NTRD-02 Final Project Report The Effects of Low Rolling Resistance ...

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Figure 13. (a) 10-bolt pattern wheel (b) “spider hub” as used on chassis trailers. 5.2 Test Phase 5.2.A Texas Drayage Truck Driving Cycle Track testing of the tires was done on an 8.5-mile oval track at the Continental-General Proving Grounds (CCPG) in Uvalde, TX. The Texas Drayage Truck Driving Cycle was adapted for use at the CGPG. Signs were placed at locations where the vehicle started, stopped, or made a significant change in acceleration rate. The drivers used the GPS speed from the PEMS rather than the speedometer to drive the route to ensure the truck speed profile was as close as possible in all laps regardless of potential differences in rolling radius of the drive tires. In-cab observers aided the drivers with time-keeping and speed matching. The track surface was asphalt and generally flat with a few rolling hills. The total distance of the cycle (31.69 miles, or approximately 3.75 times around the track) was designated one lap according to SAE J1321. The approximate average speed for a lap was 20.75 mph. 5.2.B Test Method Prior to each day of operation, tire inflation pressures were checked and adjusted to a pressure of 100 psi. The truck fuel tanks were filled, and a separate removable weigh-tank was filled and installed on each truck. The trucks were driven around the 8.5-mile oval track three times at a constant speed of 65 mph as a warm-up each day before testing. According to SAE J1321, one test lap consisted of simultaneous operation of the test truck and the control truck. After completion of a test lap, the weigh tanks were removed and weighed, and the mass of fuel consumed by the test truck (T) was compared to the mass of fuel consumed in the control truck (C). These were combined in a T/C ratio according to SAE J1321 procedure. Prior to each test lap, the engine was stopped, and the fuel supply and return lines were switched from the truck tank to the weigh-tank. The trucks started each lap with a five to ten minute separation. The engine was restarted and the truck was idled for 10 minutes to start the Texas Drayage Truck Driving Cycle. After the driving cycle was completed, the truck was decelerated 19
to a stop. The engine was allowed to idle for approximately 60 seconds and then stopped to switch fuel lines from the weigh tank to the truck tank. The weigh-tanks were removed and weighed to determine the fuel consumed. To maintain consistent operation during a driving cycle sequence, the trucks were operated with the headlights on and the air conditioning and the blower fan controls in the same position. An observer in each truck recorded driving times at key mile markers. The total time for each lap had to match the appropriate target times within +/-0.5% for that lap to be considered operationally valid. According to SAE J1321, one test segment consisted of three valid test laps where the spread in T/C ratios of the three laps did not exceed 2.00%. The T/C ratios for the three laps were then averaged to obtain a T/C ratio for the segment. The control truck and trailer rig remained in the same configuration throughout testing, and the test tires were added or removed from the test truck rig by segment. Four segments were tested, as outlined in Table 4. The order of the segments was designed to ensure repetition of each configuration with a minimum number of setup changes. Table 4. Test Segments for SAE J1321 Testing. Segment Number 1 (baseline) 2 (test) 3 (baseline) 4 (test) Test Trailer As-received trailer spider hubs, rims, and tires 10-bolt hubs, wide-single rims, and wide-single tires 10-bolt hubs, wide-single rims, and wide-single tires Original trailer spider hubs, rims, and tires 20 Test tractor drive tires BF Goodrich tires supplied by Michelin North America Wide-single tires on the drive locations Wide-single tires on the drive locations BF Goodrich tires supplied by Michelin North America 5.3 Track Test Results Fuel consumption was measured by weighing the weigh-tanks after each completed run and subtracting the initial value. In order to account for the fuel consumed during the idle period, the data log was examined, and the values commanded by the engine controller were noted. An appropriate calibration factor was formed by forming a ratio of the total fuel consumed according to the engine control bus to the total fuel consumed as measured by the weigh tanks. This correction factor was then applied to the idle-period data recorded by the engine control bus, and the appropriate weighting factors were applied according to the test cycle specifications. In this way, the fuel consumption for each segment was determined, and a T/C ratio could be formed. By comparing the T/C ratio for each test segment, the fuel economy improvement (percent fuel saved in the test versus the baseline configurations) was calculated.
Page 1 and 2: NTRD-02 Final Project Report The Ef
Page 3 and 4: List of Figures Figure 1. Trucks A
Page 5 and 6: owner/operator, as motivated by the
Page 7 and 8: 2 PROJECT OBJECTIVES This project h
Page 9 and 10: (a) (b) Figure 3. Accelerator pedal
Page 11 and 12: observations in the datasets. Secti
Page 13 and 14: which, when concatenated, best desc
Page 15 and 16: Figure 7. Speed history of the seco
Page 17 and 18: Figure 8. The Texas Drayage Truck T
Page 19 and 20: Figure 9. Truck rig used for track
Page 21: Figure 12. Wide-single wheels and t
Page 25 and 26: Figure 14. Fuel consumption T/C rat
Page 27 and 28: Table 5. Summary of Track Test Resu
Page 29 and 30: the effect of the tires at higher s
Page 31 and 32: Appendix A - Drayage Operator Inven
Page 33 and 34: Geo-Lesco Inc Garland NA 972-205-05
Page 36: Segment No. Lap 2.7 Times Ten Minut

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