Fleetowner 6962 Xtra1e

Maintenance Bay: Unseen protection

Dec. 7, 2016

Director of equipment services: Steven Porter
Company: Xtra Lease, St. Louis, MO
Operation: Leasing and renting company offering some 80,000 over-the-road trailers through more than 50 U.S. locations for dry vans, flatbed, reefer, local cartage, storage and specialty equipment applications.


When you expect a dry van trailer to last a good 15 to 20 years in service, developing solid specs to minimize maintenance and repair costs is critical.

Steve Porter knows this better than anyone else as he’s dealt with nothing but trailers during his 31 years with Xtra Lease.

The company developed specific specs to help keep its dry van units in over-the-road service for 10 years, followed by three years in cartage or regional/local operation, and then two years in storage service, he explains.

For example, Xtra Lease specs crossmembers on its dry van trailers at 10-in. intervals versus the 12-in. standard to boost the floor-load rating to 24,000 lbs. from the typical 18,000 to 20,000 lbs.  This helps the 13/8-in. full oak flooring of the units hold up better under repeated pounding from forklifts. And a 24-in. threshold plate was added on the floor where the trailer doors meet the loading dock to provide an extra level of floor resiliency.

Porter says he wanted to keep that floor from deteriorating or buckling. Xtra Lease took a look at the front end flooring by the fifth wheel, a point where a lot of torque is transmitted up through the floor when a tractor-trailer is turning—force that could loosen floor screws over time. What to do?


To help strengthen the flooring at the front of the trailer while reducing maintenance and repair costs over the life of the trailer, Xtra Lease hit upon several spec’ing changes, Porter says. First, the company added nuts to the first two rows of floor screws near the kingpin, which is where the trailer locks into a tractor’s fifth wheel.

Porter explains that nuts help combat the force coming up through the floor during tractor turns; it’s actually the nuts that help resist the twisting stress of those turns over time.

Xtra Lease also switched to a different style of beam for several rows of crossmembers closest to the fifth wheel and the tractor’s drive axles. It’s what he calls a tub or hat-shaped beam that hugs the underside of the trailer versus the standard I-beam design.

“In the past, if a tractor blew a tire on its drive axles, its explosive force would travel back under the front end of the trailer and literally rip off traditional I-beams,” Porter says. “That would result in a lot of expensive damage to repair.”

By contrast, the force of a tire blowout travels over the hat-shaped beam, dissipating out and away from the trailer, thus causing less damage.

Xtra Lease also had to switch to a different screw pattern at the front of the trailer due to those hat-shaped tub crossmembers, but that proved a small price to pay to get a dry van trailer’s underside design adapted to better deal with tire blowouts.

About the Author

Sean Kilcarr | Editor in Chief

Sean previously reported and commented on trends affecting the many different strata of the trucking industry. Also be sure to visit Sean's blog Trucks at Work where he offers analysis on a variety of different topics inside the trucking industry.

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