28' Bus



The Supreme Corporation submitted a model BSSN28, diesel powered 30 seat/28-foot bus, for a 4 yr/100,000 mile STURAA test.  The odometer reading at the time of delivery was 2,826.0 miles.  Testing started on July 10, 1998, and was completed on September 16, 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 July 24, 1998 and was completed on September 10, 1998.

The first segment of the Structural Durability Test was performed with the bus loaded to a GVW of 17,250 lb.  The number of standing passengers was reduced from 17 standees to 13.  This reduction in passenger weight was necessary to avoid exceeding the GAWR (5,000 lbs.) of the rear axle.  The middle segment was performed at a SLW of 15,080 lb and the final segment was performed at a curb weight of 10,560 lb.  Durability driving resulted in unscheduled maintenance that consisted of a variety of subsystem failures.  These unscheduled maintenance 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.  The alternator, which is covered in Section 1.3 (Repair and/or Replacement of Selected Subsystems), had limited access along with the A/C compressor and the coolant drain.  All other components encountered during testing, were found to be readily accessible and no other 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.  Failures are classified according to the severity as defined in Section 2.  The test bus encountered no Class 1, 2 or 4 failures. The ten reported failures were all Class 3 and are available for review as defined in Section 2.

            The double-lane change was performed in both right-hand and left-hand directions.  The bus was able to safely negotiate the test course in both the right-hand and left-hand directions up to the maximum test speed of 45 mph.  Although very slight fishtailing was observed during the 40 and 45 mph portions of the test, the test driver reported no handling problems.  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 25.78 seconds.

 The Shakedown Test produced a maximum final loaded deflection of 0.580 inches with a permanent set ranging between 0.000 to 0.005 inches under a distributed static load of 17,625 lb.  The Distortion Test was completed with no water leakage observed throughout the test.  All subsystems operated properly.  The NBM was not equipped with any type of tow eyes or tow hooks; therefore, the Static Towing Test was not performed.  The Dynamic Towing Test was performed using a heavy-duty wrecker.  The bus was not equipped with tow eyes or tow hooks; therefore,  the towing interface was accomplished by chaining to both sides of the frame.  A front lift tow was performed.  Rear towing is not recommended by the manufacturer.  No problems, deformation, or damage was noted during testing.  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 4.30 inches.

 A Fuel Economy Test was run on simulated central business district, arterial, and commuter courses.  The results were 6.06 mpg, 6.42 mpg, and 13.79 mpg respectively; with an overall average of 7.36 mpg.

 A series of Interior and Exterior Noise Tests was performed.  This data is listed in Section 7.1 and 7.2 respectively.


Number: 9808
Model: 28' Bus
Vin Number: 1GBJG31F6W1065768