With the latest IMT service bodies, the workbench bumper size and height and depth of the compartments have been increased. Computer simulation allowed IMT to keep the weight gain down to around 50 lbs. This was done with a patented floor design. "Torsion-designed floors help with the twisting and racking by allowing the stresses to float around instead of concentrating where floor crossmembers attach to the side packs," says Worman.
Another area that is becoming better understood through simulations is how to support the door frames to prevent fractures from too much down pressure when the crane is stored.
Check for corrosion resistance
Premium bodies are designed to resist corrosion. "The largest improvement in service bodies has been the incorporation of galvanneal steel, and the improved preparation and paint systems, that have greatly increased corrosion resistance and longevity," says VanLaren. Some steels use more galvanneal than others. "The amount can be determined by the grade, most typically A40 and A60, with A60 having more galvanneal applied to the steel than A40. So a body built with A60 galvanneal steel will have more corrosion protection than a body built with A40."
Ollerich says you can also get good corrosion resistance with thicker, non-galvanneal metals if they are well coated. "A lot of guys are using 12- and 14-gauge bodies that are galvannealed and painted. Ours is 10-gauge and then painted," he states. This approach costs a little less, but it weighs more. Corrosion has not been an issue since Feterl uses PPG's Delfleet paint system.
"Service Trucks International bodies also use the latest PPG Delfleet polyurethane paint system for improved paint adhesion and chip resistance," says VanLaren.
Aluminum can be used to both save weight and provide corrosion resistance. But not everyone is sold on the use of aluminum for crane bodies. "Aluminum bodies cannot take the loading," says Worman. "To get the structural integrity needed for crane bodies, you have to use a thicker aluminum material, which starts to mitigate weight savings. There are also cost issues."
Sealing out the elements
"Bodies flex so much when you are going down the road," says Worman. "You want to keep them as tight as you can, but it is not going to be 100%." Sealing is accomplished through ball-type weather stripping around doors, bonded washers to seal mounting holes and three-point latch mechanisms.
Maintaining the integrity of the cabinets by minimizing the number of holes used to mount accessories and components has been a major emphasis for several service body suppliers. "Service Trucks International has put significant effort into reducing the amount of holes in the top of the body by using different brackets and hardware, and has increased the sealing efforts dramatically," says VanLaren.
Likewise, Feterl has tried to minimize the number of holes it drills to mount accessories. "If we drill a hole to mount an air compressor, for example, we are doing a better job of sealing the holes to minimize the amount of water that gets into the compartment," says Ollerich.
Weather stripping around the doors has almost become standardized. "Automotive bulb type provides the best seals," says VanLaren.
And many manufacturers have pressurized cabinets. "Pressurized cabinets make the inside of the cabinet a higher pressure zone than the outside, thereby providing an additional barrier against fine dust and moisture getting in," says VanLaren.
"If any water does try to work its way through the door seal, the pressurization will help to blow it out," says Ollerich.
Consider door latch design
Three-point door latches offer more security. "If someone wants in your truck, they are going to get in there some way," says Ollerich. But the three-point latch makes it more difficult to get in. "If you have a long vertical door, instead of just latching on the top and bottom, it also latches in the middle of the side of the door.
"A lot of times, what can happen if you don't have that third point is you can pull the door open enough that you can maybe get at the back of the latch and get it undone," Ollerich points out. "Using the three-point latch holds that tight so you can't do that."
Latches can also help better seal the compartments. "Some new latches have hit the market, called [three-point] double latches," says Worman. "You latch the door by turning the handle and it brings the door against the weather strip. Then you close the T-handle on the latch itself and it pulls the door in even tighter against the weather strip. It is more secure and offers a better seal."