Load carrying capacity and life

Basic load ratings

Basic load ratings are key data specific to the plain bearings that are not standardised and may differ from manufacturer to manufacturer. They are derived from the material-specific load parameters K and the projected load-bearing area of the bearing in each case.

Basic dynamic load rating

The basic dynamic load rating C_r or C_a is used in cases of dynamic loading. A plain bearing is subjected to dynamic loading if it performs rotary, swivel, tilt or linear motion under load.

The basic dynamic load rating is the maximum permissible dynamic load. In the case of radial spherical plain bearings, it can be utilised to the full only if the load acts purely in a radial direction. In the case of axial spherical plain bearings, it can be utilised to the full only if the load acts purely in a concentric, axial direction.

If the basic dynamic load rating is utilised to the full, there is often a considerable reduction in the operating life of the bearings. The degree to which the basic load rating is utilised should therefore always be matched to the required operating life. The basic load rating depends on the sliding contact surface and influences the rating life of the plain bearings.

Basic static load rating

The basic static load rating C_0r or C_0a is used if a plain bearing is subjected to load while stationary.

It indicates the load that the plain bearing can support at room temperature without damage to the bearing. This is subject to the precondition that the components adjacent to the bearing must prevent deformation of the bearing.

ACHTUNG

If the basic load rating C_0r or C_0a is utilised to the full, the shaft and housing must be made from high strength materials.

Bearing load

The bearing load describes the external forces acting on the bearing.

Concentric constant force F

For calculation of the static load safety factor, the specific load and the rating life, load values can be taken directly into consideration under the following preconditions:

Loads act in a radial direction only on radial spherical plain bearings, angular contact spherical plain bearings and cylindrical plain bushes.
Loads act in an axial direction only on axial spherical plain bearings.
Loads do not vary in their magnitude and direction during operation.

Concentric constant radial force F

P = F · P₀ = F₀

Radial spherical plain bearing ·

Angular contact spherical plain bearing ·

Cylindrical plain bush

Concentric constant axial force F

P = F · P₀ = F₀

Axial spherical plain bearing ·

Thrust washer

Concentric variable force F

If the concentric force varies in magnitude during motion, rating life calculation and checking of the permissible specific load must be carried out on the basis of the maximum force F_max.

One possible influence on the rating life as a result of pulsating or alternating loads is taken into consideration by means of the correction factor f_Hz, see link.

Variable bearing load

P = F_max

Combined loading by radial and axial forces

If spherical plain bearings are subjected simultaneously to radial and axial loads, combined loading is present. The equivalent static bearing load is calculated on a similar basis to the equivalent dynamic bearing load. The permissible ranges for the ratio F_a/F_r are valid for static and for dynamic loading.

In the case of dynamic loading, the equivalent dynamic bearing load P must be used in rating life calculation. This values takes the combined forces into consideration in rating life calculation.

In the case of static loading, the equivalent static bearing load P₀ must be used in calculation of the static load safety factor. This value takes the combined forces into consideration in calculation of the static load safety factor.

Calculation of radial and angular contact spherical plain bearings, ➤ Figure and ➤ Figure :

Calculation of axial spherical plain bearings, ➤ Figure :

P	N	Equivalent dynamic bearing load
X		Axial load factor for radial and angular contact spherical plain bearings, ➤ Figure and ➤ Figure
F_r	N	Radial dynamic bearing load
P₀	N	Equivalent static bearing load
F_r0	N	Radial static bearing load
Y		Radial load factor for axial spherical plain bearings, ➤ Figure
F_a	N	Axial dynamic bearing load
F_a0	N	Axial static bearing load.

ACHTUNG

The correct spherical plain bearing is selected as follows:

The permissible range for the ratio F_a/F_r in the case of radial spherical plain bearings is between 0 and 0,3.
If the ratio F_a/F_r exceeds the value 0,3, angular contact spherical plain bearings can be used. Their ratio F_a/F_r extends to a value of 3, since they can support higher axial forces.
If the axial forces are more than twice the radial forces, axial spherical plain bearings can be used.

