Two serious motorcoach crashes last month, including one that killed five people, have focused new attention on a long-running industry problem out-of-adjustment brakes.

The National Transportation Safety Board has preliminarily reported that the brakes "were seriously out of adjustment" on a coach that crashed on Interstate 94 near Osseo, Wis., in mid-October.

The coach rammed into an overturned semi-trailer that had jackknifed. The NTSB has not made a determination whether the out-of-adjustment brakes played a critical role in the crash. However, survivors on the bus said the driver applied the brakes.

The NTSB said the brakes were so badly out of adjustment the bus should never have been on the road.

The coach was carrying members of a high school band and adults traveling with them. The band director, his wife, 11-year-old granddaughter, a student teacher and the driver all died in the crash.

In the other incident, nearly 50 passengers in a coach carrying high school and middle school students to a Christian youth camp plunged into a ravine in northern Georgia after its brakes failed. Some 27 passengers were treated for broken bones, bruises and head injuries. No one died.

Bus crashes involving out-of-adjustment brakes invariably refocus industry attention on automatic slack adjusters, the much-maligned component designed to automatically adjust the slack of drum brakes that occurs with normal wear.

Their functioning sounds simple and straight-forward, and it is. However, there is considerable anecdotal evidence that mechanics and technicians by the score, if not hundreds, still do not know:

· How to properly maintain automatic slack adjusters

· What it means when the brakes are out of adjustment on a bus equipped with automatic slack adjusters

· What the proper procedure is when the brakes are out of adjustment on a bus equipped with automatic slack adjusters

· How to properly install or replace an automatic slack adjuster

Industry brake experts say there are far, far too many technicians who try to manually adjust automatic slack adjusters or the brakes themselves when they discover they are out of adjustment.

And, if those issues werent serious enough, there appears to be a serious lack of proper brake inspections in the over-the-road bus industry. Misconceptions about how to properly and accurately check drum brakes are thought to be widespread in the industry, from fleet operators, to mechanics, to government inspectors.

A major challenge with the inspection of drum brakes, whether they have manual or automatic slack adjusters, is that a mechanic has to get underneath a coach to properly examine brake adjusters, and thats very difficult to do outside of a well-equipped garage. Its essential to have a pit or a lift. Then, to do an inspection right, it takes two people.

Brakes should be inspected as part of every preventive maintenance cycle, whether its at 6,000-mile intervals, or when both the component and coach manufacturer recommends it.

Creating even more problems is the fact that many mechanics have their own ideas about what brake measurements work best on certain makes and models of coaches. Every mechanic seems to have a different theory or measurement in mind that they would like to see when someone steps on the brake to see what the throw is. If it does not meet their personal criteria then they say it is a bad brake, when, in fact, if they followed the Commercial Vehicle Safety Alliance criteria, it would not be a bad brake at all. (See Jan. 1 Bus & Motorcoach News.)

Additionally, mechanics often make the situation worse by installing automatic adjusters on one axle and leaving manually adjusted brakes on the other two axles.

And, many technicians think automatic slack adjusters last forever. They dont. Nor are they maintenance free. They should be lubricated periodically, typically every 5,000 miles.

Graham Dunnege, superintendent of maintenance at Adirondack Transit Lines in Kingston, N.Y., is an expert on brake and slack adjuster maintenance, CVSA rules, and coach safety. Here are his thoughts on proper brake and slack adjuster maintenance:

"Any commercial motor vehicle manufactured after October 1994, which has air-assisted drum brakes, is equipped with automatic slack adjusters. As brake linings wear, and the brake push-rod travel increases, a ratchet mechanism inside the automatic slack adjuster automatically rotates the adjuster, keeping the pushrod stroke within the legal and, more importantly, safe limit.

"Different slack adjuster manufacturers use somewhat different designs, but the principle is the same.

"There is one area that the manufacturers all agree on: Periodic adjustment of automatic slack adjusters is unnecessary and it can be damaging to the mechanism, possibly making it inoperative.

"Manufacturers specifically recommend not adjusting the automatic slack adjuster unless it is necessary during a maintenance procedure which requires disassembly of the brake system, such as replacing the lining, drum or S-cam.

"An automatic slack adjuster should never be adjusted unless the manufacturers procedures are followed to the letter.

"The problem with trying to routinely adjust an automatic slack adjuster is that the components adjusting mechanism is often damaged, and you have no idea of knowing how long the adjustment is going to hold.

"Will it last for 100 applications? Ten? Two? You cannot afford to take a chance.

"Here is the crux of the issue: If, during routine inspection or investigation of a driver complaint, the automatic slack adjuster is found to be out of adjustment, even once, this is an indication that something is wrong, perhaps seriously wrong, and the problem needs to be rectified before the vehicle is returned to service.

"The problem could be a faulty automatic slack adjuster, but often the problem can be found elsewhere: The slack adjuster may have been installed improperly, or there are worn components such as S-cams, bushings or brake shoe rollers. All of those things should be investigated.

"Roughly half the states in the U.S. do not have a bus inspection program. One that does is New York and its program is specifically designed to ferret out faulty brakes and bad automatic slack adjusters.

"During a New York Department of Transportation bus check, inspectors measure the brake throw at the beginning of the inspection. During the inspection process, up to 15 brake applications are made, and the brake throw is measured again. They routinely find automatic slack adjusters that do not hold adjustment for those 15 applications.

"When that happens, the bus is immediately put out of service, as it should be.

"Automatic slack adjusters are not only the law, they are a welcome addition to the industry and contribute greatly to highway safety.

"I strongly urge all operators to talk with the service representative from whichever automatic slack adjuster manufacturer you specify, and learn the proper inspection and maintenance procedures. Your companys safety record may depend on it."