Rod ends and hydraulic rod ends, requiring maintenance
Features
Rod ends requiring maintenance and hydraulic rod ends incorporate spherical plain bearings with a steel/steel sliding contact surface. Schaeffler can also supply spherical plain bearings with a steel/ bronze sliding contact surface.
Rod ends requiring maintenance
Rod ends requiring maintenance comprise a housing with integral shank and a spherical plain bearing requiring maintenance. 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.
Area of application
Rod ends requiring maintenance can support radial forces in a tensile or compressive direction and can transmit motions and forces with low moment levels. They are particularly suitable for alternating radial loads and, in certain circumstances, for unilateral loads. The thin walled design of the eye housing allows compact adjacent constructions.
Dimension series E
Rod ends to DIN ISO 12240-4, dimension series E incorporate radial spherical plain bearings GE..-DO or GE..-DO-2RS(-2TS) and have a right or left hand internal or external thread. The sliding contact surface is formed by steel inner and outer rings, ➤ Figure.
Rod ends requiring maintenance, dimension series E, steel/steel sliding contact surface
Dimension series K
Rod ends to DIN ISO 12240-4, dimension series K incorporate radial spherical plain bearings GE..-PB and have a right or left hand internal or external thread. The sliding contact surface is formed by steel inner rings and bronze outer rings, ➤ Figure.
Rod ends requiring maintenance, dimension series K, steel/bronze sliding contact surface
Sealing
Sealed rod ends have the suffix 2RS or 2TS. They are protected by lip seals on both sides against contaminants and water spray. Rod ends GIR..-DO-2TS, GIL..-DO-2TS, GAR..-DO-2TS and GAL..-DO-2TS are sealed on both sides by integrated, triple lip high performance seals.
Rod ends of dimension series K are not sealed.
Lubrication
The relubrication options for rod ends of dimension series E or dimension series K are of differing design depending on the rod end size, see tables.
Dimension series E, relubrication facility
Shaft d |
Relubrication |
|
---|---|---|
mm |
||
over |
incl. |
|
‒ |
12 |
‒ |
15 |
20 |
Lubrication hole in housing |
25 |
‒ |
Taper type lubrication nipple to DIN 71412
|
Dimension series K, relubrication facility
Shaft d |
Relubrication |
---|---|
mm |
|
5 |
‒ |
>5 |
Taper type lubrication nipple to DIN 3405
|
Series, sliding contact surface, standard
Rod ends requiring maintenance are designed according to their specific series with different sliding contact surfaces, see table.
Series and design
Series |
Sliding contact surface |
Thread |
DIN ISO |
Dimension series |
Shaft d |
|
---|---|---|---|---|---|---|
mm |
||||||
over |
incl. |
|||||
GIR..-DO |
Steel/ |
Internal, |
12240-4 |
E, |
6 |
30 |
GIR..-DO-2RS |
17 |
80 |
||||
GIR..-DO-2TS |
30 |
80 |
||||
GIL..-DO |
Internal, |
6 |
30 |
|||
GIL..-DO-2RS |
17 |
80 |
||||
GIL..-DO-2TS |
30 |
80 |
||||
GAR..-DO |
External, right hand |
E, |
6 |
30 |
||
GAR..-DO-2RS |
17 |
80 |
||||
GAR..-DO-2TS |
30 |
80 |
||||
GAL..-DO |
External, |
6 |
30 |
|||
GAL..-DO-2RS |
17 |
80 |
||||
GAL..-DO-2RS |
30 |
80 |
||||
GIKR..-PB |
Steel/ |
Internal, |
12240-4 |
K, |
6 |
30 |
GIKL..-PB |
Internal, |
|||||
GAKR..-PB |
External, right hand |
K, |
||||
GAKL..-PB |
External, |
Hydraulic rod ends
Hydraulic rod ends incorporate radial spherical plain bearings GE..-LO or GE..-DO. The sliding contact surface is formed by steel inner and outer rings. The rod ends can be screw mounted using a thread in the shank or welded in place by means of circular or rectangular welding faces.
Rod ends GIHRK..-DO and GF..-DO are also available with maintenance-free spherical plain bearings of series GE..-UK, GE..-UK-2RS(-2TS), GE..-FW or GE..-FW-2RS(-2TS).
Rod ends GIHRK and GIHNRK are slotted on both sides up to diameter d ≦ 50 mm. Rod ends GIHRK are slotted on one side from d ≧ 60 mm and rod ends GIHNRK are slotted on one side from d ≧ 63 mm.