Radial spherical plain bearings,
combined loading

X = axial load factor for radial spherical plain bearings · F_a = axial bearing load · F_r = radial bearing load

Angular contact spherical plain bearings,
combined loading

X = axial load factor for angular contact spherical plain bearings · F_a = axial bearing load · F_r = radial bearing load

Axial spherical plain bearings,
combined loading

X = axial load factor for axial spherical plain bearings · F_a = axial bearing load · F_r = radial bearing load

Static load safety factor

Before the rating life is calculated, it is advisable to check the static load safety factor.

The static load safety factor S₀ is the ratio between the basic static load rating C₀ and the equivalent static load P₀:

S₀		Static load safety factor
C₀	N	Basic static load rating
P₀	N	Equivalent static bearing load.

ACHTUNG

The static load safety factor must always be ＞1. Any instructions relating to specific series must be observed.

Specific bearing load

The specific bearing load describes the contact pressure present in the bearing in the dynamic state. It is the decisive criterion for assessing the suitability of a plain bearing in the particular application.

The specific bearing load occurring in a bearing is dependent on the load, the sliding contact surface, the lubrication conditions and the mounting situation. Due to the influence of these factors, precise calculation is not possible.

If the required operating life is to be achieved, the specific bearing load must be matched to the actual operating conditions.

ACHTUNG

Under extreme loading conditions, such as high axial load in the case of radial spherical plain bearings, elastic deformation of the bearing and housing may lead to contact pressure concentrations. Please contact Schaeffler in this case.

Calculation

The specific bearing load p for a plain bearing is calculated with the aid of the specific load parameter K.

Radial and angular contact spherical plain bearings:

Axial spherical plain bearings:

Bushes and radial component of flanged bushes:

Thrust washers and axial component of flanged bushes:

p	N/mm²	Specific bearing load
K	N/mm²	Specific dynamic load parameter, see table
P	N	Equivalent dynamic bearing load, see link
F_r	N	Radial dynamic bearing load
F_a	N	Axial dynamic bearing load
C_r, C_a	N	Radial or axial basic dynamic load rating.

ACHTUNG

For spherical plain bearings with ELGOGLIDE operated under the condition of the specific bearing load p ≦ 25 N/mm², please consult Schaeffler.

Specific load parameter

Sliding layer, sliding contact surface	Specific dynamic load parameter K
Sliding layer, sliding contact surface	N/mm²
ELGOGLIDE	300
ELGOGLIDE-W11	300
PTFE composite	100
PTFE film	100
ELGOTEX	140
E40, E40-B	140
E50	70
Steel/steel	100
Steel/bronze	50

Alternative calculation method for bushes and thrust washers

Due to the simple geometry of plain bushes EGB, ZWB and ZGB as well as flanged bushes EGF and thrust washers EGW, their specific bearing load can alternatively be determined by means of the following relationships. It is assumed in this case that there is uniform load distribution over the projected area, ➤ Figure.

Projected area of a bush

Alternative calculation

Bush:

Flanged bush, radial force:

Flanged bush, axial force:

Thrust washer:

p	N/mm²	Specific bearing load
F_r	N	Radial dynamic bearing load
D_i	mm	Inside diameter of bush, flanged bush or thrust washer
B	mm	Width of bearing
R	mm	Radius of flange
s_fl	mm	Thickness of flange
F_a	N	Axial dynamic bearing load
D_fl	mm	Outside diameter of flange
D_o	mm	Outside diameter of bush or thrust washer.

Bearing motion

The bearing motion describes the dynamic conditions in the bearing. These are essentially indicated by the swivel angle and tilt angle, the velocity of motion and the frequency of motion.

Sliding velocity

The sliding velocity is dependent on the plain bearing and its diameter.

Rotary motion:

Swivel motion:

v	m/s	Sliding velocity
d_x	mm	Specific diameter, see table
n	min^–1	Operating speed
β	°	Swivel angle, ➤ Figure
f	min^–1	Swivel frequency, ➤ Figure.

ACHTUNG

For combined swivel and tilt motions in spherical plain bearings, the angle of motion β₁ must be used, see link.

Specific diameter

Plain bearing	Specific diameter d_x
Radial spherical plain bearing	d_K
Axial spherical plain bearing	0,7 · d_K
Angular contact spherical plain bearing	0,9 · d_K
Bush	D_i
Flanged bush (radial sliding surface)	D_i
Flanged bush (axial sliding surface)	D_fl
Thrust washer	D_o

Frequency of motion

The number of motions per time period, the frequency, has a significant influence on the operating life of spherical plain bearings.

