Friction and increases in temperature

Internal clearance and operating clearance

Operating clearance of spherical plain bearings

The operating clearance or preload is determined on a fitted bearing still warm from operation.

It is derived from the radial internal clearance and the change in the radial internal clearance as a result of interference fit and thermal influences in the fitted condition.

Internal clearance of radial spherical plain bearings

The radial and axial internal clearance is determined on the dismounted bearing.

The radial internal clearance of radial spherical plain bearings is defined as the distance by which the inner ring can be moved in a radial direction relative to the outer ring from one extreme position to the precisely opposite extreme position, ➤ Figure.

Maintenance-free spherical plain bearings

Maintenance-free spherical plain bearings have a very small internal clearance. As a result, preloads may be present once the bearing is fitted.

Spherical plain bearings requiring maintenance

The radial internal clearance is subdivided into three groups in accordance with DIN ISO 12240-1, see table. The precondition is a housing bore that causes no dimensional changes in the bearing with the exception of geometrical inaccuracies.

Radial internal clearance

Group 2 to Group 3 = internal clearance groups

Radial internal clearance groups

Internal clearance group in accordance with ISO 12240-1	Description	Application range
Group N (CN)	Normal internal clearance; CN is not included in bearing designations	Under normal operating conditions and with the recommended fits, this gives optimum operating clearance
Group 2^^ (C2)	Internal clearance ＜ CN (suffix C2)	For bearing arrangements with very small clearance
Group 3 (C3)	Internal clearance ＞ CN (suffix C3)	For bearing rings with press fits or a large temperature differential between the inner and outer ring

Internal clearance group in accordance with ISO 12240-1

Description

Application range

Group N

(CN)

Normal internal clearance; CN is not included in bearing designations

Under normal operating
conditions and with the recommended fits, this gives optimum operating clearance

Group 2^**^**

(C2)

Internal clearance ＜ CN
(suffix C2)

For bearing arrangements
with very small clearance

Group 3

(C3)

Internal clearance ＞ CN
(suffix C3)

For bearing rings with press fits or
a large temperature differential between the inner and outer ring

^**Relubrication only possible with tilt angle α = 0°.

^**Example of bearing with restricted internal clearance: GE220-DO-2RS-C2.

Radial internal clearance

Series		Radial internal clearance
Series		μm
GE..-DO GE..-DO-2RS(-2TS) GE..-HO-2RS GE..-LO	GE..-FO GE..-FO-2RS(-2TS)	Group 2 (C2)		Group N (CN)		Group 3 (C3)
Bore d		Group 2 (C2)		Group N (CN)		Group 3 (C3)
mm		min.	max.	min.	max.	min.	max.
6	6	8	32	32	68	68	104
8	8	8	32	32	68	68	104
10	10	8	32	32	68	68	104
12	‒	8	32	32	68	68	104
‒	12	10	40	40	82	82	124
15	15	10	40	40	82	82	124
16	‒	10	40	40	82	82	124
17	17	10	40	40	82	82	124
20	‒	10	40	40	82	82	124
‒	20	12	50	50	100	100	150
25	25	12	50	50	100	100	150
30	30	12	50	50	100	100	150
32	‒	12	50	50	100	100	150
35	‒	12	50	50	100	100	150
‒	35	15	60	60	120	120	150
40	40	15	60	60	120	120	180
45	45	15	60	60	120	120	180
50	50	15	60	60	120	120	180
60	‒	15	60	60	120	120	180
‒	60	18	72	72	142	142	212
63	‒	18	72	72	142	142	212
70	70	18	72	72	142	142	212
80	80	18	72	72	142	142	212
90	‒	18	72	72	142	142	212
‒	90	18	85	85	165	165	245
100	100	18	85	85	165	165	245
110	110	18	85	85	165	165	245
120	120	18	85	85	165	165	245
140	‒	18	85	85	165	165	245
160	140	18	100	100	192	192	284
180	160	18	100	100	192	192	284
200	180	18	100	100	192	192	284
‒	200	18	110	110	214	214	318
220	220	18	110	110	214	214	318
240	‒	18	110	110	214	214	318
250	240	18	125	125	239	239	353
260	260	18	125	125	239	239	353
280	280	18	125	125	239	239	353
300	‒	18	125	125	239	239	353

Axial internal clearance

The axial internal clearance is defined as the distance by which the inner ring can be moved in an axial direction relative to the outer ring from one extreme position to the precisely opposite extreme position, ➤ Figure.

