Earth Eaters

The mechanical crackle of a brand new trencher attachment can be beautiful music in the morning. It can sound like victory — the satisfaction of a well-purchased piece of iron and the knowledge that your skid steer crew is well equipped in the field. In order to achieve such celebrated buyer’s gratification (and hear that grand buzz saw sound), shoppers need to find the perfect trencher attachment for their operations. Matching your implement to your tool carrier, picking the right digging depth and width and deciding on choices in chains and price will almost guarantee a post-purchase victory dance. The first time you attach that new implement to your skid steer, hook up the hydraulic hoses and flip on the auxiliary flow will be glorious moment indeed — full of conquest and accomplishment.

Size Always Matters

Trenchers are gnarly-looking attachments. Their cool look and brawny construction helps these earth cutters do one of the hardest jobs on a construction site — slice soil. With a 4-ft boom jutting out in front of your skid steer loader, swirling with sharp cutter teeth and splitting the soil with extreme prejudice, your correctly outfitted trencher attachment can cut through ground conditions to install a myriad of end products.

“You have a pile of applications for these attachments,” says Richard Lowe, president of Lowe Mfg., a manufacturer of trencher attachments for 20-plus years. “There are short run utilities off
of mainlines. Applications include electric, TV, cable, drain tiles, irrigation ditches, silt fencing, different down spouts and almost anything you can use your imagination for. Plus, the trencher, unlike a vibratory plow, allows you to see what’s down there so you can do the proper visual inspections to make sure everything’s right — depth, width and placement.”

Once you figure out your specific application (trenching for sprinklers, lighting, broadband, buried treasure, etc.) and how deep and wide you want it installed, you can begin to determine what size trencher attachment you will need for your operations. The vast majority of trencher attachments sold today come in two main boom sizes — a 36-in. (3-ft) boom or a 48-in. (4-ft) boom. Both of those categories typically come in a 6-in. digging width.

“But you must be careful when people say a 36-in. boom,” cautions Lowe. “Some people say a 36-in. boom measures 36 in., but be careful because a 36-in. boom may only dig upward of 30 in. But the common ones are 3-ft and 4-ft digging depth booms with 6-in. digging widths.”

Besides the mainstays, there are a variety of other boom sizes for skid steer trencher attachments. Most companies have a range from 2 to 6 ft. Bobcat Co., one of leading manufacturers of compact loaders and attachments, breaks its trencher attachment options into three different categories:

1. Light-to-Medium Production: 2- to 3-ft dig depth and 4- to 8-in. width

2. Medium-to-High Production: 3- or 4-ft dig depth and 6- to 12-in. width

3. High-Production : 4- or 5-ft dig depth and 6- to 12-in. width

Beyond boom size, knowledgeable buyers also will need to understand the hydraulic capabilities of their skid steer loader to match their trencher’s gallons per minute (gpm) flow. All skid steers utilize auxiliary hydraulic systems to power a variety of hydraulic attachments (from breakers to brooms) and most new skid steers today have a standard hydraulic flow of 16 to 25 gpm and pressures of 3,000 to 3,300 psi or the option of a high-flow hydraulic flow system of 26 to 45 gpm and pressures of 3,000 to over 4,500 psi.

“It’s important for the customer to match the auxiliary hydraulic flow capacities of the trencher to the attachment
carrier for optimum use,” explains Mark Teckenburg, construction marketing manager at Bobcat Co. “The smaller Bobcat trencher attachments have a flow range of 9 to 15 gpm, while the medium trenchers have a 15- to 22-gpm range. The large trencher has a 21- to 32-gpm range and is ideal for use with high-flow hydraulic systems on attachment carriers.”

High flow output systems allow for changes in the trencher system that may provide more torque at the desired speed of operation. In many conditions, more torque means a better performing, harder working and more efficient trencher attachment. But just so you know, most trenchers will run fine on a standard-flow attachment system. High flow is only used for the most extreme ground conditions and those long, high-volume jobs.

“We don’t typically recommend high flow,” says Lowe. “Today’s standard flow is what was once considered high flow years ago. Something that used to be special is now normal. A lot depends on your ground conditions, but in our view a good standard-flow setup will tackle the vast majority of applications and save you thousands of dollars, unless you are in extremely difficult conditions or your productive rate is really a major concern.”

Sharpen Your Teeth

Of course, you can have the right-sized trencher attachment matched to the perfect skid steer hydraulic system and still be spinning your wheels without the right chain. Your trencher attachment’s chain needs the correct metal teeth to be tough enough to chew up plenty of earth. Today, most trencher attachments are sold with a chain of cup cutter teeth — designed with a front-cutting edge that’s shaped to actually dig and move spoil out of the ditch — but application will decide your ideal chain and teeth.