In addition to the load, the coefficient of friction and the motion parameter, the frequency influences the frictional energy generated in the bearing. This is dependent on the relevant sliding contact surface and must not exceed the permissible pv values, see table.

ACHTUNG

The frequency can only be used for calculating the sliding velocity in applications with continuous operation or periodic stationary periods.

Swivel angle

Swivel motion is defined as relative motion with reversing direction about the bearing axis. In the case of spherical plain bearings, the two bearing rings move relative to each other, in the case of bushes the shaft and bush move relative to each other.

The centring angle described by the two return points is described as the swivel angle β, ➤ Figure. This describes the motion between the two extreme points.

Swivel motion and swivel frequency taking the example of a spherical plain bearing

β = swivel angle · A = start point · B = end point · f = swivel frequency
(number of motions from A to B per minute)

Tilt angle

In tilt motion of spherical plain bearings, the inner ring and shaft locating washer move relative to the outer ring and housing locating washer in a direction transverse to the bearing axis. The axes of the relevant bearing rings intersect below the tilt angle α, ➤ Figure.

The maximum permissible tilt angle α must be observed. Full utilisation of the basic load ratings is only permissible within the stated tilt angle α.

Tilt motion

α₁, α₂ = tilt angle

Combined swivel and tilt motion

The motion angle β₁ corresponds to the resultant sliding distance in the case of simultaneous tilt and swivel motion, ➤ Figure.

Combined motions are calculated as follows:

β₁	°	Motion angle corresponding to the sliding distance
β	°	Swivel angle, see link
α₁	°	Tilt angle from centre to left, see link
α₂	°	Tilt angle from centre to right, see link.

Swivel and tilt motion

β₁ = motion angle

Specific frictional energy pv

The specific bearing load p and the sliding velocity v are in a reciprocal relationship. The product p · v gives the specific frictional energy pv and is an important key value for a plain bearing.

pv	N/mm² · m/s	Specific frictional energy
p	N/mm²	Specific bearing load
v	m/s	Sliding velocity.

ACHTUNG

In the case of intermittent operation, the sliding velocity during one motion cycle must be used.

Rating life

Calculation of the theoretical rating life is based on a large number of laboratory tests and takes account of certain operational data.

The rating life is defined as the number of motion cycles or operating hours that can be achieved by the majority of a sufficiently large number of plain bearings under identical operating conditions before certain failure criteria are met.

The amount of wear and increase in friction are dependent on the sliding contact surface and the application. Under identical operating conditions, the operating life achieved may therefore differ significantly.

The calculation of the theoretical rating life gives comparative values for the bearings. It gives information about the higher or lower performance of the selected bearings.

Failure criteria

In plain bearings, wear occurs as a result of solid body and mixed friction conditions. The failure criteria are test limit values that are related to a quantity of wear as a function of the bearing size or an upper coefficient of friction that is exceeded, see tables.

Operating clearance as a failure criterion

Load direction	Sliding layer
	ELGOGLIDE	PTFE composite	PTFE film	ELGOTEX
	Increase in radial operating clearance by
	mm
Unilateral or point load	0,5	0,15	0,25	0,5
Alternating or circumferential load	1 ^**	0,3	0,5	1

^**In the case of axial and angular contact spherical plain bearings with the sliding layer ELGOGLIDE, the increase in the operating clearance, irrespective of the operating clearance, is 0,5 mm.

Wear of the load zone as a failure criterion

Failure criterion	Sliding layer
	E40	E50
	%
Wear of sliding layer thickness in the load zone by	80	90

Operating clearance and friction as a failure criterion

Load direction, failure criterion		Sliding contact surface
		Steel/steel	Steel/bronze
		Failure criterion
Unilateral		Fretting of sliding surfaces	Fretting of sliding surfaces
Alternating

	Increase in radial operating clearance	＞ 0,004 · d_K	＞ 0,004 · d_K
	Increase in friction	μ_R ＞ 0,22	μ_R ＞ 0,25

Influences on the rating life

Calculation of the basic rating life applies to plain bearings that perform rotary, swivel or linear motion.