It is dependent on the bearing geometry and is in a direct relationship with the radial internal clearance. Depending on the bearing type, it may be several times greater than the radial internal clearance.

Axial internal clearance

s_a = axial internal clearance

Fit conditions for spherical plain bearings

The interference fits and clearance fits for practical use are determined from the corresponding ISO fit in conjunction with the normal bearing tolerances in accordance with DIN ISO 12240-1 to DIN ISO 12240-3, see tables. The actual dimensions must correspond to the centre tolerance.

Definitions:

– indicates an interference fit
+ indicates a clearance fit.

Shaft fits

Example:

A shaft of diameter ⌀50 m6 Ⓔ has a probable interference fit of 0,023 mm.

Interference fit Ü_I or clearance fit

Nominal shaft diameter in mm
over incl.	3 6	6 10	10 18	18 30	30 50	50 80	80 120	120 180	180 250	250 315	315 400	400 500
Normal tolerance, interference fit or clearance fit in μm^**
h6	0	0	+1	+1	+2	+2	+1	0	0	–2	–2	–2
j6	–6	–7	–7	–8	–9	–10	–13	–14	–17	–17	–20	–22
k6	–9	–9	–9	–14	–16	–20	–24	–28	–30	–33	–38	–42
m6	–12	–15	–17	–20	–23	–28	–34	–40	–47	–53	–59	–65
n6	–16	–19	–22	–27	–31	–37	–44	–52	–61	–67	–75	–82

^**Not applicable to series GE..-LO, GE..-PB, GE..-SX, GE..-PW and GE..-SW.

Housing fits

Example:

A housing bore of diameter ⌀75 M7 Ⓔ has a probable interference fit of 0,009 mm.

Interference fit Ü_A or clearance fit

Nominal housing bore diameter in mm
over incl.	6 10	10 18	18 30	30 50	50 80	80 120	120 150	150 180	180 250	250 315	315 400	400 500
Normal tolerance, interference fit or clearance fit in μm^**
J7	+4	+5	+6	+7	+10	+12	+15	+18	+22	+27	+31	+34
K7	+1	+1	–1	0	0	–1	+1	+4	+5	+7	+8	+8
M7	–4	–5	–7	–8	–9	–11	–11	–8	–8	–9	–9	–10
N7	–8	–10	–14	–16	–18	–21	–23	–20	–22	–23	–25	–27

^**Not applicable to series GE..-SX and GE..-SW.

Influence of interference fit

The radial internal clearance of radial spherical plain bearings changes due to the fit as a result of:

expansion of the inner ring
contraction of the outer ring.

ACHTUNG

If the remaining internal clearance of spherical plain bearings requiring maintenance is ≦ 0, a bearing of another internal clearance group with a larger internal clearance must be selected.

Factors for expansion or contraction

Factors for the cross-section:
b = inner ring · c = outer ring · f = factor for expansion of the housing

Expansion of the inner ring

a	μm	Expansion of the inner ring when using solid shafts, measured on the sphere diameter
Ü_I	μm	Effective interference fit, see table
b	–	Factor for the cross-section of the inner ring, see table, and ➤ Figure
0,9	–	Factor for the roughness, ovality and unevenness of the supporting component surface.

