For some work trucks, carrying equipment is just part of the job.
MONTREAL, Que. – Every truck consumes energy when traveling from one destination to the next. But when work trucks arrive on the job site, many of the vehicles also double as powerful tools of the trade.
Even when the business involves supplying energy to others.
Énergir, the largest natural gas distribution company in Quebec, is a perfect example. Its Ford Transit and GMC Savana panel trucks are used to help maintain and repair the gas lines that deliver fuel from Western Canada and the U.S. And while the units arrive from manufacturers with a complete body, specialists are needed to incorporate racking, road signage, and the all-important electrical supplies.
Énergir’s heavy artillery takes the form of International 7600s/WorkStars with MaxxForce engines, as well as a Peterbilt Model 567 powered by a Paccar MX engine. These vehicles – all equipped with Allison automatics — are mostly used for excavation jobs, such as drilling the ground to access gas lines or digging trenches. “We call these trucks ‘trios’,” says Julien Dolléans, senior adviser, vehicle engineering at Énergir. The truck’s dump body carries excavated soil; the trailer hauls the excavating machinery.
The gas company sometimes uses diesel generators to power electric tools on work sites, but relies mostly on power packs — groups of six-volt or AGM batteries — to provide 120 volts through power inverters. This way, there’s no need to idle the truck’s engine when working on a job. Batteries are recharged by the truck’s alternator as the vehicle drives from one job to another or during the night, using the terminal’s shore power.
And since gas lines are generally concentrated in urban areas where stringent anti-idling rules are enforced, this zero-emission solution is a perfect fit for Énergir.
Onboard compressors drive air tools such as asphalt drills or wrenches to torque the bolts that connect pieces of steel piping. Énergir teams also put compressed air to work when using a “pipe blower” to remove the dirt around a pipe section, or to drive away gas from a confined area like an underground access well, says Roger Constantin, fleet and maintenance manager at Énergir.
Nick Knapp, director of field operations for KTI Utility Construction in Georgetown, Conn., also uses compressed air when planting utility poles in the field. “If we hit ground water or mud and the hole starts collapsing, if it’s in a swampy environment or along a river, I have another truck that comes out,” he says of the six-wheel vacuum truck.
To dig pole holes in the first place, KTI uses an auger driven by hydraulic power via a PTO. If a rock formation stands in the way, crews switch to a pneumatic hammer drill.
“Like a jackhammer would, just on a larger scale,” says Knapp. “It needs to be a minimum of anywhere from 1,000 to 1,300 CFM [cubic feet per minute] of air, anywhere from 200 to 350 psi. However, the rotation of the actual rock drill is powered by hydraulics from the boom,” he adds. A hydraulic circuit is also used to power the tool that tamps down the soil at the base of the utility pole.
The helping hand of a crane.
Both companies use PTO-driven hydraulic cranes, too. The gas distributor will use them mostly to lift heavy steel pipes, as opposed to the lighter polyethylene pipes found elsewhere in the network. “Many of Énergir’s trucks are equipped with HIAB articulated cranes and hydraulic outriggers to keep them stable,” says Dolléans. Cranes are also useful when time comes to install or replace a metering station that comes with heavy steel mounts.
Cranes also lift metal at KTI – in its case, the copper wires used by telephone, cable or telecommunications companies. While some cables are rather small in diameter and light, others are “insanely heavy”, according to the company’s field operations director. “If you get a 900-pair or a 1,200-pair cable, it could be as big in diameter as almost a softball,” says Knapp. These larger size cables can be installed in sections almost 400 feet long, and each foot of wire weighs six to eight pounds. Hydraulic power from the truck transmission’s PTO comes to the rescue once again. “In that instance, you would use the crane winch on the digger derrick truck to hoist the cable up and down,” Knapp says.
Énergir’s polyethylene pipes are much lighter than copper, but present challenges of their own. Fusing them together requires a lot of electrically-generated heat. “It’s like a suitcase housing a machine with electrodes that heat the plastic on localised areas,” Dolléans explains. A 9.6 kW PTO driven generator is used when the electricity demand exceeds 3,000 watts, which is pretty much the limit of the battery pack.
Most of the time, electricity and natural gas don’t go together too well. That’s why Énergir picks its tools with caution, says Constantin. “As soon as a tool is available in intrinsic safety mode, we’re selecting it over others,” he says, referring to options that limit the release of heat or sparks that could ignite flammable material.
And even if Knapp doesn’t care much about the brand of trucks he drives, he appreciates the reliability of diesel engines over gasoline — especially when planting poles and tightening aerial wires in frigid conditions. “I’ve been on storms where the trucks have run for two weeks straight and never even shut off,” he says.
Energy on the go.
Mobile energy facts
The choice of onboard diesel generator depends on the amount of electricity you want to draw. According to Wajax’ special projects expert Pierre Bélair, one of the most popular ratings is 15 kW. Spec’ing bigger than that could be an issue because it would take too much space in the truck’s body. “When it goes beyond 100 kW, usually the customer will opt for a generator with its own trailer,” notes Bélair. A 15 kW unit could make your wallet about $20,000 lighter and the truck almost 1,000 lb. heavier. Think about it when spec’ing the weight rating of your cab and chassis truck.
As vice-president of eastern Canada operations for Drive Products, Ro Kumar, looks for specific details when spec’ing a PTO. “Most PTO applications — where the power source is the engine crank — are hydraulic pumps that are used when the vehicle is in motion,” he says. “A PTO connected to a transmission will be used more for static applications, where the truck is standing still.”
Bélair explains that a truck-mounted PTO isn’t always enough: “In some cases where a higher hydraulic capacity is needed, an auxiliary engine will be installed to drive the hydraulic accessories or tools. There’s a limit to what a truck engine or transmission can deliver in terms of hydraulic power. For instance, if you need to drive multiple pumps at the same time, it will need a lot of power and people will install what’s referred to as an auxiliary Open Power Unit (OPU).” Even if the unit is smaller than the truck’s engine, it provides more hydraulic power because the pump is directly connected to the flywheel.
“Combo” diesel machines are highly popular in the mobile generator industry. Three-in-ones and six-in-ones can provide hydraulic power, electric outlet power, or electricity to drive an integrated air compressor, battery booster, or welder.
Bélair notes that modern illuminated road work signs will run on batteries. Solar power – the ultimate free mobile energy source – is used to keep those batteries charged. There are no more fuel tanks to fill on the job site.