Spec'ing Van Trailers
The Box Needs To Stay Rigid - And Don't Forget The Tires
Tom Berg
Equipment Editor
In the market to buy a van-type trailer? Or just keeping tabs on what the boss orders? Whether new or used, a trailer needs certain equipment that makes it right for your haul. Some things relate to specific cargoes. Others are more basic, thus applicable to a wide variety of vehicles.
For example, the sides, roof and doors of a box-type trailer combine with the floor and underframe to form a "monocoque" structure, similar to an aircraft's fuselage. This means the upper panels help support the load. Opening the rear doors, in effect, breaks the structure's integrity and lessens its ability to carry a load.
That's why arc-shaped steel "corner heels" have come into use in trailers that occasionally travel with their rear doors open. These braces connect floors with the sides just inside the doors, keeping the sides from flopping and weakening as trailers bounce down rough roads. The heels are often found in trailers that go into Mexico; long lines of rigs snake their way to customs inspection stations, and one or both doors are left open so inspectors can quickly look inside the trailers.
Anything that adds rigidity to a van's monocoque structure contributes to the vehicle's overall strength and its life. Conversely, skimping on specifications in this area will result in a weak structure that won't last as long as you'd like. This doesn't necessarily mean spending a lot more money, as long as a trailer shows quality in its basic design, materials and workmanship. That includes:
• Crossmembers spaced close enough together to take heavy loading from forklifts - Six-inch centers in the last eight to 10 feet of the trailer are common where heavy forklift traffic is expected. So is a "crash plate" of steel over the last one or two feet of flooring.
• Double-racking door locks - An extra set of locking posts on each swinging rear door positively presses doors against the trailer's sides, squaring up the body and ensuring that its monocoque design is working. Extra hinges - four per door instead of two or three - also help. The sides stay stiff and the trailer's useful life is extended by at least two years, fleets have found. Yet these options typically costs less than $100 per trailer.
• Composite doors - Reinforced plastics, honeycomb aluminum and foam can replace the plywood cores in "plymetal" doors. Plywood is fairly cheap and strong, but it absorbs water that eventually seeps or leaks inside and rots. Composites shrug off moisture and last longer, but they are cost more. Composite doors are available in swing and roll-up (overhead) types.
• Cargo securement provisions - Recently imposed federal tie-down regulations apply not only to flatbed trailers, but to vans and reefers with incomplete loads that are likely to shift. (Fully loaded box trailers are exempt because the massed cargo keeps itself in place). Securement devices keep loose items from falling through walls and onto roadways and from spilling out when doors are opened. Another object of the regs is to keep dissimilar loads separate.
Logistic tracks along the sides and even floor tie-down points should be used. One builder offers side posts that double as vertical logistic tracks; locating such posts at the trailer's rear allows easy use of straps and nets; they can also be hung on the posts when not needed to keep them in the trailer but off the floor and out of the way of feet and forklifts.
• Smooth-surface liners - Plastic, composite or even steel liners are preferred for food shipments because they can be cleaned easier. Some food shippers are getting picky and will reject trailers with plywood liners.
• Stainless steel components - Stainless door sills and upper coupler parts do not rust, and thus remain strong, good looking and don't need repainting. These tend to be popular on reefers that see a lot of moisture from cargo.
• E-tech coatings - Some suppliers are switching to specially applied paints (usually with electro spraying or dipping) that stand up better to aggressive road salts than sprayed-only paints. These, too, keep structures (such as landing gear) strong and less likely to need repainting.
• Decking devices - Tracks in walls and posts allow the set up of second and third decks so fragile items can be stacked and the trailer filled, making the most use of its cube. Home Depot, Central Freight Lines, Estes, Schneider National and other operators have long used these.
• LED lights - Light-emitting diodes last 10 times as long and use only 10% of the current required by incandescent lights. LEDs are especially useful at top positions (like above the rear doors), where the lights are hard to get to if bulbs burn out. LEDs burn very cool, so they won't ignite bumper pads above loading docks (as incandescents have been known to do). However, some fleet managers stick to cheaper incandescent lamps at the upper-front corners of trailers subject to being whacked by low tree limbs and other obstructions.
• Rear impact guards with bolt-on parts - Damaged members can be easily and quickly replaced if the guards are assembled with bolts rather than welds. Replacements should be of the same strength so that the guard can continue to absorb impacts as designed, and the horizontal member with the manufacturer's certification label should be replaced with another labeled member. However, a damaged impact guard is NOT an out-of-service condition; an inspector might issue a fix-it ticket, but the vehicle should be allowed to proceed.
• Steps and hand holds - If drivers must regularly climb into the trailer, there should be ways for them to do so safely. For starters, the upper surface of the impact or under-ride guard's horizontal bar can be faced with non-skid material, and hinge frames can double as handles. Preventing one slip and fall can save thousands of dollars in worker's compensation claims, not to mention pain and suffering.
Thoughts On Tandems
Running gear is almost a subject unto itself, but recent innovations are worth including here. One is a trend toward integrated axle/brake/suspension products, including entire tandem-axle assemblies. These are put together by a supplier and shipped as a unit to the trailer manufacturer. The buyer gets better assembly of troublesome parts like wheel seals, and the entire unit is warranted by a single maker instead of several suppliers. The price can be better, too.
Air-ride suspension continues to gain in popularity because it cushions the load. Thus, less road shock is transmitted through the fifth wheel into the tractor and then to the driver. Some air suspension designs, though, are prone to flexing under forklift loads and "walking" the trailer body away from the dock. This can lead to falls and serious injuries. So be sure the suspension compensates for the walking tendency through blocks in the air bags, or is of a type that can't walk in the first place. Ask the trailer salesman about this before you buy.
Finally, tires: Trailer tires are among the most neglected components in the trucking world, especially when they're on trailers that are dropped and left for who-knows-how-long in a customer's yard. "Sticking" the tires with a gauge is too much trouble for most guys, but looking at an indicator screwed onto the valve stem of each tire is easy as you make your way around the rig during a pre-trip inspection.
"Whoops - I see a yellow flag on that inside dual. Better get some air to it." That's one type of indicator. And there are others - and most have gotten more rugged as modern materials have been incorporated into them. Others monitor air pressure and temperature and broadcast warnings right to the cab. These might be next best thing to electronic "chips" imbedded in the tire - something that's been talked about for about 10 years, but for reasons of price, always seem to recede into the future.
Maybe best of all are systems that connect the valve stems to the trailer's compressed air supply. These not only monitor tire air pressure but also pump them up. Some products have been proven in fleet use, and have testimonials to prove their worth.
Ask about them, because they'll save you some work and - if you own the trailer and its tires - they'll save you some money in the long run.
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