Contraction of the outer ring

In the case of ring-shaped housings, expansion of the housing must be taken into consideration. The expansion is dependent on the wall thickness and is taken into consideration in the factor f:

e	μm	Contraction of the outer ring, measured on the raceway diameter
Ü_A	μm	Effective interference fit, see table
f	–	Factor for expansion of the housing, see link
0,9	–	Factor for the roughness, ovality and unevenness of the supporting component surface.

Factor for the cross-section of the inner ring

Bore d		Factor for series b
mm		Factor for series b
from	to	GE..-DO(-2RS), (-2TS) GE..-HO-2RS GE..-LO^** GE..-UK(-2RS), (-2TS)	GE..-FO(-2RS), (-2TS) GE..-FW(-2RS), (-2TS) GE..-PB^ GE..-PW^
6	10	0,65	0,55
12	20	0,72	0,64
25	70	0,79	0,71
80	140	0,8	0,75
160	300	0,84	0,78

^**Interference fit Ü_I not listed in the overview, see table.

Factor for the cross-section of the outer ring

Bore d		Factor for series c
mm		Factor for series c
from	to	GE..-DO(-2RS), (-2TS) GE..-HO-2RS GE..-LO GE..-UK(-2RS), (-2TS)	GE..-FO(-2RS), (-2TS) GE..-FW(-2RS), (-2TS) GE..-PB GE..-PW
‒	6	0,7	‒
6	20	‒	0,81
8	25	0,81	‒
25	35	‒	0,83
30	40	0,83	‒
40	280	‒	0,85
45	300	0,85	‒

Calculation of the factor f for expansion of the housing

When determining the factor f, the cross-section of the bearing ring and the ring thickness of the bearing locating housing are taken into consideration, ➤ Figure and ➤ Figure.

Housing ring thickness

D_A = diameter of housing bore · D_G = outside diameter of housing

Factor f for expansion of the housing

f = factor for expansion of housing · D_A = diameter of housing bore · D_G = outside diameter of housing · c = factor for cross-section of outer ring

Calculation example for internal clearance

The internal clearance of a radial spherical plain bearing in the fitted condition is calculated using the influence of the interference fit, see link.

Given data

Radial spherical plain bearing GE50-DO with steel/steel sliding contact surface:

Fit between locating bore and shaft		M7/m6
Outside diameter of housing	⌀	120 mm
Solid steel shaft	⌀	50
Locating bore	⌀	75
Radial internal clearance Group N		60 μm to 120 μm

Required

Radial internal clearance in fitted condition.

Assumption

Production to centre of tolerance.

Expansion of the inner ring

Expansion of the inner ring, measured on the sphere diameter:

a	=	Ü_I · b · 0,9
Ü_I	=	0,023 mm	see table
b	=	0,79	see table

a	=	0,023 mm · 0,79 · 0,9
a	=	0,016 mm.

Contraction of the outer ring

Contraction of the outer ring, measured on the raceway diameter:

e	=	Ü_A · f · 0,9
Ü_A	=	0,009 mm	see table
c	=	0,85	see table
f	=		➤ Figure
e	=	0,009 mm · 0,72 · 0,9
e	=	0,006 mm.

Reduction in radial internal clearance

The reduction in the radial internal clearance is calculated by adding a and e:

ΔC	=	a + e
	=	0,016 mm + 0,006 mm
	=	0,022 mm.

Maximum restriction of internal clearance

Maximum possible restriction of radial internal clearance with production to acceptable values:

Solid steel shaft	⌀ 50,025 mm (maximum diameter ⌀ 50m6)
Bearing bore	⌀ 49,988 mm (minimum diameter according to DIN 620)

Ü_I max	= 0,037 mm
a_max	= Ü_I max · b · 0,9 = 0,037 mm · 0,79 · 0,9
a_max	= 0,026 mm.

Locating bore	⌀ 74,97 mm (minimum diameter ⌀ 75M7)
Bearing outside diameter	⌀ 75 mm (maximum diameter according to DIN 620)

Ü_A max	= 0,03 mm
e_max	= Ü_A max · f · 0,9 = 0,03 mm · 0,72 · 0,9
e_max	= 0,019 mm

Maximum reduction in internal clearance

Maximum reduction in the internal clearance in the fitted condition:

ΔC_max = a_max + e_max = 0,026 + 0,019 = 0,045 mm.

