It’s a common situation: Your equipment isn’t working as effectively as it was the day it came off the manufacturing line. With most tools and machines, regular maintenance and replacement of worn-out parts can be the key to restoring it to maximum power. Earth drills are no exception. Knowing how to prevent, recognize and repair the most common problems goes a long way toward keeping a mechanical drill running efficiently. The following tips can help contractors running these types of machines.

Monitor Transmission Oil Level

Check the transmission oil level every 30 days or after 40 hours of operation. Inspect the transmission or gearbox immediately if it begins making unusual sounds or experiences extreme heat. Heat from the gearbox is normal, but higher temperatures or the smell of burnt oil are indicators of extreme heat.

Unusual sounds and heat are the first problem indicators, and if ignored, the gearbox might start to lock up when in use. This is a symptom of low oil in the gearbox. Look for seepage or oil leaks along the top of the transmission, especially around the bottom seal at the output shaft. If these issues are present, check the fluid in the gearbox and change if necessary. Maintain the correct fluid levels by changing the transmission oil after every 40 to 50 hours of use.

When adding oil, hold the transmission top level and remove the pipe plug. Squeeze oil into the transmission until oil just comes out of the hole. Then replace the pipe plug and tighten to 10 foot-pounds of torque. Always go by the recommended oil in the operator’s manual to ensure the drill operates to OEM specifications.

Examine the Flexible Drive Shaft

For models with a flexible drive shaft, examine every 50 hours of operation. Inspect the shaft housing and look for tears or breaks in the rubber casing. Repairing with duct tape or shrink tubing can be effective for small tears, but replace the housing if there are deep cuts or torn wire braids.

On the core, check for broken wires and kinks. Replace the core if there are broken wires or sharp kinks so the shaft will function properly. Small kinks or twists shouldn’t cause any large concerns.

When disassembling, cleaning and greasing the drive shaft, follow the manufacturer recommendations. Disassembly of the flexible drive shaft includes removing the kill switch and throttle wires, detaching the shaft from the transmission, disconnecting the complete shaft assembly, and removing the flexible shaft core and housing. After removing the flexible shaft core, wipe off the old grease with a cloth. Clean the inside of the flexible shaft housing by pulling a clean rag through with a long piece of wire. This might require several passes for removal of all grease. Then apply a light coat of manufacturer-recommended grease to the core and reassemble.

Some manufacturers recommend white lithium grease — a lightweight, high-temperature tool grease. Lithium grease can withstand excessive heat without damaging the shaft. Some lithium combination greases can withstand 430 degrees Fahrenheit with frequent lube intervals.

Operators should not use regular axle grease when lubricating, due to its risk of degrading in high temperatures. Degraded lubricant runs to the lowest point in the flex shaft, increasing risk of burning the flex shaft. Be careful in choosing the right grease for the drill, and don’t over lubricate. Excessive grease can gum up in the flex shaft and burn, which causes excessive heat and reduces the shaft’s life. Not enough grease can dry out the cable, which will then break easily or generate enough heat to burn through the outer housing.

Check Clutch, Throttle Cable and Throttle Bracket Assembly

Check the clutch for wear every 30 days or when the flexible shaft is lubricated, if applicable to the operator’s drill. When the clutch requires maintenance, operators can’t always detect audible or visual signs, because the clutch continues to run even if no more clutch padding exists. A worn clutch causes a weaker performance when engaging the auger and when accelerating the engine from idle to full speed. If a clutch starts slipping, check the shoes and drum, clean and replace if the padding is missing.

Drills with a centrifugal clutch drive the auger as the engine speeds up to full throttle. Not only does the clutch ensure positive power transfer, it also protects the unit from shock while drilling. If the auger turns while the engine idles, first inspect the engine for proper idle speed and throttle linkage.

The throttle regulates the power and speed of the engine. In some earth drills, the throttle lever is under the handlebar next to the transmission box. The throttle lever should pull smoothly without binding the throttle wire.

Some manufacturers include a special throttle bracket assembly. Check that the throttle bracket is fully engaged before the lever bottoms out against the handlebar. In the idle position, the throttle bracket pulls the rivet clip tightly against the sliding clip, forcing the governor arm to idle. When fully engaged, the bracket clip slides over the rivet as the governor arm moves. If binding does occur, remove the clip and twist it slightly, then reinstall and check again.

Some models do not use the sliding clip. With these, check that the moving arm on the bracket pulls away from the governor arm in the full throttle position. In the idle position, it should push against the governor arm.

Inspect the throttle cable and bracket assembly before each use or if the drill isn’t running smoothly. If the problem persists, check for stretched, discolored or broken clutch springs or broken clutch shoes and replace if needed.

Inspect (and Replace) Blades

Operators often allow the points and blades to wear beyond effectiveness. The drill can run perfectly and spin all day, but if the blades and points are worn, the unit will become less and less effective. It’s important to monitor the blade sharpness and replace them when they become dull. If the auger needs new blades or points, discontinue use until they have been replaced. Always having replacement parts on hand will make this a quick and easy fix and will keep downtime to a minimum.

Keep an Eye on the Torque Tube

Premium earth drills might feature torque tubes, which prevent unexpected kickback when the auger hits a rock or underground obstruction by absorbing the shock, keeping operators safe and the drill under control at all times. The tube itself does not require extensive maintenance, besides inspecting for cracks before each use.

Pay attention to the spring and button attachment system. Ensure the button stays securely snapped into place before operation and replace the spring-button attachment if bent or broken. Spring-button attachment systems eliminate the chance of losing pins or bolts that some drills use for attachment purposes.

Utilize Resources

For most routine maintenance and inspections, operators can use ordinary hand tools like a wrench and screwdriver. An operator’s manual is a great resource for specific instructions. Beyond routine maintenance, work with a manufacturer that offers service or in-house technical consultations. Check with the drill’s manufacturer for the most accurate instruction on any service or repairs.

A regular maintenance schedule will keep your drill working as well as it did on day one.