There are some new designs that hardly anyone knows about, because the main manufacturers don't consider them sufficiently mature, or they are concentrating on their own product line. Also, be absolutely sure that the ratings for the gear boxes are consistent in terms of stress. I've discovered that in some cases the big gearboxes have a higher "Name Plate Rating" for torque or force that actually results in a much higher stress on the components than the smaller gear boxes. So, the big ones have a much shorter life. In one case, the life was stated to be 100,000 inches of travel for the big ones, and 1,000,000 inches for the smaller ones, but there were no precise data...it was essentially anecdotal, but still instructive.
~James B, Professor, Huntsville, AL
When selecting service factory use AGMA rating systems instead of DIN Standards. DIN tends to be too light. Check for shock loading in applications. Don't always buy on price, understand your application and service factor requirements.
~James Haldane, Technical Support, Black Diamond, Canada
Make sure when comparing geared motors that you keep in mind that you need to compare similarly rated gearboxes. For example, you need to compare worm geared motors with worm geared motors and helical geared motors with helical geared motors. You need to keep an eye on the service factors and also whether the gearbox comes filled with oil. A major consideration should be whether the motor used is a standard motor or a designated motor. I personally would always recommend that clients would use standard AC designed motors as when it comes to replacement costs they are a fraction of the price of a designated motor.
~Cal M, General Management, Dublin, Ireland