TRANSIT BUS Performance Report

Improved Performance & Extended Life with Power Brake Drums on a Transit Bus

One of the nation’s largest metro transit agencies has provided Power Brake with performance data on a transit bus that had a history of changing out all brake components every 18-20,000 miles on rear axles and twice that on front axles using standard transit drums. We would like to share the results after 100,785 miles of service with the September 17, 2008 installation of Power Brake’s unique Diamond Technology Drums. No brake components on either axle were replaced during this 22 month cycle.

Bus 6173 outfitted with Power Brake Drums–Marathon MBST Shoes The following data was collected on Tuesday, June 29, 2010, under overcast skies, 89 degrees and in dry conditions: After driving 10 miles through the city to ensure normal operating temperatures, 5 panic stops were made and the distances recorded. Immediately thereafter drum temperatures were taken.

23.5 feet @ 20 MPH	Left Front – 121.6 degrees
22.8 feet @ 20 MPH	Right Front-122.6 degrees
24.3 feet @ 20 MPH	Left Rear – 123.9 degrees
23.3 feet @ 20 MPH	Right Rear- 127.8 degrees
23.3 feet @ 20 MPH

Power Brake Note: Industry standards call for optimum maximum differential temperatures for the 4 corners of the bus to be 10 degrees F. Operating temperatures on traditional drums are typically 400 degrees F or higher.

Pushrod stroke
Left Front – 1 ¼”	Maximum allowed stroke is 2 inches.
Right Front- 1 ¼”	All slack adjuster angles were good.
Left Rear -1 ½”	There was no lateral movement of S-Cam.
Right Rear – 1 ½”

The same transit agency is testing Power Brake Extended Life Drums on 3 additional buses. At high mileage levels, all 3 are tracking to achieve or exceed the same results as Bus 6173 shown here. Photos of Front Diamond Drums and brake shoes after 22 months and 100,785 miles of transit service.