NAVISTAR INC. Download PDF Report
Navistar Inc. submitted a model PC 50500, diesel/electric-powered 39 seat (including the driver) 38-foot bus, for a partial STURAA test in the 10 yr/350,000 mile category. The Federal Transit Administration determined that the following tests would be performed: 1. Maintainability, 2. Reliability, 3. Safety, 4. Performance, 5.7 Structural Durability, 6. Fuel Economy 7.1 Interior Noise (excluding Condition #1) and 7.2 Exterior Noise. Testing started on October 21, 2009 and was completed on May 7, 2010. The Check-In section of the report provides a description of the bus and specifies its major components.
The primary part of the test program is the Structural Durability Test, which also provides the information for the Maintainability and Reliability results. The Structural Durability Test was started on October 23, 2009 and was completed on May 3, 2010.
The interior of the bus is configured with seating for 39 passengers including the driver. Free floor space will accommodate 21 standing passengers resulting in a potential load of 60 persons. At 150 lbs per person, this load results in a measured gross vehicle weight of 28,690 lbs. In order to avoid exceeding the GAWR (17,500 lbs) of the rear axle, the 6 rear fold-away seats were stowed and ballast for 2 wheelchair positions (1,200 lbs) was used. This reduction from full capacity resulted in an adjusted measured gross vehicle weight of 27,760 lbs and was used for all dynamic testing. The middle segment was performed at a seated load weight of 25,700 lbs and the final segment was performed at a curb weight of 19,850 lbs. Durability driving resulted in unscheduled maintenance and failures that involved a variety of subsystems. A description of failures and a complete and detailed listing of scheduled and unscheduled maintenance is provided in the Maintainability section of this report.
Accessibility, in general, was adequate. With the exception of the transmission/hybrid motor, components covered in Section 1.3 (repair and/or replacement of selected subsystems), along with all other components encountered during testing, were found to be readily accessible and no restrictions were noted. In order to remove the transmission/hybrid motor, the floor had to be removed and the welded access panel was cut free to accomplish complete removal.
The Reliability section compiles failures that occurred during Structural Durability Testing. Breakdowns are classified according to subsystems. The data in this section are arranged so that those subsystems with more frequent problems are apparent. The problems are also listed by class as defined in Section 2. The test bus encountered no Class 1 or Class 4 failures. Of the 9 reported failures, 3 were Class 2 and 6 were Class 3.
The Safety Test, (a double-lane change, obstacle avoidance test) was safely performed in both right-hand and left-hand directions up to a maximum test speed of 45 mph. The performance of the bus is illustrated by a speed vs. time plot. Acceleration and gradeability test data are provided in Section 4, Performance. The average time to obtain 50 mph was 39.64 seconds.
A Fuel Economy Test was run on simulated central business district, arterial, and commuter courses. The results were 5.09 mpg, 5.26 mpg, and 8.69 mpg respectively; with an overall average of 5.84 mpg.
A series of Interior and Exterior Noise Tests was performed. These data are listed in Section 7.1 and 7.2 respectively.