The Dump Truck Basics

Dump-Truck Specs Include Basics and Advanced Designs

Thinking about ordering a new dump truck? It seems most everyone has their favorites, Freightliner dump trucks, Mack dump trucks, Kenworth dump trucks, Peterbilt dump trucks, International dump trucks, and so on. But before you go to your local dealer and place your order, Tom Berg from the Kenworth Truck Corporation offers the following tips you should know about spec’ing your new dump truck.

Tom Berg
November 01, 2007

In the market for new trucks? Even if you’re an old pro at setting up and buying trucks, you can always pick up a tip or two from the people who design and build them because they see what kind of equipment, old and new, is used all over the country. It could be that the tried-and-true you’re accustomed to might be improved upon.
To that end, Kenworth Truck published advice on how to spec a dump truck. Brian Lindgren, vocational market sales director at the company’s headquarters in Kirkland, Wash., started with the basics:

• Know the state and local weight laws in your area of operation. These limit legal poundage and, in effect, dictate wheelbase, number of axles and other details of chassis configuration. Knowledgeable salespeople at the dealership might suggest new components that can boost payload, revenue and profit.

• What exactly will you be hauling, and where? Some cargoes are rougher on the chassis and body than others, especially when they’re loaded. Will you be going off road a lot or staying mostly on pavement? These considerations affect the type of frame and suspensions, and the material in the body.

• Don’t buy too much power. High-horsepower big-block engines are heavy and cost more to buy than lighter alternatives that still produce good power and torque. Generally, 400 horsepower and the torque that comes with it are plenty for most applications, and an 11- or 13-liter engine can save 500 to 700 pounds and thousands of dollars over a 15-liter model.

• Be sure ratio range is sufficient. An 8LL-type of transmission, paired with a proper axle ratio, has low-low ratios that can get a heavily loaded truck started, but a high enough top gear for brisk cruising on freeways and highways. But trucks or tractor-trailers grossing over 90,000 pounds need more ratios, such as those in a 13- or 18-speed transmission.

• Get the axle ratio correct. Working with the transmission and tire/wheel size, the axle ratio should allow the engine to spin at about 1,600 rpm at your desired cruising speed. Operating characteristics vary with engine make and model, and gearing is especially important with the latest diesels.

• Be sure axles and suspensions are tough enough. A rear tandem and suspension rated for 46,000 pounds can handle an assortment of applications and duties. If it’s on a truck with two or more auxiliary axles, it also needs enough “creep” rating — the capacity to shoulder the heaviest loads at low speeds when the auxiliary axles are raised. Also, consider locking differentials for extra traction.

• Are components too heavy? Recent suspension designs can be as strong as the old-style type you’re used to, and will probably ride better. It might also save hundreds of pounds. Think about suggestions you get from salespeople, ask for referrals to truckers who are already using newer stuff, then pick their brains.

• Right-size the tank. Diesel fuel in summer weighs about 7 pounds per gallon, so that 120-gallon tank that extends range can also reduce legal payload and lower fuel economy. Maybe an 85- or even a 56-gallon tank might be enough to get through a work day.

• Pick the right air cleaner(s). An underhood air filter with an optional pre-cleaner can do a good job at low cost and with less weight than a pair of external air cleaners. But if the truck will spend a lot of time in dusty conditions, whether on or off road, the dual cleaners might be worth their considerable extra cost. Dual 15-inch air cleaners will last more than seven times as long as a single 11-inch underhood air cleaner before needing replacement.

• Consider maintenance. Look at where everyday checks must be made, where fluids must be replenished, where electrical components and air parts are located. How easy is it to replace a cracked windshield, and what does a new piece of glass cost?

• Make drivers comfortable. The make and model of the truck establishes how roomy the cab is, but options like a longer cab and extra noise insulation can keep drivers more rested and therefore safe and productive.