Area of application
Hydraulic rod ends can support radial forces in a tensile or compressive direction and can transmit motions and forces with low moment levels. They are also suitable for alternating radial loads.
Hydraulic rod ends with thread clamping device
The spherical plain bearings used are located in the rod end by means of retaining rings. A thread clamping facility comprising two hexagonal socket screws to DIN EN ISO 4762 is present on the threaded shank, ➤ Figure.
Rod ends GIHNRK..-LO conform to DIN 24338 and ISO 6982. They are used in standard hydraulic cylinders to CETOP recommendation RP 58 H and to the standards DIN 24333, DIN 24336, DIN ISO 6020-1 and DIN ISO 6022.
Rod ends GIHRK..-DO are particularly suitable for hydraulic cylinders. They have very small linkage distances with maximum stroke utilisation.
Hydraulic rod ends with thread clamping device
Hydraulic rod ends with welding face
Rod ends of series GK..-DO conform to DIN ISO 12240-4. They have a circular welding face, a locating pin on the shank base and a 45° welding chamfer, ➤ Figure. These rod ends are suitable for fixing to piston rod ends and cylinder bases. The spherical plain bearings are located in the rod end by staking on both sides.
Rod ends of series GF..-DO are available in a heavy-duty design with a rectangular welding face. They are suitable for fixing to hydraulic cylinder bases. The spherical plain bearings are located in the rod end by retaining rings and can be dismounted.
Hydraulic rod ends with welding face
with circular welding face, locating pin on shank base and 45° welding chamfer · GF..-DO,
with rectangular welding face
Sealing
Rod ends with integrated spherical plain bearings GE..-DO-2RS or GE..-FO-2RS are protected by lip seals on both sides against contaminants and water spray.
Rod ends with integrated spherical plain bearings GE..-DO-2TS or GE..-FO-2TS are sealed on both sides by integrated, triple lip high performance seals.
Lubrication
The relubrication options for hydraulic rod ends are of differing design depending on the rod end size, see tables. Hydraulic rod ends GIHRK..-DO and GF..-DO are relubricated by means of taper type lubrication nipples to DIN 71412 on the rod end eye housing.
Hydraulic rod end GK..-DO, relubrication facility
Shaft d |
Relubrication |
|
---|---|---|
mm |
||
over |
incl. |
|
‒ |
12 |
‒ |
15 |
20 |
Lubrication hole in housing |
25 |
‒ |
Taper type lubrication nipple |
Hydraulic rod end GIHNRK..-LO, relubrication facility
Shaft d |
Relubrication |
---|---|
mm |
|
12 |
‒ |
>16 |
Taper type lubrication nipple |
Series, sliding contact surface, standard
Hydraulic rod ends requiring maintenance have a steel/steel sliding contact surface, see table.
Series and design
Series |
Sliding contact surface |
Standard |
Shaft d |
|
---|---|---|---|---|
mm |
||||
from |
to |
|||
GIHNRK..-LO |
Steel/steel |
DIN 24338, |
12 |
250 |
GIHRK..-DO |
20 |
120 |
||
GK..-DO |
DIN ISO 12240-4, |
10 |
80 |
|
GF..-DO |
‒ |
20 |
120 |
Materials
Materials and material variants for rod ends requiring maintenance and hydraulic rod ends differ according to their specific series, see table.
