Web Exclusive: Packing a punch
September 9, 2010 By: Ben Peotter
Brandeis Machinery and Supply, a construction/mining equipment dealer based in Kentucky and Indiana, recently analyzed 170,000 work orders spanning more than 10 years to better understand how field service technicians use their trucks. In addition to equipment use and field practices, Brandeis began to examine idle times and the resulting effects on engine wear and fuel use.
“These trucks are constantly idling, and that represents fuel burn,” said Todd Coffey, the company’s corporate service manager. “A couple of years ago we put together a service initiative team to identify potential inefficiencies. The dilemma we always ran into was that, ‘I’m running anywhere between a 200- to 250-horsepower engine [to power the mechanic’s tools], where a far lower horsepower will take care of it.’ That’s just not good.”
This led Brandeis to explore options for running air tools, crane hydraulics and power tools in the field without relying on a power take-off (PTO) system, thus allowing field service technicians to turn the truck off while working. Brandeis worked with Miller Electric Mfg. Co. to install the new EnPak Mechanic Series, a truck-integrated power system run by a 27-hp engine that includes a rotary-screw air compressor, hydraulic pump and a generator.
After six months of data from this system, the company discovered a 55 percent reduction in idle time, a 36 percent reduction in overall engine hours, preliminary fuel-savings estimates that pay for the system’s premium on its own, and the expectation of longer service life and service intervals due to these efficiencies. According to the company, combining asset life extension, fuel savings, reduced maintenance costs and the potential to transfer the EnPak from one chassis to another yields a potential total system payback of less than two years.
Addition by subtraction
Prior to EnPak, Brandeis’ mechanic’s trucks (Ford F650s and F750s) featured PTOs, a hydraulic pump for the hydraulically run air compressor and crane (10,000 to 12,000 lbs.), a 40-cfm air compressor and a separate welder/generator. The welder/generator had its own engine and fuel tank, while the hydraulic crane and compressor required the truck’s PTO to operate.
The independently run power source eliminates the need for a PTO by plugging directly into the truck’s fuel and electrical systems and powering all of the pneumatic, hydraulic and electric components off its own 27-hp Kubota diesel engine. The internal generator (6,000 watts), hydraulic pump (20 gpm max flow, 3,400 psi max pressure) and rotary screw air compressor (40 cfm) eliminate the need for separate pieces of equipment while taking up less space on the truck.
“The first thing we were able to do was pull the compressor and the welder off of the side pack,” Coffey said. “We put a smaller hydraulic tank on there, so that allowed us to carry less fluids and less weight around. It got it down to a much cleaner package. And when we installed it, we were wondering about the plumbing and how it was going to work, and it’s a much cleaner installation than what we had previously, so we were very happy with that. It’s allowed us to minimize the number of units on the truck.”
Operating a power source that runs independently of the truck’s engine required a behavioral shift for Kevin Conner, field service technician for Brandeis. Prior to his new set-up, Conner pulled into a site and left the truck running all day – a learned habit repeated daily by many field service technicians. Now, he turns off the truck, powers EnPak and operates the air compressor and crane, and welds using a portable welding inverter running off the unit’s generator.
Reductions in engine hours
Fleet data at nearly six months shows Coffey what happens when the field service technician is able to turn the truck off while working:
“We’re trying to crack down on excessive idle times where there is no payback,” Coffey said. “It’s all cost recovery, really. If something on that truck is mechanically operating, it needs to do the best it can do so that we have payback. The amazing data is the 55 percent reduction in idle time and then almost a 40 percent reduction in overall engine time. This will extend the component life for the engine and the transmission, and it will cut down on our service intervals.”
Extended service intervals potentially save as much as $1,000 per truck over the course of the year, but overall asset life extension is the true goal of the reduction in engine use/idling, according to the company.
“The useful life of a service truck typically is cut short by how much maintenance you keep having to throw into the engine,” Conner said. “With EnPak you’re taking that wear and tear and those hours off of the engine and prolonging that useful service life. The truck should last a lot longer.”
“We’re at eight to 10 years with our current set-up,” Coffey added. “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.”
Turning off the engine also nets other benefits. By reducing truck engine idling, EnPak helps to reduce regen cycles. It also eliminates a potentially costly PTO system, which involves numerous mechanical parts. It also centralizes all functions in one self-contained unit that can be serviced without interfering with the truck’s functions. If something happens with the truck, EnPak still powers all of the mechanic’s equipment.
“If you’re running off the PTO, you’re spinning that transmission the whole time,” Coffey said. “Working clutches and drives, it’s not the most efficient system. And if the PTO breaks down, that’s not something I can walk up to and work on. I have to be under the truck. If the transmission goes, then I have to take off all the PTO stuff, replace the transmission, and then re-install all the PTO lines and drives and make sure they match up correctly.”
Reductions in fuel use
Fuel savings alone will also achieve payback (and savings) over the life of the truck. At idle with the hydraulic pump engaged, EnPak uses 1/4 gallon per hour less than the truck at idle with the PTO engaged. When you flip the compressor to standby with EnPak, its engine idles at 2,600 rpm and draws more than 1/2 gallon per hour less than a comparable load off the truck’s PTO. At work, with the air compressor in full use, EnPak draws almost 2/3 gallons per hour less than the truck/PTO.
“In the six months we’ve been running it,” said 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.”
Calculating the potential fuel savings for an independent power source over the course of a whole year, at full use and taking into account engine size and local fuel prices, shows a potential annual savings of $1,741.
“That’s just from the standpoint of what we’re going to save on fuel,” Coffey said. “If you add in engine maintenance costs, oil change costs, filters and everything else, it’s a significant savings overall.”
Ben Peotter is engineering manager, mobile utility group, for Miller Electric Mfg. Co.
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