MOTOR COACH INDUSTRIES Download PDF Report
Motor Coach Industries submitted a model D4500, ultra low sulfur diesel-powered 58 seat (including the driver) 45-foot bus, for a 12 yr/500,000 mile STURAA test. Testing started on May 24, 2006 and was completed on December 7, 2006. 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 May 24, 2006 and was completed on November 20, 2006.
The interior of the bus is configured with seating for 58 passengers including the driver. Free floor space will accommodate 25 standing passengers resulting in a potential load of 83 persons. At 150 lbs per person, this load results in a measured gross vehicle weight of 49,200 lbs. In order to avoid exceeding the GAWR (22,500 lbs) of the rear axle and (12,000 lbs) of the tag axle, ballast for 4 standing passengers was eliminated. This reduction from full capacity resulted in an adjusted measured gross vehicle weight of 48,540 lbs and was used for all dynamic testing. The middle segment was performed at a SLW of 45,430 lbs and the final segment was performed at a CW of 37,000 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, 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.
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 twenty-six reported failures, eighteen were Class 3 and eight 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 28.06 seconds.
The Shakedown Test produced a maximum final loaded deflection of 0.142 inches with a permanent set ranging between -0.006 to 0.005 inches under a distributed static load of 31,125 lbs. The Distortion Test was completed with all subsystems, doors and escape mechanisms operating properly. No water leakage was observed throughout the test. All subsystems operated properly.
The Static Towing Test was performed using a target load (towing force) of 58,752 lbs. All four front and rear 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, a rear test was 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 5.9 inches.
A Fuel Economy Test was run on simulated central business district, arterial, and commuter courses. The results were 2.84 mpg, 3.59 mpg, and 6.67 mpg respectively; with an overall average of 3.66 mpg.
A series of Interior and Exterior Noise Tests was performed. These data are listed in Section 7.1 and 7.2 respectively.