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Product information pages 22 and 23

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Recommendations

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Product data Page ................4 ( Diagrams to inclusive). Thespecific bearing load p and the sliding velocity v needed to perform this check can be calculated as explained in the following sections.If, having checked the pv diagram, it is found that the bearing or rod end can be used, then the basic rating life Selection of bearing size Page ..............57 Table can be used to obtain therequisite basic dynamic load rating C. A suitable bearing or rod end can then be selected from the product tables. It should then be checked whetherthe chosen size can be used under the actual load and sliding velocity condi- tions using the appropriate diagram for the sliding contact surface combination from those shown on

Requisite bearing size

is calculated. If the calculated ratinglife is shorter than the requisite rating life, a larger bearing or rod end should be chosen and the calculation repeated. If, on the other hand, the first checkshows the pv range is exceeded, a bearing having higher load carrying capacity should be chosen.The bearing (or rod end) size is often dictated to a greater or lesser degree by the dimensions of the asso- ciated components. In such cases the pv diagram should be consulted first to check that the product can be used.

Specific bearing load

The magnitude of the specific bearingload can be determined usingPp = K ––Cwherep=specific bearing load, N/mm When determining the requisite size ofbearing (or rod end), it is necessary to know the basic ratinglife required for the particular application. This is de- pendent on the type of machine, the operating conditions and the demands regarding operational reliability. As a first approximation the guide-line values of the load ratio C/P given in

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2 K=a specific load factor depending onthe basic dynamic load rating ( âž” Table ), N/mm
3 4 2 P=equivalent dynamic bearing load,kNC=basic dynamic load rating, kN

Mean sliding velocity

The mean sliding velocity for constant movement can be obtained fromv = 5,82 × 10
5 10 –7 d
m β fwherev=mean sliding velocity, m/s When operation is intermittent (not continuous) the mean sliding velocity should be calculated for a cycle of operationd
m =mean diameter of inner ring orshaft washer, mm d
m = d
k for radial spherical plainbearings d
Guideline values for C/P Specific load factors m = 0,9 d
k for angular contactspherical plain bearings d
Table 3 Table 4 Spherical plainLoad ratio bearings/rod ends C/Pwith sliding contact Sliding contact Specific loadsurface combinationfactors m = 0,7 d
k for spherical plainthrust bearings
dyn.stat.KK surface combinationSteel-on-steel β =half the angle of oscillation( ➔ fig
3 , page 16 ), degreesFor rotation
– N/mm 2 2 β = 90°f=frequency of oscillation, min
–1 ,or rotational speed, r/minFor intermittent movement, the angleof oscillation is usually given per unit time. In this case the mean sliding velocity can be calculated using2
Steel-on-bronze 2 Steel-on-steel Metric sizes100500 Inch sizes100300 Steel/sinter bronzecomposite Steel-on-bronze 5080 1,6 Steel/sinterbronze composite Steel/PTFE fabric 2 100250 v = 8,73 × 10 β
Steel/glass fibre reinforced plastic Steel/PTFE fabric 300500 GAC .. F1,25GX .. F1,25GEP .. FS1,6GEC .. FSA1,6Rod ends1,25 Steel/glass fibre reinforced plastic GAC .. F5080 GX .. F5080GEP .. FS80120GEC .. FSA80120Rod ends5080 –6 d
m –––twhere β =half the angle of oscillation, degreest=time taken to pass through 2 β (= whole angle of oscillation), s 21