Bus Maintenance News

Paying attention to details is probably the most important part of maintenance. This includes proper order of tune-up procedures, proper tune-up specifications, year and model of the engine and it's installation.

When scanning computer systems it is important to maintain a record of all logged trouble codes kept with the maintenance records. This will help to determine which codes are "garbage" or service induced, versus true problem codes.

Electrical problems can be attributed to the system or component having too much or too little resistance. A broken wire creates high resistance. A short to ground creates low resistance in a circuit. A motor that turns too slowly has several potential problems. Is it getting too little voltage, does it have improper resistance or a mechanical drag?

Electrical systems are full of "Black Boxes" and almost all of them have a definite sequence of connecting and disconnecting wiring to prevent damage to sensitive electronic parts.

The air system has a definite sequence of draining tanks in order to test for proper operation of the check valves. Some problems could be eliminated as well as the possibility of an emergency system not working if your maintenance people followed these guidelines: Allow the bus to reach maximum air pressure, drain the supply reservoir, until all air has escaped.

From this point on any reservoir found to be empty when you try to drain it has a leak, probably either a bad inlet check valve or pressure protection valve. Either of these defects must be corrected under federal law.

Drain the primary reservoir. Drain the secondary reservoir. Drain the accessory reservoir. By draining reservoirs as outlined, the check valves will be tested for proper operation. Any contamination in the supply tank will be drained out of the system instead of being pulled into other reservoirs.

This is not a complete air system service, however, it may eliminate some simple problems and possibly some major liabilities.
A mechanic is better off to take a few extra minutes and pay attention to detail.