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From page 1... ... TCRP WOD 65 Part 1 Wheel wear is another reason for wheel truing. Wheels wear into worn shapes in service, with most wear on the tread and flange, as Figure 2 shows. Read the entire page →
From page 2... ... TCRP WOD 65 Part 1 Configuration 2. As Table 3 shows, the left and right side of the first and fourth axles were exchanged so each truck had hollow wheels only on one side. Read the entire page →
From page 3... ... TCRP WOD 65 Part 1 Figure 3. Freight Car Hollow Wheel Stability Test Wheel wear on treads can lead to the formation of false flanges. Read the entire page →
From page 4... ... TCRP WOD 65 Part 1 No comprehensive study of the effects of wheel diameter differences on rail transit vehicle stability has been performed recently. In 2006, a freight car tolerance study (Tunna et al. Read the entire page →
From page 5... ... TCRP WOD 65 Part 1 Figure 5. Longitudinal Forces on the Right Wheel of the Leading Wheelset at 60 mph (96.6kmh) Read the entire page →
From page 6... ... TCRP WOD 65 Part 1 MiniProf™ (Greenwood Engineering A/S, Denmark) profilometers and software have been widely used for wheel and rail cross section profile measurement. Read the entire page →
From page 7... ... TCRP WOD 65 Part 1 The effects of wheel diameter difference in one truck on transit vehicle dynamic performance, such as wheel load equalization, will be examined based on American Public Transportation Association (APTA) criteria (APTA 2007) Read the entire page →
From page 8... ... TCRP WOD 65 Part 1 A wheel profile with a higher flange angle can reduce the risk of flange climb derailment and can have much better compatibility with any new designs of vehicles and trucks that may be introduced in the future compared to wheels with lower flange angles. Also, with a higher lateral to vertical (L/V) Read the entire page →
From page 9... ... TCRP WOD 65 Part 1 Most rail transit agencies trued wheels based on fixed cycle (certain number of mileage or service years) regardless of condition. Read the entire page →
From page 10... ... TCRP WOD 65 Part 1 Figure 8. Lathe Type Wheel Truing Machine Several rail transit agencies have reported flange climb derailments occurring at curves or switches in yards when the cars were just out of the wheel re-profiling machines. Read the entire page →
From page 11... ... TCRP WOD 65 Part 1 Figure 9. Rough Wheel Surface from Milling Type Truing Machine The rough surface produced by wheel truing increases the effective coefficient of friction between wheel and rail, which significantly reduces the L/V ratio limit for flange climb. Read the entire page →
From page 12... ... TCRP WOD 65 Part 1 Once a new wheel profile has been accepted, any changes to the wheel profile (especially tread and flange width) must be evaluated by both vehicle and track designers. Read the entire page →
From page 13... ... TCRP WOD 65 Part 1 Figure 11. Worn Wheel Contact on Worn High Rail The design wheel profile (truing template) Read the entire page →
From page 14... ... TCRP WOD 65 Part 1 C H A P T E R 3 State-of-the-Art Wheel Profile Design and Maintenance Principles Wheel profiles have a significant effect on wheel/rail contact and overall vehicle and track dynamic performance. A design of a new wheel profile well suited for a specific vehicle, track, and service environment can improve vehicle and track dynamic performance and reduce wear and damage on wheel and rail. Read the entire page →
From page 15... ... TCRP WOD 65 Part 1 of a vehicle fitted with these wheel profiles and calculating a penalty index. An inverted penalty index was used as the fitness value in the genetic algorithm. Read the entire page →
From page 16... ... TCRP WOD 65 Part 1 3.2 Wheel Profile Design and Maintenance Criteria The objectives of optimum wheel and rail profiles are to provide: Stable performance over the range of normal train speeds Safety from derailment under adverse but realistic operating conditions Maximized wheel and rail life Wheel and rail profile design is a matter of optimizing several criteria. Some criteria must be satisfied, but some can be compromised to achieve an overall optimum solution. Read the entire page →
From page 17... ... TCRP WOD 65 Part 1 The kinematical properties of wheel and rail contact, such as rolling radius, contact angles, and wheelset roll angle vary as the wheelset moves laterally relative to the rails. The nature of the functional dependence between these geometrically constrained variables and the wheelset lateral position is defined by the wheel and rail profiles. Read the entire page →
From page 18... ... TCRP WOD 65 Part 1 Figure 13. Contact of New AAR-1B Narrow Flange Wheel on New AREMA 136-RE Rail, 10-inch Crown Radius, 1:40 Cant, at a Gage of 56.5 inches Figure 14. Read the entire page →
