Combatting Trailer Corrosion
There are ways to combat damage from aggressive ice-control chemicals, including spec'ing premium products and properly maintaining everything in the fleet.
January 2008, TruckingInfo.com - Feature
Grief wrought by aggressive ice-control chemicals has been well documented, mostly recently in the November issue of HDT. There are ways to combat it, including spec'ing premium products and properly maintaining everything in the fleet.
Calcium- and magnesium-chloride compounds do an efficient job in preventing and removing ice and snow, which is why highway departments spread them. But where common sodium chloride salt can be sprayed off, the newer chemicals must be scrubbed off, which is difficult to do; and they are insidious in where they'll go.
While corrosion can attack many parts of a trailer, one area that is particularly susceptible - and one where you can really make a difference - is in wiring. One of the best ways to thwart the action of these chemicals is to specify sealed wiring harnesses, say manufacturers such as Grote, Phillips and Truck-Lite. All make modular systems with heavily insulated wiring and physically self-sealing connectors. The manufacturers also recommend that you spec both wiring and light fixtures from the same company, not just so they get more of your money, but also because modules of the same make and type will fit together better and seal tighter.
Roy Gambrell, director of maintenance at Truck-It Inc. in Franklin, Ky., says he spec'd one of those manufacturer's sealed wiring systems on a group of van trailers. At least he thought he did. Within a year he started seeing corrosion problems in the wiring and lights, and he looked closely at what products were on the trailers. He found that the lights were from the manufacturer he spec'd, but the wiring was from another manufacturer. Apparently the trailer builder interpreted his specification to mean lights only, and substituted the other maker's wiring.
Gambrell, who is chairman of the ATA Technology and Maintenance Council's Corrosion Control Action Committee, thinks the two makers' connectors don't seal well enough to keep out road chemicals that are fouling his wiring and lighting systems. He also believes that the trailer builder's workers didn't assemble the parts properly; they didn't coat the connectors' contacts with dielectric grease and didn't snap them together tightly enough.
He says he has seen similar lapses in material and assembly quality at other vehicle builders and suppliers in recent years.
Gambrell has declared at TMC meetings and to anyone who'll listen that builders could start rectifying the problems by paying their employees more and supervising them better, and avoiding cheap fasteners and other parts. He believes much of the metal in today's parts is smelted in China and is contaminated with who-knows-what, and he has challenged manufacturers to divulge where their raw materials come from. But that's another story.
"Now I know better," he says of this wiring issue. "You've got to spell out everything" in the specifications. If he wants one manufacturer's complete wiring and lighting system, he must say so. And if he wants the connectors greased, etc., it's a good idea to say that, as well. If he is willing to pay for what he wants and how he wants it put together, manufacturers will probably appreciate the extra guidance.
10 Tips For Coping
Phillips Industries, a maker of electrical wiring products, notes that all de-icing agents used by highway departments are composed of chlorides (salts) and all contain some level of chlorine, which is one of the most corrosive elements for metals. Electrical terminals are made of copper or brass, which react negatively when exposed to road salts containing chlorides. The electricity flowing through the metals accelerates this reaction.
The J560 seven-way connector between tractor and trailer is often the first piece of wiring to corrode. This is because it's the only automotive connection that is routinely opened and exposed directly to harmful environmental conditions. When coiled cables are unplugged from the trailer side only, they remain "live" and need to be stored properly. Unfortunately, many times they are not. Even when connected, the nature of the J560 design allows for considerable waterborne contaminant attacks.
The most common warranty claim for the seven-way connector is the loss of electrical function on the "blue" circuit. This powers the trailer's anti-lock brakes, and the constant flow of electricity over the blue and the ground attracts corrosion to those areas. (The blue circuit is powered as long as the tractor's ignition key is in the "on" position.)
The J560 is among the things addressed in Phillips' Top 10 Cures for Corrosion which, if followed, can help truck and trailer operators avoid some of the increased costs associated with winter operations:
1. Use heavy-duty, adhesive-lined heat shrink tubing on all electrical connections.
2. Protect battery posts and terminals with anti-corrosive spray.
3. Make sure grounds lead directly to the batteries' negative posts. Grounding to the chassis or engine will lead to corrosion, poor contacts and faulty electrical operations.
