In the case of a system with two parallel guides, one side needs to be fitted with floating bearings. A suitable solution comprising fixed and floating bearings is available for every installation position, whether horizontal, vertical or lateral. This type of assembly prevents jamming and blockage on the guides resulting from discrepancies in parallelism. Floating bearings are created through a controlled extension of the clearance in the direction of the expected parallelism error. This creates an additional degree of freedom on one side.
During installation, take care that the floating bearing has approximately the same clearance on both sides. In the designs below you can see the version of the fixed and floating bearing system recommended by us. The mounting surfaces of the guides and carriages should be even (e.g. machined surface) to prevent tension in the system. Smaller areas of mounting surface unevenness can be compensated to a certain extent by floating bearings.
Assembly is easy with the drylin® WQ square profile. Floating bearings for all directions (±1mm) compensate misalignments and parallelism errors between rails. This eliminates jamming, otherwise only prevented by time-consuming manual alignment of the system.
Although drylin® W is a profile rail system, it is able to compensate angular errors around the x-axis. An angular adjustment of ±7° is possible here. This effectively eliminates the misalignment known to occur when assembling sheet metal fabrications.
To ensure successful use of maintenance-free drylin® linear bearings, it is necessary to follow certain recommendations: if the distance between the driving force point and the fixed bearings is more than twice the bearing spacing (2:1 rule), a static coefficient of friction of 0.25 can theoretically result in jamming.
This principle applies regardless of the value of the load or drive force. The friction product is always related to the fixed bearings. The greater the distance between the drive and guide bearings, the higher the degree of wear and required drive force.
Failure to observe the 2:1 rule during the use of linear plain bearings can result in uneven motion or even system blockage. Such situations can often be remedied with relatively simple modifications.
If you have any questions regarding design and/or assembly, please make use of our technical support.