Across North America, it’s getting to be that time of year: Temperatures are dropping, and fleets and owner-operators are prepping for chilly conditions and wintry roads. Before things get too harsh out there, the Bendix Tech Tips series from Bendix Commercial Vehicle Systems LLC and Bendix Spicer Foundation Brake LLC (BSFB) offers some simple steps to help keep wheel-ends and air dryers operating effectively, and staving off hazardous corrosion of components.
“Winter can be really tough on the components of air-braked systems,” said Keith McComsey, BSFB’s director of marketing and customer solutions. “There’s added moisture on the roads in the form of snow and ice, and it’s often mixing with salt or corrosive chemicals used to keep highways clear. Conditions are ideal for the kind of corrosion that poses a serious hazard to safe brake operation and highway safety.”
It’s important to prepare wheel-ends and air dryers for winter with a few steps that can help keep moisture, contaminants, and corrosion from gaining a foothold. For starters, a clean air supply is crucial, regardless of whether the vehicle or trailer is equipped with foundation drum or air disc brakes, so the air tanks should be drained of moisture and the potential contaminants it can carry. Remember that ambient temperature shifts of greater than 30 degrees Fahrenheit can cause a temporary accumulation of moisture, so if a significant temperature change took place in the previous 24 hours, continue to operate the vehicle as normal, and check the air system again after a week.
Drum Brake Checkup
Winterizing drum brake components begins with a watchful eye: Check the chamber housings for corrosion or damage that could allow corrosive materials to take hold. Excessive corrosion can lead to failure of the housing. Next, verify that the chamber’s dust plug is properly installed to prevent contamination of the interior. Effective lubrication keeps moisture at bay and is a powerful tool in the battle against corrosion. Make sure all automatic slack adjusters are properly greased, and lubricate the clevis pin connection points, verifying that they rotate freely. Ensure that other drum brake components are also lubricated, including cam tubes, shafts, and bushings.
Air Disc Brake Care
As with drum brakes, begin with a visual inspection, checking the chamber housings and dust plug. Next, inspect the guide pins and look for cuts or tears on the boots, replacing them if necessary. (Ripped or punctured boots can allow contaminants and moisture to enter the caliper, causing corrosion and long-term damage.)
Prepping air disc brakes for winter also requires ensuring that:
- Pads move freely in the carrier; if not, remove them and clean the carrier surface with a wire brush
- The brake moves freely on the guidance system; if not, replace the guidance system
- Pads and rotors have enough remaining thickness to last until the next service interval—minimum rotor thickness is 37mm, and minimum friction thickness is 2 mm
Air Dryer Maintenance
Especially in cold or harsh climates, fall is a good time to replace air dryer cartridges to prevent moisture from getting into the system and causing air brake freeze-up. If the vehicle has an oil-coalescing cartridge, always replace it with another oil-coalescing cartridge to maintain the quality of the air serving the brakes and other connected systems like automated manual transmissions.
“We also recommend examining the air dryer’s purge valve for signs of corrosion or an accumulation of grit, and replacing it if necessary,” said Richard Nagel, Bendix director of marketing and customer solutions, charging. “Like a lot of winter preparation, it’s a simple procedure that can go a long way toward keeping a system operating safely, preventing malfunction and headaches down the road.”
Also critical for vehicle operators to keep in mind as cold weather approaches: adding alcohol to unfreeze brake components may solve an immediate problem, but alcohol can damage seals in the air brake system, requiring additional unexpected service. Bendix does not recommend using alcohol in air brake systems under any conditions.