Machine Matters – September 2009

60- to <130-horsepower trenchers keep you focused on installing product

Trenchers in the 60- to <130-horsepower size classes are production machines, prompting manufacturers to key in on features that keep your attention dialed in on putting product in the ground instead of constantly monitoring machine functions.

For example, says Jon Kuyers, Vermeer's utility product segment manager, some control systems automatically maximize the productivity of the machine by keeping the engine operating within its maximum torque range without the operator having to constantly adjust controls. These systems decrease the ground drive speed when going through tough soil and automatically speed up when the ground is softer.

"Cruise control helps eliminate operator fatigue," says Kevin Smith, product planning manager, Ditch Witch. "A trencher typically goes through a variety of soil conditions, all which require adjustments. With cruise control, the machine automatically adjusts the ground drive speed to match the horsepower to the digging conditions." Cruise control is optional on Ditch Witch's hydrostatic machines in this size classification.

Manufacturers have also simplified machine controls. For example, Astec Underground's RT1160 has integrated key machine functions into a color LCD monitor, giving operators one location to switch between trencher, plow and saw controls, monitor engine rpm and hydraulic pressure, and select two-wheel or four-wheel steering. "You can focus on the job at hand and not have to go from one side of the machine to the other to find controls," says Carl Seeliger, Astec's utility products manager.

Push a button on the Astec monitor to put the machine into trenching mode, and the joystick mounted on the armrest controls the forward and backward speed of the trencher. To plow, replace the trencher attachment with a plow, push another button on the monitor, and the same joystick operates the plow moving forward. In addition, another joystick operates auxiliary functions such as plow lifting, blade pivot and plow swing from side to side.
In another nod to all-day operator comfort, Ditch Witch's cab features include a 90-degree swivel seat, tilt steering wheel, adjustable arm rests and an easy-to-read gauge cluster.

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To add maneuverability, Vermeer put quad tracks on three models in this size class: rubber tracks on the RTX750 and RTX1250 models and steel quad tracks on XTS1250. The quad tracks maintain a constant four-point ground contact, giving these models extra stability on side hills, plus more tractive effort and higher flotation. "You can go over hills and undulations and load trailers and you don't have a breakover point," Kuyers said. "Experiencing that breakover point, especially when loading a trailer, can be nerve wracking for some operators."

Quad tracks also have benefits in mud, giving you the ability to maneuver out of a sticky situations since the tracks have independent front and rear steering. Another advantage: no flat tires, which can be the bane of residential work.

Use all the available muscle: One key benefit of a four-wheel steer machine is its ability to turn a tight radius around obstacles. Not only does four-wheel steering give you more maneuverability, it doesn't put as much loading on the trencher boom as using two-wheel steering would, Seeliger says.

Match your chain speed to the soil: Full-bore operation can put unnecessary wear on your machine. Most trencher drive systems will operate at their optimum productivity at around 75 percent of the maximum chain speed. In addition, many soil types simply don't require the gung-ho approach. For instance, if you're plowing all-out in sandy soil, much of the vibration will be transmitted back up to the machine and operator. You simply don't need the full rpms to get the job done.

Maintain a consistent chain speed: Set the chain speed for the most efficient way to excavate the soil without constantly lugging the engine down. Newer engines are made to run optimally at a consistent higher rpm. This is especially critical when running a saw, where inconsistent speeds can result in chatter, which causes premature wear and will shorten the life of the machine.

Maintain the balance: There's a finite supply of hydraulic power available simultaneously to the ground drive and trencher circuit. When you decrease the chain speed, you increase the torque to the trencher and ground drives, achieving a more productive balance of the operating system.

Extract rocks on the go: Kuyers advises using this method when you run across a rock: Back up and put your boom behind the rock, digging to the maximum dig depth. Then gently raise your boom – with the chain still running – and dig over the rock until you're just on top of it. As soon as you get past the rock, put your boom down in the maximum digging position again, over digging on the other side of the rock. If the rock is a size you can pull out, lift your boom up, reverse, then ease your boom down on top of the rock and slowly engage the chain, pulling the rock out of the ground.

Pay attention to the chain, teeth and sprocket: Several things affect the wear rate on these, Smith says, including maintaining the proper chain tension. If you over- tighten the chain, you will increase the wear, shortening the life of the rollers, bearings and idlers. Over tightening the chain also eats up horsepower. And every time you change the chain, also change the drive sprocket. If you put a new chain on a worn sprocket it will accelerate the wear on the chain. (Check out the video on this in our digital edition.)

Consider maintenance part of your productivity plan: It's easy to be tempted to put in that extra 100 feet of product instead of taking the time to do daily service checks. Over time, however, ignoring preventive maintenance will take a huge bite into your productivity.
When plowing, make sure the plow blade is parallel to the path of the tractor: When plows are offset outside the wheels of the trencher, keep the plow blade straight, since tilting will side load the blade and increase wear.