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Sliding trailer suspensions — desired by many in the truckload industry as a standard feature on dry vans — have proved to be a mixed blessing, offering operating flexibility for drivers, but putting them at some risk of injury, said some fleet managers and product makers.

Suppliers of safety technology are offering fleet managers new and maturing products for their vehicles, designed to watch over and aid driver performance or compensate for human error.

While the National Highway Traffic Safety Administration has yet to release a proposed rule, fleets and suppliers are resigned to the fact that Class 8 trucks built after 2007 will have to be able to stop in a shorter distance than do today’s models.

A typical Class 8 truck generates about 10 gallons of used oil at every oil change. Assuming 100,000 miles driven a year and oil changes every 25,000 miles, it does not take long for most fleets to build up a lot of spent lubricant.

Automated truck transmissions — a compromise between classic manuals and the automatics found mainly in cars — are gaining in popularity because of recent production improvements and their appeal among less-experienced drivers, said fleet managers and manufacturing executives.

So far, so good, but many questions about durability and maintenance remain.

It sounds simple on paper: a bearing, some oil and a seal. But keeping wheel bearings correctly lubed has caused fleets considerable consternation for years..

Using electronic signals instead of compressed air to actuate heavy truck brakes opens a realm of new possibilities. Electronically controlled brake systems (ECBS), commonly referred to as "brake by wire," promise far greater control and modulation of braking at individual wheels, some vehicle engineers say.

The design of disc brakes has undergone a metamorphosis in recent years, thanks to a strong effort in Europe to make discs standard on heavy trucks. The product is far better than it used to be, say brake manufacturers.

Managing tire wear is going high tech. The rubber on the pavement is typically a fleet's first- or second-largest maintenance cost, and proper inflation is considered essential to getting the most life out of truck tires. But keeping tire pressures within tolerances is one of the most vexing jobs in maintenance.