MOTOR COACH INDUSTRIES Download PDF Report
Motor Coach Industries submitted a model D4500, diesel-electric hybrid powered 56 seat (including the driver) 45-foot bus, for a 12 yr/500,000 mile STURAA test. The odometer reading at the time of delivery was 4,973 miles. Testing started on November 12, 2007 and was completed on June 23, 2008. 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 November 21, 2007 and was completed on June 11, 2008.
The interior of the bus is configured with seating for 56 passengers including the driver. Free floor space will accommodate 30 standing passengers resulting in a potential load of 86 persons. At 150 lbs per person, this load results in a measured gross vehicle weight of 51,720 lbs. In order to avoid exceeding the GAWR (16,000 lbs) of the front axle and (22,500 lbs) of the rear axle, ballast for 18 standing passengers was eliminated. This reduction from full capacity resulted in an adjusted measured gross vehicle weight of 49,240 lbs and was used for all dynamic testing. The middle segment was performed at a SLW of 47,410 lbs and the final segment was performed at a CW of 39,260 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), were found to be readily accessible and no restrictions were noted. The only accessibility issue noted was poor access to the upper mounting studs of the forward shocks on the drive axle.
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 failures. The two Class 2 failures were transmission related. Of the remaining 34 reported failures, 23 were Class 3 and 11 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 40.00 seconds.
The Shakedown Test produced a maximum final loaded deflection of 0.232 inches with a permanent set ranging between -0.002 to 0.004 inches under a distributed static load of 32,250 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.
Static Towing Test was performed using a target load (towing force) of 47,112 lbs. All four front and all four 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 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 3.9 inches.
A Fuel Economy Test was run on simulated central business district, arterial, and commuter courses. The results were 2.09 mpg, 2.16 mpg, and 3.71 mpg respectively; with an overall average of 2.41 mpg.
A series of Interior and Exterior Noise Tests was performed. These data are listed in Section 7.1 and 7.2 respectively.