Liftgates
Changes in equipment and materials have made them more reliable and lightweight.
Tom Berg
Equipment Editor
Whenever heavy or bulky cargo has to be picked up or delivered someplace other than a loading dock, you'll find liftgates at work. They spare drivers from sore muscles and aching backs, and thus boost morale and reduce workers' compensation claims.
But liftgates themselves are heavy, requiring attention to chassis spec'ing in order for trucks and bodies to support them. And they have electrical controls and moving parts that can be troublesome and expensive to repair. These all used to be good excuses to avoid using 'gates. But now, manufacturers have corrected those shortfalls with new designs and materials.
Therefore, what you buy today should differ from what you might have purchased not that many years ago.
For starters, electrical glitches have traditionally accounted for a high percentage of liftgate problems — as much as 90%, according to Jack Wyatt, manager of field service at Waltco Truck Equipment and chairman of an industry task force that's writing a new recommended practice on liftgates. Due out in fall of 2004, the RP will concentrate on electrical issues experienced on liftgate-equipped semitrailers. It will join an existing set of recommendations published by the Technology & Maintenance Council of the American Trucking Assns.
High incidence of electrical problems is not surprising if you think about where liftgates are — at the rear of a truck body or trailer, sitting close to the pavement where tires send splash, spray and road grime directly at wiring, switches and connectors. It's the worst possible environment, especially in cold, wet climates.
Better electrical gear is one of the changes made by manufacturers in recent years, according to Waltco, Thieman, Leyman and other makers. Starting in the mid-'90s, they took the same improvements made to lighting systems — heavily insulated wiring and plug-in connectors — and applied them to the electric control systems of liftgates. Also new are switches with magnetic (rather than mechanical) contacts, and with circuitry "potted" in polyurethane to make them moisture-proof.
Upgraded electrical parts are now standard on many liftgate models and optional on lower-cost ones. Sealed wiring, connectors and switches on a liftgate should cost well under $100, manufacturers say, and will save many times that in repairs. Also available from some manufacturers are electronics that record liftgate activity and allow quick diagnosis of any malfunctions. Ask about such features when you're getting bids.
Wyatt's TMC task force is addressing additional electrical issues: Battery failures, and lack of voltage and decent grounding at the rear of trailers. Trailer-mounted liftgates usually use one or more batteries to back up the power sent through a dedicated circuit from the tractor. These can be depleted through continued use or insufficient recharging. Straight trucks should also have battery backup if liftgates are cycled often or if truck engines must be turned off during liftgate use, Wyatt says.
Discussions of the battery drawdown problem by task force members have identified the best battery to use in this role: a "dual-purpose" type that can be recharged more quickly than deep-cycle batteries, but also has high amp-hour capacity. Dual-purpose batteries are also economical to buy and readily available at parts outlets, he says. Delco and Interstate make them.
But no battery will stay charged if not enough voltage and amperage get to them and/or the ground is bad. Liftgate systems need high amps that would fry the standard seven-pin cable running between tractor and trailer, so a second single-pole connector cable is commonly used. That cable carries power, but does not ensure a good ground.
Grounding of a trailer liftgate's circuitry is done through the fifth wheel, which is usually smeared by dirty grease, and these days can be entirely insulated by low-friction Teflon plates. Thus only the kingpin is the ground connection, which may not be sufficient.
So, Wyatt says, that second cable really should be a two-pole type, which will both carry power and effectively ground the trailer to the tractor. The best time to wire the trailer and get the two-pole connector is when the vehicle is new.
Users of liftgates tend to skip maintenance — primarily, the greasing of pivot points — so manufacturers have made greaseless bushings and slider pads standard in many models. Look for these when pricing new liftgates; if you're buying a used liftgate-equipped truck, consider greaseless points a plus.
Liftgates look heavy and are, if they're made entirely of steel. But there's a trend toward aluminum components that greatly lighten things up. Bartt Suchland, Thieman's marketing manager, provides one example: A 48- by 95-inch platform on one 'gate model weighs 370 pounds in steel but 170 pounds in aluminum.
That 200 pounds comes right off the very rear of the truck, so reduces the see-saw effect and weight transfer from the truck's front. This could allow more forward placement of the rear axle, which means a slightly shorter wheelbase for better maneuverability. Aluminum also resists corrosion and looks better longer.
No matter how a liftgate is made, right-sizing it involves certain basic considerations:
• Capacity — How big and heavy are the commodities your drivers will be handling with the 'gate? This determines size and heft of the platform, and strength of lifting components, including the motor and hydraulic cylinders.
• How are commodities handled? On pallets, in crates or boxes or on wheeled carts? Do you need wheel stops on the platform? Would both a liftgate and a roll-up ramp be useful?
• Duty cycle — How often is the 'gate used? Just a few times a week lets you get away with a lighter-duty model, but multiple pickups and deliveries every day demands a much more robust type.
Many years of experience in dealing with customers has taught manufacturers, distributors and body builders how to supply the correct liftgate for any job. Meld their knowledge with your own and you should get the correct product for your hauling and delivery task.