The significant factors for a long rating life are the pv value and the design of the mating surface. In the case of metal/polymer composite plain bearings as well as ELGOGLIDE and ELGOTEX bushes, particular attention must be paid to the material, roughness depth and surface structure of the mating surface. In the case of spherical plain bearings, an optimum mating surface is provided by the inner ring.

The ambient temperature, heat dissipation via the shaft, bearing and housing as well as the operating duration have a fundamental influence on the operating temperature and thus on the rating life.

Extraordinary factors

The following parameters are not taken into consideration in rating life calculation and may in certain circumstances have a very considerable influence on the operating life:

corrosion
ageing of the lubricant
contamination
humidity
vibrations
shocks.

ACHTUNG

Contamination and moisture as well as oils, greases or similar substances have a severe, negative effect on the life of maintenance-free bearings and, in some cases, reduce the life drastically. The elements interfere with the sensitive bearing tribology and, as a result, hinder the dry lubrication of the bearing.

Even for spherical plain bearings supplied with seals, consideration should be given to protecting the bearings with additional seals in the adjacent construction, or isolating the entire unit, in extremely contaminated applications (outside or inside).

Operating life

The operating life is the life actually achieved by a plain bearing. It may deviate from the calculated rating life.

Basic rating life

Due to the large number of influences, the calculated basic rating life is a guide value. In the case of plain bearings, the values may therefore be excessively high at very low bearing loads or very low sliding velocities.

If the sliding layer E50 is used in linear motion, advice should be sought from the Schaeffler engineering service.

ACHTUNG

Theoretical rating life calculations are only valid for the products presented in this catalogue when used in accordance with the validity range (load, sliding velocity and operating temperature) and with the recommendations described. Theoretical rating life calculations can under no circumstances be transferred to other products.

The rating life calculation is not valid for large radial spherical plain bearings GE..-DW, axial spherical plain bearings GE..-AX and strips EGS. For a rating life estimate in the case of these series, the Schaeffler engineering service should be contacted.

In the case of thrust washers EGW, the rating life calculation is only valid if the bearing runs free from clearance at all times and the mating surface is at least as large as the thrust washer.

Dry friction, mixed friction and hydrodynamics

The preconditions for rating life calculation are as follows:

Maintenance-free plain bearings must undergo dry running.
Mixed friction must be present in plain bearings that require maintenance or are low-maintenance.
Where hydrodynamic conditions are applied, the Schaeffler engineering service should be contacted.

Range of validity of rating life calculation

Sliding layer, sliding contact surface	pv value^**		Specific load^** p
	N/mm² · m/s		N/mm²
	N/mm² · m/s		min.	max.
	from	to	min.	Constant	Variable
E40	0,01	1,8	0,01	140	140
E50	0,1	3	0,01	70	70
ELGOGLIDE^**	0,005	6,9	25	300	150
ELGOGLIDE-W11^**	0,005	6,9	1	150	150
ELGOTEX	0,005	2,8	1	140	140
PTFE composite	0,005	2	1	100	60
PTFE film	0,002	1,2	2	100	50
Steel/steel	0,001	0,4	1	60	100
Steel/bronze	0,001	0,4	1	50	50

^**The maximum permissible bearing load as function of velocity is determined by means of pv diagrams.

^**In the case of values lower than 1 N/mm², calculation of the basic rating life must be carried out using the value p = 1 N/mm².

^**The operating limits of ELGOGLIDE sliding layers must be observed.

Range of validity of rating life calculation

Sliding layer, sliding contact surface	Sliding velocity^**	Temperature
	v	ϑ
	m/s	°C
	max.	from	to
E40	2,5	–200	+280
E50	2,5	–40	+110
ELGOGLIDE	0,3	–40	+150
ELGOGLIDE-W11	0,3	–40	+150
ELGOTEX	0,18	–20	+130
PTFE composite	0,4	–50	+200
PTFE film	0,21	–50	+200
Steel/steel	0,1	–60	+200
Steel/bronze	0,1	–60	+250

^**In the case of values lower than 0,001 m/s, calculation of the basic rating life must be carried out using the value v = 0,001 m/s.

Calculation service

In the product selection and information system medias, http://medias.schaeffler.de, it is possible to carry out computer-aided rating life calculation of individual bearings.

