Inhaltsverzeichnis
Rod ends, maintenance-free
Features
Maintenance-free rod ends and maintenance-free corrosion-resistant rod ends comprise a housing with integral shank and a maintenance-free spherical plain bearing. The shank has an internal or external thread, the spherical plain bearing is firmly seated and located in the housing.
The rod ends are available in open designs and in designs sealed on both sides. The housings and shanks are protected against corrosion by a zinc coating.
The sliding layer between the inner ring and outer ring is PTFE composite , ELGOGLIDE or PTFE film .
Area of application
Maintenance-free rod ends can support radial loads in a tensile or compressive direction. They are particularly suitable for slow movements with small to moderate swivel angles and unilateral loads. For alternating loads, rod ends with bearings of series GE..-UK-2RS(-2TS) and GE..-FW-2RS(-2TS) can be used.
Dimension series E
Rod ends to DIN ISO 12240-4, dimension series E incorporate radial spherical plain bearings GE..-UK or GE..-UK-2RS(-2TS) and have a right or left internal or external thread, ➤ Figure. The sliding contact surfaces are hard chromium/PTFE composite or hard chromium/ ELGOGLIDE. The thin walled design of the eye housing allows compact adjacent constructions. These rod ends are also available by agreement with radial spherical plain bearings GE..-FW or GE..-FW-2RS(-2TS) of dimension series G.
Rod ends, dimension series E
Dimension series K
Rod ends to DIN ISO 12240-4, dimension series K incorporate radial spherical plain bearings GE..-PW and have a right hand or left hand internal or external thread, ➤ Figure. The sliding contact surface is steel/PTFE film .
Rod ends, dimension series K
Corrosion-resistant rod ends
Corrosion-resistant rod ends to DIN ISO 12240-4, dimension series K incorporate radial spherical plain bearings GE..-PS and have a right hand or left hand internal or external thread, ➤ Figure. The sliding contact surface comprises corrosion-resistant steel and corrosion-resistant PTFE film attached to the curved outer ring surface.
The housing and shank has a thread to DIN 13 and the diameter range extends from 5 mm to 30 mm. The bore tolerance of the spherical plain bearings is H7 Ⓔ.
Corrosion-resistant rod ends with an internal thread are also available with CETOP mounting dimensions to ISO 8139 for pneumatic cylinders. These are used in preference in control and automation engineering.
Corrosion-resistant rod ends, corrosion-resistant, dimension series K
Series, sliding layer, standard
Maintenance-free rod ends are designed according to their specific series with different sliding layers.
Series and design for sliding layer ELGOGLIDE or PTFE composite
Series |
Thread |
DIN ISO |
Dimension series |
Shaft d |
|
---|---|---|---|---|---|
mm |
|||||
over |
incl. |
||||
GIR..-UK |
Internal, right hand |
12240-4 |
E, |
6 |
30 |
GIR..-UK-2RS |
17 |
80 |
|||
GIR..-UK-2TS |
30 |
80 |
|||
GIL..-UK |
Internal, left hand |
6 |
30 |
||
GIL..-UK-2RS |
17 |
80 |
|||
GIL..-UK-2TS |
30 |
80 |
|||
GAR..-UK |
External, right hand |
12240-4 |
E, |
6 |
30 |
GAR..-UK-2RS |
17 |
80 |
|||
GAR..-UK-2TS |
30 |
80 |
|||
GAL..-UK |
External, left hand |
6 |
30 |
||
GAL..-UK-2RS |
17 |
80 |
|||
GAL..-UK-2TS |
30 |
80 |
Series and design for sliding layer PTFE film
Series |
Thread |
DIN ISO |
Dimension series |
Shaft d |
|
---|---|---|---|---|---|
mm |
|||||
over |
incl. |
||||
GIKR..-PW |
Internal, right hand |
12240-4 |
K, |
5 |
30 |
GIKSR..-PS |
|||||
GIKPR..-PW |
Internal, right hand, |
||||
GIKPSR..-PS |
|||||
GIKL..-PW |
Internal, left hand |
||||
GIKSL..-PS |
|||||
GAKR..-PW |
External, right hand |
12240-4 |
K, |
5 |
30 |
GAKSR..-PS |
|||||
GAKL..-PW |
External, left hand |
||||
GAKSL..-PS |
Materials
Maintenance-free rod ends fulfil all the requirements in terms of fatigue and wear resistance, hardness, toughness and structural stability as well as maintenance-free operation.
