Rule 6.1.1 Braking Capability Test

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Each buggy shall pass a braking capability test, at least once each school semester, with each person who will be driving it, before that person will be permitted to drive that buggy in any type of practice session at Carnegie Mellon University during that semester.

The purpose of the braking capability test is to ensure that each buggy meets a minimum braking standard when moving in both the forward and rearward directions, while a particular person is driving it. The braking capability test shall be administered by the Safety Chairman, or anyone designated by that Chairman.

The procedure for the braking capability test shall be as follows:

The test shall take place on a flat, level, and smooth area, that is paved with either concrete or asphalt. If the area chosen is not completely level, the test shall be run in a direction such that the buggy being tested shall be moving toward the lower end of the area during the test. The sidewalk starting at Purnell and moving towards the University Center shall be used if it is available and in acceptable condition. If this area is not available or acceptable the Safety Chairman, or anyone designated by that Chairman, shall choose an alternate location for the test.

The test shall be conducted as follows:

  • The buggy shall be pushed until it is moving at a speed greater than or equal to 15 miles per hour (22 feet per second).
  • After the pusher releases the buggy, the average speed of the buggy shall be measured while the buggy travels through a 50 foot long timing zone. The average speed of the buggy shall be determined by

measuring the time required for the nose of the buggy to travel from the beginning to the end of the 50 foot long timing zone. A stopwatch or other suitable timing device shall be used to make this measurement.

  • When the nose of the buggy reaches the end of the 50 foot long timing zone, the driver shall be signaled to apply the buggy’s brakes.
  • After the buggy stops, the test administrator shall tell the driver to release and reapply the brakes two more times, while the administrator is pushing on the buggy’s pushbar to verify that the brakes are being released and reapplied.
  • The final portion of the brake capabilities test, shall be completed on hill 1. Each buggy driver combination will be placed on the steepest point of hill 1 pointing uphill and must be able to hold its own weight using only the standard braking mechanism.
  • Two members of the buggy’s sponsoring organization shall be located in a position such that they will be able to stop the buggy in the event that the buggy’s braking system fails to stop the buggy during the test.
  • The organization whose buggy is being tested shall provide an adequate number of people to control pedestrian traffic in the test area and to properly attend to all of the buggies that they are using. If

the braking capability test is performed between sunset and sunrise, any buggy that is tested must have all lights and reflectors that are required during night push practices.

To successfully complete the test, the following requirements must be met:

  • Only the driver may touch the buggy while it is being tested.
  • The average speed of the buggy while it is traveling through the 50 foot long timing zone must be determined to be 15 miles per hour (22 feet per second) or greater.
  • The buggy must stop within the distance prescribed by the schedule that follows. This schedule lists the measured time required for the buggy to travel through the 50 foot long timing zone, the average

speed of the buggy through that zone, and the allowable stopping distance for that speed. The stopping distance shall be measured from the end of the 50 foot long timing zone to the nose of the buggy, i.e. that part of the buggy that is farthest forward, after the buggy has stopped.

Measured Time Average Speed Distance
2.25 sec 15.2 mph (22.2 fps) 35 feet
2.20 sec. 15.5 mph (22.7 fps) 35 feet
2.15 sec. 15.9 mph (23.3 fps) 35 feet
2.10 sec. 16.2 mph (23.8 fps) 40 feet
2.05 sec. 16.6 mph (24.4 fps) 40 feet
2.00 sec. 17.0 mph (25.0 fps) 45 feet
1.95 sec. 17.5 mph (25.6 fps) 45 feet
1.90 sec. 17.9 mph (26.3 fps) 45 feet
1.85 sec. 18.4 mph (27.0 fps) 50 feet
1.80 sec. 18.9 mph (27.8 fps) 50 feet
1.75 sec. 19.5 mph (28.6 fps) 56 feet
1.70 sec. 20.1 mph (29.4 fps) 62 feet
  • While the buggy is stopping, its centerline must not deviate more than 15 degrees from the line that it was moving along, in the 50 foot long timing zone.
  • After the buggy has stopped, it must remain in a stable position with no external assistance, and its driver must successfully release and reapply its brakes two additional times.
  • The buggy’s brakes may not be applied during the 50 foot long timing zone.

If a buggy fails to successfully complete the braking capability test during any four consecutive attempts on any one day, that buggy shall not be permitted to attempt the braking capability test again for a period of 24 hours.

The buggy shall be in the same physical state as would be expected for regular free rolls practice. No tactics may be employed to aid in passing the drop test or slowing forward motion of the buggy that would not be used in an emergency condition on the course. Actions not allowed include but are not limited to: overtightening of the retaining mechanism on wheels, use of spacers or shims to cause additional friction, use of worn or dirty bearings, and objects dragging on the ground. Any organization’s buggy caught violating this policy will be treated as if it failed a spot safety check