4. Store electrical and air coils in stowage devices designed for this purpose when not in use for extended periods of time.
5. Swap plug ends on the J560 tractor-to-trailer cord every six months. This will even out plug wear.
6. Never puncture a hole in wire jacketing, because it will allow chemicals to wick into wires and rot their innards. Instead, when tracing down circuits, work from the metal connectors.
7. Remove build-ups of salt, especially magnesium chloride and calcium chloride, by frequently brush-washing equipment during cold weather. Do not power wash, because water can be forced into areas from which it can't escape.
8. After every cleaning, re-apply dielectric grease on plugs and socket pins.
9. Clean connectors with a plug-and-socket brush and water (not soap) every six months.
10. Specify sealed wiring harnesses and other components designed to guard against corrosion, like Phillips' own Sta-Dry products. One is the Slim-7, for which Phillips has just received a U.S. patent. It has thin, molded connectors that easily fit through a trailer's frame rails. Connectors have special ribs and O-rings that keep out moisture and contaminants.
RSSplus Has Enhanced Features, Lower Price
Meritor Wabco has an enhanced version of its Roll Stability Support, a stand-alone electronic anti-rollover system for trailers. Called RSSplus, the new system includes event data recording and communications via the powerline connector, and will cost somewhat less than the current product when it becomes available in March, said the joint-venture company's executives in announcing it.
Like RSS, introduced in 2003, RSSplus was adapted for North America from Wabco's European products. It builds on a trailer's anti-lock braking system, which by law it must have anyway, to provide protection against expensive rollovers. It does so by sensing instability in the trailer and applying the brakes, usually in tight turns that the driver has entered too fast. There is no communication with a tractor's ABS or roll-stability system, if it has one; the trailer system works on its own. RSSplus adds "intelligence" with the data recording and PLC communications with the driver in the tractor's cab, said Tom Parrott, engineering manager.
The system's electronic control unit records driving events such as RSS-applied braking, which the owner can use to better manage the driver. Meanwhile, the ECU's brain can learn from severe events to adjust the threshold at which brakes are applied during an RSS "intervention." Other data that can be recorded include tire pressure, wheel-end temperatures and weight at the suspension. These can be sent over the PLC to a display in the cab and, if the owner wants, transmitted to company headquarters via a telemetry service.
The ECU has new connectors that are more positive and prevent incursion of contaminants, which reduces chances of internal corrosion. RSSplus retains standardized SAE diagnostics that customers requested, said Bob Sibley, director of Meritor Wabco Trailer Products. To check or repair the system, technicians can use the company's Toolbox PC software or observe blink codes in a hand-held tool.
RSSplus can be installed on trailers with steel-spring and air-ride suspensions, and with various combinations of sensors and modulators. Its software works on many types of semitrailers, including vans, reefers, tankers, flatbeds and dumps.
It works on B-train doubles, which are connected by a fifth wheel, but not on drawbar-pulled doubles and triples, whose loading characteristics vary widely. Meritor Wabco engineers are devising software to accommodate them, Parrott said.
Trailer builders are charging fleets $700 to $900 for Meritor Wabco's current Roll Stability Support system, but RSSplus should sell for about $200 less, executives said. The prices include ABS, which is part of RSS and RSSplus, so customers should consider that in assessing the worth of a roll-mitigation system, they argued.
Rollovers can be expensive and sometimes catastrophic, so the cost of an anti-rollover system is minor by comparison. The presence of roll-stability interventions on the recorder suggest that the system probably prevented one or more rollovers, and thus more than paid for itself.
RSSplus can be retrofitted to an existing trailer, which might cost $1,200 to $1,500 if the ABS wheel exciter ring and sensors are already there.
The new wiring should connect to the wheel hardware, so it's a matter of removing the old wiring and ECU and mounting the new pieces; this should take about two and a half hours, Parrott said. Meritor Wabco might have a retrofit program in place by summer.