When machines are set in place, aligned, and buttoned-down, it becomes too easy to forget about the gear couplings that may be used to transmit power between the machines. Gear couplings are tough work horses that perform well in many applications because they operate quietly and efficiently. Since they are so reliable, we tend to take them for granted, forgetting about them unless trouble develops. Many times problems do occur simply because of neglect. Faults can usually be eliminated by keeping the shafts properly aligned and ensuring that the coupling lubricant is in good condition. Remember the old adage, “The right time to put in new lubricant is while the old lubricant is still good”. Open, inspect, and re-lubricate gear couplings every six months. If they operate in harsh conditions such as high ambient temperatures, they may need to be re-lubricated more frequently. On opening the coupling, a close inspection of the lubricant will tell if the re-lubrication interval is too long. Adjust the interval accordingly, and be sure to use a lubricant specified for gear couplings. Also, make sure you do not over-lubricate. Pumping away with the grease gun until the lubricant oozes out past the containment o-ring is just as harmful as having too little lubricant. Finally, it is imperative that the lubricant fits the application and operating environment.