Chain-Drive Innovations Boost Trencher Reliability

By Larry Stewart, Executive Editor | September 28, 2010


It's still cheaper to trench long runs where there's not a lot of finished surface to repair, and the economy is forcing utilities to make that call rather than over-using directional boring.
Ditch Witch
Ditch Witch devised a powershift transmission to drive the RT70 and RT0 trencher, hoping to attract customers who are suspicious of hydrostatic drives but want better control over trencher speed.
Hydrostatic drives keep coming in smaller packages, such as on this 23-hp Vermeer RT200, and its 15-hp counterpart, the RT100.


Over the past 10 years, the utility industry has been so distracted by the rapidly developing directional-boring business that it may have been easy to overlook steady improvements made in small trenchers. Now that the economy has reined in utilities' unbridled enthusiasm for trenchless methods, trencher manufacturers have reacted by bringing some fairly substantial changes to the trencher drives in less-than-100-horsepower machines.

"The choice between boring and trenching is a little more economically driven now," says Carl Hoffman, general manager of Sun Communications in Westfield, Ind. "It had been customer driven for a while—utilities were boring because it made good public relations. Now, if it's cheaper to trench, they'll trench and restore."

The most aggressive, recent changes in trencher specifications involve the drive system that turns the chain. The secret to trencher productivity and durability is matching the chain speed to the soil conditions and ground speed. Most ground drives are hydrostatic or hydraulic, both of which offer infinitely variable ground speeds.

To improve control over chain speed, manufacturers have employed just about every conceivable power-transmission option to the trencher drive. The industry started with mechanical drives to transmit power from the engine to the trencher chain, but hydrostatic drives have gained in popularity. Of the 53 models of chain trenchers currently available with under-100-hp engines, 19 are hydrostatic. As with the ground drive, infinitely variable speed with fairly constant power output is the main advantage. It allows the operator to refine chain speed to match conditions.

Hydrostatics, and even less-expensive hydraulic drives, are more difficult to damage when the trencher bar is in the ground. And the flexibility of transmitting drive power through hydraulic fluid offers the ability to build machines with sliding offsets, so the trencher bar can shift left or right to reach out near the machine's edge.

Hydraulic drives, of course, use a pump and motor to transmit power, but they use an open-loop system where hydraulic fluid drains to the reservoir after leaving the motor. Hydrostatics typically have a pressurized drain circuit that goes from the motor directly back to the pump. Hydrostats tend to be more efficient than hydraulics working at higher pressures over time. But very few small trenchers are expected to do high-production work over long shifts. Twelve of those 53 trencher models still have hydraulic drives.

For a long time, hydrostats have seemed like overkill for smaller pedestrian trenchers—more system, and more money, than an under-20-hp trencher needs. But manufacturers of hydraulic pumps and motors have invested heavily in developing hydrostatics. Few of them still offer hydraulic-drive systems big enough for trenchers approaching 100 horsepower. And as component manufacturers have become more competitive with smaller hydrostatic systems, Burkeen and Vermeer have introduced pedestrian trenchers down into the 15-hp range with hydrostatic drives.

In extreme conditions, some of the first generation of hydrostatic trencher drives had problems with overheating and maintaining productivity. Today's trencher product managers admit that they've accumulated invaluable experience with hydrostats, and the manufacturers are showing practical wisdom in the designs of cooling and filtration systems. Hydrostatic drives have gained productivity thanks to larger reservoirs, better radiators and more efficient cooling fans.

But a persistent bias against hydrostats by some of the hardest-working trencher owners drew a significant technology challenge into the under-100-hp trencher class a little more than a year ago. Ditch Witch introduced the RT70 and RT90 with optional powershift transmissions. The powershift is an adaptation of the clutchless mechanical transmission common in tractors, which allows the operator to change gears without interrupting power.

Ditch Witch customers have purchased the powershift machines at slightly lower cost than their hydrostatic counterparts, which is certainly attractive. But the technology has drawn the attention of some trencher users because it offers a mechanical drive link with a choice of two speeds. The operator can adjust chain speed without interrupting digging power. Ditch Witch stands alone in applying powershift technology to chain drives.

