drylin® R - Design tips
Floating bearing for shaft guide
drylin® linear plain bearings of the type series 03 offer great advantages in applications with parallel shafts. They compensate for alignment and parallelism errors by their special geometry and should be used on the shaft farthest from the drive.The design provides a spherical area on the outer jacket of the aluminum bearings for self-alignment. Reductions in load capacity are prevented as the shaft always lies on the total projected surface. By the even load distribution over the entire bearing, edge loads do not occur with the self-aligning drylin®- linear bearings. In order to compensate for parallelism errors between two shafts, the outer diameter is designed smaller than the housing bore diameter by (according to size) 0.2 to 0.3 mm. These bearings acquire an elastic seating by the use of the O-rings. The excess give the maximum permitted deviation from the parallelism.
The self-aligning bearings in the drylin® product range are supplied hard anodized. These surfaces guarantee the highest wear resistance if the aluminum bearing moves in the housing during compensation adjustments.
Another option are the housing bearings of the type series OJUM06 LL and RJUM-06 LL. The mounting of the bearing allows a parallelism adjustment between the shafts by ±3 mm. The unique suspension of the supporting housing on an axis running in the z-direction enables an angular error compensation of up to 3.5°.
Compensation of misalignments
| Series RJUM-03 / OJUM-03 | +/- 0,5° |
| Series RJUM-06 LL / OJUM-06 LL | +/- 3,5° |
Compensation of parallelism errors
| Series RJUM-03 / OJUM-03 | +/- 0,1 mm |
| Series RJUM-06 LL / OJUM-06 LL | +/- 3 mm |
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.
