Rod Ends / Spherical Bearings - HIRSCHMANN - (Version JPG) - Page n° 9 - PDF Catalogue | Technical Documentation

HIRSCH*

Type of load

t>4

Material factor b3----Maintenance-free bearing

---Lubricated bearing

invariable

pulsating

time

3 b

_to^r_ct

_fa _ia^l

_te^r_at

0,5 (0,35)

time

variable

time

0,5 (0,35)

-Fr

Fig. 11

The values written in brackets are valid for rod ends with male threads and lubricating nipples or lubrication holes.

It is necessary that: p < p

¹ — ¹ perm.

p < p

o perm.

Service life:

The service life of a rod end or spherical bearing is a function of several factors, some of which are difficult to determine. A precise calculation is therefore not possible. The calculation method following, which has been proved correct in many test stand trials, gives a relatively accurate result for the service life. Influences as shocks, vibrations, soiling etc. are not taken into consideration. This calculation is based on a total abrasion of the linings of 0.3% of the diameter of the inner ring. The coefficient of the sliding friction of the linings increases of about 0.25.

Load ratio

Fig. 13

If the required service life is not obtained, repeat this calculation with next bearing size up.

Checking of linings for overheating: Permissible running speed:

The permissible running speed is largely a function of the surface exerted, the friction pairing, the lubrication and cooling if applicable. The heat building up in the bearing is proportional to the product of surface pressure and running speed. When checking the bearing size, therefore the p • v value must be determined and compared with the permissible value (Fig. 14). The bearing running speed must also be checked.

_ _ b₁ • b₂ • b₃ ₇ _c_ ^Gh_ K • ß • f P

G_h = service life

C = dynamic bearing capacity

P = dynamic equivalent bearing load

K = inner ring diameter

/3 = swing angle ^ 1

(by pivoting movements /3 = 180°)

[h] [N] [N] [mm] [degrees]

To avoid overheating, the following is necessary:

^p-^v ^ (^p"^v)perm.

N ml mm² ' minj

f = swing frequency bi = load direction factor (Fig. 12) b2 = temperature factor (Fig. 12) ba = material factor (Fig. 13)

[rpm]

v — v

^v — ^vperm.

p = surface pressure = k_c • k_c = specific surface pressure (Fig. 4) v = mean running speed = 1,745 • 10-5 • K • /3 • f

[m/min]

[N/mm²] [N/mm²]

[m/min]


Operating-factors	Load direction factor b₁		Temperature factor
Bearing type	Load di single direction	rection alternat. direction	80	Tempera 100	rture [° 150	C] 200	250
lubricated	1	2,5	1	1	1	0,8	0,5
maintenance-free	1	0,3	1	1	0,8	0,5	0,3

Guideline values for the permissible p ■ v -value


Bearing type	^(p ■ ^v)perm. N _m _m_ mm² ^■ min	perm. running speed ^vperm. ^[m/min] swing pivot
lubricated	30	15 60
maintenance-free	80	60

Fig. 12

Very low loads or running speeds result in a relatively high arithmetic service life. In practice, with a longer service life, environmental influences can acquire importance and lead to an error in the results.

Fig. 14

Rod Ends / Spherical Bearings - HIRSCHMANN - #9

Shaft seal, Tool storage magazine, Manipulator, Plain bearing, Spherical plain bearing