NORTH AMERICAN BUS INDUSTRIES Download PDF Report
North American Bus Industries submitted a model CLFW-CNG (COMPO), CNG-powered 46 seat/45-foot bus, for a 12 yr/500,000 mile STURAA test. The odometer reading at the time of delivery was 512 miles. Testing started on February 24, 2003 and was completed on August 13, 2003. 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 March 11, 2003 and was completed on July 17, 2003.
The interior of the bus is configured with seating for 46 passengers including the driver. Free floor space will accommodate 34 standing passengers resulting in a potential capacity of 80 persons. At 150 lbs per person, this load results in a measured gross vehicle weight of 41,810 lbs. In order to avoid exceeding the GAWR (14,600 lbs) of the front axle, ballast for 2 standing passengers was eliminated. This reduction from full capacity resulted in an adjusted measured gross vehicle weight of 41,480 and was used for all dynamic testing. The middle segment was performed at a seated load weight of 36,820 lbs and the final segment was performed at a curb weight of 30,130 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. The only accessibility issue noted regarding the components covered in Section 1.3 (Repair and/or Replacement of Selected Subsystems), was with the right side, forward engine cradle mounting bolt. Access is limited due to the close proximity to the battery compartment housing. All other components encountered during testing, were found to be readily accessible and no further restrictions were noted.
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 2 failures. Of the 21 reported failures, 17 were Class 3 and four were Class 4.
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 48.51 seconds.
The Shakedown Test produced a maximum final loaded deflection of 0.373 inches with a permanent set ranging between 0.000 to 0.005 inches under a distributed static load of 30,000 lbs. The Distortion Test was completed with all subsystems, doors and escape mechanisms operating properly. Water leakage was observed during the test at the rear window and 2nd window from the rear, right side, around the frames.
The Static Towing Test was performed using a target load (towing force) of 36,156 lbs. All four front pulls were completed to the full test load with no damage or deformation observed. The Dynamic Towing Test was performed by means of a front-lift tow. The towing interface was accomplished using a hydraulic under-lift wrecker. The bus was towed without incident and no damage resulted from the test. The manufacturer does not recommend towing the bus from the rear, therefore, the Static and Dynamic Towing Tests were not performed. The Jacking and Hoisting Tests were also performed without incident. The bus was found to be stable on the jack stands, and the minimum jacking clearance observed with a tire deflated was 5.0 inches.
A Fuel Economy Test was run on simulated central business district, arterial, and commuter courses. The results were 0.55 M/lb, 0.74 M/lb, and 1.16 M/lb respectively; with an overall average of 0.71 M/lb.
A series of Interior and Exterior Noise Tests was performed. These data are listed in Section 7.1 and 7.2 respectively.