In addition, the versatile calculation software BEARINX facilitates the calculation and estimation of rating life of plain bearings in shaft systems. BEARINX is available in a simplified and freely accessible form as an “Easy” module and as a complete, powerful calculation module in various versions; information can be found at www.schaeffler.de/en ➥ Products & Services ➥ Industrial ➥ Calculation.

Information can be found at www.schaeffler.de/en ➥ Products & Solutions ➥ Industrial ➥ Calculation & Advice ➥ Calculation.

Calculation of the basic rating life

The basic rating life is calculated using the following equations and is dependent on the specific plain bearing factor and any correction factors necessary, see link and tables.

The procedure for rating life calculation is shown in a diagram, ➤ Figure. Ordering examples are given in the corresponding product descriptions.

ACHTUNG

Before calculation of the rating life, it is absolutely essential to check the permissible loads, sliding velocities and temperatures, see tables.

For flanged bushes, the rating life must be checked for both the radial sliding surface and the axial sliding surface (flange).

Procedure for rating life calculation

Symbols, units and definitions, see link

Checking of the range of validity,
see tables

Maintenance-free and low-maintenance bearings

Rating life of maintenance-free and low-maintenance bearings:

Bearings requiring maintenance

Rating life of bearings requiring maintenance:

Rating life of bearings requiring maintenance taking account of correction factors for periodic relubrication, see link:

Conversion of rating life value

Conversion of the rating life from operating hours to revolutions:

Conversion of the rating life for v ＜ 0,001 m/s

For sliding velocities v ＜ 0,001 m/s, at which the rating life must be calculated using v = 0,001 m/s, the rating life is converted from operating hours to revolutions as follows.
For rotation:

For swivelling:

d_x

Specific diameter, see table.

Specific plain bearing factor

Sliding layer, sliding contact surface	Specific plain bearing factor K_L
E40, E40-B	1 000
E50	2 500
ELGOGLIDE	25 000
ELGOGLIDE-W11	25 000
ELGOTEX	7 000
PTFE composite	1 000
PTFE film	1 000
Steel/steel	30
Steel/bronze	2,3

Load and motion duty cycle

Where plain bearings are subjected to varying loads and motions, the rating life can be calculated in approximate terms. This requires data for the load, the motion and the corresponding proportional operating times (operating duration), ➤ Figure.

L_h	h	Theoretical rating life taking account of variable conditions
t₁, t₂, ..., t_n	h or %	Proportional duration of defined corresponding operating period
Σt	h or %	Total operating time (t₁ + t₂ + t₃ ... t_n)
L_h1, L_h2, ..., L_hn	h	Rating life for individual periods.

Rating life for specified load and motion duty cycle

P = equivalent dynamic bearing load · β = swivel angle · f = frequency · t = time ·

Calculation of L_h1, L_h2, ..., L_hn
in accordance with calculation principle

Symbols, units and definitions

L_h	h	Rating life of plain bearing
L_osc	revolutions	Rating life in oscillations
L_hN	h	Rating life with periodic relubrication
K_L		Specific plain bearing factor
p	N/mm²	Specific load
v	m/s	Sliding velocity
C_r	N	Basic radial load rating
P	N	Equivalent bearing load
f	min^–1	Swivel frequency
f_p		Correction factor for load
f_v		Correction factor for sliding velocity
f_pv		Correction factor for frictional energy
f_pv*		Correction factor for frictional energy for ELGOGLIDE and ELGOTEX
f_ϑ		Correction factor for temperature
f_R		Correction factor for roughness depth
f_W		Correction factor for material
f_A		Correction factor for condition of rotation
f_B		Correction factor for width ratio
f_L		Correction factor for linear motion
f_α		Correction factor for tilt angle
f_β		Correction factor for swivel and oscillation angle
f_Hz		Correction factor for variable load
f_NH		Correction factor for relubrication, as a function of frequency
f_Nβ		Correction factor for relubrication, as a function of β
f_dK		Correction factor for sphere diameter.

Correction factors

In calculation of the basic rating life, numerous influences are taken into consideration for the specific bearing by means of correction factors, see link.

Preselection of correction factors

The correction factors are selected as a function of the sliding layer or the sliding contact surface and applied in the appropriate rating life equation, see tables.

The lists of the series also include the sealed variant with lip seals 2RS or high performance seals 2TS.

