By Nick Zubko

The open road. That’s the locale most often associated with trucks, truck drivers and CB radios with cool handles like Bandit and Snowman floating about the airwaves. While that’s probably the only place most people ever see them, there’s an entirely different breed of hefty commercial trucks that do their best work off the road. In construction, one of the most common varieties is the dump truck — a working man’s load carrier designed to haul and dump all kinds of rock, dirt and debris around and away from the roughest and toughest jobsites they can find.

From the front, most dump trucks look similar to the semis you see rolling down the interstate or pulling into a weigh station as you commute to and from the daily grind. For the most part, they’re pretty close. The difference comes in once the contractors determine the rest of the specs to exactly match the application for which the truck is going to be used. A buyer can sit down and engineer the ideal work vehicle for their business model. They pick the chassis and cab manufacturer, then upfit that clean slate frame with whatever they need on the back. As a result, some previously untapped markets have taken on a life all their own.

“The medium-duty dump truck market, for one, really exploded back in the early 1990s,” explains Brad Pugh, product planning manager for Ram Chassis Cab, which is part of Chrysler’s Dodge Truck Division. “Once these trucks became accepted in the market for their reliability and capability, customers had a lower-cost solution to fleet buyers and owner-operators. They are just the right size for most small commercial contractor needs like landscaping and home construction. Manufacturers can now offer affordable and durable vehicles in this segment that are capable of up to 5-yd dumps.”
     
Size Matters

As the entire truck market matured, a number of manufacturers stepped up to the plate to offer all types of contractors the perfect dumping machine to help move material and equipment to, from and around the jobsite. Major names in the biz run the gamut from recognized auto manufacturers like Ford, Dodge, Chevy and GMC to the guys that pretty much stick with the big guns — International, Kenworth, Freightliner and Mack Truck, just to name a few. And many of them have close ties to the auto industry. 

Sterling Truck (which is a subsidiary of Freightliner along with Western Star) was originally the heavy truck division of Ford until it was purchased by DaimlerChrysler and re-branded in 1997. Mack Trucks (architect of the industry-changing Maxidyne high-torque rise engine back in the 1960s) has been a market mainstay for decades and recently become a subsidiary of the Volvo Group.

All of these manufacturers have at least a few things in common. For example, truck classes are universally defined by Gross Vehicle Weight Rating (GVWR). The amount of cargo a truck can carry is found by subtracting the vehicle’s weight, passengers and an upfit body (flatbed, dump body, etc.) from the vehicle’s GVWR. 

The truck you buy needs to be able to carry the load you intend to move, so understanding GVWR is a key consideration. So before you get too far in your search for a truck, verify what upfit body will go onto it and how much weight it will be expected to carry. Medium-duty trucks today are classified as Class 4 through 7, while heavy-duty trucks are categorized as Class 8. Here’s how the various GVWRs are actually broken down.

Class 3 GVWR — 10,001 to 14,000 lbs
Class 4 GVWR — 14,001 to 16,000 lbs
Class 5 GVWR — 16,001 to 19,500 lbs
Class 6 GVWR — 19,501 to 26,000 lbs
Class 7 GVWR — 26,001 to 33,000 lbs
Class 8 GVWR — 33,001 lbs and above

In today’s business climate of lower margins, savvy fleet buyers can save their companies large amounts of money when they buy the correct trucks for their needs. The smaller end, pickup style bodies (Class 3 to Class 5) are popular because the driver licensing requirements are less than those in Class 6 or higher. However, those larger, more expensive trucks also can offer a significantly higher payload capacity — and the more you can haul, the fewer trips you will need to make. The result of those considerations will help control your labor costs along with your fleet budget.

“Getting the right size truck for the required job is the most important selection criteria,” says Mike Satlak, segment manager for International Truck and Engine Corp. “Weight definitely comes into play for a contractor, since they are always going to want to carry the maximum payload that a vehicle is capable of. Plus, the power and reliability of the hydraulic system of the truck are very important. Any dealer will work the local body company to create the best truck to meet all of the customer’s needs.”

