With open gearing such as rack & pinions, lubrication is extremely critical. A thin film of grease should always be present on the contacting tooth flanks to ensure that there is no metal-to-metal contact, which can quickly damage the teeth.
All of our rack & pinion load ratings are based on adequate grease lubrication. If adequate lubrication is not provided to the rack & pinion tooth flanks, their loading carrying capacity and lifetime will be reduced.
Manual lubrication (applied by hand) can be unreliable and inconsistent and reduce the lifetime of the gearing. It is highly recommended to use our Automatic Lubrication Systems, which precisely pump grease through an applicator directly to the rack and pinion tooth flanks. This provides continuous lubrication at the tooth flanks, extending the lifetime and maintaining the quality of the gearing.
Although it is not recommended, it is possible to run our Rack & Pinions without lubrication. To discuss the limitations and concerns of running dry, please consult the factory.
To supply the lubricant to the applicator, we have Automatic Lubricators available which has a fully adjustable flow rate. These lubricators are available in two sizes (125 cc and 475 cc) and are battery operated, externally powered lubricators and are also available.
The lubricator flow rate is controlled by a set of DIP switches, which can adjust the emptying time of the lubricator from one month to eighteen months; the amount of lubricant required per day depends on the gearing size (module) and the linear operating speed (v), please see graph below:
Example: For a module 3.0 rack and pinion running at 2.0 meters per second, the required lubricant flow rate per day would be ~0.63 cc. The dip switch setting to achieve this flow rate for the 125 cc lubricator would be #5 and #7 (switches #1 through #6 adjust the flow rate; #7 switch turns the lubricator on and makes light blink).
The operation of the lubricators can be synchronized with the machine operation by use of a contact cable, so the grease only flows when needed. It is also possible to electronically detect when the lubricator is empty and needs to be refilled or replaced.
When mounting the Automatic Lubricators, the lubricator should be located below the applicator discharge point, so the grease does not flow by gravity. Ideally, the lubricator should also be mounted sideways or upside down to prevent undesired flow. If this is not possible, then a non-return valve should be used before the applicator.
We have two different lubricant applicators available: a brush and felt gear. The brush can be located near the gear mesh and although it can provide continuous lubrication, it can not precisely place the lubricant at the gear mesh. This should only be used when the felt gear applicator is not practical.
To precisely place the lubricant at the gear mesh, a felt gear applicator should be used. The felt gear is actually a gear made out of felt that can mesh directly with the pinion or rack to supply the lubricant. The lubricant flows through a mounting shaft and directly in-between the teeth of the felt gear. Ideally, the felt gear should mesh with the pinion, since it sees the most cycles. By meshing directly with the pinion or rack, the felt gear can provide continuous lubrication to the tooth flanks before they are loaded.
The felt gear should be primed with lubricant before it is mounted into the machine.
We have the most experience with grease lubrication, which typically does not flow and stays where you apply it. When using our felt gear applicators, we recommend Kluber Structovis AHD grease. Kluber Microlube GB0 can also be used, but does not flow as well through the felt gear.
Other greases that have been tested with good results include: Oest Langezeitfett LT 200, BP Energrease LS EP 00, DEA Glissando 6833 EP00, Fuchs Lubritech Gearmaster ZSA and Molykote G-Rapid plus 3694.
We do not recommend oil lubrication because it will flow away from the tooth flanks.
For use with our Servo-Worm Reducers, we have complete automatic lubricator assemblies, which include a 125 cc automatic lubricator, hose connection set, check valve, mounting shaft and felt gear - all mounted to a bracket for easy mounting directly onto the servo-worm reducer housing.
For more information on our Automatic Lubricator Assemblies, please follow this PDF link.