CALGARY, Alta. – Spec’ing a dump truck is much like planning for the weather; it’s very region specific and what works in one area of the country may not be applicable in another. The only difference is a local dealer will probably be able to help out a little more than the weather man. So before asking for the keys to a new dump truck, it’s important to find the answers to some key questions regarding the truck’s intended usage and where it will be travelling.

“If someone from B.C. wants to buy a gravel truck in Saskatchewan they may not know the regulations and the dealer should be able to help them out,” explained Brian Burgoyne, sales manager for Nanaimo Mack.

Regulations

Laws regarding length and weight regulations differ in many provinces, as well as laws legislating the use of lift-axles.

“The best opportunity to assure that you have the correct configuration is to notice other dump trucks in your area that are hauling similar material and duplicate CA and set-back dimensions, as well as lift-axle usage,” said Shawn Waterman, marketing segment manager with Sterling and Western Star. Taking maximum advantage of weight laws can help to maximize payload. But bridge laws (in some regions – particularly south of the border) may also have an influence on how the axles are set up and spaced.

“Bridge laws will also help you understand how many axles you need to legally haul your load,” said Vince Cerni, construction segment manager with International. “International offers factory installed steerable lift axles up to 9,072 kg.”

“A Bridge Formula truck will tend to be longer to spread the weight,” added Brian Lindgren, vocational market sales director for Kenworth. “You may need to have lift-axles, but there are different rules on how much load you can add with lift-axles.”

Load application

Another key factor in spec’ing a dump truck is the type of product being hauled and what roads the truck will be travelling on to complete the job. A different chassis spec’ may be required when hauling bulk loads such as asphalt, sand or gravel than if hauling a load such as demolition debris.

“The primary concern, regardless of state (or provincial) regulations, is to maximize the opportunity to get the most weight over the front axle,” noted Waterman. “This typically requires a shorter BBC versus longer. Assure that you spec’ the appropriate frame strength to maximize stability but not to increase weight of the chassis.”

Whether travelling on highway pavement or off-road rugged paths, road terrain can affect everything from tire size to transmission and rear ratio, noted Cerni.

“If you will be going off-road a lot into rough terrain, you’ll need a suspension that is heavier duty and has more articulation,” added Lindgren. “But if you’ll be 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.”

Under the hood

The horsepower required to get a job done is in direct relation to the weight being hauled.

One of the big mistakes many people make with dump truck engines is they spec’ too much power, revealed Lindgren.

“You should get just enough horsepower to do the job,” he explained. “Generally, 350 to 400 hp is plenty for most applications. Extra horsepower just uses more fuel, puts more strain on the rest of the drivetrain, and adds cost up front.”

As well, with the introduction of new engines in 2007 spec’ing the proper horsepower to get a job done is even more important.

“With the new engines, they have to be running hot so the engine doesn’t have to go through a pre-burn,” said Burgoyne. “If you’re not utilizing the horsepower you have, you run into a situation where the DPF will clog at an earlier stage.”

Mack offers two engine sizes, an 11-litre MP7 and a 13-litre MP8.

“To use an MP8 in a straight dump truck would make no sense – economically,” Burgoyne noted.

“Engine size typically falls within 430 to 500 hp at 1,450-1,650 lb.-ft. of torque,” added Waterman. “Some areas will only require 300 to 400 hp; therefore money can be saved by spec’ing less horsepower at lower torque. This will require a less expensive transmission and possibly a less expensive rear axle due to the lower torque requirements.”

The transmission needs a lot of ratio range, to provide a low enough gear to get out of a hilly job site and high enough top gear to attain decent highway speeds.

“The most popular is the Eaton 8LL transmission at 1,550 to 1,650 lb.-ft. of torque,” said Waterman. “Additionally, Allison automatic transmissions are gaining more and more popularity regardless of their considerably higher cost.”

Lindgren also suggested an 18-speed transmission for larger and heavier trucks.

“The 8LL gives you two low gears for startability off-road and enough top-end range for the highway,” he explained. “But if you are hauling over 90,000 pounds, you should consider an 18-speed because you get much closer splits from bottom to top.”

Dumping frequency

If the truck will be hauling a number of loads per day, cutting vehicle weight can be profitable. It is possible to slim down by spec’ing components – such as wheels, air tanks and clutch housings – in aluminum rather than steel.

“Depending on the load, some drivers load and unload 20-plus times daily, others as low as once every other day,” said Cerni. “Longevity of a dump truck will also depend on if the unit is loaded correctly, not overweight, and with the correct material the body can handle.”

With the new Mack MP7 and MP8 engines, the hydraulic power take-off (PTO) has been shifted from the transmission to the engine.

“If you’re dumping constantly on-site it is available,” said Burgoyne. “The hydraulics are live and constant so you don’t have to manually engage the PTO.”

Driver comfort

As part of the spec’ing process, it’s also what is on the inside that counts. Making sure the driver of the dump truck is comfortable and protected from whatever elements the weather man has predicted is also an important step.

“Spec’ the truck with maximum ease of entry and egress, with a solid HVAC system, maximum belly room and overall maximum cab space,” suggested Waterman.

A premium spec’d cab can provide the driver with a number of features that will make the truck feel a little more luxurious.

“Our top-line is the Pedigree, which comes in two colours and offers amenities such as power door locks, power mirrors, tilt and telescopic steering and the Guard Dog maintenance system,” explained Burgoyne.

Lindgren also recommended trying to spec’ as much glass area as possible and plenty of mirrors; and a little extra cab space could go a long way.

“The Extended Day Cab gives the driver six inches more room fore-and-aft, and five inches more headroom,” he noted. “The QuietCab option reduces in-cab noise by two decibels, meaning it cuts perceived noise by almost 50%. These options can dramatically reduce driver fatigue, and that helps keep them more productive.”