Maintenance-free rod ends are manufactured from drop forged quenched and tempered steel C45 QT in accordance with DIN EN 10083-2 and have a zinc coated surface.
Corrosion-resistant rod ends have an inner ring made from a corrosion-resistant steel such as X105CrMo17. The outer ring and the housing are made from X8CrNiS18-9. Alternative materials are permissible.
Sealing
Sealed rod ends of dimension series E have the suffix 2RS or 2TS. They are protected by lip seals on both sides against contaminants and water spray. Rod ends GIR..-UK-2TS, GIL..-UK-2TS, GAR..-UK-2TS and GAL..-UK-2TS are sealed on both sides by integrated, triple lip high performance seals.
Rod ends of dimension series K are not sealed.
Lubrication
During the running-in phase, PTFE particles are transferred from the sliding layer to the opposing running surface. As a result, the small roughness features of the inner ring surface are filled in. It is only once this tribologically smooth surface is produced in conjunction with the detached PTFE particles that the bearings can achieve a long operating life.
ACHTUNG
Maintenance-free rod ends do not have relubrication facilities and must not be lubricated.
Any lubrication of maintenance-free rod ends after dry running-in will impair the smoothing effect necessary and will considerably reduce the operating life of the bearings.
Operating temperature
The permissible operating temperature is dependent on the sliding contact surface and the sealing arrangement, see table.
ACHTUNG
If the temperature exceeds the stated values, there will be a reduction in the operating life and the effect of the sealing arrangement.
At temperatures below 0 °C, a reduction in the load carrying capacity of the rod ends must be taken into consideration.
Operating temperature
Series |
Temperature |
Reduced load carrying capacity |
|
---|---|---|---|
°C |
°C |
||
over |
incl. |
from |
|
GIR..-UK GIL..-UK GAR..-UK GAL..-UK |
–50 |
+200 |
+100 |
GIR..-UK-2RS GIL..-UK-2RS GAR..-UK-2RS GAL..-UK-2RS |
–30 |
+130 |
|
GIR..-UK-2TS GIL..-UK-2TS GAR..-UK-2TS GAL..-UK-2TS |
–30 |
+100 |
|
GAKR..-PW, |
–50 |
+200 |
|
GIKSR..-PS, |
–10 |
+80 |
+80 |
Special designs
The following are available by agreement:
- rod ends with special threads
- rod ends with different anti-corrosion protection.
Suffixes
Suffixes for available designs: see table.
Available designs
Suffix |
Description |
Design |
---|---|---|
2RS |
Standard lip seals on both sides |
Standard |
2TS |
Triple lip high performance seals on both sides |
|
‒ |
With special thread |
Special design, available by agreement only |
‒ |
With different anti-corrosion protection |
Design and safety guidelines
The chapter Technical principles brings together the essential guidelines on the subjects of friction, rating life and the adjacent construction.
Dimensioning
In the case of rod ends, the permissible static load of the housing and shank must always be checked. In calculation of the rating life of the rod end, the decisive factor is the rating life of the spherical plain bearing fitted in the housing.
The direction of load and the type of load determine the design of the rod end and the sliding contact surface of the spherical plain bearing.
Permissible loading of rod ends
The permissible load depends on the type of load.
Pulsating or alternating loads subject the material of the rod ends to greater stress than constant loads. For calculation, these operating conditions must be taken into consideration by means of the load factor fb , see table.
ACHTUNG
The maximum equivalent bearing load P must not exceed the permissible load on the rod end Pper , see ➤ equation.
In the case of rod ends with the sliding material ELGOGLIDE, the basic static load rating C0r of the rod end is lower than the basic dynamic load rating Cr of the bearing.
Loading of rod end
The following applies: The permissible load on the rod end Pper is calculated as follows:P | N |
Maximum equivalent bearing load |
Pper | N |
Permissible load on the rod end |
C0r | N |
Basic static load rating of the rod end |
fb | – |
Load factor, see table. |
Load factors
Type of load |
Series |
Load factor fb |
---|---|---|
Unilateral load |
All series |
1 |
|
||
Pulsating load |
GIR..-UK(-2RS, -2TS) GAR..-UK(-2RS, -2TS) GIKR..-PW GAKR..-PW GIKSR..-PS GIKPSR..-PS GAKSR..-PS |
2,25 3 2,25 3 2,25 2,25 3 |
|
||
Alternating load |
||
|
Basic static load rating
In this case, the basic static load rating C0r indicates the load carrying capacity of the housing and shank under static tensile load. At room temperature, it includes a safety factor of at least 1,2 in relation to the yield strength of the material used for the housing and shank. The basic load rating describes the maximum permissible static tensile load when utilising 83% of the material yield strength at the most highly stressed cross-section.