The radial internal clearance in the unfitted condition is 0,06 mm to 0,12 mm. The smallest possible initial clearance is 0,06 mm:

minimum internal clearance = 0,060 mm – 0,045 mm = 0,015 mm.

The internal clearance in the fitted condition in the least favourable case is 0,015 mm.

Theoretical bearing clearance of metal/polymer composite plain bushes

Bushes with the sliding layer E40 and E50 are pressed into the housing. This provides axial and radial location. No additional means of location are required.

If the recommended mounting tolerances are used with rigid housings and shafts, this gives an interference fit or bearing clearance.

ACHTUNG

Expansion of the housing bore is not taken into account in calculation of the bearing clearance.

Calculation of the interference U is carried out using the tolerances of the housing bore and the deviations for the bush outside diameter D_o.

Calculation of bearing clearance

The theoretical bearing clearance is calculated as follows:

Δs_max	mm	Maximum bearing clearance, ➤ Figure
Δs_min	mm	Minimum bearing clearance, ➤ Figure
d_{G max}	mm	Maximum diameter of housing bore
d_{G min}	mm	Minimum diameter of housing bore
d_{W max}	mm	Maximum shaft diameter
d_{W min}	mm	Minimum shaft diameter
s_{3 max}	mm	Maximum wall thickness
s_{3 min}	mm	Maximum wall thickness.

Theoretical bearing clearance

D_o = outside diameter of bush · D_i = inside diameter of bush · d_W = shaft diameter · d_G = diameter of housing bore · s₃ = wall thickness of bush · Δs = bearing clearance

Theoretical bearing clearance
after pressing in

The theoretical bearing clearance after pressing in of bushes or flanged bushes of metric sizes or inch sizes is calculated without considering any possible expansion of the bore, see tables.

The theoretical bearing clearance is calculated taking account of the recommended mounting tolerances.

Theoretical bearing clearance
for metric sizes

Diameter of bush		Bearing clearance Δs
Diameter of bush		E40, E40-B		E50
D_i	D_o	Δs_min	Δs_max	Δs_min	Δs_max
mm	mm	mm	mm	mm	mm
3	4,5	0,000	0,054	‒	‒
4	5,5	0,000	0,056	‒	‒
5	7	0,000	0,077	‒	‒
6	8	0,000	0,077	‒	‒
7	9	0,003	0,083	‒	‒
8	10	0,003	0,083	0,040	0,127
10	12	0,003	0,086	0,040	0,130
12	14	0,006	0,092	0,040	0,135
13	15	0,006	0,092	0,040	0,135
14	16	0,006	0,092	0,040	0,135
15	17	0,006	0,092	0,040	0,135
16	18	0,006	0,092	0,040	0,135
18	20	0,006	0,095	0,040	0,138
20	23	0,010	0,112	0,050	0,164
22	25	0,010	0,112	0,050	0,164
24	27	0,010	0,112	0,050	0,164
25	28	0,010	0,112	0,050	0,164
28	32	0,010	0,126	0,060	0,188
30	34	0,010	0,126	0,060	0,188
32	36	0,015	0,135	0,060	0,194
35	39	0,015	0,135	0,060	0,194
40	44	0,015	0,135	0,060	0,194
45	50	0,015	0,155	0,080	0,234
50	55	0,015	0,160	0,080	0,239

