Efficiencies in Green Waste Reduction
Most logging operations face — probably routinely — the same issue: a need to get rid of “slash” and tree tops left behind after usable timber is harvested from a site. Some operations have means to take care of this material themselves. Others hire contractors to do final cleanup or even complete landclearing. Either way, someone needs the right equipment for the job, which typically translates into a large brush chipper, or a tub or horizontal grinder.
Chipper or Grinder?
Two primary criteria are often crucial for clearing operations when making equipment selection decisions: mobility and productivity (and the first usually has a hand in the latter). But, the usual size of areas being cleared is a key consideration also.
For example, if the land being cleared is most often limited to one to five acres, a large towable brush chipper is an option. Vermeer produces larger models ranging from 18-inch to 20-inch (diameter) capacity. And, assuming that the slash left behind would mostly involve smaller-diameter material (compared to usable timber) in this size range, these machines would be sufficient.
But, if the majority of jobs involve five acres or more, jumping up to a horizontal or tub grinder may be the best bet. One could assume that logging operations are most often harvesting land that falls into this category. In fact, most statistics show that logging involves 40 acres or more, even if it’s a selective harvest.
In regard to mobility, larger chippers are usually towed, which can be a challenge when trekking through narrow trails of a forest. Vermeer offers larger grinders equipped with tracks, which do not require a tow vehicle for movement around a jobsite. This can be a distinct mobility advantage. Then come productivity considerations. Vermeer manufactures larger horizontal and tub grinders ranging from 300 HP to 1000 HP. Obviously, they grind greater amounts of material faster. And, the size capacity of the units requires less handling of the branches — horizontal models feature 14- to 20-foot feed tables.
One final consideration: some landclearing operations sell the end material as a commodity product, such as mulch for landscaping. Mulch yards (buyers) sometimes require a uniform chip size. Larger grinders give you the ability to size the product while chippers usually do not.
Grinders for Larger Jobs
For many years, both types (tub grinders and horizontal grinders) have been successful in the market. This used to put manufacturers head-to-head — few used to offer both. Vermeer is one manufacturer that now does, which allows the sales force to objectively evaluate advantages of each.
Both types of grinders excel in conditions and applications that match up with their capabilities. In short, tub grinders generally perform better with heavy, large-diameter material such as stumps and root balls. Certainly, a logging operation may leave behind unusable stumps. If stumps are the majority of cleanup, tubs are a good option. But, if processing longer raw material is the consistent application, a horizontal model may be the best choice.
Also, smaller loading equipment can be used for horizontal grinders, because they typically have a lower feeding height than a tub grinder. This could be a major factor, depending on the auxiliary equipment an operation has on-site.
These grinder “categories” sometimes come with options that are specific to each. For example, Vermeer offers both track-mounted horizontal units and conventional towed models. In a situation where a single job site may have several debris piles — such as a landclearing job, the self-propelled track-mounted option can be highly efficient. So rather than having to tow the machine short distances, it can be moved by the operator, possibly into areas where it could not be towed. Vermeer tub grinders, on the other hand, offer both loader and non-loader options.
Among the primary advantages of having a grapple loader on your tub grinder is better visibility of the tub; the loader cab provides excellent view of the tub cavity, so operators can load material more efficiently. It also helps the operator identify and clear contaminants mixed in with material. Self-contained loaders may also eliminate the need for extra pieces of equipment, because transporting or renting a loading unit may not be required.
Non-loader machines are common on work sites that include a fleet of multi-purpose loading equipment. Some non-loader tub grinders require multiple auxiliary loaders to meet the production capabilities of the machine.
Selecting the right equipment for landclearing can be a challenge — there are many options. But, this is a positive. Brush chippers, for example, have traditionally been used in tree-care applications. Now, larger models have made their way into the landclearing market. Just a few years ago, tub grinders dominated the market for 400 HP and above. Since then, horizontal options are on the rise, and now tracked models (like those offered by Vermeer) are taking off.
Also, large machines have unique maintenance and safety concerns. But, manufacturers like Vermeer are taking steps to make maintenance much easier and improve machine safety.
Once a buyer has determined what’s important and prioritized, the decision will be much easier.
Addressing Maintenance and Safety
So, now a buyer has settled on grinder type, options and size. In addition to resulting in more choices and more customized “fits” for certain operations and applications, advancements are also addressing what have in the past been two primary concerns about owning and using any type of large grinder: maintenance and safety.
As with any machine, proper preventive maintenance for a grinder is crucial to its longevity and productivity. Hammers, teeth, hammer shafts, anvils and screens are high-wear items. Because of the difference in types of grinding materials and varying amounts of use from application to application, it is difficult to formulate a specific “rule of thumb” for average wear or longevity. Key variables include how well the raw material is cleaned, how fine the material is ground and how effectively the operator prepares the material.
Some grinder owners have in the past resisted regular maintenance of teeth and hammers, particularly because of the time involved. It used to take up to a day to replace these components. And, if hammers are allowed to wear without proper maintenance, the hammermill could go out of balance and its vibration will cause excessive bearing wear and other vibration-related issues.
Vermeer is one manufacturer to address this issue with their patented Duplex Drum System for tub and horizontal grinders. It offers a 35 percent increase in rotational inertia with a 10 percent weight reduction. And, it offers the operator the ability to change out any individual hammer within minutes without removing other hammers. It is much more efficient than the conventional “pin and plate” drums that have dominated the market in the past. The hammers also reverse for nearly double the life span, and the drum skin adds life by protecting them from wear and tear.
Grinders, by nature, are aggressive material processors. Owners and operators must realize that these types of machines are inherently prone to throw debris, especially if non-organic (prohibited) material is mistakenly introduced into the grinder.
Understanding this fact, Vermeer Manufacturing has successfully developed the patented Thrown Object Restraint System (TORS) for tub grinders and the Thrown Object Deflector (TOD) for the horizontal grinders. When in use, these systems substantially reduce the quantity of and distance that objects can be thrown. This can amount to a 4/5 reduction in the required safe operating area for tub grinders using the TORS. Vermeer tub grinders also feature a Falling Object Canopy, positioned directly above the ground control station, which provides protection for the ground operator.
Provided standard with each tub and horizontal grinder is a radio remote controller, which allows the operator to run the machine from the safety and comfort of an independent, enclosed loader cab.
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