Construction Trucks: Do Yours Need All Wheel Drive?
We talk a lot about heavy duty equipment such as excavators and wheel loaders – how we can get top performance and ROI from each of these machines. But what those other indispensable vehicles in your fleet – construction trucks? They have to be reliable and road-worthy, but often they have to negotiate challenging off-road terrain as well.
There are steps you can take to equip your construction trucks so they are more capable and better protected no matter where they’re working. Manufacturers are taking a variety of approaches to help customers achieve these goals. Let’s take a look at some of them.
Reducing tire pressure gives each wheel a larger footprint that improves flotation as well as traction. This solution can be especially effective in sandy soils, particularly if it’s used in conjunction with differential locks. However, the driver has to deliberately activate the system, which can be cumbersome.
All Wheel Drive Offers Power and Flexibility
AWD promotes better traction in mud, sand, snow and ice. It also enables trucks to climb steeper slopes safely. Construction truck owners are using 6×6 and even 8×8 AWD systems because adding more axles and wheels increases overall traction. In conditions where wheel-slip might be an issue, there are more tires to take up the slack. However, for these systems to work efficiently, they require the proper amount of torque. Some systems don’t provide enough torque, and hydraulics are subject to failure, so mechanical operation is often the best choice.
Until recently, increased vehicle height and weight have been deterrents to adding AWD systems, as has the simple cost of refitting trucks. Western Star’s Samantha Parlier, VP of marketing and product Strategy, says the higher cost usually means owners opt for AWD only when it is operation-critical. However, she also notes that costs can be recouped through increased productivity and less downtime.
And, in fact, several models and configurations of Western Star trucks can be fitted with AWD at the factory. Western Star’s sister OEM, Freightliner, also offers a full line of AWD vehicles for applications ranging from light duty to severe duty.
It all comes down to how you spec your truck, says Freightliner’s director of product marketing, Kelly Gedert. “What’s important is that the customer works closely with the vocational sales person. Freightliner dealers have a deep understanding of the best equipment needed based on application and terrain to ensure optimal performance.”
Pros and Cons: Benefits Depend on the Application
Weight becomes an issue when construction trucks are delivering a payload of some type. Adding a front-drive axle and second transfer case adds weight and changes the weight distribution. The extent of the changes depend on the exact configuration, but the upshot is that owners and fleet managers have to be cognizant of overall vehicle weight restrictions and the high cost of exceeding those maximums.
To counter the increased weight of AWD systems, manufacturers have switched to aluminum materials for many components. But spec’ing a lower displacement engine can also help reduce a truck’s weight without sacrificing necessary power. Ultimately, however, if the jobsite itself is difficult to access or navigate, the ability to get around may outweigh the weight issue.
Height becomes a factor because AWD systems typically raise the truck chassis – about 5” for the typical Western Star truck. According to Samantha Parlier. “The increased vehicle ride height improves driver visibility and provides greater ground clearance, as well as improves performance navigating unimproved surfaces.” That boosts overall reliability while reducing expensive downtime that can result from debris-damaged chassis-mounted components or the chassis itself.
She cautions that spec’ing the proper gear ratio is crucial. “Front and rear axle ratios should match for AWD configurations,” she notes, adding that “they need to be compensated for if front and rear tire sizes differ.”
Alternatives to Traditional AWD
Because all wheel drive can greatly improve construction performance in a number of difficult conditions, manufacturers continue to look for ways to overcome traditional negatives. For example some newer model trucks are designed without a transfer case. There is a power divider on the front rear axle which can be locked too engage the front axle. This no-transfer-case design can greatly reduce overall weight.
Hydraulic AWD systems are also available, based on systems used for some agricultural equipment. This alternative also functions without a transfer case. It can reduce weight by as much as 1,000 lbs. and does not alter original ride height or turning radius.
We’re Here to Help You Spec the Right Truck
Spec’ing a new construction truck is never simple. We can say that whether your construction truck needs all wheel drive or not comes down to the vehicle’s likely working conditions, but there are other considerations as well. So let’s talk. We’ll help you arrive at the best solution, one that is custom-tailored for your jobsite performance needs.