At government-run green waste recycling sites, members of the public drop off material such as trees and shrubs, or residents participate in curbside pickup. Those green waste materials then go into a grinder to break them down.

But sometimes, people place material in the green waste containers that should not be in there. That could include large pieces of metal, large rocks, or a car alternator.

“Curbside green waste pickups don’t always have green waste,” said Cory Gross, regional sales manager for Morbark. “They have contaminants, things that should not go through a grinder.”

To help limit that damage, Morbark has released a new VTECTION System option for its 3000, 3400, and 6400 series Wood Hog horizontal grinders.

When contaminants enter the grinder, the VTECTION system will sense the vibration and reverse the feed, which lowers the rotor’s chance of repeatedly striking the foreign object.

Gross said the system will idle down the machine and disengage the drive or clutch so the machine is no longer grinding. That can help cost-conscious government entities prevent damage to a grinder.

The operator can change parameters on the fly. He or she can set an acceptable operating vibration level through the electronic controller of the VTECTION system. Different material produces different vibration levels, so the operator can adjust the trip point to match the grinding application. As an example, the operator can set the system to chunk wood, and the system will trip if it senses a vibration level that was not considered acceptable for chunk wood.

The adjustment could stop the machine from grinding when rock or metal is present, for example. In that case, the grinder would grind wood waste, but trip on “ungrindables” like rock or metal, and that can protect the mill.

Morbark’s Integrated Control System (MICS) initiates several actions in the following order to remove the offending material out of the rotor area once the VTECTION system is triggered: reversing and stopping the infeed, bringing the engine speed to idle, and disengaging the clutch.

The system then displays a warning message on the MICS screen. The operator can then inspect the grinder and remove the object before resuming operation.