ACHTUNG
The basic static load rating C0r of the rod end refers only to the load carrying capacity of the rod end housing. It is based on tensile and compressive loads acting across or in the direction of the rod end shank.
If the basic static load rating C0r is used to the full, the shaft and housing must be made from high-strength materials.
Basic dynamic load rating
The basic dynamic load rating Cr refers to the spherical plain bearing fitted and is a parameter for calculating the bearing rating life. It is dependent on the sliding contact surface and has a significant influence on the rating life of the rod ends.
ACHTUNG
The equivalent bearing load and additional bending stresses in the shank area must be taken into consideration if, in addition to radial load in a tensile or compressive direction, other transverse forces act in an axial direction to the shank.
Calculation example for radial rod end GAR25-UK
The rating life of the radial rod end is calculated on the basis of the sliding layer PTFE composite .
Given data
The given data for calculation of the rating life are as follows:
- linkage bearing arrangement of a transfer unit
- unilateral combined load.
Operating parameters
Bearing load |
Fr |
= |
16 000 N |
Fa |
= |
1 200 N |
|
Swivel angle |
β |
= |
27° |
Swivel frequency |
f |
= |
12 min–1 |
Operating temperature |
ϑ |
= |
+100 °C |
Bearing data
Radial rod end |
= |
GAR25-UK |
||
|
Basic dynamic load rating |
Cr |
= |
51 100 N |
Basic static load rating of housing |
C0r |
= |
105 000 N |
|
Sphere diameter |
dK |
= |
35,5 mm |
|
Sliding material |
PTFE composite |
Required
- Bearing with the required rating life Lh ≧ 6 000 h.
Checking of permissible loads
ACHTUNG
The validity of the permissible loads and sliding velocities must be checked, since useful rating life calculation is only possible within this range.
Combined load
For calculation of the combined load, the factor X must be determined from the diagram for radial spherical plain bearings using the ratio Fa/Fr = 1 200 N / 16 000 N = 0,075:Specific bearing load
The specific bearing load must be calculated with the aid of the specific load parameter K and checked for validity:Sliding velocity in swivel motion
The sliding velocity must be calculated with the aid of the sphere diameter dK and the swivel angle β and checked for validity:Specific frictional energy pv
The specific frictional energy pv must be checked for validity:Permissible load on the rod end
The load carrying capacity of the rod end must be considered separately from that of the spherical plain bearing. Calculation of the load carrying capacity required should be carried out using the load factor fb, see table.
The rod end GAR25-UK with a housing having a basic load rating C0r = 105 000 N is suitable.
Determining the rating life equation
For calculation of the rating life, the valid rating life equation must be selected and then subjected to correction.
Selection of the valid rating life equation
For maintenance-free plain bearings, the following applies:Correction factors, as a function of bearing type
The correction factors necessary for the plain bearing material PTFE composite must be selected from the matrix and used to correct the rating life equation appropriately.
Series |
Sliding layer |
Correction factors |
|||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
Spherical plain bearing |
Rod end |
fp |
fv |
fpv |
fpv* |
fϑ |
fA |
fα |
fβ |
fHz |
|
GE..-UK |
GAR..-UK |
PTFE composite |
■ |
■ |
■ |
‒ |
■ |
■ |
‒ |
‒ |
■ |
Rating life equation following correction
Calculation of rating life
The values for the correction factors in the corrected rating life equation must be taken from the diagrams. The specific plain bearing factor KL = 1 000.
Correction factors
Correction factor |
Value |
---|---|
Load fp |
0,96 |
Sliding velocity fv |
0,99 |
Frictional energy fpv |
1 |
Temperature fϑ |
0,92 |
Condition of rotation fA |
1 |
Variable load fHz |
1 |
Rating life Lh
The rating life is calculated as follows:Result
The selected rod end GAR25-UK fulfils the requirement for a rating life Lh ≧ 6 000 h.
Accuracy
The main dimensions of the rod ends conform to DIN ISO 12240-4.
The stated thread length is the minimum usable length, based on normal chamfering practice for the thread of the mating component.