Click for next page ( 9


The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement



Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.

OCR for page 8
8 3500 High Rail Contact, No Guard Rail Guard Rail 3000 Rolling Resistance (lb) Guard Rail Contact, Philosophy II 2500 High & Guard Rail Contact, Philosophy I 2000 1500 1000 500 0 100 250 320 500 755 955 Curve Radius (ft) Figure 7. Wheel and horizontal guard/restraining rail installed Figure 5. The vehicle rolling resistance of a Type 1 at a low position. transit rail car with a guard rail. steering capability was not changed significantly by installing and the restraining rail, compared with a contact angle smaller a guard/restraining rail, especially on tight curves. Both philoso- than 80 between the wheel flange tip and the guard rail. The phies resulted in a slightly larger AOA on the leading axle higher the contact angle is, the higher the spin creepage is, than did the case with no guard rail; Philosophy I generated which leads to a higher wear index. a smaller AOA than Philosophy II. This conclusion was con- The axle steering capability was compared by using the firmed by the test results of the transit rail car on TTL track axle AOA in curves. Figure 14 shows that the axle steering in 1982, as Figure 10 shows. capability was not changed significantly by installing a guard/ The differences between the two guard rail installation restraining rail, especially on tight curves. Both philosophies philosophies on restraining rail applications (with a flange back resulted in a slightly larger AOA on the leading axle than did contact angle of about 90) were also investigated through the case with no guard rail, with Philosophy I generating a simulations. Figure 11 shows that the wheel lateral force of the smaller AOA than Philosophy II. Figure 14 shows that the Type 1 transit rail car with a restraining rail had a similar trend axle AOA of the Type 1 transit rail car with a restraining rail to that of guard rail cases. However, the vehicle rolling resist- had trends similar to the trends of the guard rail cases; the ances with restraining rail were much bigger than those of guard AOA change caused by guard/restraining rail installation was rail cases, except the case of 100 ft radius curves, as Figure 12 negligible compared with the cases with no guard rail, regard- shows. Because the vehicle rolling resistance is the sum of the less of which philosophy was used. wear index on all wheels, a similar trend was found in the wheel wear index. As expected, Figure 13 shows that the leading 3.2 Light Rail Vehicles (Type 1) axle wear index with a restraining rail was much larger than that of the guard rail cases except for the case of 100 ft radius curves. This section compares the two guard rail installation philoso- The Phase I study of this project (1) showed that the wear phies with applications to the Type 1 light rail vehicle with a index increases with the contact angle. The increase of the wear 75 flange angle wheel. Simulations were conducted only for index and the vehicle rolling resistance with a restraining rail a guard rail installation with a back of flange contact angle to is due to the high (90) contact angle between the wheel back the guard rail of less than 80. Figure 6. Wheel back/restraining rail contact.

OCR for page 8
9 Table 3. Transit vehicle traction force measurement on TTCI's TTL track. Measured Traction Average Traction Case Location Test Date Force (lb) Force (lb) 119,000 3,250 Without Guard Rail 118,700 2,400 2,716 5/11/1982 118,700 2,500 118,300 3,600 118,500 3,400 With Guard Rail 118,700 3,400 3,600 5/28/1982 118,900 3,900 119,100 3,700 Figure 15 shows that the wheel lateral forces on the guard Figures 15 through 18 show similar trends compared with rail using Philosophy II on most curves except the 100-ft radius Figures 4 through 9 for the transit rail car. The conclusions curve were larger than those of the cases with no guard rail. drawn from the simulations of the Type 1 light rail vehicle with This was caused by the wheel flange tip climbing on the guard 75 flange angle wheels will be the same as the Type 1 transit rail rail at the 100-ft radius curve. As a result, the high-rail contacts car with 63 flange angle wheels as discussed in Section 3.1. were close to the wheel flange root and shared part of the lateral The following conclusions can be drawn from the Type 1 force, which reduced the lateral force on the guard rail. transit rail car and the Type 1 light rail vehicle steady-state Leading Axle Wear Index (lb in./in.) 1400 45 High Rail Contact, No Guard Rail 40 1200 Angle of Attack (mrad) Guard Rail Contact, Philosophy II 35 1000 High & Guard Rail Contact, Philosophy I 30 800 25 With Guard Rail 600 20 Without Guard Rail 15 400 10 200 5 0 0 100 250 320 500 755 955 0 5 10 15 20 Curve Radius (ft) Speed (mph) Figure 8. The wear index of a Type 1 transit rail car Figure 10. Measured transit rail car leading axle AOA with a guard rail. on TTL track. 12000 High Rail Contact, No Guard Rail 60 High Rail Contact, No Guard Rail 10000 Restraining Rail Contact, Philosophy II Wheel Lateral Force (lb) 50 Angle of Attack (mrad) Guard Rail Contact, Philosophy II High & Restraining Rail Contact, Philosophy I High & Guard Rail Contact, Philosophy I 8000 40 6000 30 4000 20 10 2000 0 0 100 250 320 500 755 955 100 250 320 500 755 955 Curve Radius (ft) Curve Radius (ft) Figure 9. The axle AOA of a Type 1 transit rail car Figure 11. The wheel lateral force of a Type 1 transit with a guard rail. rail car with a restraining rail.