One of the reasons other trencher manufacturers have not rushed to compete with mechanical-drive trenchers may be the major influence that rental companies wield. Since 1999, the number of rented rubber-tired trenchers at work in the United States has grown 26 percent, according to the Construction Equipment Universe Study. In 2003, 19 percent of all rubber-tired trenchers in the field are rented.

Rental-fleet owners like hydrostatic and hydraulic machines because, for them, filters are easier to maintain than clutches and belt or chain tensions. Turnaround time in the rental yard is reduced. With pump manufacturers improving the performance and affordability of small hydrostatic systems, and a major customer group like the rental houses expecting fluid power, a great deal of trencher manufacturers' resources for trencher development are clearly going to hydraulic and hydrostatic drives.

Pedestrian trenchers are the most popular configurations because there are so many applications for a small trencher. Plumbing and electrical services, irrigation systems, communications and cable television, even some larger utility work can be done most economically with a trencher that can squeeze into small spaces. The rise of rental work has brought simplified, color-coded controls so that people who don't use trenchers every day can quickly learn to operate them. It's a development that has probably been good for the whole market.

Small trenchers have continued to grow up, as manufacturers respond to customer demand for improved durability by putting more horses under the hood. Look for an acceleration of this trend as they comply with the Environmental Protection Agency's Tier II emissions requirements. One example: When Vermeer replaced the 44-hp V3550A rider in June with the RT450, frame size hardly changed but the RT450 comes with a Tier-II-compliant engine rated at 50 horsepower.

At the ICUEE show in September, Ditch Witch introduced an option for its larger utility machines that provides the operator a digital readout of how deep the machine is trenching. The electronic system—called the Trench-Depth Meter (TDM)—uses a version of bore-locating technology. Its memory can be integrated into mapping systems that are being used to keep an accurate underground inventory of installed lines.

More common options tend to be less high-tech. The vast majority of riding trenchers have a backfill blade. About half of the large riders being sold today go out the door with a backhoe and four-wheel steer. Four-wheel steer has been available for quite a long time, but demand has risen rapidly of late as a result of congested workplaces and increasingly delicate installations amid other underground lines. For similar reasons, sliding offset trenchers are also growing in popularity.

Options make small trenchers versatile, and the array of drive options makes them productive. Expect technology in this smaller category of trenchers to continue to improve, as the long-run installations of telecom industry are finishing up. There's plenty of last-mile trench to be cut—installations where there are not expensive improved surfaces to refinish—in lengths perfectly suited for tough, under-100-hp trenchers.

Average Trencher Costs

  Base price  Hourly cost* 
18 hp - 35 hp  $24,500  $32 
36 hp - 60 hp  $39,900  $45 
61 hp - 94 hp  $59,800  $59 
*Combined ownership and operating expensesSource: "Contractors' Equipment Cost Guide," published by EquipmentWatch - 800/669-3282. 


Basic Specifications: Pedestrian Chain Trenchers
Manufacturer/Model Gross Horsepower Operating Weight (lbs.) Max. Trench Depth Trench Width Range Chain Drive
Specifications shown here are based on information provided by manufacturers and Spec Check, and are given for comparison only. Specifications are subject to change. For more information on specific models, visit Construction Equipment's website at
Of 23 pedestrian trencher models available, three are hydrostatic and eight have hydraulic trencher drives. The smallest hydrostatic machines are the Vermeer RT100 at 15 horsepower and Burkeen's B-16 at 16 horsepower. Ditch Witch recently introduced its hydraulic 1330 to compete with Barreto's hydraulic 13-hp units.
Ground Hog T-4 5 230 1' 0" 3.0"– 3.5" Mechanical
Vermeer RT60 6 270 1' 0" 3"– 3" Mechanical
Parsons T80 8 640 2' 6" 4"– 6" Mechanical
Ditch Witch 1030 11 780 2' 6" 4.3"– 6" Mechanical
Parsons T120 11 640 3' 0" 4"– 6" Mechanical
Vermeer V1150 11 850 2' 6" 4"– 6" Mechanical
Burkeen B-13 12 820 3' 0" 4"– 6" Mechanical
Barreto 1318-H 13 860 2' 6" 4"– 6" Hydraulic
Barreto 1324D 13 1,025 3' 0" 4"– 6" Hydraulic
Barreto 1324D4 13 1,075 3' 0" 4"– 6" Hydraulic
Case 60 13 720 3' 0" 4"– 6" Mechanical
Ditch Witch 1230 13 780 3' 0" 4.3"– 6" Mechanical
Ditch Witch 1330 13 920 3' 0" 4.3"– 6" Hydraulic
Parsons T130 13 700 3' 0" 4"– 6" Mechanical
Vermeer V1350 13 850 3' 0" 4"– 6" Mechanical
Vermeer RT100 15 880 3' 0" 4"– 6" Hydrostatic
Barreto 1624D 16 1,025 3' 0" 4"– 6" Hydraulic
Barreto 1624D4 16 1,075 3' 0" 4"– 6" Hydraulic
Burkeen B-16 16 1,290 4' 0" 4"– 6" Hydrostatic
Ditch Witch 1820 18 1,300 4' 0" 3.3"– 16" Mechanical
Vermeer RT200 23 1,485 4' 0" 4"– 8" Hydrostatic
Vermeer LM25 25 2,570 3' 0" 4"– 6" Hydraulic
Vermeer LM42 45 3,335 3' 6" 4"– 6" Hydraulic