Maintenance-free and low-maintenance bushes, flanged bushes and thrust washers

Series	Sliding layer	Motion	Correction factors
Series	Sliding layer	Motion	f_p	f_v	f_pv	f_pv*	f_ϑ	f_R	f_W	f_A	f_B	f_L	f_α	f_β	f_Hz
EGB EGF EGW	E50	Rotary	■	■	■	‒	■	■	‒	■	‒	‒	‒	‒	‒
	E40	Rotary	■	■	■	‒	■	■	■	■	‒	‒	‒	‒	‒
	E40	Linear	■	■	■	‒	■	■	■	■	‒	■	‒	‒	‒
ZGB	ELGOGLIDE ELGOGLIDE-W11	Rotary	■	‒	‒	■	■	■	■	■	■	‒	‒	■	■
ZGB	ELGOGLIDE ELGOGLIDE-W11	Linear	■	‒	‒	■	■	■	■	■	‒	■	‒	‒	‒
ZWB	ELGOTEX	Rotary	■	‒	‒	■	■	■	■	■	■	‒	‒	■	‒
ZWB	ELGOTEX	Linear	■	‒	‒	■	■	■	■	■	‒	■	‒	‒	‒

Maintenance-free spherical plain bearings and rod ends

Series		Sliding layer	Correction factors
Spherical plain bearing	Rod end	Sliding layer	f_p	f_v	f_pv	f_pv*	f_ϑ	f_A	f_α	f_β	f_Hz
GE..-UK GE..-FW GE..-SW GE..-AW GE..-PW GE..-DW	GIR..-UK GAR..-UK GIKR..-PW GIKPR..-PW GAKR..-PW GIKSR..-PS GIKPSR..-PS GAKSR..-PS	ELGOGLIDE ELGOGLIDE-W11	█	‒	‒	█	█	█	█	█	█
		PTFE composite	█	█	█	‒	█	█	‒	‒	█
		PTFE film	█	█	█	‒	█	█	‒	‒	█

Spherical plain bearings and rod ends requiring maintenance

Series	Sliding contact surface	Correction factors
GE..-DO GE..-HO GE..-FO GE..-ZO GE..-LO GE..-SX	GIR..-DO GIL..-DO GAR..-DO GAL..-DO GIHNRK..-LO GIHRK..-DO GK..-DO GF..-DO	Steel/steel	■	■	■	■	■	■	■
GE..-PB	GIKR..-PB GIKL..-PB GAKR..-PB GAKL..-PB	Steel/bronze	■	■	■	■	■	■	■

Series

Sliding contact surface

Correction factors

Spherical plain bearing

Rod end

f_p

f_v

f_ϑ

f_A

f_dK

f_β

f_Hz

GE..-DO

GE..-HO

GE..-FO

GE..-ZO

GE..-LO

GE..-SX

GIR..-DO

GIL..-DO

GAR..-DO

GAL..-DO

GIHNRK..-LO

GIHRK..-DO

GK..-DO

GF..-DO

Steel/steel

■

GE..-PB

GIKR..-PB

GIKL..-PB

GAKR..-PB

GAKL..-PB

Steel/bronze

■

Legend

■

The selected correction factor must be applied in the rating life equation. The value is determined from the diagrams and tables.

Load f_p and sliding velocity f_v

The values for the correction factor for load f_p are shown in an overview diagram and two enlarged areas, ➤ Figure to ➤ Figure. The correction factor for sliding velocity f_v can also be read from a diagram, ➤ Figure.

Correction factor for load, overview

f_p = correction factor · p = specific bearing load, see link · A = detail, see ➤ Figure · B = detail, see ➤ Figure

ELGOGLIDE ·

ELGOGLIDE-W11 ·

PTFE composite ·

PTFE film ·

E40 ·

E50 ·

ELGOTEX ·

Steel/steel ·

Steel/bronze ·

ELGOGLIDE-W11 is recommended ·

ELGOGLIDE is recommended

Correction factor for load, requiring maintenance

Detail A

Steel/steel ·

Steel/bronze

Correction factor for load, maintenance-free and low-maintenance

Detail B

ELGOGLIDE ·

ELGOGLIDE-W11 ·

PTFE composite ·

PTFE film ·

E40 ·

E50 ·

ELGOTEX ·

ELGOGLIDE-W11 is recommended ·

ELGOGLIDE is recommended

Correction factor
for sliding velocity

f_v = correction factor · v = sliding velocity, see link

PTFE composite ·

PTFE film ·

E40 ·

E50 ·

Steel/steel ·

Steel/bronze

Frictional energy f_pv

The correction factor f_pv is derived from the product of the bearing load and the velocity, ➤ Figure. In the case of bearings with ELGOGLIDE or ELGOTEX, the relative specific frictional energy pv* is necessary, see ➤ equtions.