Dump beds can have many different styles, lengths and features, but are typically made of aluminum or steel. What’s being hauled in the dump bed will typically determine the style, features and material used to make the bed. Dump bed styles are predominantly either square or elliptical. These two types apply to both the floor and the side of the body and are far more predominant in heavy-duty bodies. Also, various tailgates are available to accommodate different applications.

Body height is determined by the size of the body and removable side boards can be used on bodies to slightly adjust the hauling capacity (cubic yds) in light-, medium- and heavy-duty bodies.

“Most technological advances have included designing trucks with lighter, durable steel, elliptical bodies and updated body support styles such as floor and side bracing,” notes Shawn Waterman, construction segment manager at Sterling Truck Corp. “These enhancements are predominant in heavy-duty bodies, while advances in medium-duty models have been fairly minimal. Popularity is primarily determined by local and regional bridge laws that dictate the amount of payload carried across axle capacity and axle spacing.”

Bridge laws (which only apply to Class 8 trucks) can actually help in the selection process because they are determined by what part of the country you call home. Specifications for dump trucks are rigidly regionalized, so it’s important to do some research on the length and weight regulations in your state. Try to take maximum advantage of the weight laws to maximize payload.

“Some states require compliance with the Federal Bridge Formula, while others don’t. This will have a big influence on how the axles are set up and spaced,” explains Brian Lindgren, vocational market sales director for Kenworth Truck Co. “A Bridge Formula truck will tend to be longer to spread the weight. You may need to have lift axles, but there are different rules on how much load you can add with lift axles. And some states don’t allow pusher axles. Your dealer should know the rules and regulations. In states where you don’t need to comply, you can spec trucks shorter and heavier, making them more maneuverable on jobsites.”

The Right Truck for the Job

Construction is a demanding job, so your equipment has to be able to keep up. That means you might need a different chassis spec when hauling bulk loads such as asphalt, sand or gravel than you would if you hauled mostly demolition debris. If you’re planning to visit a lot of demolition sites, you will need to have the body and suspension beefed up to handle the pounding it will inevitably take.

The first step is to make sure you have the appropriate front and rear axle ratios and capacities. Front axle capacities tend to range from 6,000 to 16,000 lbs, depending on class and size of your medium-duty truck, while rear axle capacities run from about 12,000 to 45,000 lbs. The gross axle weight rating is the load rating of what the axles can safely support to meet the truck’s maximum GVWR. Determine axle capacities and payload and bed capacities to upfit properly.

“If you will be going off-road a lot into rough terrain, you’ll also need a suspension that is heavier duty and has more articulation,” notes Lindgren. “But if you’re hauling longer distances, you’ll need to consider the trade-off between the ease of dumping and the ability to haul more load per trip. For example, a transfer dump will allow you to haul more with one driver, but it will take longer to unload. Double bottom-trailers carry a lot of payload, too, but with those you’re limited on where you can drop the load.”

Gear ratios are also important. This is a specification that tracks the turning of the drive shaft, rear axle and wheels on your truck. For example, if your truck has a 3:42 axle ratio, that means your drive shaft will turn 3.42 times in order to turn the rear wheels once. Why does this matter? A lower axle ratio improves on gas economy, while a higher ratio will give better torque and pulling power under heavier loads.
“Maneuverability, for one, is a key characteristic in driving these trucks around a jobsite,” notes Pugh. “Quite often you’re trying to squeeze the truck amongst existing structures, piles of material and fences. You want the tightest turning radius possible. We recognized this when designing the Ram 4500/5500 chassis cabs and pushed the front axle out 6 in., to increase the amount of wheel cut at full turn. The more wheel cut you have, the tighter turns you can make.”

