Equipment dealer's field service technicians encounter different challenges every day: a stress fracture on the boom of a hydraulic excavator, an overhaul of a large wheel loader in a quarry, servicing equipment in an underground mine. Each of these tasks requires a combination of air, electricity and hydraulics—most of which typically run off a truck's power take-off (PTO). This creates excessive engine idling time, excessive hours on the engine and drive train, and on-site noise pollution that is unpleasant both to the technician and anyone else within earshot.
Brandeis Machinery & Supply, a construction/mining equipment dealer based in Kentucky and Indiana, recently analyzed 170,000 work orders spanning 10 years in order to better understand how field service technicians used their trucks. Their findings showed an opportunity to reduce idle times and engine hours if they found a way to turn the truck off. The company found a solution by installing EnPak Mechanic Series from Miller Electric Mfg. Co., an integrated power source that runs pneumatics, hydraulics and power tools with the truck turned off. Not only did the truck achieve a 55 percent reduction in idle time and 36 percent reduction in engine hours, but the performance of operating functions (such as air power and consistency) and overall operator environment also improved.
An Experienced Hand Tries Something New
Kevin Conner, field service technician, Brandeis, grew up tinkering with anything that had mechanical parts and isn't happy unless he's elbows-deep in an engine or a technical component of a machine.
"I like taking things apart and putting them back together," he says. "I got started doing it on go-karts and mini-bikes and it just went from there. I'm lucky enough to do it for a living."
For 23 years he's worked on everything from small utility equipment up to agricultural equipment and large mining trucks. Travelling from his shop at Brandeis' Indianapolis location, Conner services equipment for everyone from contractors to coal miners. Brandeis typically outfits its trucks (Ford F650s and F750s) with a Stellar 10,000 lb. crane, a hydraulic pump, a 40-cfm hydraulically-driven compressor and a Miller Trailblazer® 302 welder generator. The welder/generator has its own engine and fuel tank while the hydraulic crane and compressor ran off the truck's PTO.
An independently-run power source such as EnPak eliminates the need for a PTO by powering all of the pneumatic, hydraulic and electric components off its own 27-HP Kubota diesel engine. With its internal generator (6,000 watts), hydraulic pump (20 GPM max flow, 3,400 PSI max pressure) and rotary screw air compressor (40 CFM), it eliminates the need for each of those separate pieces of equipment while taking up less space on the truck as the previous welder/generator and air compressor did. Conner was intrigued from the start.
"My very first thought was that's a really novel idea to have your hydraulic pump to run the crane in a separate unit," he says. "I'd just like to get my hands on that and see how that works. But my biggest reservation was getting rid of my Trailblazer because that's a nice welder, and I didn't think that there was any way that you could replace that gas drive with a smaller unit."
Non-Stop Air Pressure
Brandeis' study of its work orders confirmed what they already knew: air tools are used far more than any other tools in the field.
"My air tools consist of everything from die grinders, air drills, air grinders, 3/8-in. impact wrench, 1/2-in. impact wrench, 1-in. drive impact wrench," says Conner, "and I notice a significant increase in the volume of air available with EnPak, especially using a 1-in. drive impact. You no longer have to wait between fasteners for the air to build back up."
EnPak's variable speed rotary screw air compressor offers 40 CFM at 100 percent duty cycle with a maximum 175 PSI. Conner previously waited between fasteners to let pressure build back up, a costly drag on time efficiency. The inefficiency of a hydraulically-driven compressor on the truck versus EnPak's direct drive also effects fuel use and noise.
"There are some smart features built into the way that EnPak generates air," he says. "When I'm just using cleaning air in a small quantity, the compressor kicks on, and stays at an idle and keeps up just fine. Then, if I use a 1-in. impact and it sees that big drop in air pressure really fast, it will kick up immediately instead of waiting all the way down to the cut-in pressure. With the old system, as soon as you hit cut-in pressure and you start building air, the truck idles up to 1,200 RPM and noise level obviously goes way up. There is also a certain amount of fuel being used there. It's a lot more efficient to make air at an idle. And the way that the compressor is driven is a lot smarter, more efficient way to make air (compared to hydraulically off the PTO)".
Hydraulic Pressure Offers Power and Finesse, Accurate Operation of Crane
The second most critical tool for a field service technician is the truck's crane. In this case, Conner runs a 10,000-lb. Stellar crane off EnPak's built-in hydraulic pump. Prior to EnPak, this ran independently off the truck's PTO. Switching to EnPak allowed the company to remove that separate pump and operate the crane at full capacity without having to turn the truck on. Conner is also able to use the crane control he's already familiar with.
"We still have full control capabilities, and one nice new feature we've incorporated is an inching (low speed) feature where, if you're under 20 percent of the trigger function, EnPak doesn't even idle up," says Conner.
