Tech Updates

Truck Tire Safety

Truck tire wheel-off events can cause catastrophic failure so it is important that you remind technicians and customers to follow a proper tire inspection routine to ensure greater tire and wheel-end safety.

“When wheel-off events occur, they result in damage to property or people, and the main culprit of these events is a lack of basic, routine maintenance,” says Doug Jones, customer engineering support manager, Michelin Americas Truck Tires.

The most critical element of any tire maintenance program is maintaining correct tire pressure. Remind customers to have an accurate tire pressure gauge and show them how to check the pressure in the truck’s tires everyday on all tires, including inner duals.

During pre- or post-trip inspections, advise customers they should look at the entire wheel end, including the tire, wheel, studs and fasteners, the hub area and the brakes. While there are many different methods for tightening wheel fasteners, the most accurate approach has been the manual torque method. It is important that on disc wheels each fastener is torqued to 400 to 500 ft.-lbs.

In a combined effort with the Tire Industry Association, Michelin has produced a video outlining steps to help ensure wheel-end safety and help avoid wheel-offs or wheel-end fires. It is available on the Michelin Truck Tires YouTube channel (www.youtube.com/watch?v=wrsj2UoMeys) as well as the Michelin Web site, www.michelintrucls.com and TIA Web site, www.tireiindustry.org. n

Slack Adjuster Maintenance

Mack offers the following maintenance and lubrication recommendations for Gunite automatic slack adjusters on LEU, MRU, GU, CHU and CXU vehicles.

Every three months or 25,000 miles:

Check the condition of the foundation brakes, including drums, shoes, linings, cams, rollers, bushing, etc.

Check for structural damage to the housing, worn clevis, worn clevis bushings and the boot for cuts or tears. Replace if necessary.

After allowing the brake drum to cool to room temperature, check for correct chamber stroke. Because of the variety of vehicle operating conditions, you may need to perform chamber stroke tests at earlier intervals.

Gunite automatic slack adjusters are factory lubricated and sealed to protect against dirt, water, salt and other corrosive elements. Nevertheless, periodic lubrication is recommended. Every six months or 50,000 miles, grease the slack adjuster using an approved grease.

The adjusters have a grease fitting to allow lubrication during normal chassis servicing. With a conventional grease gun, apply lubricant until grease appears on the camshaft or grease flows from the grease relief.

The current Gunite automatic slack adjusters are produced without a grease relief, forcing lubricant through the drilled worm wheel onto the camshaft. Previous designs incorporate a grease relief.

National Lubricating Grease Institute (NLGI) grade 1 and 2 greases without moly sulfides or EP additives having a working range of -40ºF to +120ºF are the recommended greases. Thick greases should be avoided. n

Recommended Brake Drum Applications

Webb Wheel says its 76864 brake drum should only be used for standard duty, van, tractor-trailer or flatbed combinations. Standard duty cycle is considered typical line haul, over-the-road applications. Webb says that duty cycle is independent of gross axle weight ratings.

The 76864 drum is not recommended for liquid and dry-bulk tankers, dump trucks, dump trailers, refuse applications or other similar applications.

For heavy-duty cycle applications (applications that are subjected to a higher frequency of mechanical and/or thermal cycling compared to standard duty), customers should use Webb Part No. 66884 for 16.5 x 7 brake size.