserves ND (~ 2/3 of which is shipped by rail)
2009:
11,000 crude oil car loads
2013: 400,000 crude oil car loads (estimated)
Many unit trains in crude oil service
•
•
286,000 pounds GRL = 31,800 gallons crude oil
> 100 cars and > 1.0 mile in length
Currently ~ 10% crude oil shipped by rail
•
•
•
Unit trains account for 70% of crude oil rail shipment
2010:
207 unit trains dispatched
2012:
1,775 unit trains dispatched
Production has exceeded pipeline capacity
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Current Tank Car Fleet
335,000 tank cars in today’s fleet
•
•
•
228,000 are DOT‐111
92,000 DOT‐111 are used to transport flammable liquid
14,000 are built to latest industry standard (CPC‐1232)
~30% of crude oil tank cars are built to the latest industry standard (CPC‐1232)
A mix of pipeline and rail will always be necessary
• Pipeline permitting takes years to get through Federal, State and local authorities; land acquisitions take time
• Rail is flexible and can transport crude according to market demand and refinery efficiency
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Existing DOT-111 Tank Cars
Retrofit or aggressive phase out possible
• ~78,000 DOT‐111 cars would need this
• ~14,000 DOT‐111 may need additional upgrades
Safety is main concern
Wheel / Rail Interaction
•
•
•
Key to rail safety
Alleviate RCF
Eliminate failure modes
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Maintenance
Heavier loads and longer trains increase demands placed on railcar equipment (wear and tear)
Running gear selection can mitigate effects
… but, to keep assets moving safely…
Inspection is required to determine repairs, and/or
• Preventive (scheduled) maintenance
• Corrective (reactive) maintenance
• Setouts via wayside detectors, or alternative
An effective maintenance program is essential
Asset utilization / uptime vs. Safety / security vs. Maintenance
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Real-time Asset Monitoring
GPS location / speed / “active” asset time
Evaluate system status and condition with sensors
Impact on maintenance: • Preventive (scheduled) vs. Corrective (reactive)
• Consider pre‐emptive maintenance
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Condition Based Maintenance
Preventive maintenance may prevent some failures, but premature failures can still occur; cost is high
Corrective maintenance promises lower costs, but cost of reaction to failures is high
CBM strategy • Can be effected using Rail Wayside Detection technology or On‐board Wireless Sensor technology
• Lower operating costs; extend useful life of equipment
• Increase productivity and maximize asset uptime
• Measure / analyze real‐time; relay message to effect pre‐
emptive maintenance or repair (before a failure occurs)
CBM strategy enables pre‐emptive maintenance
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ISO 13374
Advisory Generation (AG)
CBM
Prognostic Assessment (PA)
Predict
Health Assessment (HA)
Alert
Alarm
Data Manipulation (DM)
Sensors
Infer future health (life expectancy)
Infer current health (condition) from key metrics
Use metrics for condition assessment
State Detection (SD)
Data Acquisition (DA)
Condition Based Maintenance $$$
Observe acceptable thresholds
Calibrate, process, analyze
Status
A/D conversion, sampling frequency
Pick up a copy of ISO13374 for some late night reading…
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Increasing Maintenance Value $$$
Condition Monitoring and Diagnostics of Machines
On-board Wireless Sensing
Hatch open
Hot bearing
Wheel impact
Bearing condition
Door open
Acceleration
Handbrake set
Bearing remaining life
Real‐time information to keep trains moving safely
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Onboard System approach
Onboard wireless sensors and preprocessing of data
Action messaging via satellite and/or cellular comm. Maintenance only when necessary
Alarms
GPS
Data
Instructions
CMU
Web portal
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Wireless Sensor Applications
Impact sensing (g’s)
Handbrake status
Hatch / Gate open
Railcar weight
Temperature
Pressure
Bearing condition
34
Case Study: Ride Quality
Lateral
Impact waveforms from website
Vertical
Longitudinal
Measure impact acceleration
Send alert when pre‐defined threshold is exceeded
Capture location, date and time of impact View data on fleet management dashboard
35
Case Study: Temperature
Track temperature of crude oil in near real‐time to determine need to steam cars
Temperature changes based on commodity, car type and season can reduce heating and cooling costs
Alert on criteria including rapid temperature change and crossing of absolute values
36
Case Study: Onboard Load Weigh
Measure railcar weight directly – alternative to flow rate, etc.
CMU
Monitor weight during loading to improve accuracy
WSN
Alternative to trackside scales Maximize loadings and minimize overloaded conditions to avoid penalties
Alert to return asset after unloading
37
Case Study: Handbrake Monitor
Monitor linkage tension and report status wirelessly to CMU
Alert when handbrake is applied and motion is detected to identify time and location of potential wheel damage
Monitor and audit operational rule compliance: Behavioral change and Real‐time status to avoid accidents
Safety and security through compliance monitoring and real time status
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Technology Advancement
Advance through technology to avoid failures and enhance productivity
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