The Hole Picture

Downtime is a four-letter word in the road repair business, and whether you’re looking at hours or days rests largely on your concrete drill. To make sure it’s up to performing day after day to the best of its capabilities, a little upfront investigation and preventive maintenance are a must. By implementing a few best practices, you’ll spend less on repairs and new parts, and keep that dreaded D-word to a minimum.
IT’S ALL IN THE HOMEWORK
Long before you hit the pavement, do your research on the different types of drills and their components, and how each can impact maintenance and performance.
For example, drills operate with either a roller bearing feed system or a nylon pad system. With a roller bearing feed system, rollers gently move the gangs forward and backward on the carriage without causing friction. With a nylon pad system, however, the pad slides across the carriage to move the gangs forward and backward. This creates friction that causes the pads to loosen and wear much faster, which results in more maintenance, replacement parts, and downtime.
KEEP AN EYE OUT
While you might have selected the right drill for the job with high-quality components, you’re not done yet. You also need to perform regular maintenance checks to ensure it’s operating at full capacity.
Oil is vital to the performance of your drill, and if you’re not using the right kind you could be putting your engine and components in jeopardy. Rock drill oil is the only kind of oil you should be using. Other lubricants, like pneumatic tool oil and automatic transmission fluid, are too light for concrete drills and will burn off quickly, which could damage the drill motor. In addition, they contain synthetics that can damage blades, hoses, and O-rings.
Once you have oil in your drill, don’t forget to check it often—as frequently as once or twice a day if your drill is in high use. If the oil level is too low, the motor will slow and the power will decrease until the lack of lubrication causes it to seize. Also remember to keep the fittings and guide wheels well greased.
In addition to keeping the oil in check, you’ll also want to keep an eye on the trunnion bolts, which secure the latch that holds the bit in the drill. Trunnion bolts can become loose or even break as a result of repetitive dry firing, which occurs when the drill is operating but not drilling into anything. Replacing these bolts is not only inconvenient, but costly as well. To prevent this, only run the drill when the bit is touching the concrete and drilling into the slab. Also, be sure to turn the motor off before removing the drill from the hole.
The repetitive hammering motion of the drill can also loosen parts like thru-bolts, which are located on the motor. Operating the drill with loose thru-bolts can cause them to break, so check and tighten them often. And remember to keep an eye on other parts that wear over time, like pawls and pawl springs, air tubes, ratchet rings, and chucks. And, finally, be sure to keep your drill clean. Dust can accumulate quickly on parts and affect performance, so use an air hose or pressure washer to clean your drill daily.
SIZING IT UP
The most important thing to keep in mind is air. Your drill can’t perform at its best without air, and will perform poorly without enough of it.
First, make sure the air hose is the proper diameter. While a hose that is too wide has no effect on a drill’s performance, a hose that is too narrow can’t transport enough air to the drill. That results in reduced power and drilling force, and can limit how deep you can drill. If you’re using a multi-gang drill and want to check if you have the right size of hose, turn off one or more of the gangs. If the remaining one speeds up, there’s not enough air volume to keep all the drills operating at full capacity.
Hose length also can impact how much air reaches the drill. As the length of the hose increases, the air pressure decreases, which again reduces the power and drilling force and limits how deep you can drill. The same thing happens when the air compressor doesn’t deliver enough air at the necessary rate. Most drills need 100 cfm for each gang to operate. A two-gang drill requires 200 cfm, a three-gang requires 300 cfm, and so forth. Using a lower cfm air compressor might work fine when drilling smaller diameter holes—1 inch or less—but for larger holes it will slow down the drill considerably. Always refer to your owner’s manual for recommended hose sizes and cfm requirements.
TAKING A BREAK
If your drill is going to be inactive for a while—whether it’s through the winter or just a few days—it’s a good idea to lubricate its working parts to prevent rust from forming. Rust can develop from the tiniest amount of moisture and it only takes a simple speck to cause the drill’s motor to seize.
To lubricate your drill, disconnect the hose from the motor and pour a small amount of rock drill oil directly into the motor. Run it at half throttle for a moment to thoroughly coat components. Drain any condensation from the machine’s filters and cover the drill with a tarp if it will be stored outside.
When you’re ready to start using the drill, ensure the oiler is full and bolts are tight. If it has wheels, check the tire pressure and blow out the hose that runs between the drill and compressor to ensure it’s clean. If dirt or debris accumulated in the hose, it could be forced into the motor when you start it and affect your drill’s performance. ■
About the Author
Randy Stevens is the vice president of sales at E-Z Drill. He has been with the company for more than 20 years. Stevens has served on the committee of the Association of Equipment Manufacturers (AEM) and is a member of the American Concrete Pavement Association.