Dump trucks typically come with either automatic or manual transmissions, but for most applications automatic is preferred. Transmission options will range from five- to 13-speed manuals to automatic four-, five- and six-speed units (with common OEMs like Allison and Fuller).
Both gas and diesel engine choices abound as well (ranging from 190 to 300 hp), with brand names like Vortec, International, Duramax, Caterpillar, Cummins and HEMI. According to manufacturers, one of the biggest mistakes many customers make with dump truck engines is that they spec too much power when they don’t really need it.

“Required horsepower is a combination of the payload you will be carrying and the terrain that you will be operating in,” says Waterman. “Too much horsepower can result in unnecessary money spent, while too little horsepower will sacrifice productivity. The best way to judge this is to look at what others in your area are utilizing for horsepower and what optimum torque and horsepower is needed for your workload and region of the country.”

Quality power take-off (PTO) systems are another constantly improving technology. A truck’s PTO is a device usually mounted to the side of the transmission or transfer case (or maybe off the front of the crankshaft) and is used to transmit engine power to auxiliary equipment such as pumps, winches and lighting.

“When you spec out your vehicle, pay attention to how your selections affect the gross combined weight rating (GCWR), because that rating ultimately tells you how much trailer you can pull,” Pugh explains. “Additionally, your specific application may require that you also select a PTO prep package so you can install PTO-driven equipment.”

Daily Operation

When your new dump truck first arrives on the jobsite, it’s full of potential. But if it isn’t kept up and running, that potential might never be realized. As a result, serviceability is very important to dump truck customers.

“Serviceability is always a concern and challenge for customers,” says Satlak. “Anytime a truck is having service done to it, even routine preventative maintenance, is time that the truck isn’t being used by the customer to help them do their job. Anything a manufacturer can do to shorten service times or make the truck easier to work on is only to the advantage of the customer.”

Many manufacturers have integrated sophisticated monitoring systems on their truck lines to further reduce the impact downtime can have on productivity. International trucks, for example, feature the Diamond Logic Electrical System, which continuously monitor critical vehicle functions, relaying information to the driver to ensure efficient vehicle operation.

Earlier this year, Kenworth introduced a new electronic center for its 2008 Class 8 models that allows drivers to more closely monitor fuel economy, optimum engine speed and idling, plus access additional information on engine diagnostics. With the system, drivers receive instant access to current trip data, including miles per gallon, engine and idle hours, idle percentage and optimum rpm range for the engine. The driver can use this information to help optimize fuel usage and reduce wear and tear on the engine and transmission.

In addition to giving operators and owners the ability to keep a close eye on the health and well-being of their masters the dump and haul, manufacturers also realize the importance of doing the same for the operators. Over the last few years, the insides of these rough and tumble material movers are as polished and pristine as the fanciest luxury cars. More than ever, cabs today are being designed with driver comfort and productivity in mind, offering more shoulder room, headroom and leg room — improving visibility for operators of all shapes and sizes.
“Cabs in general have become more ergonomic and contain many more creature comforts than they have in past,” notes Satlak. “The truck cab has become a mobile office for many people. Customers also have been leaning toward bigger cabs. They want to be able to carry more of their workers to a jobsite in one vehicle. The International DuraStar has one of the roomiest cabs in the industry. It can come in a single cab, extended cab, or crew cab configuration.”

In addition, features such as cab air suspension protects the driver and cab from the shock and vibration associated with severe terrain, while improved insulation make for an exceptionally quiet driver environment. Features like high-back seats with integrated headrests, easy-to-read gauges and easy-to-use controls ensure that driver needs come first.

In the end, selecting the right truck comes down to a few simple criteria. Contractors need to evaluate the work they will be doing today and up to 10 years from now, evaluating the optimum size (light-, medium- or heavy-duty) that fits across various applications. They need to choose components like a reputable engine with adequate torque capacity, along with proven transmission and axel models, that will provide them with the best possible working truck for years to come - and can retain resale value some time down the road.