“The chain pattern used on the trencher is heavily dependent of the type of soil conditions,” explains Teckenburg. “Bobcat offers a cup tooth chain, a cup/carbide chain, a solid carbide bit chain pattern and a cup/shark tooth chain pattern. The last two would be utilized in some of the harshest digging conditions.”

Specialty chains and teeth abound for trencher attachments and they run the gamut of cool descriptors. Scorpion, shark, H-plate, alligator, rock, frost and carbide teeth are all options for contractors who need to deal with hard soils and tough terra firma. Besides being bolt-on or weld-on, each tooth will be engineered for harder and tougher ground and rock conditions. Lowe suggests you work with your dealer for the proper set of teeth for your local conditions.

While operating, crews should always be observant of the trencher chain tension. If a trencher chain looks too loose or sloppy, it’s often a sign that it needs to be adjusted. However, adjusting the chain so that it fits too tight can also pose both maintenance and performance problems. Both too tight and too loose can induce wear on both the chain’s drive sprocket and end-wheel, as well as rob your implement of performance and power.

For a quality attachment, check how your trencher adjusts chain tension. Make sure it’s simple and easy. Some trenching attachments use grease cylinders with high-pressure grease fittings to adjust tightness, but many require the loosening and tightening of bolts and screws, which might be a pain on the jobsite. The replacement of trencher teeth will also be a major maintenance concern for trencher attachments, so make sure to understand how to replace these wear parts at the time of purchase. Replacement chains can range from $500 to $2,000 or $100 up to $1,000, depending on the model. Teeth can run from $6 to $10 each depending on type — a little more for the conical carbides. Always look for quality construction, and then think of ways to prevent premature wear during operation.

“The trencher teeth are the major wear items operators should inspect regularly. One way to prevent the teeth from wearing prematurely is to equip the attachment with teeth that are appropriate for the digging conditions.
The trencher chain and the trencher boom sprocket also wear because they are both ground engaging,” says Teckenburg. “The spoil auger that pushes the material away from the trench is another important item for
maintenance and inspection. The trencher’s spoil auger is made adjustable because most trencher attachments can be set to trench as narrow as 4 in. or as wide as 18 in. So in order for the spoil auger to move the dirt away from the trencher, it must be set according to the width of the trench.”

Make Sure It’s Really Built to Eat Earth

Once your trencher attachment is fitted with a sharp set of shiny new teeth, you can finally decide on a last few odds and extras for your earth cutter. If you’re interested in putting some real ritz into your trencher attachment, you could always purchase an implement with a hydraulic side-shifting boom, enabling the driver to move the trencher left or right without moving the machine or leaving the cab.

“You can look at hydraulic side-shift instead of the standard manual side-shift,” says Lowe. “It’s several hundred dollars more expensive and most people are well off just using the manual side-shift. When you keep the trencher in the middle of the tire tracks of your loader, you’re going to get the best productivity.”

Conscientious buyers also will need to take a lot of interest in the trencher’s construction (how well it’s designed and manufactured). Find out what type of motor drives the attachment and what design is utilized — direct drive or reduction drive. Direct drive is typically a hydraulic motor that runs directly into your head shaft and propels everything straight from the motor. Reduction drive is done either through a planetary gearbox or a heavy-duty chain reduction system, where you’re able to use a smaller motor to be more efficient, having a higher pressure system rating and yet still accommodating the proper power requirements needed through the reduction. Many manufacturers say reduction drive is better, but ittypically more expensive too.

Also take notice of the boom construction and safety features. Look for operator protection from flying debris and rotating components — shields or guards over the spoil discharge auger, for example. Safety bars over the trenching boom itself are always smart and may even be required by safety inspectors. Then make sure there are plenty of safety warnings located in easy-to-read locations.

Overall, make sure your trencher attachment purchase is as well researched as your skid steer purchase.
“People should look at buying attachments with the same diligence they look at buying the base machine,” muses Lowe. “A lot of people will spend a lot of time looking at a base machine and treat the attachments as an afterthought. That’s a mistake.If you don’t put the thought into it, you may not get the best attachment for your needs. It may be extra work, but you’ll be pleased when you find the extra benefits and features that work for you.”

That sort of attention will get you the best implement for your buck. And with trencher attachments running from $3,000 to $10,000 (the most popular size being around $3,900 to $4,200), you need to get the best cut for your cash.

Keith Gribbins is managing editor of Compact Equipment.