From page 19... ... TCRP WOD 65 Part 1 There are several other definitions and methods for equivalent conicity calculation. Among them the following methods are frequently used to calculate the equivalent conicity: Equivalent linearization by the application of Klingel formula defined in International Union of Railways UIC 519 standard 2004 Linear regression of the function of RRD defined in UIC 519 standard 2004 Harmonic quasi-linearization (Polach 2009) Read the entire page →
From page 20... ... TCRP WOD 65 Part 1 Figure 15. RRD Functions Measured in a Freight Railcar 24 Read the entire page →
From page 21... ... TCRP WOD 65 Part 1 C H A P T E R 4 Conclusions and Recommendations The following conclusions and recommendations are made from the survey of wheel profile maintenance practices in rail transit agencies and the literature review: • Wheel slide and wheel flats are mainly caused by braking and low adhesion conditions. New antislip technologies and devices are needed to reduce wheel flats. Read the entire page →
From page 22... ... TCRP WOD 65 Part 1 References American Public Transit Association. APTA SS-M-014-06, Standard for Wheel Load Equalization of Passenger Railroad Rolling Stock, 2007. Read the entire page →
From page 23... ... TCRP WOD 65 Part 1 Shu, X Read the entire page →
From page 24... ... Wheel Profile Maintenance Guidelines PART 2 Wheel Profiles Design and Maintenance Guidelines for Rail Transit Operation Read the entire page →
From page 25... ... Table of Contents TABLE OF CONTENTS ............................................................................................................................... Read the entire page →
From page 26... ... List of Figures Figure 1. Measured Wheel Profiles .................................................................................................. Read the entire page →
From page 27... ... Figure 27. Comparison of Wear Index for the Existing and New Design Wheel .......................... Read the entire page →
From page 28... ... List of Tables Table 1. Case Study Parameters ..................................................................................................... Read the entire page →
From page 29... ... TCRP WOD 65 Part 2 Summary Transportation Technology Center, Inc., (TTCI) , a wholly owned subsidiary of the Association of American Railroads (AAR) Read the entire page →
From page 30... ... TCRP WOD 65 Part 2 – Systems with many curves may need tighter tolerances on wheel diameter differences than systems with few curves and mostly straight track. • Wheel wear has significant effects on both hunting speed and switch frog impact. Read the entire page →
From page 31... ... TCRP WOD 65 Part 2 C H A P T E R 1 Introduction The Transportation Technology Center, Inc. Read the entire page →
From page 32... ... TCRP WOD 65 Part 2 C H A P T E R 2 Development of Wheel Profile Design and Maintenance Guidelines for Rail Transit Operation Wheel profile shape has significant effects on rail vehicle and track performances. Wheel and rail profile optimizations have been investigated intensively to improve car performances with the increase of car running speed and axle load, as described in the Task 1 literature review report for this study (Shu 2014) Read the entire page →
From page 33... ... TCRP WOD 65 Part 2 Authority's Type 8 car demonstrated that derailment accidents were significantly reduced by increasing wheel maximum flange angle from 63 to 75 degrees (Griffin 2006) Read the entire page →
From page 34... ... TCRP WOD 65 Part 2 Figure 1. Measured Wheel Profiles If wheels with a flange angle greater than 70 degrees are directly introduced, such as the 75-degree flange angle wheel that has been commonly adopted for many newly built transit systems, the resulting incompatible contact pattern with the existing worn rails will require aggressive wheel truing and rail grinding. Read the entire page →
From page 35... ... TCRP WOD 65 Part 2 • Truck Center Spacing: 52 feet • Wheel load: 9.45 kips • Wheel diameter: 27 inches Vehicle model parameters were measured through characterization tests. The measured primary suspension longitudinal and lateral stiffness and damping were reduced by half to simulate a worn truck condition. Read the entire page →
From page 36... ... TCRP WOD 65 Part 2 Figure 3. L/V Ratio, Existing 63-degree Wheel on New Rail, No Track Perturbations Figure 4. Read the entire page →
From page 37... ... TCRP WOD 65 Part 2 Figure 5 shows the car with the 63-degree flange wheel exceeding the L/V ratio limit at 0.5-friction coefficient, derailing at 0.5-friction coefficient on a No. 8 turnout. Read the entire page →
From page 38... ... TCRP WOD 65 Part 2 Increasing the maximum flange angle can effectively reduce flange climb derailment risk. APTA recommends a 72 degree (with tolerance +3 degrees and -2 degrees) Read the entire page →
From page 39... ... TCRP WOD 65 Part 2 ) Read the entire page →
From page 40... ... TCRP WOD 65 Part 2 The hunting criteria adopted by the railroad industry are different from that in academic research. The hunting speed in Figures 8 and 9 was defined as the speed at which the axle lateral motion starts to increase without damping after the excitation of track perturbations, as Figure 10 shows. Read the entire page →