Materials
Series |
Material |
---|---|
GIR..-DO, GIL..-DO GIR..-DO-2RS, GIL..-DO-2RS GIR..-DO-2TS, GIL..-DO-2TS GIKR..-PB, GIKL..-PB GAR..-DO, GAL..-DO GAR..-DO-2RS, GAL..-DO-2RS GAR..-DO-2TS, GAL..-DO-2TS GAKR..-PB, GAKL..-PB |
Drop forged quenched and tempered steel C45+QT to DIN EN 10083-2, |
GIHNRK..-LO GIHRK..-DO |
drop forged quenched and tempered steel C45+N to DIN EN 10083-2 surface with preservative. |
spheroidal graphite cast iron GJS 400-15
surface with preservative. |
|
GK..-DO |
Drop forged structural steel S355J2G3
|
GF..-DO |
Forged or rolled structural steel S355J2G3
|
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 |
||
from |
to |
from |
|
GIR..-DO GIL..-DO GAR..-DO GAL..-DO |
–60 |
+200 |
+100 |
GIR..-DO-2RS GIL..-DO-2RS GAR..-DO-2RS GAL..-DO-2RS |
–30 |
+130 |
|
GIR..-DO-2TS GIL..-DO-2TS GAR..-DO-2TS GAL..-DO-2TS |
–30 |
+100 |
|
GIKR..-PB GIKL..-PB GAKR..-PB GAKL..-PB |
–60 |
+250 |
|
GIHNRK..-LO GIHRK..-DO GK..-DO GF..-DO |
–60 |
+200 |
Special designs
In addition to the special designs with suffixes, Schaeffler can also supply further designs by agreement:
- hydraulic rod ends requiring maintenance with other types of lubrication nipple or threaded connector for central lubrication
- hydraulic rod ends with maintenance-free spherical plain bearings GE..-UK, GE..-UK-2RS(2TS), GE..-FW, GE..-FW-2RS(2TS)
- 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 |
|
C2 |
Radial internal clearance Group 2, |
Special design, available by agreement only |
C3 |
Radial internal clearance Group 3, |
|
‒ |
With other types of lubrication nipple or |
|
‒ |
Hydraulic rod ends with maintenance-free spherical plain bearings GE..-UK, GE..-UK-2RS (2TS),GE..-FW, GE..-FW-2RS (2TS) |
|
‒ |
With special thread |
|
‒ |
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.
Principles of lubrication
The lubrication of spherical plain bearings requiring maintenance is covered in detail in the corresponding chapter for spherical plain bearings.
Relubrication
Rod ends requiring maintenance must be lubricated.
They have relubrication facilities, except for smaller rod ends of some series that do not have lubrication grooves and lubrication holes. These rod ends are indicated in the dimension tables.
Rod ends to DIN ISO 12240-4, dimension series E with bore diameter d = 15 mm to 20 mm are relubricated via a hole in the rod end eye housing, ➤ Figure. For reasons of housing strength, these rod ends do not have lubrication nipples.
Relubrication via hole
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.
Loading of rod end
The following applies: The permissible load on the rod end P 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 |
GIHNRK..-LO GIHRK..-DO GK..-DO GF..-DO GIR..-DO(-2RS, -2TS) GAR..-DO(-2RS, -2TS) GIKR..-PB GAKR..-PB |
2 2,75 2,75 2,75 3 3 3 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.
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 GIKR25-PB
The rating life of the radial spherical plain bearing is calculated on the basis of the steel/bronze sliding contact surface.
Given data
The given data for calculation of the rating life are as follows:
- machine on a packaging line
- pulsating load.
Operating parameters
Bearing load |
Fr min |
= |
10 000 N |
Fr max |
= |
20 000 N |
|
Swivel angle |
ß |
= |
45° |
Swivel frequency |
f |
= |
20 min–1 |
Time required for indexing operation (cycle) |
= |
3 s |
|
Number of indexing operations |
|
= |
300 cycles/h |
Relubrication interval |
Iw |
= |
40 h |
Operating temperature |
ϑ |
= |
21 °C |
Bearing data
Radial rod end |
= |
GIKR25-PB |
||
|
Basic dynamic load rating |
C r |
= |
47 100 N |
|
Basic static load rating |
C0r |
= |
72 900 N |
|
Sphere diameter |
dK |
= |
42,85 mm |
Required
- Bearing with the required rating life LhN(ED) ≧ 5 000 h.
Calculation of rod end size
The permissible static load on the rod end is calculated using the load factor fb = 3, see table.
The rod end GIKR25-PB with the basic load rating C0r = 72 900 N is suitable.
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.
Specific bearing load
The specific bearing load must be calculated with the aid of the specific load parameter K and checked for validity. In the case of a concentrically acting, variable force F, P = Fmax = 20 000 N: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: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 plain bearings requiring maintenance, the following applies:Correction factors, as a function of bearing type
The correction factors necessary for the steel/bronze sliding contact surface must be selected from the matrix and used to correct the rating life equation appropriately.
Series |
Sliding contact surface |
Correction factors |
|||||||
---|---|---|---|---|---|---|---|---|---|
Spherical plain bearing |
Rod end |
fp |
fv |
fϑ |
fA |
fdK |
fβ |
fHz |
|
‒ |
GIKR..-PB |
Steel/bronze |
■ |
■ |
■ |
■ |
■ |
■ |
■ |
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 = 2,3.
