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drylin® N - Design rules

Compensation of misalignment in mm

floating bearing NW-17 NW-27 NW-40 NW-80
LL Y 0,6 0,45 0,4 0,6
LL Z 0,5 0,8 1 0,8
LL YZ Y: 0,6, Z: 0,5 Y: 0,3, Z: 0,4 Y: 0,4, Z: 2,0 Y: 0,6, Z: 0,8


Schematic diagram of the floating bearing options

LLZ Floating bearing in z-direction
LLY Floating bearing in y-direction
LLYZ Floating bearing in yz-direction


Floating bearing for guide system

For application with two parallel guide systems, one side must be designed as floating bearing. There is a suitable fixed-/floating-bearing solution for every installation location, whether it be horizontal, vertical or lateral. This installation method prevents a sluggishness and/or a jamming of the guide with parallelism deviations between the guides. The floating bearing can be implemented by a controlled extension of the clearance in the direction of the estimated parallelism error. Thus an additional degree of freedom arises on one side.

During installation, take care that the floating bearing has the same clearance on both sides. You can see the version of the fixed/floating bearing system recommended by us in the designs given in the individual sections of the systems. The mounting surfaces of the rails and carriages should possess a good evenness (e.g. machined surface) to prevent twisting in the system. Smaller unevennesses in the mounting surfaces can be compensated up to a certain measurement by the floating bearing.

Automatic adjustment of parallelism errors,
1. Floating bearing, 2. Fixed bearing

Eccentric forces

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.

Design rules for floating bearings The 2:1 rule,
1. Floating bearing, 2. Fixed bearing