With a bit of zig and a bit of zag, a Canadian manufacturer is creating a more robust trailer floor
August 1, 2002
Until recently all trailer floors used similar gluing techniques and the joints between the boards were all based on roughly the same single-overlap hook design. That is until Cap-Saint-Ignace, Quebec...
Until recently all trailer floors used similar gluing techniques and the joints between the boards were all based on roughly the same single-overlap hook design. That is until Cap-Saint-Ignace, Quebec-based Prolam unveiled its new zigzag design, resulting in a spec that’s claimed to be much more robust than traditional wooden trailer floors.
“Thanks to Prolam, traditional hook joints are now a thing of the past,” says Pierre Thabet, the company’s owner. “For years, trailer floors have weakened under the stress of the weight of cargo and forklifts, and have allowed water to damage valuable cargo.”
The new flooring approach involves precision cutting the floor strip ends in a zigzag pattern (thus the name).
“Anyone can do the joint,” says Prolam’s General Manager Ben Risi referring to the special cutting angle. “The other thing is getting it closed.”
To that end, Prolam uses a patent-pending process where the strips are fitted together and glued under 200 pounds of pressure to form exceptionally strong joints. The flooring industry’s standard test for brute strength is the dry sheer test — the glue joints are snapped apart and the force needed to do that is measured. Risi explains since going to the new technique, Prolam’s dry sheer test results have improved by more than 200%.
If you’re having trouble picturing how Prolam’s design improves on the old technology, try the following demonstration: Extend your index fingers and then bend them both at the middle knuckle to 90-degree angles. Now interlock the two with one fingertip pointing straight up and the other pointing straight down. If you try to pull them apart it’s hard to do, but that’s not how trailer floors break – joints separate under the weight of a load. So instead, try to keep your fingers locked as you push your lower hand down while keeping both fingers rigid. You probably can’t do it. This basically simulates a traditional trailer floor joint.
To picture the new Prolam zigzag design, turn your hands so your palms are facing you. Extend your three longest fingers on each hand. Now interleaf these fingers so they look like they’re stacked one on top of another. Again push down on the lower hand while keeping all of your fingers rigid. This time the joint is much harder – if not impossible – to pull apart under a downward force. In simple terms, that’s the zigzag advantage.
There is, however, more to a good trailer floor than simple strength. As Thabet earlier alluded to, water penetration has always been a problem in van trailers. Wooden floors are generally built right on top of the trailer cross members so they can be directly exposed to the harsh road environment.
“When water soaks the underside of a standard floor, the wood expands and the joints start to come apart, which then allows even more water to get into the van,” says Risi. “The zigzag eliminates this problem. If water expands the wood, the new joint actually seals itself shut.”
Because there are multiple surfaces in contact with each other the swelling wood crushes together, even tighter than it was before. Proof of this, Prolam claims, can be observed in the industry’s other standard benchmark: the wet sheer test. After a section of floor has been thoroughly soaked and dried over a period of days, the folks in quality control try to break it apart. Prolam says it has seen a 300% increase in its wet sheer results.
“The trailer manufacturers require a wet sheer score of 525 pound, we typically score above 1,400 pound.”
Maybe that’s why the company has enjoyed a warranty claim rate of a microscopic 0.001% for the last 60 months – they’ve only made a single trailer floor that was defective in that time.
There is another distinct difference between Prolam’s floors and competing offerings from the U.S.-based producers and geography has a lot to do with it.
“We use about 80% maple, to take advantage of what’s available in our area,” explains Risi. As with many products that take more than one launch to get right, an initial failure by another manufacturer of maple floors spawned a rash of misinformation. According to Prolam, and contrary to popular belief, maple trailer floors do not decay more quickly than those made of oak. In order for any wood to develop decay, it is necessary to have a proliferation of fungi, which is tied entirely to moisture content. Again better bonding and sealing eliminates the pitfalls experienced during earlier attempts.
The company insists a well-tested gluing technique is the true key to superior wood bonding, not the species of wood. As well, for extremely weight conscious haulers, maple can perform as well as oak and holds another advantage, according Prolam. It is less dense than oak. A hard maple trailer floor can weigh up to 100 pounds less than an oak floor — in the case of Prolam it generally estimates 75 pounds less.