CALGARY, Alta. - It's a blustery February morning in Northern Manitoba and you awake to find your brakes have seized up overnight. Assuming the culprit is moisture in the air lines, what do you do? If...
MAINTAIN IT: Air dryers should be checked each fall and their dessicant filter should be replaced annually when running in cold areas.
Photo provided by Bendix
NET RESULT: This picture shows what can happen when you use alcohol to thaw valves and seals. This plastic part was melted after a propane torch was used to thaw it out once alcohol stopped working.
CALGARY, Alta. – It’s a blustery February morning in Northern Manitoba and you awake to find your brakes have seized up overnight. Assuming the culprit is moisture in the air lines, what do you do? If you’re like many drivers, you curse the maintenance manager and then pour alcohol into the system to thaw out any ice that’s accumulated there.
But experts warn that’s a dangerous habit to get into, which could cause costly – not to mention dangerous – ABS failures.
The best way to avoid problems caused by alcohol is to ensure the need to use alcohol doesn’t arise in the first place.
Nearly all Canadian trucks are equipped with an air dryer, and proper maintenance of this key component can virtually eliminate all instances of frozen air lines.
“Many fleets assume that the air dryers on the tractors are working well,” says Ray Camball, fleet sales manager with Trailmobile Canada.
“If things go wrong on a cold day with a rush load, the driver does what he can to get the load moving and it may mean that some alcohol gets dumped into the red air line.”
In a pinch, a tablespoon or two will likely solve the problem and allow you to continue on your way, but Camball says drivers sometimes use too much alcohol which can make the situation far worse.
“The driver is cold and he has a litre container in his hand and more can be dumped in just to be sure,” says Camball.
“It may also get poured into the blue line which is not a good idea because it can sit on top of the ABS valve in a pool and cause the O-ring to stick. The trailer may get rolling, but the pool of liquid alcohol can wash off protective grease and after a few soaks with alcohol, the ABS valve can stick resulting in no service brakes and a $1,000 cost to replace the alcohol-damaged valve.”
Camball has seen his share of damaged valves, many of which are not covered under warranty. The disturbing trend has prompted him to check with various fleets to see how they are avoiding the problem.
TST Overland Express has addressed the issue by paying close attention to its trucks’ air dryers – particularly on trucks that operate in extreme weather.
“In order to reduce air system freeze-ups without the need for using alcohol, a good air dryer service program is crucial,” insists Geoff Eaves, fleet superintendent with TST.
Eaves found that trucks operating in areas with long, cold winters were more likely to encounter air dryer failures, and as a result, the company developed a customized maintenance program. Trucks operating in Quebec, for instance, have their air dryers serviced and replaced more often than trucks that operate primarily in warmer Ontario.
“This helps to reduce downtime and makes the equipment more reliable,” says Eaves.
“When you are running on remote roads in conditions well below 0 degrees C and a long distance from the nearest service location, you want to do your best to provide your drivers with reliable equipment. Air line freeze-ups are inconvenient in southern climates but can be a major problem in remote northern areas.”
Glenn Bauer, president of Ventures West Transport, knows all about operating in remote northern areas.
The Edmonton, Alta.-based fleet runs the ice roads in the Northwest Territories each winter – an environment that can push air dryers to the limit.
“The biggest thing for us is preventive maintenance,” says Bauer. “Before the units go on the winter roads, everything is checked over and the air tanks are drained and cleaned.”
When his drivers encounter frozen brake lines, they are advised to use small amounts of a specially lubricated brake line antifreeze, which is less likely to remove the protective coatings from valves and seals than straight alcohol.
Operating in the far north requires extra measures to avoid freezing as well. Drivers try not to shut the units down for long periods of time (which can allow condensation to form) and they never dynamite the brakes.
The air dryer is maintained every fall and the desiccant cartridge is replaced annually.
“By following our preventive maintenance schedule, we’ve had next to no problems at all in winter road operation,” Bauer says.
Bill Fornof, senior staff engineer with Bendix Commercial Vehicle Systems, says replacing the air dryer’s desiccant cartridge each fall is a good idea, as contaminants can accumulate there. (A new cartridge costs about $50). He also said it’s important to test the air dryer’s heater by using a volt meter to measure the resistance across the heater.
“When you measure the resistance across the heater, there should be virtually nothing,” says Fornof. “If you’re getting a break in that line showing very high resistance, you know the heater’s not functioning properly.”
TST Overland’s Eaves takes this one step further, noting the thermostat for the heater should also be checked and it can only be tested in a cold environment, not inside a warm shop.
Fornof also suggests fleets and O/Os examine the air brake system to ensure there are no leaks which could cause additional strain on the compressor.
Trailer air dryers are now available and are recommended for fleets that find moisture is accumulating in their trailer brake systems (most likely through the gladhands). While trailer air dryers aren’t yet commonplace, Bendix officials say fleets in Northern Canada have been among the first to embrace the technology.
If alcohol is used too frequently, the long-term damage can be severe. Camball points out valve O-rings can stick to the cylinder walls after the alcohol acts as a type of glue.
“Liquid alcohol can free up the symptoms temporarily, but the valve will keep sticking more often until it totally fails,” he warns. “To ensure safe long valve life, clean, dry air is the best bet rather than having O-rings bathing in liquid alcohol.”
Bendix officials are quick to agree.
“Alcohol removes lubrication from the valves, shortens life of the components and in its purest form, it’s highly combustible,” says Chuck Eberling, principle engineer, Bendix Vehicle Systems Group.