By Shawn Hutchings

Oil distributor trucks play a large role in asphalt road maintenance and road building. These trucks are used for things such as applying chip seal oil, spraying emulsion for tack coating between asphalt lifts and top coating asphalt roads with sealants also known as fog sealing, just to name a few.

In each of these applications, the distributor truck needs to not only have a high production rate but it must apply these various products with precision. If the truck isn’t very precise with the spray application, it can miss your yield target, which in turn will possibly lose your margins calculated for the project or even lower the quality of the final product you’re trying to achieve. A precise, well-tuned distributor truck can help you bid jobs more accurately and help you manage product delivery needed to complete your project.

The distributor truck has a few components that play a role in achieving the precision demands in today’s jobsites.

Asphalt pump controls: Although most distributor trucks have manual pump controls, it’s best to let the processor control the product pump automatically based on factors such as travel speed, desired application rate, spray pattern width and engine rpm.

Travel speed sensor: Travel speed is registered through a speed sensor that can be GPS, radar horn or pulse pick-up. I have found the radar horn to be the most accurate.

Asphalt pump speed sensor: Asphalt pump speed sensors record the gallons or liters per minute back to the processor so it can do its work processing the needed gallons or liters per minute required for application rate, travel speed and desired spray width. These sensors are typically pulse pick-up style and mount at the asphalt pump or asphalt pump drive motor.

Spray bar: The spray bar is the final component to touch the product being applied. Spray bars come in varies sizes and styles. The two main styles are telescoping and folding.

Folding spray bars are designed to fold up for transport and fold down to achieve larger spray widths than when they are folded up. Folding spray bars have one-foot on/off spray controls that when turned on spray three 4-inch wide spray pattern nozzles to make up the foot worth of spray pattern. If you desire less than a foot spray width, you will need to exit the cab of the truck and manually close off one or two of the three spray nozzles making up the foot width of spray to achieve lower spray width. Folding bars also have a feature called side shift, in which you toggle a switch in the cab to shift the bar left or right to maneuver the bar around obstacles such as mail boxes or guard rails. Although this side shift feature is nice for the side that has the obstacle that you need to maneuver around, it affects the other side by pushing the bar that direction, possibly into live traffic or somewhere you don’t want the bar to stick out. While this side shift takes place, the operator also has to flip spray nozzles off on the live traffic side to maintain a straight edge of the applied product.

When the operator flips these nozzles off it creates a step effect with the product on the ground because they can’t turn each 4-inch nozzle off individually and instead 1ft is turn off at time.

This step effect tends to create more overlap of material used on the job, thus changing your yields. On chip seal jobs, this can create uneven surface levels of the newly applied chip rock or bleeding of material through the rock layer.

Other disadvantages of the folding spray bar are it has more moving parts where the bar is folded and can be a place for a leak to appear. These moving parts also cost more to maintain as they must be lubed properly and serviced more often.

The telescoping bar has many advantages over the folding bar. Unlike the folding bar, the telescoping bar doesn’t have side shift. Instead, it has two parallel bars that slide left or right to a desired width. This eliminates the risk of the spray bar being side shifted into live traffic when making an adjustment of the width on the curb side.

When a telescoping bar is sucked in to a narrower spray width, it turns off each 4-inch spray nozzle one at a time automatically as its retracted, rather than the operator having to toggle each one-foot spray nozzle off on the folding bar. And guess what? No step effect on the sprayed application width. Instead, you have a smooth edge line to work with that doesn’t have the extra material overlap or chip rock uneven surface due to extra oil.

With the telescoping spray bar turning each 4-inch spray nozzle off individually, it will have less pressure differential in the bar compared to the one-foot spray nozzle being cut off. This pressure differential will slightly change your application rate momentarily and throw your yields off slightly.

The telescoping spray bar has a lower maintenance cost due to fewer components, and it tends to stay cleaner than its folding brother.

If you haven’t ran a telescoping bar on your oil distributor truck, I would highly suggest you check it out. With its ease of operation and precise spray pattern, you will benefit from tighter yields and fast productivity.

Shawn Hutchings is a Territory Manager with LeeBoy. He can be reached at shawn.hutchings@leeboy.com