Correction factor for frictional energy

f_pv = correction factor · pv = specific frictional energy, see link

f_pv* = correction factor · pv* = relative specific frictional energy, see ➤ equtions, link

ELGOGLIDE ·

ELGOGLIDE-W11 ·

PTFEcomposite ·

PTFEfilm ·

E40 ·

E50 ·

ELGOTEX

Relative specific frictional energy pv*

ELGOGLIDE and ELGOGLIDE-W11:

ELGOTEX:

pv*		Relative specific frictional energy
p	N/mm²	Specific load, for calculation see link
v	m/s	Sliding velocity, for calculation see link.

ACHTUNG

An increasing pv or pv* value necessitates an increased level of heat dissipation. This must be ensured by means of the adjacent construction.

Temperature f_ϑ

The influence of temperature is taken into consideration in relating life calculation with the aid of the correction factor f_ϑ, ➤ Figure and table.

Correction factor for temperature for maintenance-free and low-maintenance bearings

f_ϑ = correction factor · ϑ = temperature

ELGOGLIDE ·

ELGOGLIDE-W11 ·

PTFE composite ·

PTFE film ·

E40 ·

E50 ·

ELGOTEX

Correction factor f_ϑ for bearings requiring maintenance

Sliding contact surface	Operating temperature ϑ
	≦ 150 °C	150 °C ＜ ϑ ≦ 180 °C	180 °C ＜ ϑ ≦ 200 °C	200 °C ＜ ϑ ≦ 250 °C
	Correction factor f_ϑ
Steel/steel	1	0,9	0,7	‒
Steel/bronze	1	0,9	0,8	0,5

Roughness depth f_R

In the case of spherical plain bearings and rod ends, a mating surface with the most suitable roughness depth is already provided by the inner ring. For bushes, flanged bushes and thrust washers, the correction factor for roughnesss depth f_R must be taken into consideration, ➤ Figure.

Correction factor for roughness depth

f_R = correction factor · Rz, Ra = roughness depth

ELGOGLIDE ·

ELGOGLIDE-W11 ·

E40 ·

E50 ·

ELGOTEX

Material f_W

The correction factor f_W is dependent on the material of the mating surface with a roughness depth Rz 2 to Rz 3, see table.

Correction factor f_W

Mating surface material		Layer thickness	Correction factor f_W
		Layer thickness	E40	ELGOGLIDE ELGOGLIDE-W11 ELGOTEX
		mm	E40	ELGOGLIDE ELGOGLIDE-W11 ELGOTEX
Steel^**

	Unalloyed	‒	0,5	‒
	Nitrided	‒	0,5	1
	Corrosion-resistant	‒	1	1
	Hard chromium coating (Durotect CMT)	≧ 0,013	1	1
	Zinc plated	≧ 0,013	0,1	‒
	Phosphated	≧ 0,013	0,1	‒
Flake graphite cast iron Rz 2		‒	0,5	‒
Anodised aluminium		‒	0,2	‒
Hard anodised aluminium 450 + 50 HV		0,025	1	‒
Copper-based alloys		‒	0,2	‒
Nickel		‒	0,1	‒

^**

For increased loads, the steel hardness should correspond to the following values:

		in the case of E40, at least 25 HRC to 50 HRC
		in the case of ELGOGLIDE and ELGOTEX, at least 55 HRC.

Condition of rotation f_A

The correction factor f_A is dependent on the type of bearing and the type of load, ➤ Figure:

plain bushes, thrust washers:

point load f_A = 1 (rotating shaft, stationary bush)
circumferential load f_A = 2 (stationary shaft, rotating bush)
thrust washer f_A = 1
linear motion f_A = 1

spherical plain bearings, rod ends:

f_A = 1.