Correction factors
Correction factor |
Value |
---|---|
Load fp |
0,75 |
Sliding velocity fv |
0,71 |
Temperature fϑ |
1 |
Condition of rotation fA |
1 |
Swivel angle, oscillation angle fβ |
0,76 |
Sphere diameter fdK |
0,97 |
Variable load fHz |
1,45 |
Rating life Lh
The rating life is calculated as follows:Rating life LhN with periodic relubrication
The rating life can be increased by means of periodic relubrication as a function of the relubrication interval.
The necessary relubrication interval and preferred relubrication interval must be calculated and checked for validity: Based on a relubrication frequency Lh/lW = 280 h/40 h = 7, a correction factor fNH = 2,1 is determined. Based on a swivel angle β = 45°, the correction factor fNβ = 3,2.Taking account of the operating duration
3 s/cycle gives 20 cycles/min at a utilisation of 100%. The number of indexing operations of 300 cycles/h gives 5 cycles/min
The operating duration ED is calculated as follows: Rating life LhN taking account of the operating duration ED:Result
The selected radial rod end GIKR25-PB fulfils the requirement for a rating life LhN(ED) ≧ 5 000 h.
Welding of hydraulic rod ends
The thermal distortion occurring during welding must be kept as small as possible.
Recommendation
The following procedure has proved effective in the welding of rod ends:
- The thickness of the weld seam should be as small as possible. This should be based on the load.
- If thicker weld seams are necessary, these should be welded in several layers.
- Electrodes with low heat generation should be used, such as Kb electrodes.
- The current strength selected for welding should be towards the lower limit.
ACHTUNG
Welding current must not pass through the rod end, otherwise macroscopic protrusions may occurr on the curved inner or outer rings.
Tightening torques for fixing screws in hydraulic rod ends
The fixing screws in hydraulic rod ends must be tightened according to a defined scheme, ➤ Figure and table.
Hydraulic rod ends
Tightening torques
Designation |
Fixing screw |
Tightening torque MA |
|||||
---|---|---|---|---|---|---|---|
Step, screw |
|||||||
1 |
2 |
3 |
4 |
1, 2, 3, 4 |
|||
A |
B |
A |
B |
C, D, C, D |
|||
Nm |
|||||||
GIHNRK12 |
‒ |
M 5 |
0,16 |
2,6 |
8 |
8 |
‒ |
GIHNRK16 |
‒ |
M6 |
0,26 |
4,3 |
13 |
13 |
‒ |
GIHNRK20 |
GIHRK20 |
M8 |
0,64 |
11 |
32 |
32 |
‒ |
GIHNRK25 |
GIHRK25 |
M8 |
0,64 |
11 |
32 |
32 |
‒ |
‒ |
GIHRK30 |
M8 |
0,64 |
11 |
32 |
32 |
‒ |
GIHNRK32 |
‒ |
M10 |
1,2 |
21 |
64 |
64 |
‒ |
‒ |
GIHRK35 |
M10 |
1,2 |
21 |
64 |
64 |
‒ |
GIHNRK40 |
GIHRK40 |
M10 |
1,2 |
21 |
64 |
64 |
‒ |
GIHNRK50 |
GIHRK50 |
M12 |
2,2 |
36 |
110 |
110 |
‒ |
‒ |
GIHRK60 |
M10 |
‒ |
‒ |
‒ |
‒ |
46 |
GIHNRK63 |
‒ |
M12 |
‒ |
‒ |
‒ |
‒ |
80 |
GIHNRK70 |
‒ |
M16 |
‒ |
‒ |
‒ |
‒ |
195 |
‒ |
GIHRK70 |
M12 |
‒ |
‒ |
‒ |
‒ |
80 |
GIHNRK80 |
GIHRK80 |
M16 |
‒ |
‒ |
‒ |
‒ |
195 |
GIHNRK90 |
GIHRK90 |
M16 |
‒ |
‒ |
‒ |
‒ |
195 |
GIHNRK100 |
GIHRK100 |
M20 |
‒ |
‒ |
‒ |
‒ |
385 |
GIHNRK110 |
GIHRK110 |
M20 |
‒ |
‒ |
‒ |
‒ |
385 |
‒ |
GIHRK120 |
M24 |
‒ |
‒ |
‒ |
‒ |
660 |
GIHNRK125 |
‒ |
M20 |
‒ |
‒ |
‒ |
‒ |
385 |
GIHNRK160 |
‒ |
M24 |
‒ |
‒ |
‒ |
‒ |
660 |
GIHNRK200 |
‒ |
M30 |
‒ |
‒ |
‒ |
‒ |
1 350 |
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.