Basic Specifications: Ride-On Chain Trenchers (Less than 100 horsepower)
Manufacturer/Model Gross Horsepower Operating Weight (lbs.) Max. Trench Depth Trench Width Range Chain Drive
Specifications shown here are based on information provided by manufacturers and Spec Check, and are given for comparison only. Specifications are subject to change. For more information on specific models, visit Construction Equipment's website at
Vermeer still offers riders with hydraulic and mechanical chain drives up to 85 horsepower, but the over-50-horsepower market is awash in hydrostatic drives (10 of the 17 models available are hydrostats). Parsons' recent decision to stop making a riding trencher reduced the competition by three.
Case TF300B 18.5 2,315 3' 9" 4"– 16" Mechanical
Burkeen B-25 25 2,290 3' 0" 4"– 6" Hydraulic
Ditch Witch HT25 25 4,080 3' 3" 4"– 16" Mechanical
Case 360 32 3,906 5' 0" 6"– 12" Mechanical
Case 460 37 5,660 5' 0" 6"– 16" Hydrostatic
Case Maxi-Sneaker C 37 2,346 3' 0" 4"– 6" Hydraulic
Ditch Witch 3610 45 3,765 5' 0" 0"– 16" Mechanical
Ditch Witch 3700 45 5,425 4' 4" 6"– 12" Hydrostatic
Vermeer V4150A 45.3 5,640 5' 0" 5"– 16" Hydrostatic
Burkeen B-36B 49.5 4,600 5' 0" 6"– 12" Hydrostatic
Ditch Witch 3700CD 50 4,200 5' 3" 6"– 12" Hydrostatic
Vermeer RT450 50 3,350 5' 0" 5"– 12" Hydrostatic
Case 560 51 7,000 6' 0" 6"– 16" Hydrostatic
Ditch Witch 5700 57 n/a 5' 2" 6"– 12" Hydrostatic
Vermeer V5750 60 6,300 5' 0" 6"– 16" Hydrostatic
Vermeer V5800 60 13,565 5' 0" 7"– 16" Mechanical
Case 660 67 11,219 6' 0" 6"– 16" Hydrostatic
Vermeer V6500 67 8,570 5' 0" 6"– 18" Mechanical
Ditch Witch RT70 Hydrostatic 70 n/a 8' 1" 24"– 24" Hydrostatic
Ditch Witch RT70 Powershift 70 10,770 8' 1" 24"– 24" Powershift
Vermeer RT700 70 10,050 6' 0" 6"– 16" Hydraulic
Vermeer Flextrak 75 79 8,700 5' 0" 6"– 12" Hydrostatic
Vermeer V8100 80 12,395 5' 0" 6"– 18" Mechanical
Ditch Witch RT90 Hydrostatic 85 n/a 8' 1" 24"– 24" Hydrostatic
Ditch Witch RT90 Powershift 85 11,830 8' 1" 24"– 24" Powershift
Vermeer RT850 85 10,050 6' 0" 6"– 16" Hydraulic
Vermeer V8550A 90 11,783 5' 0" 6"– 18" Hydrostatic
Case 960 99 16,000 7' 0" 7"– 18" Hydrostatic




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