You also need to know the weight capacity in a concentrated area. This is how much weight is going to be carried over a given area. This is especially important with certain types of equipment. "A forklift has a high concentrated load area," says Mel Holle, Landoll Corp. The entire weight of the machine is transferred to the trailer deck through the small contact areas of the wheels. With an excavator or a dozer, the amount of track in contact with the trailer helps determine the concentrated load. "You can buy 50-ton trailers that have a concentrated load at 16 feet, 12 feet or 10 feet," says Holle. "The smaller the concentration, the stronger the trailer."
Again, you have to be very careful when looking at the concentrated load rating. "There are manufacturers out there that say concentrated at 10 feet," says Marv Odegaard, Trail King. "If you read the fine print, it says the center of the deck only. Think about this for a second. If you are hauling an excavator, your weight is going to be in the front. You are going to get it all the way forward so you can get your stick down. If you are hauling a scraper, your weight will be in the rear and on the front.
"When we design a trailer, we bring the load all the way to the front and we design it to a 2.5:1 safety factor to be carried 16 feet from the front, 16 feet from the back," Odegaard continues. "So we think it makes sense to put a 2.5:1 safety factor in the wheel area, which is a critical area for a trailer to crack, and a 2.5:1 safety factor in the gooseneck area, which is a critical spot. We back off to 2:1 in the center of the deck where you hardly ever have a failure."