From page 41... ... TCRP WOD 65 Part 2 Figure 11. Limit Cycle Movements of Conical Wheel Hunting (65 mph) Read the entire page →
From page 42... ... TCRP WOD 65 Part 2 The industry uses an acceleration-based hunting speed criterion instead of an axle motion based criterion for the following reasons: • It is difficult to measure the dynamic axle displacements in the field. • The definition of hunting using axle motion is not clear; for some cases, the axle lateral motion bursts into hunting with hard flange contact, while for other cases, the axle lateral oscillation slowly grows into flange contact, while the truck and carbody accelerations may exceed safety limits before flange contact. Read the entire page →
From page 43... ... TCRP WOD 65 Part 2 in two different trends, namely supercritical and subcritical Hopf bifurcation. Hopf bifurcations occur when a railway vehicle runs above a critical speed (True 1994) Read the entire page →
From page 44... ... TCRP WOD 65 Part 2 Figure 14 shows the ride quality of the simulated car equipped with 45-degree wheels is better than that with 63-degree wheels at speeds lower than 79 mph, which is consistent with their hunting performances (the hunting speed of the car equipped with 45-degree wheels is higher than that with 63-degree wheels) Read the entire page →
From page 45... ... TCRP WOD 65 Part 2 Figure 15. Truck Frame Accelerations at Different Speeds (45-degree flange angle wheel) Read the entire page →
From page 46... ... TCRP WOD 65 Part 2 Figure 17. Truck Frame Accelerations at Different Speeds (70-degree flange angle wheel) Read the entire page →
From page 47... ... TCRP WOD 65 Part 2 Figure 18. W/R Equivalent Conicity and Clearance Effects on Hunting Speed Figure 19. Read the entire page →
From page 48... ... TCRP WOD 65 Part 2 The HSC chart in Figure 19 was developed based on a specific type of transit car model. It can be used to determine the hunting speed of this type of transit car with new and worn wheels. Read the entire page →
From page 49... ... TCRP WOD 65 Part 2 wheels were estimated to be 70 mph and 65 mph for the new design 70-degree wheel and existing 63degree wheel, respectively. Figure 21. Read the entire page →
From page 50... ... TCRP WOD 65 Part 2 The application of the HSC chart includes the following steps: • Generate a HSC chart for a representative type of car: – Build the car model by using parameters measured through characterization test – Generate a series of simplified wheel profiles consisting of tread (with different tread slopes) and flange (with different flange angles) Read the entire page →
From page 51... ... TCRP WOD 65 Part 2 Figure 23. Measured Rail Profiles in Curve Figure 24 shows the new design 70-degree flange angle wheel running on a new 115RE rail generates lower contact stress than that of the existing 63-degree flange angle wheel for almost all simulated curves. Read the entire page →
From page 52... ... TCRP WOD 65 Part 2 Figure 25. Contact Stress of the Existing and New Design Wheels on Worn Rails Figure 26. Read the entire page →
From page 53... ... TCRP WOD 65 Part 2 The W/R wear was evaluated by using the wear index, defined in Equation 2. It is calculated as the sum of the tangential forces (Tx, Ty and Mz) Read the entire page →
From page 54... ... TCRP WOD 65 Part 2 2.5 Guidelines for Compatibility with Special Trackwork 2.5.1 Turnouts 2.5.1.1 Switch Points Wheel profile changes have significant effects on existing special trackwork because the special trackwork has been either worn or adjusted into shapes compatible with existing wheels. To avoid derailments on worn switches, the new design wheel has to be checked against worn switches to make sure the new wheel profile will not increase flange climb derailment risk. Read the entire page →
From page 55... ... TCRP WOD 65 Part 2 It is a common practice in European railroad and rail transit systems to add an increased taper roll-off segment to the wheel tread near the field side, as Figure 29 shows. Compared to the tapered wheels without the roll-off, the wheel tread roll-off provides additional rolling radius difference on curves where high rail contacts on the wheel flange and low rail contacts on the roll-off segment. Read the entire page →
From page 56... ... TCRP WOD 65 Part 2 compatible with cylindrical wheels. A new design wheel with a tapered tread will bluntly strike the existing frog nose and result in a depressed nose, as Figure 31 shows. Read the entire page →
From page 57... ... TCRP WOD 65 Part 2 Figure 33 shows the wheel with a large chamfer (45 degrees) contacting on a new switch point guard at about a 78-degree contact angle. Read the entire page →
From page 58... ... TCRP WOD 65 Part 2 2.5.3 Spring Switches Spring switches are often used in light rail transit systems, especially in urban city areas. They lower costs by using a mechanical device (spring or retard) Read the entire page →
