Lifting the curtain of underground construction
By DAVID GODKINEquipment
Equipment manufacturers tell us the same thing every day: choosing the right equipment will improve productivity, profit margins and offset costs. Naturally, this requires that we first understand our current productivity limits, i.e. what we can do and what we cannot. The next question is: what’s required of manufacturers?
In this issue we pull back the curtain on the people whose job it is to give us more power, more precision and more control.
KING OF THE FOREST
It’s true: there’s a forest of underground technology companies out there willing to sell you augurs, small and large trenchers, and horizontal drilling machines. But this particular forest has not one king but two—Vermeer and Ditch Witch. Each has taken steps to enhance their trenchers and horizontal drilling equipment for faster and more productive performance.
“How do we get better? How do we get our customers more productive and profitable?” poses Vermeer’s senior product manager John Kuyers. “We’re asking those questions every day.”
Horizontal directional drilling is first and foremost a push and pull business. But as Kuyers explains, drilling a single bore hole and then back reaming to enlarge the hole is not always necessary.
“If the soil is easy to work in and the pipe is relatively small, the old chain and motor directional drills may suffice,” he says. In larger applications, where rack and pinion HDDs have become standard for productivity and durability, you’ll need something quite a bit bigger.
A good example, Kuyers says, is Vermeer’s D60x90 Navigator HDD, tailored to each application with three firestick drill rod options, using single-piece, high-carbon alloy steel rods and a quick-change rod box to reduce the need for manually loading a drill rod. Kuyers’ real excitement though is reserved for a new HDD introduced this
July, the D20x22 S3 Navigator, a smaller machine designed for very tight, urban jobsites.
“It’s for our customers in fibre/telecom and gas service installation who told us they wanted more precise control,” says Kuyers.
The D20x22 S3 features a new hydraulic system design with superior rotation, thrust and tracking performance over its predecessor, the D16x20 Series HDD. The D20x22 S3’s faster carriage speed (167 feet, or 50.9 metres per minute) has placed the D20x22 S3 “at the front of its class,” says Kuyer.
Wanna go bigger? Vermeer will help you do that, too, but why not travel further west to product manager Seth Matthesen at Ditch Witch’s head office in Perry, OK. Last year Ditch Witch introduced its AT60 horizontal directional drill, a 200-horsepower all-terrain machine with a patented dual-pipe system, i.e. an outer pipe that places the drill head in the proper position for steering and an inner pipe that mechanically drives the bit. Matthesen says this provides the contractor with a distinct advantage over larger rigs that normally rely on mud motors. “Instead of using a mud motor, pumping 200 gallons a minute and also having a large reclaimer on the site, the AT60 reduces your overall capital expenditures on the job site.”
Vermeer has a dual-pipe system, too. However, Matthesen maintains its one disadvantage is a threaded inner pipe that increases the time it takes to disconnect the pipe once the job is complete. Instead, Ditch Witch uses a dither system with a hex connection. Imagine you’re shaking someone’s hand, Matthesen says. Now rotate it from 10 o’clock to 2 o’clock back and forth. “That’s what that inner drive does; it connects and disconnects automatically.”
“It might not sound like much but if you can save one minute per drill pipe making and breaking it this way and you have sixty drill pipes out there, that’s an hour’s transition time. And that saves revenue.”
GIVE ME A MACHINE WITH HEART
Yes, lots of power. Just make sure it’s properly matched to the job, i.e. high-output/high-torque equipment tailored to whatever you’re working in: silt, sand, cobble or rock. Here’s where the rack and pinion design again helps. “Actually it gives you more power because of the way it was designed,” explains Mike Sequino, an engineer and vice-president of Directional Technologies Inc., in Wallingford, Conn. “Rack and pinion allows you to transfer your push and pull pressures in a way the chain design can’t.”
Another key, adds Matthesen, is torque—and not just any torque. When you’re back reaming at 180 rpm, he says you want sustainable torque. “You don’t need torque at 10 rpms; you need it at working rpms.” While acknowledging the importance of static torque when you’re steering and want to break out of that steer, he adds: “when you’re back reaming sustainable torque is vital. Otherwise, the job is slower and your production rates lower.
Who can argue with ample power and torque? asks Jeff Lyons, owner and president of Trenchless Utility Equipment Inc. Just don’t forget this: “You want ample push and pull but these are also very self-destructive machines. Drilling practices are even more critical.” Over-steer a drill rod by more than eight per cent “and you’re going to damage the drill rod, shorten its life and potentially lose tooling down hole.” The best way to avoid this is proper training. The operator can’t just apply maximum power whenever he wants it.
“Often this means finessing the drill head by rocking and sawing it, rolling it properly, working longer in an area rather than trying to ram right through,” says Lyons.
