Dirty dozen

Max Kvidera | July 01, 2010

• Replace bulging or cracked hoses.

• Tighten loose clamps. Replace if corroded, cracked or worn.

• Carry spare belts, hoses and clamps.

• Be attentive to brake hoses on the axles and secure them properly so they do not rub.

Dry U-joints

New longer-lasting U-joints don’t need to be greased as often, but that doesn’t mean you can ignore their maintenance. “People feel they can save maintenance by not greasing as much,” Moore says. “They’re trying to save money on the front end, and it costs them on the back end. We’ve had some trucks in here where the cost to repair has gone as high as $10,000, with an average of $3,500 to $5,000.”

If grease doesn’t ooze out of all four channels, one of them is probably dry. Skimp on your greasing, and the U-joint can come loose. “At 60 mph, the driveline is ripping valves, lines, air bags, anything it can possibly come in contact with,” Moore says. “We’ve seen it break rear ends.”

How to prevent

Moore recommends greasing U joints every 10,000 miles, which is more frequent than specified by manufacturers. Greasing takes less than 30 minutes to complete. A tube of grease costs about $7.

Saturated air dryer

It’s easy to overlook the air dryer because of its lengthy service interval, but its cartridge should be checked regularly for saturation.

Since the air dryer service interval is about 300,000 miles for a long-haul truck, operators tend to forget about air dryers, and particularly the cartridge that absorbs moisture. Yet if the cartridge gets saturated, moisture creeps into air system valves and can cause corrosion. In cold weather, in can freeze. “If you’re not paying attention, it can be a full day of downtime,” McClusky says.

How to prevent

• During your daily truck inspection, drain water from the air tanks via the drain valves. If you notice a significant amount of water coming out, it’s a good sign the cartridge is saturated and should be replaced by a trained mechanic. Cartridges range from $85 to $300.

Air pressure loss

The air compressor pumps air into the reservoir tanks for the brake system, while the air compressor governor controls the in and out points of the air compressor to maintain pressure in the tanks. Neglecting the compressor can lead to loss of pressure. The dash gauge will give a warning.

Leaky connections are common. Although air hoses and lines are sturdy and built to last, they can become damaged.

How to prevent

• Perform pre-trip and post-trip inspections of hoses.

• Start the engine and listen for high-pressure leaks. Watch the air pressure gauge to ensure the truck is building air quickly.

• At full air pressure, release the parking brake and turn the engine off. Listen for any air leaks.

• Apply the brake pedal and listen for any air leaks. Continue pushing the pedal and watch the pressure gauge. The pressure should hold steady.

• Investigate any automatic warnings about the compressor.

• Inspect the glad hands. Make sure the rubber gaskets are free of cracks and seated properly. A failed gasket will cause air pressure to leak from the brake system.

Power divider failure

McClusky says a catastrophic failure of the power divider, or interaxle differential lock, can cost $5,000 to $7,000. The interaxle differential lock divides power to the two tandem drive axles, McClusky says.

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