Keep on grinding

A stump grinder can be a powerful attachment tool when mounted on a skid steer loader, but only when it is kept in peak running condition. The stump grinder is a simple cutting device with a round, steel wheel with perforations holding a set of carbide cutters around the circumference of the wheel.

Carbide cutting teeth in action. Properly torqued and repaired teeth are key to proper operation.

These attachments are most commonly used for landscaping construction and stump removal applications. The attachment is robust enough to handle tough, dirty jobs – and that kind of work can create problems for the machine if it is not properly maintained.

First and foremost, keep safety in mind when performing any type of maintenance on the attachment. Make sure the stump grinder is lowered to the ground and the parking brake is set. Make absolutely certain that the hydraulic circuit is in the off position, turn off the skid-steer engine and remove the key. If the stump grinder must remain in the raised position during maintenance, block the unit securely to prevent accidental release of the lifting mechanism. Finally, disconnect the hydraulic couplers as a backup safety measure.

Proper lubrication
All maintenance begins with proper lubrication. Each moving part should be lubricated using a quality lubricant. “We recommend the use of SAE Multi-Purpose Lubricant or equivalent SAE Multi-Purpose type grease,” says Dave Aldrich, product support and training representative for Paladin Attachments, manufacturer of the Bradco Stump Grinder attachment. “Neglecting proper lubrication can lead to reduced efficiency, increased wear, early breakdown, and the needless replacement of parts.”

All parts with grease fittings should be lubricated on a daily basis or every eight hours of operation, whichever comes first. Be sure to clean the grease fittings before using the grease gun so as not to inject dirt into the system. After greasing, wipe off any excess grease from the grease fittings. Dirt can collect on exposed excess grease, causing increased wear. If a grease fitting is missing, replace it immediately.

The gearbox is critical to attachment longevity. The oil level in the gearbox should be checked at least once a week. This is a simple, but very important step. “For example,” states Aldrich, “on a Bradco Stump Grinder, this check can be performed by removing the access cover from the front of the frame and then removing the pipe plug from the end of the gearbox. The lubricant should be at the same level as the plug. If the lubricant level is low, fill it with 80-90 weight gear lubricant. Do not overfill. Too much lubricant might rupture the gearbox seals.”

Maintenance requirements
Regular maintenance is the key to long life and safe operation. Most manufacturers have reduced maintenance requirements on the stump grinder to a minimum, but it is very important that they be performed correctly and in a timely manner.

Disc perforations assist with chip discharge. Make sure all safety guards are in place to prevent the operator being hit by flying debris.

Before using the stump grinder each day, routinely look it over. Run your hand over the entire machine to make sure nothing is loose or broken. Make sure nothing that should be sharp is dull, and nothing that should be dull is sharp. If hydraulic fluid is leaking from a hose connection, tighten it or replace it. If a bearing needs greasing, grease it. If the bearings are over-greased, wipe them off.

Check the brazed joints of the cutter head to make sure all the cutters are bolted on and meet the torque specs of the manufacturer. Make sure the cutters aren’t folded down or broken off. This check should be performed at least once a day; twice a day if possible.

Hydraulic safety should be a key point in any maintenance program. A garden hose flows at approximately five to 10 gallons per minute. In comparison, the stump grinder has a flow rate of up to 40 gallons per minute in high-flow units. That immense amount of pressure builds up in the hose and, if the hose breaks or is cut, it can be a life-threatening issue. The hydraulic fluid can escape the hose with enough pressure to lacerate the skin or sever an appendage.

Maintenance checklist
The following items should be checked on a daily basis:

• Skid-steer loader hydraulic oil level
• Gearbox castle nut – Make sure it is torqued to a minimum-250/maximum-350 foot pounds. (Every nut and bolt has an SAE torque rating. If under-torqued, the nut can become loose. If over-torqued, the pressure exerted can begin to pull down on and distort the threads on the nut and bolt, causing the nut to loosen.)
• Teeth hardware mounting – torque to a minimum-150/maximum-180 foot pounds
• All other hardware tight and in good repair
• No leaks in hydraulic system
• Gearbox power shaft free of foreign material around the shaft. (Any foreign material around the shaft can become an abrasive, which can amplify the wear of seals and shafts.)
• No damage to teeth – replace if necessary. (If the teeth are broken off or folded over, the performance of the stump grinder diminishes greatly, requiring the use of more time and more fuel to perform the task.)
• All safety guards and devices are installed correctly. (Without safety guards in place, the operator and those standing nearby are at risk of being hit by flying debris.)
• No missing or illegible safety/warning decals. (There may be three different warning emblems on the attachment. One indicates the potential to hurt someone; a second indicates the potential for catastrophic injury; and the third indicates the potential to kill.)

The operator’s manual is your best source of information for maintaining your stump grinder attachment, but common sense plays an important role as well. If something doesn’t look right or sound right, check it. It just makes good sense.

About the author
Stephen Kingsley is a Market Manager for Paladin Attachments, which includes the Bradco brand, based in Dexter, Mi. For more information, visit www.paladinattachments.com .