Theoretical bearing clearance
for metric sizes

Diameter of bush		Bearing clearance Δs
Diameter of bush		E40, E40-B		E50
D_i	D_o	Δs_min	Δs_max	Δs_min	Δs_max
mm	mm	mm	mm	mm	mm
55	60	0,020	0,170	0,080	0,246
60	65	0,020	0,170	0,080	0,246
65	70	0,020	0,170	0,080	0,246
70	75	0,020	0,170	0,080	0,246
75	80	0,020	0,170	0,080	0,246
80	85	0,020	0,201	0,080	0,251
85	90	0,020	0,209	0,080	0,251
90	95	0,020	0,209	0,080	0,259
95	100	0,020	0,209	0,080	0,259
100	105	0,020	0,209	0,080	0,259
105	110	0,020	0,209	‒	‒
110	115	0,020	0,209	‒	‒
115	120	0,020	0,209	‒	‒
120	125	0,070	0,264	‒	‒
125	130	0,070	0,273	‒	‒
130	135	0,070	0,273	‒	‒
135	140	0,070	0,273	‒	‒
140	145	0,070	0,273	‒	‒
150	155	0,070	0,273	‒	‒
160	165	0,070	0,273	‒	‒
180	185	0,070	0,279	‒	‒
200	205	0,070	0,288	‒	‒
220	225	0,070	0,288	‒	‒
250	255	0,070	0,294	‒	‒
300	305	0,070	0,303	‒	‒

Theoretical bearing clearance
for inch sizes

Designation	Nominal diameter	Recommended diameter of
	Nominal diameter	Shaft		Housing bore
	inch	inch/mm		inch/mm
	inch	d_{W min}	d_{W max}	d_{G min}	d_{G max}
EGBZ03	3/16	0,1858	0,1865	0,2497	0,2503
EGBZ03	3/16	4,719	4,737	6,342	6,358
EGBZ04	1/4	0,2481	0,2490	0,3122	0,3128
EGBZ04	1/4	6,302	6,325	7,930	7,945
EGBZ05	5/16	0,3106	0,3115	0,3747	0,3753
EGBZ05	5/16	7,889	7,912	9,517	9,533
EGBZ06	3/8	0,3731	0,3740	0,4684	0,4691
EGBZ06	3/8	9,477	9,500	11,897	11,915
EGBZ07	7/16	0,4355	0,4365	0,5309	0,5316
EGBZ07	7/16	11,062	11,087	13,485	13,503
EGBZ08	1/2	0,4980	0,4990	0,5934	0,5941
EGBZ08	1/2	12,649	12,675	15,072	15,090
EGBZ09	9/16	0,5605	0,5615	0,6559	0,6566
EGBZ09	9/16	14,237	14,262	16,660	16,678
EGBZ10	5/8	0,6230	0,6240	0,7184	0,7192
EGBZ10	5/8	15,824	15,850	18,247	18,268
EGBZ11	11/16	0,6855	0,6865	0,7809	0,7817
EGBZ11	11/16	17,412	17,437	19,835	19,855
EGBZ12	3/4	0,7479	0,7491	0,8747	0,8755
EGBZ12	3/4	18,997	19,027	22,217	22,238
EGBZ14	7/8	0,8729	0,8741	0,9997	1,0005
EGBZ14	7/8	22,172	22,202	25,392	25,413
EGBZ16	1	0,9979	0,9991	1,1246	1,1256
EGBZ16	1	25,347	25,377	28,565	28,590
EGBZ18	1 1/8	1,1226	1,1238	1,2808	1,2818
EGBZ18	1 1/8	28,514	28,545	32,532	32,558
EGBZ20	1 1/4	1,2472	1,2488	1,4058	1,4068
EGBZ20	1 1/4	31,679	31,720	35,707	35,733
EGBZ22	1 3/8	1,3722	1,3738	1,5308	1,5318
EGBZ22	1 3/8	34,854	34,895	38,882	38,908
EGBZ24	1 1/2	1,4972	1,4988	1,6558	1,6568
EGBZ24	1 1/2	38,029	38,070	42,057	42,083
EGBZ26	1 5/8	1,6222	1,6238	1,7808	1,7818
EGBZ26	1 5/8	41,204	41,245	45,232	45,258
EGBZ28	1 3/4	1,7471	1,7487	1,9371	1,9381
EGBZ28	1 3/4	44,376	44,417	49,202	49,228
EGBZ32	2	1,9969	1,9987	2,1871	2,1883
EGBZ32	2	50,721	50,767	55,552	55,583

