All of a trencher's mighty horsepower, incredible traction, and reinforced steel frame mean nothing without a well-operating digging system—the one feature that makes a trencher a trencher. With digging systems, one defective part—a stripped bolt, worn tooth or cracked sprocket—can mean the failure of the entire system, and every rental company knows how costly this kind of downtime can be.
A trencher's rapidly rotating steel, tungsten-carbide teeth are designed to pulverize any type of dirt, mud, and even rock. But wear and tear eventually occurs, and sooner than many rental fleet owners are aware. Without timely maintenance on its digging system, the trencher becomes less productive. Not paying attention to digging system maintenance over the long term will actually impact the entire trencher—from performance to trenching productivity.

Marty Piel, Parts Training Specialist at the Ditch Witch® organization, likens the use of overly worn digging teeth to a "dull-axe effect." "If you're chopping wood with a dull axe, you feel the shock right up through your arm and into your shoulder," Piel explains. "It's the same with dull digging teeth: the shock is transmitted from the digging chain through the attachment and up to the operator's station. This is one reason it's so important to keep a properly maintained chain on your digging boom. It's not just the production of the digging system itself; you're saving wear and tear on the entire trencher."

Rules to trench by.

Piel says there are three cardinal rules for properly maintaining digging systems, no matter what brand of trencher you own.

1) Always replace sprockets and digging chains at the same time. Replacing one without the other will cause premature wear of the new component.

The shock load can cause a chain to stretch. As the chain stretches, the sprocket teeth that were designed to fall directly between the chain's rollers begin to strike those same rollers and wear them down prematurely. Worn chain rollers will begin to resemble an hourglass or apple core. Digging chains should be replaced before wearing through the roller to the chain pin.

2) Replace worn digging teeth.

As teeth wear, shock load can increase on the chain. Generally speaking, as the tungsten-carbide cutting edge wears away, the teeth begin to become dull and transmit shock to the digging system. Also, the more the cup of the tooth is worn away, the less capability the tooth has to carry dirt out of the trench.

3) Maintain the proper tension on the digging chain.

Improperly adjusted digging chain can result in premature wear on the chain and sprockets. The chain should be tight enough so that it doesn't slip off the sprockets but loose enough to keep from binding. Chain tension depends on the size of the trencher. Refer to your operator's manual for the correct tension.

It may seem like a lot to keep track of, but Piel says being religious about maintenance will pay big dividends. "The time you invest in maintaining your digging system is nothing compared to the damage your equipment can suffer—not to mention loss of productivity—if you don't," he says.

What to look for in digging system components.

All digging systems are made up of teeth, sprockets, sidebars, pins and rollers. But it's the way these components are put together that determines their durability. The ideal digging system is one whose components are engineered to work and wear together.

"Ditch Witch digging systems have always been engineered to maximize the overall life and productivity of each component," says Piel.

Sprockets.
When looking for replacement sprockets, there are several factors to consider. First, it's a good idea to choose those that are engineered with proper mud relief. Buildup of spoils can cause a chain to stretch and prematurely wear all digging system components. Piel says Ditch Witch sprockets are manufactured with mud relief between the teeth to allow spoils to escape.

Another desirable quality of sprockets is a longer tooth. Sprockets with longer, tapered teeth enter the well between the rollers easier and deeper to have minimal contact with sidebars and rollers.

Chains and teeth.
There are dozens of chains designed specifically for different types of soils, so it's important to understand the predominant soil types in the regions where your equipment is operated. If you know your customer is going to be digging in soft soil, for example, a four-pitch, cup-tooth chain would be the ideal choice. A two-pitch, cup-tooth chain—designed for medium to hard soil—would not be necessary. Conversely, using a four-pitch chain in place of a two-pitch chain in hard or rocky soils could be extremely detrimental to your digging system as well as the trencher itself.

Digging chain is categorized three ways: by tensile strength, by pitch (two-pitch, four-pitch, or alternating sidebar), and by type (cup, combination, alligator or Shark Chain®). Ditch Witch chain is available in tensile strengths of 33,000 up to 225,000 pounds. Chain spacing refers to the number of chain pins between sidebars. Two-pitch chain has a sidebar on every station, four-pitch chain has a sidebar on every other station, and alternating sidebar chain has one sidebar at each station on alternating sides of the chain. On raised rivet chains, the chain pin is positioned higher on the sidebar, putting more steel on the sliding surface and heel, which are the main wear areas of the chain's sidebars. This design increases the life of the digging chain.

Piel says a welded, low-profile chain such as a Shark Chain or Shark Chain II® can be good choices for general-purpose trenching or where trenching conditions are diverse. With a low-profile chain, the sidebars are only about half as tall as a normal digging chain, so the teeth are positioned closer to the chain or the boom it rides on. In general, the closer the teeth are to the boom, the smoother the cut. "Those teeth act like a lever; anything they catch will cause the chain to kick back," says Piel. "A low-profile chain reduces kickback, which reduces wear on the heel (the bottom backside of the chain sidebar) and shock load to the unit."

A lot of thought has been put into the design of digging systems. Taking a little time to consider all of the variables and develop a regular maintenance schedule can dramatically extend the life of your equipment fleet.