From page 59... ... TCRP WOD 65 Part 2 Figure 36. W/R Contact on Spring Switch Points While the friction coefficient 𝜇𝜇3 can be decreased as low as possible by using grease to ease the sliding movement of the switch point on the plate, the W/R friction coefficient 𝜇𝜇2 cannot be controlled because of environmental changes. Read the entire page →
From page 60... ... TCRP WOD 65 Part 2 Figure 37. Wheel Diameter Difference (in the Same Axle) Read the entire page →
From page 61... ... TCRP WOD 65 Part 2 Figure 38. Wheel Diameter Difference Effect on Wear Index Figure 39. Read the entire page →
From page 62... ... TCRP WOD 65 Part 2 Figure 40. Wheel Diameter Difference Effect on Wheel L/V Ratio Figure 41. Read the entire page →
From page 63... ... TCRP WOD 65 Part 2 2.6.1.3 Effect on Wheel Unloading Wheel diameter difference effects on vertical wheel unloading were investigated by running the car through measured pitch and bounce track perturbations (AAR Chapter 11, Pitch and Bounce track perturbations, 39-feet wave length and maximum ¾-inch amplitude) at different speeds. Read the entire page →
From page 64... ... TCRP WOD 65 Part 2 2.6.2 Wheel Wear 2.6.2.1 Effect on Hunting and Ride Quality Transit agencies usually adopt wear limits on wheel and rail wear to maintain acceptable vehicle and track performances. A new wheel quickly wears into a shape conformal with existing rails, which decreases contact stress, but may deteriorate car ride quality as it becomes heavily worn. Read the entire page →
From page 65... ... TCRP WOD 65 Part 2 Figure 44. Hunting Speed Estimation for a Car Equipped with Measured New and Worn Wheels Figure 45 shows the predicted car hunting speeds. Read the entire page →
From page 66... ... TCRP WOD 65 Part 2 Figure 45. Truck Frame Accelerations of a Car Equipped with Measured New and Worn Wheels (56.25-Inch Gage) Read the entire page →
From page 67... ... TCRP WOD 65 Part 2 Figure 47. Measured New and Worn Wheel Conicity, Track Gage 57 inches Figure 48. Read the entire page →
From page 68... ... TCRP WOD 65 Part 2 The car hunting speeds of new measured wheels with track gage variations are higher than that of worn wheels. However, the heavily worn wheel wore the tapered tread into a flat shape, which lowered the conicity. Read the entire page →
From page 69... ... TCRP WOD 65 Part 2 2.6.2.2 Effects on Frog Impact Figure 50 shows four frog cross section profiles at locations A, B, C, and D in a standard AREMA No. 20 turnout. Read the entire page →
From page 70... ... TCRP WOD 65 Part 2 Figure 51 shows the impact ratio on frog nose increases with wheel wear and running speed. The heavily worn wheel impact ratio was increasing by about 25 percent compared to that of the new wheel. Read the entire page →
From page 71... ... TCRP WOD 65 Part 2 Figure 53. New and Worn Wheel Lateral Forces in Curves with New Rails 2.6.2.4 Wheel Wear Summary Wheel wear effects on hunting performance depend on W/R wear patterns: • If W/R wear results in high W/R conicity and larger gage clearance, a car may start hunting at speeds lower than that with new wheels and rails. Read the entire page →
From page 72... ... TCRP WOD 65 Part 2 C H A P T E R 3 Conclusions and Recommendations The following conclusions and recommendations are made from this study: • Both W/R contact conicity and W/R gage clearance have significant and complex effects on car lateral stability (hunting) , especially as the wheels and rails wear. Read the entire page →
From page 73... ... TCRP WOD 65 Part 2 • Effects of wheel profiles with zero and negative W/R conicity (hollow worn wheels) on rail transit car hunting performance are recommended for further investigation. Read the entire page →
From page 74... ... TCRP WOD 65 Part 2 References American Public Transit Association. APTA SS-M-014-06, Standard for Wheel Load Equalization of Passenger Railroad Rolling Stock. Read the entire page →
From page 75... ... TCRP WOD 65 Part 2 A P P E N D I X Light Railcar Hunting Speed Contour Chart A.1 Vehicle Model A typical light rail vehicle model consisting of two carbodies and three trucks with the following specifications was used in this study: • Two carbodies articulate on the middle truck • Primary Chevron suspension • Secondary airbag suspension • Lateral and vertical damper in secondary suspension • Axle spacing: 6.3 feet • Truck Center Spacing: 23 feet • Wheel load: Mid truck: 5.2 kips, End truck: 8.2 kips • Wheel diameter: 27 inches Vehicle model parameters were measured through characterization tests. The measured primary suspension longitudinal, lateral stiffness, and damping were reduced by half to simulate a worn truck condition. Read the entire page →
From page 76... ... TCRP WOD 65 Part 2 Figure A1. Hunting Speed Contour Chart for a Light Railcar 48 Read the entire page →

From page 1...

... TCRP WOD 65 Part 1 Wheel wear is another reason for wheel truing. Wheels wear into worn shapes in service, with most wear on the tread and flange, as Figure 2 shows.