Productivity Guide: Trenchers: 40 to 60 gross horsepower
| June 12, 2007 |
When you’re looking at small trenchers for construction and utility installation applications, you are, in essence, talking about two different types of machines. That’s because trenchers in the 40-to-60-gross-horsepower range are the delineation point between walk-behind and ride-on machines.
There is no set breaking point for these two types of machines. Both Vermeer and Ditch Witch market ride-on trenchers with less than 40 horsepower. Fortunately, machine selection is fairly easy since each style of trencher is designed to excel in a specific role on your jobsite.
Take walk-behind models, for instance. These machines are highly compact and easy to transport. They are also exceedingly maneuverable in tight working conditions, and a single operator can easily handle them. Following those criteria, walk-behind trenchers are perfect for short jobs like street-to-house utility and fiber optics installation. They can tackle multiple jobs in a single work day and are the perfect fit for small utility installation companies or even one-man operations.
“If you start getting larger jobs, things change,” notes Todd Roorda, an applications specialist with Vermeer. “Walk-behind trenchers are amazingly productive machines, provided they’re used in the proper application,” he notes. “Once you begin moving past 200 feet or so, you have to seriously consider switching to a ride-on trencher.”
Successful contractors know one key to profitability is the ability to complete jobs quickly. “And that’s where a ride-on trencher comes into play,” Roorda explains. “If you have room to maneuver a ride-on unit, then the ride-on unit’s four-wheel-drive power train is going to give you a significant production boost.” At the same time, Roorda notes, small ride-on trenchers in this class can be used effectively in some restrictive work environments. “They can be a little cumbersome to get into a jobsite or turn around once a run is done,” he notes.
Here’s the judgment call: Does the ride-on’s increase in trenching productivity outweigh its additional acquisition costs and the setup and tear down time it requires? “Like so many things when you’re evaluating equipment use, it often comes down to specific applications,” Roorda says.
Ditch Witch product manager Brent Bolay says ride-on trenchers have another advantage over walk-behind units: their attachment capabilities. “We can fit the machine with a backfill blade to put spoil back into a trench once lines are laid,” he says, “or we can take advantage of its hydraulic system. A trencher can now be fitted with a backhoe to excavate and make utility connections. An auger or boring attachment can dig horizontal holes or excavate under driveways and sidewalks with minimal turf or concrete damage. So a ride-on machine increases your effectiveness in utility operations in ways a walk-behind unit simply can’t.”
Bolay says many of the basic attributes that make a ride-on unit so productive are taken for granted today. “The advantages of having four-wheel drive and four-wheel steer on a machine are huge when it comes to increasing productivity,” he says. “Having all four wheels pulling is a definite advantage in hard soil conditions. And while a ride-on machine will never be able to go into tight areas like a walk-behind unit can, the high degree of maneuverability a four-wheel-steering system offers can allow it to work effectively in confined areas.”
Self-destructive by nature
Trenchers go through an extreme amount of abuse. Few other machines endure as physical a pounding daily, often in dusty, rocky conditions. “They’re constantly beating on something, whether it’s rocks, tree roots or whatever’s in the ground,” Roorda says. “And you never know what’s going to be down there. It’s a tough application.”
This doesn’t mean you should throw up your hands and allow your operators to hasten the inevitable, though. How your operators maintain and operate a trencher are the biggest factors affecting that machine’s longevity.
“You can’t always see what that blade is cutting against down there in the ground, Bolay notes. “So an operator who knows when the machine doesn’t sound or feel right as it’s cutting can really save you a lot of heartache.”
Ground conditions vary. What a Texas contractor may consider good productivity would probably be upsetting to a contractor in Iowa, where soil conditions aren’t as tough.
Again, Roorda says, experience dictates how productive a machine will be regardless of ground conditions. “But common sense has a lot to do with it as well,” he notes. “I’ve visited jobsites and seen operators just grinding away at a rock. Then when the trencher starts to smoke, and eventually fails, they’ll tell you it wasn’t tough enough for the job. And that’s not true. Any trencher will perform to its full potential if it’s used sensibly and correctly.”
One way to protect a trencher is by spec’ing an automatic engine shut-down system on the machine. Vermeer, for example, offers such a system as standard equipment on its ride-on machine models. These systems constantly watch over a trencher’s health by monitoring vital engine and hydraulic system data, such as oil temperature and pressure and engine temperature. If the system senses anything amiss – the trencher’s oil pressure is starting to drop while the engine temperature is rising, for example – it will automatically shut the entire trencher down before any serious damage occurs.
Simpler maintenance, better production
Most trenchers in the 40- to 60-gross-horsepower classes feature hydrostatic transmissions since they are an extremely effective way to transmit horsepower and torque from the engine to the drivetrain and cutting tool. “The real benefit hydrostatic drives have is for contractors who have different operators or workers running their machines,” Roorda says. “If you’ve got a trencher with a mechanical drivetrain, you really want somebody on there who’s going to pay attention to the machine.”
Hydrostatic machines are a lot more forgiving when it comes to maintenance demands because there are a lot fewer moving parts. “You constantly have to adjust things on a mechanical machine,” Roorda adds. “You still have to do daily maintenance on hydrostat machines, but because oil makes things go, it’s a lot more simple to keep up.”
Hydrostatic-drive trenchers have proven to be productive and economical in even the toughest digging conditions, says Bob Wren, training manager for Astec Underground. “We use a hydrostatically driven pump and motor in a closed loop system,” he explains. “To ensure ample power in all ground conditions, we go a step further, mounting a flywheel behind the hydraulic motor.”
Wren says this flywheel turns at the same speed as the hydraulic motor and is coupled to the trencher’s torsion shaft, which prevents shock loads (generated by rocks and other hard spots in the ground) from being transmitted back into the hydraulic motor and pump and causing damage. “The torsion shaft then plugs into a double reduction planetary drive,” Wren says. “The flywheel stores energy in soft soil conditions then transfers it to the planetary drive for torque multiplication in tough digging conditions. It gives operators an automatic boost of power when they need it most and helps simplify trenching operation while increasing productivity.”
Another way to ensure trencher productivity, Bolay says, is to pay attention to a machine’s operator station and its layout. “As our machines evolve, Ditch Witch has placed more emphasis on a comfortable, easy-to-use work environment for the operator,” he says. “Just because trenchers have a tough job doesn’t mean their operators should too. We’ve always felt the best way to keep a machine working was to keep a guy on it all day. And good ergonomics are the key to making that happen.”
Ditch Witch RT 40 & RT 55
- Heavy-duty frame, axles and backfill blade
- 90-degree swivel seat and high-visibility sloped front hood
- Cruise control system (optional)
- High horsepower Kubota diesel engine
- Four-wheel steering
- Dual hydrostatic drives
Vermeer LM42, V4150A & RT450
- Center-mounted operator backhoe seat (RT450)
- Servo-controlled ground drive system (RT450)
- Patented creep override for better machine control (RT450)