Solid Wood Products 2703 



Surface wearing characteristics of flooring materials are not generally tested 

 in the laboratory. Almost all failures in wood-base trailer flooring are due to the 

 puncture or rupture of floor strips by fork lift traffic. Service life equal to that of 

 laminated oak is generally acceptable. Truck van trailer flooring, because it is 

 usually exposed to the weather on the bottom, must be resistant to salt and 

 corrosion. For platform trailers, because the wood flooring is exposed on both 

 top and bottom, laminated wood flooring is used exclusively. This is one reason 

 why nailable steel is not expected to be used in any quantity for trailer floors. 



Dimensional stability is normally not a problem in trailers utilizing 12-inch- 

 wide floor panels so long as they are installed at between 10 and 12 percent 

 moisture content. A 1/16-inch machined crusher bead ensures an edge spacing 

 gap to accommodate subsequent swelling across the board and prevent buckling. 

 One reason why large panel sizes have not been favored is the increased problem 

 with dimensional stability. 



Nailability. — Shifting of cargo during transportation is a critical problem in 

 the trailer industry. Life safety and property loss considerations dictate that 

 cargoes must be sufficiently tied down to prevent movement and subsequent 

 damage. This is normally done by nailing hold-downs or dividers directly to the 

 floor system. Thus, it is necessary that the floor material possess good nail 

 withdrawal strength, and yet, the density must be low enough to facilitate nailing 

 operations. One general complaint about tropical hardwood species (e.g., api- 

 tong) is that nailing characteristics are poor. 



Coefficient of friction. — Trailer flooring materials must provide a certain 

 degree of friction to avoid sliding of fork lifts during loading and unloading 

 operations. When slippery material such as aluminum or steel are employed, it is 

 necessary to use an antiskid paint to protect against sliding. In general, untreated 

 laminated oak and southern yellow pine provide good skid resistance. (See 

 section 9-4 for a discussion of friction coefficients.) 



Weight-to-strength ratio. — Limited load carrying capacities of bridges and 

 roadbeds require limits on total weight of trucks and trailers. The payload is the 

 total legal weight minus the dead weight of the trailer. Any additional trailer 

 weight reduces net allowable cargo load. Thus the weight-to-strength ratio of a 

 flooring material is probably its most critical property and the primary advantage 

 of laminated oak, southern pine, and extruded aluminum for truck trailer floor- 

 ing. The high weight-to-strength ratio of nailable steel (about three times that of 

 laminated oak) eliminates it from consideration for this market. 



Trend. — Fergus et al. (1977) concluded that the low weight-to-strength ratio 

 of laminated oak and laminated southern pine establish these products as the 

 major competitors for truck trailer flooring. With good wear resistant properties 

 and high coefficient of friction, laminated wood products should continue to 

 dominate this market, although extruded aluminum will continue to be used in 

 refrigerated trailers. 



