Ditch Witch Zahn: Dedicated Versatility

Sept. 28, 2010

About a year ago, CE editors borrowed an XT1600 from Ditch Witch and placed it in the capable hands of professional operator Scott Mennenga, an instructor at the Local 150 (Operating Engineers) training facility near Joliet, Ill. Mennenga was favorably impressed with the machine, which is designed to combine the capabilities of a mini-excavator with those of an attachment-handling compact track loader. The design challenge with the XT1600, said a Ditch Witch engineer with whom we worked, was to enable it to function competitively with any dedicated machine that it might replace.

About a year ago, CE editors borrowed an XT1600 from Ditch Witch and placed it in the capable hands of professional operator Scott Mennenga, an instructor at the Local 150 (Operating Engineers) training facility near Joliet, Ill. Mennenga was favorably impressed with the machine, which is designed to combine the capabilities of a mini-excavator with those of an attachment-handling compact track loader. The design challenge with the XT1600, said a Ditch Witch engineer with whom we worked, was to enable it to function competitively with any dedicated machine that it might replace. Compromises are inevitable when trying to make a machine do multiple jobs, he said, but quickly added that Ditch Witch worked hard to minimize those areas in the XT1600.

Now, it seems, the Ditch Witch design philosophy of minimizing compromise in multi-task machines has advanced another step with the company's new Zahn. CE editors recently had the chance to spend a day with the marketing and engineering folks responsible for the Zahn — talking about the machine's unique design, visiting the Zahn assembly line and observing the machine (in various of its configurations) at work in the red clay of Perry, Okla., where the company is headquartered.

If you haven't yet seen the Zahn, it might best be described as essentially a power unit that can accommodate various work tools, which actually form the front end of the machine. The idea behind the Zahn, says Matt Collins, product manager for the Ditch Witch compact utility line, is to integrate the work tool with the power unit in a manner that allows the two basic components to function as a dedicated machine and, subsequently, to deliver dedicated-machine performance, compared with using work tools simply as attachments mated to a coupler.

Most of the three Zahn power units — R150, R230 and R300 — are shipped to dealers in what might be called a generic configuration, that is, as two-wheel-drive units with no work tools. Then, in the dealer's shop, the Zahn is equipped to meet a particular customer's specific needs. This design approach, says Collins, simplifies manufacturing, requires far less dealer inventory, and gets exactly configured machines into customer hands more quickly.

A walk through the Zahn assembly area illustrated the machine's basic design philosophy, as well as the basic similarity of the three power units. Starting with an identical base frame, all three power units are equipped with an engine, two-wheel hydrostatic propel system (with traction-assist and cruise-control), auxiliary hydraulic system (with all valves and piping), operator's console, manual parking brake, 11-gallon fuel tank, and a no-maintenance articulation joint with an actuating cylinder.

Variations in the basic power units include a different engine for each model and, for the R230 and R300, a larger hydrostatic pump and a second auxiliary-hydraulic pump. The engines, all gas powered and air cooled, are a one-cylinder Honda IGX440 for the R150, a two-cylinder Kohler CH235 for the R230, and a two-cylinder Kohler CH750S for the R300 — rated at 15, 23 and 30 horsepower, respectively.

The articulation joint on all the power units terminates in a flat vertical plate with a four-hole bolt pattern. If the power unit is to be used solely as a trencher, then the trencher (a choice of two is available) is bolted directly to the plate. These hydraulically powered trenchers, which use a third support wheel for balance, can cut to depths of 36 inches, to widths of 4 to 8 inches, and can be equipped with one of three head-shaft drive motors to yield the speed/torque combination best suited to the customer's typical jobs.

The standard trencher uses a head-shaft auger, which is driven by the chain motor and is positioned on the side of the chain. The optional trencher uses a patented, independent auger that is positioned under the chain — a location that allows it to sweep more spoil away from the chain, and, consequently, to keep the trench cleaner. Although the independent auger does require a small additional drive motor, its superior efficiency, says Collins, likely will make it the predominate choice among buyers.

Compared to conventional designs, says Collins, the two-wheel-drive Zahn trenchers, that is, those with the trencher bolted directly to the power unit's articulation joint, provide several significant advantages. The articulation joint allows the machine to easily maintain a smooth, curved trench around obstacles, and it also takes the work out of moving the machine around the jobsite. Given that the operator rides on a platform at the rear, visibility to the trench is enhanced, he says, and the machine also reaches the jobsite faster, since its travel speed no longer must be slowed to accommodate an operator on foot. Top speed for the R150 is 3.3 mph, and for the R230 and R300, 5.9 mph.

Plus, says Collins, hydraulic operation of the trencher, compared with mechanical operation, eliminates complexity, simplifies maintenance, and allows easy reversal to clear the chain. And as an added benefit, the new Zahn trenchers also can be fitted with the company's Roto Witch attachment, which allows boring under sidewalks and other obstacles to reduce restoration.

The Zahn R150 is available only as a trencher, with either the conventional head-shaft auger or the new independent auger. Although the R230 and the R300 have possibilities other than working just as trenchers, these two models — in their two-wheel-drive, dedicated-trencher configuration — are replacements for the Ditch Witch model 1820, an 18-horsepower pedestrian trencher with a mechanical trencher-drive system.

