Ditch Witch directional boring machines, made by Charles Machine Works Inc., Perry, Okla., range from the compact JT520 that can pull 2-in. diameter conduit up to 150 ft, to the JT100 Mach 1, which develops 80,000 lb of tension for pipe lengths to 2000 ft. Ten models offer a range of capabilities for trenchless underground installation of all types and sizes of conduit, pipe, and other service lines.
According to Dirk Wilson, a Ditch Witch product designer, the company’s earliest drilling equipment simply used slack in the hoses to accommodate the carriage travel. He says, “It was the first of its kind, and the operator just walked along next to the machine as the carriage went back and forth.”
Long life under repetitive motions
To extend cable life and eliminate the need for the operator to follow the carriage back and forth, the company now uses Gortrac cable and hose carriers, made by A & A Mfg. Co. Inc., New Berlin, Wis. Wilson reveals, “When we let the carriage move independent of the operator, we needed more hose management as the hoses move back and forth.”
The main application for the carriers is in the hydraulic lines to the carriage that feeds drill pipe used in the drilling operation. On some of the units, electrical cables also are included for controls, speed sensors, and solenoid-operated valves. “They are used on everything from our small JT520 machine up to our JT100 Mach 1, which is a 268-hp machine,” Wilson points out.
Under the constant back-and-forth motion, the cable carriers keep the hoses and electrical lines from kinking and impart a gentle rolling motion as they follow the carriage. Operating conditions include dirt, oil, and a variety of weather extremes. Wilson says, “They’re exposed to the weather all the time, and they run a water and mud mixture when they are operating. When you’re making and breaking pipe connections, you’re splashing abrasive mud over everything. There’s also some exposure to hydraulic oil whenever the machine is serviced.”
Duty cycles for the carriage typically average between 15 and 18 sec, Wilson notes, with travel speeds of around 120 ft/min on the return. He explains, “When you drill the pipe into the ground, it’s under control. But as soon as you need to come back up to get another pipe, you want to get drilling again as quickly as possible. We run a two-speed carriage, with a button that shifts it into fast speed to increase productivity.”
On two of the company’s largest drills, a smaller Nylatrac carrier also is used to control the hoses to a shuttle on the pipe loader. Wilson explains, “There’s a magazine on the side of the machine that carries the drill pipe, which drops down into a shuttle arm that grabs the next length of pipe and shuttles it over to the drill frame. A little gripper on the end of the shuttle arm grabs the pipe to keep it from sliding and holds it in position as it is loaded out, and the smaller carrier manages the hoses that go out to the gripper.”
In addition, many of the applications also use hose sleeves, which surround the hoses within the carriers, to help control the hoses and to contain any oil. Wilson states, “For anything in an area where an operator could be exposed to oil, we used to put an individual sock on each of the hoses, and it was difficult to feed a 200-in. hose through them. Now we’ve switched to one larger sleeve with Velcro up the side to enclose all the hoses.”
This not only makes it easier to install in production, but simplifies field repair or replacement as well. Wilson adds, “We found that it keeps the hoses more organized. The sleeves have a strap that connects to the hose carrier’s cross pieces, so things stay positioned better and don’t bunch up on either end.” The sleeves also are made by A & A Mfg.
The main carrier on a typical machine includes perhaps five to seven lines, Wilson states. “They vary in size from 12 in. on the smaller machines, to 1 in. diameter on the larger ones. We also run a 114-in. mud line through them.” He points out that the electrical cables generally are run inside a separate conduit or hose to provide further protection. The hydraulic hoses are constantly expanding and contracting in diameter and length as they pressurize and relax during operation. Working pressures typically run from 3000 to 5000 psi on the larger machines.
To help accommodate more lines and manage them better, Charles Machine Works uses carriers with internal dividers to keep hoses separated by size. Wilson says, “We use solid bars across the bottom part of the track for the larger hoses and extenders that give us another section on top for the smaller ones. It improves hose life because the hoses are constantly expanding and contracting. And if they are all together, the smaller hoses can get abraded between the larger ones.”
For more information on hose carriers and hose sleeves from A & A Mfg., call (262)786-1500 or visit www.gortrac.com.