Rock Products

FEB 2019

Rock Products is the aggregates industry's leading source for market analysis and technology solutions, delivering critical content focusing on aggregates-processing equipment; operational efficiencies; management best practices; comprehensive market

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www.rockproducts.com ROCK products • February 2019 • 51 between compartments. With access between multiple compartments, technicians have minimal concerns about working in confined spaces. To allow technicians into the tank for maintenance, some manufacturers incorporate external doors, which can pro- vide fresh air and natural light throughout the tank after opening all of the external and baffle doors. When the tank is empty and the inside needs servicing, technicians simply enter the tank and open the baffle doors. This system offers easy service and maintenance, allowing technicians to access the inside of the tank safely and easily, instead of putting off the difficult work for later. Having complete and easy control over their tank's water output gives truck drivers control over their safety on haul roads. For instance, individually controlled spray heads help water truck drivers optimize their water usage as well as minimize the chance of oversaturating haul roads, which can create slick driving conditions. Inside the cab, operators can turn on the individual spray heads – and, in some systems, program a spraying interval. This optimizes water usage, so operators cover more sur- face area with minimal risk of making haul roads too slick for other equipment. Water metering controls contribute to overall safety by allowing the water truck driver to better focus on his or her surroundings while driving. Overburden Body Design On the surface, it may appear as though truck bodies don't deviate much from one design to another. But each truck's design is created with safety and efficiency in mind. New designs on the bodies of trucks being used to move over- burden now address two major concerns: •  First, the designs have virtually eliminated the loafing effect – that loads of packed material that releases all at once from a truck body during the dumping stage. •  Second, they minimize material carryback, ensuring the bulk of the load is dumped the first time for greater efficiency. With a significant amount of load over the rear axle, the dumping motion of a truck body not properly designed to combat material loafing often causes the front of the truck – which weighs hundreds of tons on its own – to lift up off of the ground. The entire weight then releases at once, slam- ming the truck and its driver back to the ground. This process stresses both the truck chassis and the driver. Several carefully engineered modifications now move truck bodies from standard dumps to proficient machines. First, the shape of the truck bed has been redesigned. Traditional truck beds are parallel-sided, forming a chute for the material to release all at once without breaking up. This often causes the truck to rock with the sudden weight on the rear of the bed. By tapering the sides of the truck and making the end of the truck bed wider than the front, the overburden and other materials are given an opportunity to spread out while exiting the truck body. Material is further broken up by angling the back third of the body floor down and raking the edge of the floor away from the center point. By taking the floor away from the underside of the loaf, it's forced to break apart and exit the truck body with considerably less force on not only the truck chassis, but the driver, who isn't jolted as greatly within the cab. Additionally, many materials, when transported in truck beds, adhere to the truck's surface. In essence, the same load is carried again and again when it fails to release when dumped, so it takes a joyride back at the expense of the com- pany. As much as 30 percent of a truck body's volumetric capacity can stay behind through added carryback, making for a significant decrease in productivity unless it's manually scraped from the body floor and sides. The answer to carryback problems lies in both the design of the truck body and the materials used within and outside of the body itself. Coating key parts of the truck body underside with a hydrophobic paint will produce what's known as the "lotus effect." The square design of Philippi-Hagenbuch's water tanks lowers the unit's overall center of gravity, enhancing stability and allowing drivers to safely fill the tank to capacity. The tapered design of the truck bed makes it easier for the overburden materials to spread out evenly when exiting the truck body.

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