Generator Power, Welding Versatility
The one component that Conner didn't rely on the truck for was his engine-driven welder/generator. EnPak has taken its place on the truck's side pack but does not have welding functions built in. Conner now relies on a portable Maxstar® 200 TIG/Stick power source to perform welding repairs in the field.
"With the 6,000 watts available power off EnPak I use an electric drill, a 4-1/2-in. angle grinder and the 200 amp Miller Maxstar welder," he says. "We have all the power we need to run those things."
Conner was hesitant to switch to the physically smaller welder, but he's found that it allows him to do everything he could previously do in the field with the engine-driven unit.
"That's a tough sell," he says, "when you bring in that small of a unit. I had no idea I could get that kind of power out of an inverter. The largest electrode I'll run is either 5/32- or 1/8-in. 7018. Anywhere from 140 to 180 amps will run that fine. The Maxstar 200 runs that all day long. I ran about ten pounds of 5/32-in. rod one day and it never missed a lick."
Having a smaller, portable unit also gives Conner more flexibility in how and where he welds. It takes just about as long to set up to weld, but he can bring the machine closer to him when he's working in tight spots.
"I had a crusher job where I was able to run an extension cord and bring the Maxstar up in the crusher with me," he explains. "I was able to change the settings right there and dial it in to where I was working. It would have taken quite a bit more time with a welder/generator to crawl out of the crusher several times and make the trip back and forth for adjusting. It's quite a bit handier to have it right there with you."
EnPak also offers an optional EnVerter™, an electrical power converter that provides a steady output of 120-volt sine wave power up to 2,400 watts at reduced RPM, regardless of loads placed on the system. This can be used to run tools such as laptops, microwaves, battery chargers, and other seasonal amenities—such as cab heaters—that further allow the field technician to keep the truck turned off.
"I bought an extension cord and wired it right into the box on the EnPak and ran it into the cab and I've got a ceramic heater like you'd use in an office area," says Conner. "It heats the cab just fine. It does a real nice job."
Reducing Sound, Exhaust in the Operator Environment
Another advantage of turning the truck off is the improvement it creates to the operator environment. No longer is a truck's tailpipe spilling fumes out the back of the truck and in to the work area, overall emissions are reduced, and EnPak is considerably quieter than running tools with the truck turned on. EnPak is 3 to 7 dB quieter than a traditional truck with a reciprocating compressor and 4 to 9 dB quieter than a truck with a screw compressor.
"The truck, the compressor and the PTO—you put all three of those together and it's just a constant hum. The noise reduction of having the truck shut off is significant," says Conner. "The sound level and quality is such that normal conversation between mechanics is easier. Over the course of the day, it makes a big difference in frustration level and fatigue level. For me, the noise reduction is the biggest advantage in the field. The exhaust emissions are also quite a bit less, it's not even noticeable."
The reduction in emissions has proved to be a particular benefit when working on equipment in underground mines where Conner actually drives his truck down into a designated work area. The Mine Safety and Health Administration (MSHA) has tightened its restrictions on air quality in mines, and by burning less fuel and reducing emissions, Brandeis is helping improve that work environment.
"It's a big deal when we go under there with a Tier 4, 27-HP engine that's burning less fuel," says Todd Coffey, corporate service manager, Brandeis. "Typically in the mines, you have a shop area. It's a section of the mine that's been mined out that they convert into a shop. And you go in there, and there's three different service trucks in there just sitting and idling their engines. It's not a good situation—this addresses that."
Fuel Savings and Asset Life Extension
Turning the truck off and letting a 27-HP engine do the work that was once left to a 200- to 250-HP truck engine not only provides these operational benefits, but has a substantial effect on asset life and operating costs. After six months of data, the results speak for themselves: a 55-percent reduction in idle time, a 36-percent reduction in overall engine hours, and preliminary fuel-savings estimates that conservatively pay for the system's premium on its own. The expectation of a longer service life and longer service intervals due to these efficiencies brings overall payback to less than two years.
"In the six months we've been running it," says Coffey, "the off season and the economy have put us in a position where we're probably not running the truck as hard. The numbers that we have gotten back are very conservative compared to what it will be when things pick up, but we're possibly talking $750 to $1,000 a year in fuel savings. And that is particularly significant when I look at my fleet and I start talking about putting an EnPak on 60 trucks."
"We're at eight to 10 years (of service truck life) with our current truck set-up," he adds. "We're realistically thinking, with a couple other things we've done, we may be able to go 12 to 15 years. Chassis life and how well the bodies hold up will be the telling tale on that. We still have to consider all that, but I think component-wise we're doing a lot of things that could definitely extend us into that range."
 Calculate your truck's savings with EnPak at http://www.millerwelds.com/products/enginedriven/enpak-calc/