Optimizing horsepower to weight ratio is vital to any machine, but this is especially so when assessing the capacities of a brand new trencher, i.e. hydraulic circuits, cutting capabilities, depths and widths. Vermeer describes its T655 Commander II trencher, for example, as “a small machine with big power.” But Vermeer also knew, says Kuyers, that to exceed 225 horsepower would spell disaster. “If we put a 400 horsepower engine in there we would have virtually destroyed the machine.”
“By contrast, we wouldn’t go with a 20-foot boom, three-feet wide on a machine with 200 horsepower; we’d need a machine with 400+ power.”
IF I ONLY HAD A BRAIN
Ok, so just how smart are all these smart machines? You know, the ones uploaded with GPS, lasers and the latest in monitoring systems? Very smart, says Kuyers. He barely misses a beat before launching into a description of a new feature aboard Vermeer’s utility trenchers called TrenchSense. Your chain gets latched onto a large rock or other obstacle slowing you down? No worries. TrenchSense stops the trencher, reverses slightly to dislodge the object and starts the chain back up again “all without the operator touching a button or lever,” explains Kuyers.
“It does that within a split second, where generally what happens when a human is operating the machine is the chain would grab and they would have to turn a dial or grab a lever to neutralize the chain and physically back up the machine.”
Not to be outdone, Tesmec in Alvarado, Texas features Techtronic 3.0, an electronic control system to be used on a range of machines from the TRS-885, an entry-level 20-ton trencher powered by a 152kW Caterpillar diesel engine up to and including the 267,000 pound (121, 563 kilograms) TRS 1675 (trenching depth 3.05 meters – 7.3 meters; width up to 4.8 meters). Both are equipped with dual-path, hydrostatic drives. But the best parts are those automatic controls.
“The machine itself is capable of digging automatically,” says Tesmec’s national sales manager, Bryan Blan
kenship. “In addition, the machine can handle depth requirements by itself and also does self-steering using laser or GPS.”
Automatic trencher controls simplify the process for the operator as well, which is particularly important because finding operators qualified to handle conventional machines is as hard as recruiting people for space travel. Another important component are hydrostatic drives. Blankenship says Tesmec is proud of the fact its first trencher, a mechanical drive machine introduced in 1984, is still in operation today. But things have changed since then.
A case in point: Tesmec’s rock saw trencher suitable for narrow and deep cuts and normally used for installing fibre optics. Picture the circular saw on your work tool bench at home; now imagine it at least a hundred times larger and you’ll have a good idea of both this trencher’s size and capacity. It cuts up to 60 inches in depth and eight inches wide, but it also has a dual-path, hydrostatic drive.
This machine is particularly helpful in hard rock environments like those found in San Antonio, Texas. Monolithic rock requiring 10,000 psi of pressure before it chips will barely budge using a smaller hydrostatic trencher better suited to light or slightly rocky soils found in Kansas, says Blankenship. “If you came in with a hydrostatic machine where the chain turns very fast you would have high tool wear, excessive cost and reduced [progress], maybe one foot a minute.” Another option is to go to a mechanical machine, slowing the chain speed down to 100 feet per minute from 350 feet per minute to “get a higher level of productivity and major reductions in wear.”
“Your productivity almost quadruples; but you can also get four to seven feet per minute using our mechanical machine.”
TOTO, I’VE GOT A FEELING WE’RE NOT IN KANSAS ANYMORE
Yes, you’ve heard this before, but it bears repeating. To help you get a clear picture of what’s underground you need a well-detailed, up-to-date utility map. In a heavy utility corridor, Lyons points out, you can face a sanitary sewer 12-feet deep, a three-foot, eight-inch gas main, a 12-inch water main at five-feet deep and an electric bank and a large telecom duct bank, each anywhere from three- to five-feet deep. “Having your locates and a good understanding of what infrastructure you’re going to be passing or running parallel to is imperative.”
Trenchless Utility Equipment specializes in both trencher and horizontal directional drilling, notably the Toro DD2024 and DD4045. These benefit not only from a current and detailed utility map but “daylighting” to expose underground services, i.e. vacuum excavating “so that you can actually see the drill head pass by the utility,” says Lyons, “especially natural gas being as volatile as it is.”
Mike Sequino agrees. But another problem underground contractors run into are municipal officials who don’t want you to complicate their utility map by adding yet another underground service. A city will sometimes nix the idea of a fibre-optic cable crossing above a sanitary sewer at an intersection to avoid the cable interfering with the repair of a sewer line. Go deeper and work underneath everything, you’re told. Gas and water companies are especially “squeamish,” says Sequino.
“They don’t want you going too deep because if something happens they have to repair it. That’s where directional drilling comes in. It gives utilities project flexibility. Each project is designed to meet everyone’s needs.”