OCR for page 8
10 High Rail Contact, No Guard Rail 3000 8000 High Rail Contact, No Guard Rail Guard Rail Contact, Philosophy II High & Guard Rail Contact, Philosophy I Restraining Rail Contact, Philosophy II 7000 Rolling Resistance (lb) Wheel Lateral Force (lb) 2500 High & Restraining Rail Contact, Philosophy I 6000 2000 5000 1500 4000 1000 3000 2000 500 1000 0 0 100 250 320 500 755 955 100 250 320 500 755 955 Curve Radius (ft) Curve Radius (ft) Figure 12. The vehicle rolling resistance of a Type 1 Figure 15. The wheel lateral force of a Type 1 light transit rail car with a restraining rail. rail vehicle with a guard rail. Leading Axle Wear Index (lb in./in.) 1800 3000 High Rail Contact, No Guard Rail High Rail Contact, No Guard Rail 1600 Restraining Rail Contact, Philosophy II Rolling Resistance (lb) 2500 Guard Rail Contact, Philosophy II 1400 High & Restraining Rail Contact, Philosophy I High & Guard Rail Contact, Philosophy I 1200 2000 1000 1500 800 600 1000 400 500 200 0 0 100 250 320 500 755 955 100 250 320 500 755 955 Curve Radius (ft) Curve Radius (ft) Figure 13. The wear index of a Type 1 transit rail car Figure 16. The vehicle rolling resistance of a Type 1 with a restraining rail. light rail vehicle with a guard rail. Leading Axle Wear Index (lb in./in.) 800 60 High Rail Contact, No Guard Rail High Rail Contact, No Guard Rail 700 Restraining Rail Contact, Philosophy II Guard Rail Contact, Philosophy II 50 Angle of Attack (mrad) 600 High & Restraining Rail Contact, Philosophy I High & Guard Rail Contact, Philosophy I 40 500 400 30 300 20 200 10 100 0 0 100 250 320 500 755 955 100 250 320 500 755 955 Curve Radius (ft) Curve Radius (ft) Figure 14. The axle AOA of a Type 1 transit rail car Figure 17. The wear index of a Type 1 light rail with a restraining rail. vehicle with a guard rail.

OCR for page 8
11 50 High Rail Contact, No Guard Rail curving simulations, regarding comparisons of the two differ- 45 Guard Rail Contact, Philosophy II ent guard rail installation philosophies: Angle of Attack (mrad) 40 High & Guard Rail Contact, Philosophy I 35 Philosophy I leads to a better vehicle dynamic performance 30 than Philosophy II in terms of lower lateral forces on rails, 25 lower vehicle rolling resistance, and lower leading axle wear. 20 Both philosophies lead to higher vehicle rolling resistance 15 10 and leading axle wheel wear, compared with the case with 5 no guard rail. 0 The axle steering capability difference between these two 100 250 320 500 755 955 philosophies is negligible. Curve Radius (ft) Restraining rails (the W/R contact angle is almost 90) and Figure 18. The axle AOA of a Type 1 light rail vehicle guard rails (the W/R contact angle is less than 80) provide with a guard rail. similar trends in performance.