Correction factor for condition of rotation

F = load · n = speed

Point load f_A = 1 ·

Circumferential load f_A = 2

Width ratio f_B and sphere diameter d_K

The factors taken into consideration in rating life calculation are the width ratio in the case of maintenance-free plain bearings and the sphere diameter in the case of plain bearings requiring maintenance, ➤ Figure and ➤ Figure.

Correction factor for width ratio

f_B = correction factor · B = width of bearing · d = inside diameter of bearing

ELGOGLIDE ·

ELGOGLIDE-W11 ·

ELGOTEX

Correction factor for sphere diameter

f_dK = correction factor · d_K = sphere diameter of bearing

Steel/steel ·

Steel/bronze

Linear motion f_L

The correction factor f_L is necessary in the case of linear motion with bushes with the sliding layer E40, ELGOGLIDE or ELGOTEX, ➤ Figure.

ACHTUNG

In the case of linear motion, the stroke length should not exceed the maximum stroke H_max = 2,5 · B, ➤ Figure.

Correction factor for linear motion

ELGOGLIDE ·

ELGOGLIDE-W11 ·

E40 ·

ELGOTEX

Maximum stroke length in linear motion

H_max = maximum stroke length · B = width of bush

Tilt angle f_α and swivel angle f_β

The tilt motions of spherical plain bearings are taken into consideration by the correction factor f_α, while the swivel motions of spherical plain bearings or bushes are taken into consideration by the correction factor f_β, ➤ Figure and ➤ Figure.

ACHTUNG

In the case of swivel angles of ≧180° or rotation, the following applies:

f_β = 0,15 for ELGOGLIDE
f_β = 0,2 for ELGOTEX.

Correction factor for tilt angle

f_α = correction factor · α₁, α₂ = tilt angle, see link

ELGOGLIDE ·

ELGOGLIDE-W11

Correction factor for swivel and oscillation angle

f_β = correction factor · β = swivel angle, see link

ELGOGLIDE ·

ELGOGLIDE-W11 ·

ELGOTEX ·

Steel/steel ·

Steel/bronze

Variable load f_Hz

The correction factor for variable load f_Hz takes account of the influence of dynamic pulsating loads and dynamic alternating loads on the rating life. Loads that pass through the zero line in the F_r-t diagram are designated as alternating loads. Loads that are exclusively in the positive or negative region are designated as pulsating loads, see table.

The load frequency P_Hz (unit Hz) indicates the number of load cycles or load oscillations per second.

Type of load and correction factor f_Hz

Sliding layer, sliding contact surface	Type of load
	Unilateral constant load	Alternating load	Pulsating load

	Correction factor f_Hz
ELGOGLIDE	1	➤ Figure
ELGOGLIDE-W11		➤ Figure
PTFE composite		➤ Figure
PTFE film		➤ Figure
Steel/steel		2	➤ Figure
Steel/bronze		2	➤ Figure

f_Hz values for ELGOGLIDE and ELGOGLIDE-W11 under alternating load and pulsating load

p = specific bearing load · P_Hz = load frequency · f_Hz = correction factor

Pulsating load ·

Alternating load

f_Hz values for PTFE composite under alternating load and pulsating load

p = specific bearing load · P_Hz = load frequency · f_Hz = correction factor

Pulsating load ·

Alternating load

f_Hz values for PTFE film under alternating load and pulsating load

p = specific bearing load · P_Hz = load frequency · f_Hz = correction factor

Pulsating load ·

Alternating load

f_Hz values for steel/steel and steel/bronze under pulsating load

f_Hz = correction factor · F_min/F_max = pulsating load values

Steel/steel ·

Steel/bronze

Relubrication f_NH and f_Nβ

If periodic relubrication is carried out on spherical plain bearings requiring lubrication, their rating life can be increased. This is taken into consideration by means of a correction factor dependent on the frequency and by a factor dependent on the swivel angle β, ➤ Figure and ➤ Figure.

The relubrication interval for spherical plain bearings requiring lubrication must be no more than half the rating life:

l_w	h	Relubrication interval
L_h	h	Basic rating life.

Correction factor for relubrication, as a function of frequency

f_NH = correction factor · L_h/l_w = frequency of relubrication

Steel/steel ·

Steel/bronze

Correction factor for relubrication, as a function of β

f_Nβ = correction factor · β = swivel angle

Steel/steel ·

Steel/bronze