Theoretical bearing clearance
for inch sizes

Designation	Nominal diameter		Inside diameter after pressing in		Bearing clearance
	inch/mm		Inside diameter after pressing in		inch/mm
	D_i	D_o	min.	max.	Δs_min	Δs_max
EGBZ03	0,1875	0,2500	0,1867	0,1893	0,0002	0,0035
EGBZ03	4,763	6,350	4,742	4,808	0,005	0,089
EGBZ04	0,2500	0,3125	0,2492	0,2518	0,0002	0,0037
EGBZ04	6,350	7,938	6,330	6,396	0,005	0,094
EGBZ05	0,3125	0,3750	0,3117	0,3143	0,0002	0,0037
EGBZ05	7,938	9,525	7,917	7,983	0,005	0,094
EGBZ06	0,3750	0,4688	0,3742	0,3769	0,0002	0,0038
EGBZ06	9,525	11,906	9,505	9,573	0,005	0,096
EGBZ07	0,4375	0,5313	0,4367	0,4394	0,0002	0,0039
EGBZ07	11,113	13,494	11,092	11,161	0,005	0,099
EGBZ08	0,5000	0,5938	0,4992	0,5019	0,0002	0,0039
EGBZ08	12,700	15,082	12,680	12,748	0,005	0,099
EGBZ09	0,5625	0,6563	0,5617	0,5644	0,0002	0,0039
EGBZ09	14,288	16,669	14,267	14,336	0,005	0,099
EGBZ10	0,6250	0,7188	0,6242	0,6270	0,0002	0,0040
EGBZ10	15,875	18,258	15,855	15,926	0,005	0,102
EGBZ11	0,6875	0,7813	0,6867	0,6895	0,0002	0,0040
EGBZ11	17,463	19,844	17,442	17,513	0,005	0,101
EGBZ12	0,7500	0,8750	0,7493	0,7525	0,0002	0,0046
EGBZ12	19,050	22,225	19,032	19,114	0,005	0,116
EGBZ14	0,8750	1,0000	0,8743	0,8775	0,0002	0,0046
EGBZ14	22,225	25,400	22,207	22,289	0,005	0,116
EGBZ16	1,0000	1,1250	0,9992	1,0026	0,0001	0,0047
EGBZ16	25,400	28,575	25,380	25,466	0,003	0,119
EGBZ18	1,1250	1,2813	1,1240	1,1278	0,0002	0,0052
EGBZ18	28,575	32,544	28,550	28,646	0,005	0,132
EGBZ20	1,2500	1,4063	1,2490	1,2528	0,0002	0,0056
EGBZ20	31,750	35,719	31,725	31,821	0,005	0,142
EGBZ22	1,3750	1,5313	1,3740	1,3778	0,0002	0,0056
EGBZ22	34,925	38,894	34,900	34,996	0,005	0,142
EGBZ24	1,5000	1,6563	1,4990	1,5028	0,0002	0,0056
EGBZ24	38,100	42,069	38,075	38,171	0,005	0,142
EGBZ26	1,6250	1,7813	1,6240	1,6278	0,0002	0,0056
EGBZ26	41,275	45,244	41,250	41,346	0,005	0,142
EGBZ28	1,7500	1,9375	1,7489	1,7535	0,0002	0,0064
EGBZ28	44,450	49,213	44,422	44,539	0,005	0,163
EGBZ32	2,0000	2,1875	1,9989	2,0037	0,0002	0,0068
EGBZ32	50,800	55,563	50,772	50,894	0,005	0,173

Interference fit and bearing clearance of metal/polymer composite plain bushes

The table shows measures that can be taken to influence the bearing clearance and interference fit:

at high ambient temperatures
depending on housing material
depending on housing wall thickness.

