Three Support Equipment Pieces are Critical to Aggregates Operation Success.
By Josh Swank
|The box-shaped structure of some water tanks makes it possible to haul more water than rounded tanks, resulting in considerable time and cost savings.|
Support equipment is in the spotlight, and for good reason. Fine-tuning your fleet means choosing the best of all equipment, not just crushers, screeners and earth-moving equipment.
While those assets are clearly key players, taking a look at things that may not be top of mind – water tanks, specialty off-highway haul trucks and rear-eject material spreaders – can be an effective way to improve productivity.
Examining these aspects of equipment doesn’t only make fiscal sense it can also be a determining factor in keeping an operation up and running efficiently and safely.
Water Tank Technology
How equipment operators haul and apply water can significantly impact an operation’s bottom line. These water trucks, primarily used for dust control, are designed with several factors that impact their efficiency. From the challenges of water movement in the tank to the water output technology, these factors impact uptime, maintenance, efficiency and safety.
In traditional applications, round water tanks are the most common. They get the job done, but not without challenges. The tank’s curved sides raise the water’s center of gravity, making the tank smaller than the truck can handle and the truck less stable when navigating haul roads. To mitigate the instability, operators often avoid filling their tanks completely. This means they need to refill more frequently, contributing to added downtime and increased fuel consumption as they backtrack to the water source.
|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.|
Alternatively, water tanks with square corners minimize churning and often have a larger capacity by simply not rounding off the sides of the tank. They also maximize productivity and operator safety due to their box-shaped structure, water baffles and water metering systems.
The design also lowers the unit’s overall center of gravity, enhancing stability and allowing drivers to safely fill the tank to capacity. The box-shaped structure makes it possible to haul about 20 percent more water than rounded tanks, resulting in considerable time and cost savings.
To minimize surging, some tanks feature sophisticated water-control systems that use baffling that runs from floor to ceiling as well as along the complete length and width of the tank, resulting in full compartmentalization of the water. Baffles inside the tank help minimize water from surging side-to-side and front-to-back.
Almost all water tanks feature baffles, but many have large holes cut out to provide maintenance personnel access to the individual compartments. Within the outer compartments, some manufacturers install side-surge stabilizers along the walls to prevent water from rolling or churning. The number of compartments can vary between tanks. For instance, a 58,500-gal. tank might have 42 or more individual compartments.
To offer the best level of water compartmentalization, these baffles require holes to allow water to flow freely throughout the tank, but they need to be small enough to prevent water from surging during use. To address this, some water tanks feature access doors that are about as tall as an average-sized worker to provide a more advanced solution than simply a hole near the ground in the baffle walls.
These baffle doors, which technicians walk through easily, practically eliminate the need to crouch down while they maintain the tank, and the doors remain shut while the water tank is in operation, further restricting water movement 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 provide 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 surface 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.
|The tapered design of the truck bed makes it easier for the overburden materials to spread out evenly when exiting the truck body.|
New designs on the bodies of trucks being used to move overburden 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, slamming 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 company. 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.”
Moisture within the haul material prevents it from sticking to the hydrophobic surface, similar to the water-repelling characteristic of a lotus leaf. As a result, it’s nearly impossible for anything to remain on the truck. Similar results can be achieved within the body when strategically using hydrophobic and oleophobic steel liners to minimize material carryback. This hydrophobic technique is being added as a retrofit to existing systems to improve productivity.
Material Spreaders on Rear-Eject Bodies
|Philippi-Hagenbuch’s material spreaders are designed with efficiency in mind, making it easy to evenly distribute material.|
Spreading materials may seem like a simple concept, but it’s actually one that involves a great deal of variability and potential for lost efficiency. Material spreaders can be used to build haul roads, for road safety in the winter by spreading sand or gravel across slick and icy roads and in other areas that require dry, solid materials to be discharged and broadcast.
Typical material spreaders operate in a passive mode by using steep slopes to move the material from the body to the material spinners. This results in unsafely raising the vertical center of gravity.
Even though the units have vibratory devices on them, the material still tends to bridge, adversely affecting the operation of the equipment. There are also safety concerns when crew members must manually address the material clogging up within the highly sloped bodies, often requiring them to get into tight, confined spaces.
An updated option involves an active system, which uses a rear eject body that horizontally pushes material towards the back of the bed and into a cross auger that delivers the material to broadcast spinners. This process increases efficiency by saving time on maintenance and upkeep and is able to cover more ground in a uniform manner safely, efficiently and effectively.
Material spreaders have the ability to evenly distribute their material to improve the efficiency. Operators no longer need to alter their haul cycles to bypass areas that have poor traction as they can maintain the traction on various grades as needed, which optimizes cycle times.
Investing in Efficiency
Carefully selecting support equipment helps prevent downtime as well as increases the longevity and efficiency of the equipment. And, as with any business, productivity and profits are the key measure of success.
Partnering with manufacturers that make efficiency and safety the core of their designs helps to ensure peak equipment performance and reliability for years to come.
Josh Swank, vice president of sales and marketing for Philippi-Hagenbuch, oversees the steel mill, refuse and mining industry sales group and has been with the company for more than 16 years. His previous roles within the company include global sales and marketing manager and account manager. Outside of Philippi-Hagenbuch, he participates in multiple industry and philanthropic organizations, including the National Stone, Sand and Gravel Association’s Manufacturers & Services Board, the NSSGA Young Leaders and the National Mining Association Board of Governors. He is a trustee of the JWAS Foundation and active within the Peoria, Ill., startup community.