CALGARY, Alta. - It's a typical harsh Canadian winter day. The snow is blowing and it's at least minus-20C with the wind chill. You put on your long johns, your warmest winter jacket and then bundle y...
SLICK THINKING: Some preparations for winter can pay dividends when the roads get slick.
CALGARY, Alta. – It’s a typical harsh Canadian winter day. The snow is blowing and it’s at least minus-20C with the wind chill. You put on your long johns, your warmest winter jacket and then bundle yourself up against the elements before making your way outside and climbing into your truck. It’s times like these you may ask yourself “What have I done to protect my truck from this weather?”
More specifically, what have you done to protect your brakes? Because, chances are, you’re going to need them – and the last thing you want while winter driving is a catastrophic brake failure.
There are several things you can do to prepare your brake system for winter. Firstly, Chuck Eberling, senior staff engineer with Bendix Commercial Vehicle Systems, says to make sure your truck has an air dryer – one that’s suited for the job.
“You want to make sure your vehicle is equipped with an air dryer that’s sized for the application,” Eberling says. “There’s a lot of situations where the actual demand on the system is greater than what a single air dryer can handle.”
In fact, if you bought a truck that was previously used primarily for local deliveries in Florida, it may not even have an air dryer. It’s a factory option, but in Canada nearly all trucks are equipped with one.
Generally the maintenance cycle on air dryers is about three years, but before winter sets in it’s a good time to ensure yours is working properly, because moisture in the system is the biggest concern (especially in winter when that moisture can freeze).
“You want to make sure there are no signs of contaminants anywhere in your system and you do that by draining your tanks,” says Eberling. “If you find contaminants in the reservoirs, it’s recommended you service that unit.”
Bendix recommends draining the tanks every three months or 25,000 miles and late fall is a good time to do so.
“The biggest detriment to the air brake system is probably moisture, so we’re trying to get the moisture out of the system before it can cause problems,” points out Larry Donaldson, senior technical representative with Bendix.
Draining the tanks and checking for contaminants is the simplest way to ensure your air dryer is working, but you should also test its heater to make sure it’s capable of keeping the purge valve from freezing.
“One way to test that would be to take the end cover off the air dryer and put it in a cold box and make sure it draws current,” says Eberling.
Some truckers pour alcohol down the discharge line of the compressor and apply it to the gladhands to prevent water buildup. This is not a practice Bendix recommends.
“It tends to wash out the lubricants in the valves themselves,” warns Donaldson.
Eberling adds “Alcohol absorbs the moisture and once it’s absorbed it, there’s nowhere for it to go. It’s still in the line so it causes the valve to act more hydraulic-like than air-like.”
Brake linings freezing to the drum while parked is an age-old problem truckers face and there’s not a lot they can do to avoid that. But when parking overnight when the mercury is expected to drop, there is one thing drivers can do to help protect their brake system.
“One thing that we find is very beneficial is if you’re going to be parking your vehicle outside and you know it’s going to be cold overnight, make sure your system pressure is below your cut-in pressure when you shut the vehicle down,” explains Eberling. “That will get the air dryer purge piston into the closed mode so when he starts the vehicle it’s ready to build pressure.”
Since the heater takes a few minutes to thaw out the purge piston once the truck is started, having the piston in the pump mode means it’s ready to go before the heater has a chance to thaw it out. Also, the air flowing through the purge valve helps warm it up.
An important consideration while driving is that brake heat buildup is just as much of an issue in winter as it is in summer when descending hills. Just because the outside ambient temperature feels much colder, doesn’t mean it’s safe to ride the brakes through the mountains.
“The ambient temperature isn’t going to offset the brake temperature all that much,” warns Eberling. If you ensure your air dryer is up to snuff and that there’s no moisture in the brake system, than the brakes should be able to handle anything winter throws its way.