Planetary Gear Heads Troubleshooting

Factors that contribute to gear head noise include input speed, gear head ratio, output torque, radial and axial loads and mounting errors.


Following the proper mounting procedure is critical to minimizing noise and maximizing performance. Many gear heads need to be mounted to the servo motor in a vertical orientation first. This allows the motor shaft to center the gear head. After being mounted to the motor, the gear head can be used in any orientation.


High gear head friction and drag may be caused by grease volume, gear quality, component dimensional accuracy and bearing quality. Look for a gear head manufacturer that tests every gear head for input drag before shipment. Each size and ratio has an acceptable range for drag. Drag should be measured in both directions for peak drag and speed.


For applications that require IP65 or IP67 protection, be sure to note that an IP65 motor and an IP65 gear head in combination do not always provide IP65 protection. Look closely at how the interface between the motor and gear head is sealed. The best approach is to use an O-ring seal between all housings for IP65 protection on the full assembly. A new type of planetary gear head meets the requirements of food and beverage handling, packaging and dispensing by providing a round stainless steel housing with no external seams and IP67 protection. Such gear heads can handle caustic cleaning chemicals and high pressure wash down, so engineers can place the gear head anywhere regardless of environmental factors, eliminating the cost of additional components such as enclosures, shielding and mechanical transmissions.


Lubrication failure is a common problem with geared motors. Either oil or grease may be used to lubricate planetary gear heads. Grease has the advantage of providing lubrication for the lifetime of the gear head, eliminating the need for maintenance. Grease enables the gear head to be mounted in any orientation and eliminates concerns about leakage. Oil requires maintenance and re-lubrication, usually every few thousand hours. Leakage is always a concern with oil lubrication. The orientation of the gear head with oil lubrication is usually restricted, must be known at the time of the order and usually cannot be changed. A common misconception is that oil-filled units always run cooler than grease-filled units. Actually, the sealing required for an oil-filled gear head generates more heat than the oil saves.


Here are some typical planetary gearing applications:

A high-speed planetary gear head makes it possible to automatically slice meat, bread and frozen foods at speeds up to 4 slices per second. The slim right-angle design fits into the machine envelope and provides quiet and smooth operation.

In a car toning application, a planetary gear head runs at high speeds 24 hours a day, 7 days a week for 30,000 hours. The high torque/size ratio of the gear head reduces the envelope size and footprint of the machine. The gear head is lubricated for life so no maintenance is required.

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