MOTOR COACH INDUSTRIES Download PDF Report
Motor Coach Industries Inc., submitted a model 102D3, CNG powered 50 seat/40-foot bus, for a 12 yr/500,000 mile STURAA test. The odometer reading at the time of delivery was 2,090.0 miles. Testing started on June 9, 1998, and was completed on November 26, 1998. 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 June 19, 1998 and was completed on November 16, 1998.
The first segment of the Structural Durability Test was performed with the bus loaded to a GVW of 43,570 lb. The number of standing passengers was reduced from 25 standees to 0 standees. This reduction in passenger weight was necessary to avoid exceeding the GAWR (14,400 lbs.) of the front axle, (22,500 lb) of the rear axle and (10,000 lb) of the tag axle. The middle SLW segment was performed at the same 43,570 lb. The final segment was performed at a CW of 36,190 lb. Durability driving resulted in unscheduled maintenance that consisted of a variety of subsystem failures. A description of the breakdowns can be found in a complete and detailed listing of scheduled and unscheduled maintenance, which 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. Data in this section is arranged so that those subsystems with more frequent problems are apparent. Failures are classified according to the severity as defined in Section 2. The test bus encountered no Class 1 or Class 2 failures. Of the fifty-one reported failures, thirty-four were Class 3 and seventeen were Class 4.
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 34.99 seconds.
The Shakedown Test produced a maximum final loaded deflection of 0.230 inches with a permanent deflection ranging between -0.003 to 0.004 inches under a distributed static load of 28,125 lb. The Distortion Test was completed with no water leakage observed throughout the test. All subsystems operated properly. The Static Towing Test was only performed on the front tow eyes, (the manufacturer does not recommend rear towing). All four front pulls were completed to the full test load of 43,428 lb with no damage or deformation observed. Dynamic Towing Test was performed by means of a front flat tow. The towing interface was accomplished by chaining to the front radius rods. The manufacturer’s recommended tow dolly was not available. A wood timber was incorporated for protection. The manufacturer does not recommend rear towing. No problems, deformation, or damage was noted during testing. A rear test was not performed as per manufacturers recommendations. 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 5.20 inches.
A Fuel Economy Test was run on simulated central business district, arterial, and commuter courses. The results were 0.49 M/lb, 0.80 M/lb and 1.09 M/lb respectively; with an overall average of 0.67 M/lb.
A series of Interior and Exterior Noise Tests were performed. This data is listed in Section 7.1 and 7.2 respectively.