Reduced clearance tolerances require tighter tolerances for the shaft and the bore.

Consequences and measures due to environmental influences

Consequences and measures for interference fit and bearing clearance in the case of high ambient temperatures, special housing materials or special wall thicknesses, see table.

Environmental influence

Design and environmental influences	Consequences			Measures
	Bearing clearance		Poor interference fit	Change in diameter
	Too large	Too small	Poor interference fit	d_G	d_W	Notes
Light metal or thin-walled housings	■	‒	‒	●	‒	The housing is more highly stressed; the permissible stress on the housing must not be exceeded.
Steel or cast iron housings^**	‒	■	‒	‒	▼	‒
Bronze or copper alloy housings^**	‒	‒	■	▲	▲	Reduce d_G and d_W by the same value so that the bearing clearance is maintained.
Aluminium alloy housings^**	‒	‒	■	❍	❍	Reduce d_G and d_W by the same value so that the bearing clearance is maintained. At temperatures below 0 °C, the housing is more highly stressed; the permissible stress on the housing must not be exceeded.
Bushes with thicker anti-corrosion layer	‒	■	‒	❑	‒	The bush and housing will be more highly stressed if appropriate measures are not taken.

■

Applicable

●

Reduce

❍

Reduce by 0,1% per 100 °C above room temperature

▲

Reduce by 0,05% per 100 °C above room temperature

❑

Increase by 0,03 mm if, for example, the layer thickness = 0,015 mm

▼

Reduce by 0,008 mm per 100 °C above room temperature.

^**At high ambient temperatures.

Theoretical bearing clearance of ELGOTEX filament wound bushes

The bushes are pressed as standard into a housing with the tolerance H7. This provides radial and axial location. Due to the contraction of the inside diameter, there is a change in the tolerance of the inside diameter of the bush after pressing in, see table.

ACHTUNG

Expansion of the housing bore is not taken into consideration in calculation of the bearing clearance.

Depending on the selected shaft fit, there is a theoretical bearing clearance, see ➤ equtions:

Δs_max	mm	Maximum bearing clearance
Δs_min	mm	Minimum bearing clearance
D_i max	mm	Maximum inside diameter of bush after pressing in, see table
D_i min	mm	Minimum inside diameter of bush after pressing in, see table
d_{W min}	mm	Minimum shaft diameter
d_{W max}	mm	Maximum shaft diameter.

Theoretical bearing clearance after pressing-in

For a housing tolerance H7 and the recommended shaft tolerance h7, the minimum and maximum theoretical clearances for the standard dimensions are stated, see table. The data do not take account of any possible expansion of the housing bore.

Theoretical bearing clearance for metric sizes

Diameter of bush		Inside diameter after pressing-in		Bearing clearance for tolerance H7/h7
D_i	D_o	D_i min	D_i max	Δs_min	Δs_max
mm	mm	mm	mm	mm	mm
20	24	20,042	20,18	0,042	0,201
25	30	25,042	25,18	0,042	0,201
28	34	28,028	28,176	0,028	0,197
30	36	30,028	30,176	0,028	0,197
35	41	35,038	35,202	0,038	0,227
40	48	40,038	40,202	0,038	0,227
45	53	45,031	45,207	0,031	0,232
50	58	50,031	50,207	0,031	0,232
55	63	55,041	55,237	0,041	0,267
60	70	60,035	60,231	0,035	0,261
65	75	65,035	65,231	0,035	0,261
70	80	70,045	70,241	0,045	0,271
75	85	75,025	75,234	0,025	0,264
80	90	80,025	80,234	0,025	0,264
85	95	85,045	85,274	0,045	0,309
90	105	90,037	90,266	0,037	0,301
95	110	95,037	95,266	0,037	0,301
100	115	100,037	100,266	0,037	0,301
105	120	105,047	105,276	0,047	0,311
110	125	110,025	110,268	0,025	0,303
120	135	120,025	120,268	0,025	0,303
130	145	130,037	130,3	0,037	0,34
140	155	140,037	140,3	0,037	0,34
150	165	150,039	150,302	0,039	0,342
160	180	160,039	160,302	0,039	0,342
170	190	170,036	170,314	0,036	0,354
180	200	180,036	180,314	0,036	0,354
190	210	190,038	190,341	0,038	0,387
200	220	200,038	200,341	0,038	0,387