Truth be told, the new Zahn two-wheel-drive trenchers could probably easily replace the heart of the Ditch Witch pedestrian trencher line (models 1030, 1230 and 1330), but the company has avoided making this move, given the popularity of these existing machines. The 1030 and 1230, with respective horsepower ratings of 11 and 13, have mechanical trencher drives, and the 13-horsepower 1330 uses a hydraulic trencher drive. (For a look at how the performance of the R150 and 1330 compared in a quick, unofficial traveling/trenching evaluation conducted on site, check out the sidebar, "Side-by-Side."

So far, we've considered just a portion of the Zahn's capabilities. If, instead of bolting a trencher directly to the articulation plate, another component — the InterChange connection — is bolted to the plate, then the Zahn becomes a four-wheel-drive machine capable of using an integrated trencher, plow, backhoe, dumper, stump grinder, tiller or tool carrier.

The InterChange connection is a beefy, U-shaped frame that has wheels at its forward corners and two hydraulic motors to drive these wheels. The two added drive wheels are quickly plumbed into the propel system by connecting hoses to an existing manifold in the power unit, thus placing the front motors in series with those driving the power unit's wheels. The front wheels also benefit from the traction-assist feature, which fixes the displacement of oil directed to each side of the machine. According to Collins, a Ditch Witch dealer can install the InterChange connection to an R230 or R300 power unit in about 45 minutes.

At the rear of the InterChange connection frame is a self-aligning dowel that indexes with any of the seven integrated tools when pushed onto the frame. Two flip-up, threaded locking devices (one on each side of the frame at the front) then secure the tool. The process requires only a 5/16-inch wrench. We watched Terry Golay, Ditch Witch product test technician, install the dumper on the InterChange connection in about five minutes.

When any of the integrated work tools is locked in place, auxiliary-hydraulic hoses are quickly attached via a connector panel at the front of the power unit. The panel also contains an electrical outlet, and an optional case-drain connection is available. The two gear pumps supplying the auxiliary system produce a combined flow of 12 gpm, and the auxiliary system operates at a relief pressure of 3,000 psi.

Of the seven front ends available for the Zahn, five attach directly to the InterChange connection. The two that don't, the trencher and the plow, require an intermediate component — the "low-lift tool carrier." This extremely robust component mates the tool to the InterChange connection frame and provides hydraulically activated linkage for lift and tilt functions (for tool positioning).

The four-wheel-drive trencher, with a maximum digging depth of 48 inches and a digging-width range of 4 to 12 inches, is equipped with the Ditch Witch independent auger. According to design engineer Jacob Hamburger, the four-wheel-drive trencher has the added advantage of using all its weight in the trenching process, since it uses no trailing wheel for support. And four-wheel-drive, he says, allows the machine to traverse rougher terrain.

The Zahn's vibratory cable plow has an operating depth of 20 inches and can pull in material up to 3 inches in diameter. The new Zahn plow, which replaces the Ditch Witch 255SX pedestrian plow, also can vary its blade pitch via the low-lift-tool carrier. Options include a reel carrier, sod cutter and skid shoes.

The low-lift tool carrier can itself be fitted with a coupler to accommodate certain attachments, for example, the trencher that a customer might have for a Ditch Witch SK350 mini skid-steer — or for that matter, any of the SK350's attachments that don't require a high lift height. But for a more utilitarian machine, the Zahn's high-lift-tool-carrier front end is probably the better choice.

The high-lift tool carrier front end has the appearance of that of a small wheel loader, and its coupler accepts more than 40 of the attachments approved for the SK350. The high-lift tool carrier, with a hinge-pin height of 73 inches, uses a four-bar linkage that provides generous dump and roll-back angles and has a self-leveling feature. A kickstand at the rear of this front end permits it to be stored in an upright position and facilitates its installation on the InterChange connection frame.

The dumper front end is available in two sizes. The larger accommodates 20 cubic feet and a payload of 3,000 pounds, and the smaller, 12 cubic feet and 1,800 pounds. The frame of the larger dumper uses an extra set of wheels to balance and support the weight of the payload. A self-loading mechanism for each dumper is an option that can be retrofitted.

The backhoe front end, sized to leave a flat-bottom trench at a 61-inch dig depth, has a swing arc of 170 degrees. The backhoe also has an integral backfill blade and stabilizers. The stump grinder, with a weight of 1,730 pounds, has an 8-inch working depth and uses a 20-inch-diameter cutting drum with 12 teeth. The tiller, almost equal in weight to the stump grinder (1,732 pounds), uses 24 tines on a 19-inch-diameter drum.

While the trencher, plow, backhoe and tool carrier front ends are familiar territory for Ditch Witch, says Collins, the tiller, stump grinder and dumpers take the company beyond its core businesses and open up the prospect of attracting new customers.

"The door opens when the customer moves into the four-wheel-drive Zahn," he says, "because now the once-dedicated trencher takes on the flexibility of performing other tasks — and performing them well."

Kevin Smith, Ditch Witch product planning manager, says he is pleasantly surprised at how quickly customers have adopted the four-wheel-drive Zahn.

"We expected the two-wheel-drive to predominate," says Smith, "because that's the configuration of the current [trencher] product. But buyers seem to have recognized the versatility of the four-wheel-drive platform."

And if you're left wondering about the name — Zahn — it's the last four letters of Malzahn, as a tribute to Ed Malzahn, the inventor of the Ditch Witch trencher and the entrepreneur who developed The Charles Machine Works (a/k/a Ditch Witch) from a tiny Oklahoma blacksmith shop into a global company.