Maintenance Q&A – February 2021

Q.) You recently wrote about returning tractors to service after being parked for a while. I’ve got a similar situation with my trailers. Business has picked up, and I’d like to bring seven Great Danes back into service. Two of them are reefers. The rest are dry vans. What do I need to do to get them on the road safely?

A.) Since you are a loyal Great Dane customer, I reached out to them for their comments. They were most helpful with their suggestions and comments. Thanks to them, I can answer you with confidence. What they presented should be applicable to all trailers, not just Great Danes.

They assumed that you had put the trailers into storage following proper procedures rather than just parking them in your yard. That involved securing wheels and tires from possible theft, trickle-charging the reefer batteries and batteries for the lift gates, if so equipped. You checked the tires for air loss since typical trailer tires lose about 1 psi per month through air permeating through the rubber. Any possible openings for wildlife infestation, whether insect or rodent, should have been sealed.

Great Dane suggested running the trailer a minimum of 1 mile every three months the trailer was in storage. That will flex tires and prevent flat-spotting, keep lubricants in the wheel bearings, and prevent brake shoe freeze-up. The reefers should have been run to normal operating temperature to keep refrigerant, lubricant and antifreeze circulating and seals from drying out. Landing gear should have been placed on pads if the trailers were stored on unpaved ground, with a minimum 18-inch square of plywood or heavy plastic under each leg. The wiring system should have been inspected and all electrical connections covered with dielectric grease.

To get the stored trailers back in service, start a thorough inspection program, preferably in an indoor shop.

Look for the typical CSA violations: the brake systems, wheels and tires, and the entire electrical system. Check lights for operation and remove any excess dielectric grease that could attract dirt or road salts.

Check the top and bottom rails of each trailer. Make any necessary repairs. Look for corrosion damage that may have occurred during storage.

Thoroughly go over the brakes, paying careful attention to the air chamber condition and smooth application. Examine each brake position separately, listening for air leaks. Pay attention to any grinding sounds that may indicate rust in the brake linkage. Make sure the brakes release smoothly.

Check all lubrication points. Check wheel ends for lubrication and end play. Whether the lubricant is grease or oil it can leak while equipment is out of service so make sure there is adequate lubrication in the hubs. You should also look at the brake drums, tires and suspension for any signs of leakage. Check for water or other contaminants in the lubricant.

Check all lines and cables especially those going through the frame and near the upper coupler plate. Great Dane tells us these are favorite nesting places for rodents that love to chew on lines and cables. Check the integrity of any wiring and air hoses. Even the slightest of pinholes can cause corrosion or brake failure.

Check any batteries and refrigeration units for leakage. Reefer seals may have dried and cracked when not in service, causing refrigerant leakage. Replace and recharge if necessary. Thoroughly inspect and clean interiors, especially reefers if they are to be used for food or pharmaceutical transport. Your trailers should now be ready to resume safe and profitable service.

Q.) I took my tractor and trailer in for my annual inspection.

The company I’m leased to insists that their shops do the inspections even if I’ve just had a Level 1 from the state police.

The techs told me I had damaged airbags and needed them all replaced. They also found cupping on my tires, but they rotated them and said it should correct that problem. They didn’t go into detail about the airbags, but I haven’t had any ride problems or anything to complain about. I know they’re not trying to sell me stuff because they’re already up to their eyeballs working on company equipment. They told me to take it to my trailer dealer for repairs. What causes this, and what can I do to avoid it in the future? This is the first time I’ve had to replace airbags in more than 20 years as an owner-operator.

A.) There are many things that can cause airbags to need replacement, from alignment issues to improper ride height. The fact that your tires were cupping indicates an alignment problem, although other things could contribute. Before spending money on a full alignment, you can do a quick check using string and a marker. Measure the distance between the front and the rear axles and the distance from the front axle to the kingpin centerline. Do the same on the other side. Compare the lengths between the marks you made. That will indicate if one or both axles are out of line and if the tandem is out of alignment with the trailer. Misalignment can cause undue wear on the airbags and can cause the pedestal or bead plate to pull away.

Do a thorough visual check of the airbag assembly.

Look for any distortion of the bead plate. Check the torque of all nuts and bolts, including the U-bolts on the axle. They should conform to original equipment manufacturer or component manufacturer specifications. Check the entire external surface of the airbag for anything that could abrade the surface. Look for cuts or damage to the bag and signs of corrosion on all metal parts. Check shock absorbers for any signs of leakage and bushing wear. Weak shocks will shorten airbag life.

TMC Recommended Practice RP643A suggests inspecting and retorquing all nuts after the first 1,000 miles and each preventative maintenance thereafter. Since some tractor original equipment manufacturers now recommend oil change out to 50,000 miles or more, suspensions should be inspected every 25,000 miles. Look for signs of leaks and tire wear that could indicate suspension problems. Your annual inspection should include the entire air system, from the compressor down the line. LL

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