Many variables dictate what trencher configuration is best suited for the task, including depth of cut, length of run, size of the product being installed, local ground conditions and space on the jobsite. You must start with the correct size machine - whether it's a walk-behind or ride-on unit with wheels or tracks - then choose the correct chain, cutting teeth and boom configuration. Next, select attachments that maximize your productivity.
Ground conditions and trench dimensions dictate the correct trencher size. "The more difficult the soil conditions, the more powerful the trencher should be," says Tim Phelps, product manager, Barreto Mfg. The depth and width of cut also affect trencher size. "For example, the deeper and wider the trench, the more earth you are taking out of the ground and the more power and size you want in your trencher to make the job easier."
Length of runs and frequency also affect choice, he adds.
When it comes to trenchers, bigger isn't always better. "You can rent a larger machine and get the work done faster, but it will cost you more. So you have to consider the budget as well as the application," Phelps states. "You also have to consider the size of the area. A smaller trencher is easier to maneuver than a larger one, and easier to transport to the jobsite."
Sizing it up
The smallest of the horsepower range is filled with walk-behind trenchers. "Walk-behind trenchers are limited in dig depth and width," says Bob Wren, training manager, Astec Underground. "However, they play a large role in the total unit sales of rubber-tired trenchers. Walk-behinds may be as much as 50% of the overall market in the 10- to 115-hp range."
According to Jon Kuyers, rubber tire and compact segment manager, Vermeer Mfg., "Most walk-behind trenchers effectively trench 24 to 48 in. deep and 4 to 6 in. wide. They are somewhat limited, as they do not have backfilling capabilities, and are smaller in size and horsepower for tough conditions.
"The advantages they have are maneuverability and overall size to get into confined areas," he adds.
Stepping up in capability are the ride-on trenchers. "Rubber-tired trenchers are mostly used for utility installations such as water, power, telephone and gas," says Wren. "Most utility companies, depending on their given area, use between 50- to 100-hp machines."
The largest trenchers are especially beneficial on longer runs in tough soil conditions. "If the utility runs are significant in length or in difficult soil conditions, such as frozen ground or caliche, more horsepower - which increases the overall size of the machine - will be required for greater productivity," Kuyers notes. "However, job limitations, such as a narrow right of way or confined areas, may require a machine with lesser horsepower that will complete the job, but not as productively."
But wide trenches require more than power to drive the cutting chain. "The larger trench widths or increased depths require greater horsepower to dig productively, but also require greater spoils-handling capabilities," says Kuyers. "The deeper or wider cuts will also require greater auger lengths or conveyors to remove the material farther away from the trench line. Along with increased depths or widths, harder soils will require more horsepower, especially when incorrect cutting tools are used."
Proper sizing really boils down to a few basic questions, according to Wren. "How deep do you always dig? How wide do you dig most of the time? How long are the longest runs going to be?" he asks.
Consult with your dealer when answering these questions, because local soil conditions also impact power requirements. "They should be familiar with some of the local conditions that you might be getting into," says Brent Bolay, the Ditch Witch organization.
Set up for conditions
Make sure the trencher is set up appropriately for local ground conditions. "If you walk into a dealership in Central Texas vs. one in Iowa, they are going to have the trenchers set up to compliment their local area," Bolay points out.