Operating clearance of ELGOGLIDE plain bushes

Due to the self-lubricating PTFE fabric, maintenance-free ELGOGLIDE plain bushes do not require a minimum radial clearance determined by lubrication conditions.

Fitting without clearance has particular advantages, especially with alternating load directions. Load distribution is also improved, especially during running-in, due to the larger load-bearing areas.

In order to achieve the largest possible load-bearing angle, the operating clearance s must not exceed defined limits. The clearance can be expressed as a function of the relative bearing clearance ψ, see ➤ equation and ➤ Figure.

The guide values for the relative bearing clearance are valid for shaft diameters d = 30 mm to 200 mm, see table.

The ranges for the operating clearance are achievable with the standard tolerances of the plain bushes and where the housing bore and shaft are manufactured to the central tolerance.

Guide values for relative bearing clearance in fitted condition

Shaft diameter d			Relative bearing clearance ψ
mm			‰
＜	80		≦ 1
≧	80	– 120	≦ 0,75
＞	120	– 200	≦ 0,5

Calculation of the operating clearance

s	μm	Operating clearance, ➤ Figure
ψ	‰	Relative bearing clearance in fitted condition, see table
d	mm	Shaft diameter, bore diameter of inner ring.

Operating clearance

s = operating clearance

Internal clearance and operating clearance

Operating clearance of spherical plain bearings

Internal clearance of radial spherical plain bearings

Maintenance-free spherical plain bearings

Spherical plain bearings requiring maintenance

Radial internal clearance

Radial internal clearance groups

Radial internal clearance

Axial internal clearance

Axial internal clearance

Fit conditions for spherical plain bearings

Shaft fits

Interference fit ÜI or clearance fit

Housing fits

Interference fit ÜA or clearance fit

Influence of interference fit

ACHTUNG

Factors for expansion or contraction

Expansion of the inner ring

Contraction of the outer ring

Factor for the cross-section of the inner ring

Factor for the cross-section of the outer ring

Calculation of the factor f for expansion of the housing

Housing ring thickness

Factor f for expansion of the housing

Calculation example for internal clearance

Given data

Required

Assumption

Expansion of the inner ring

Contraction of the outer ring

Reduction in radial internal clearance

Maximum restriction of internal clearance

Maximum reduction in internal clearance

Theoretical bearing clearance of metal/polymer composite plain bushes

ACHTUNG

Calculation of bearing clearance

Theoretical bearing clearance

Theoretical bearing clearanceafter pressing in

Theoretical bearing clearancefor metric sizes

Theoretical bearing clearancefor metric sizes

Theoretical bearing clearancefor inch sizes

Theoretical bearing clearancefor inch sizes

Interference fit and bearing clearance of metal/polymer composite plain bushes

Consequences and measures due to environmental influences

Environmental influence

Theoretical bearing clearance of ELGOTEX filament wound bushes

ACHTUNG

Theoretical bearing clearance after pressing-in

Theoretical bearing clearance for metric sizes

Operating clearance of ELGOGLIDE plain bushes

Guide values for relative bearing clearance in fitted condition

Calculation of the operating clearance

Operating clearance

Interference fit Ü_I or clearance fit

Interference fit Ü_A or clearance fit

Theoretical bearing clearance
after pressing in

Theoretical bearing clearance
for metric sizes

Theoretical bearing clearance
for metric sizes

Theoretical bearing clearance
for inch sizes

Theoretical bearing clearance
for inch sizes