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Motion Without Limits

®

Individual ‘V’ Bearing Calculations

Many systems do not use a standard 4 bearing carriage. In such cases it is necessary to use conventional statics calculations to determine the loading on each bearing in the system, by resolving loads into axial (L

L

3

A

*

1 1 A

* ) and radial (L

R

* ) components. The maximum L

L

R

A

and L

R

load capacities for all types of ‘V’ bearing are given in the tables below. Capacities are included for both ‘dry’ and ‘lubricated’ conditions - this refers to the ‘V’ contact, since all bearings are greased internally for life. Values are based on shock-free duty. Axial Load Radial Load

Load Capacities for Twin Standard BearingsBearing Part Numbers Load Capacities for Double Row Standard BearingsBearing Part Numbers Load Capacities for Slimline BearingsBearing Part Numbers

Dry

Lubricated

L Dry Dry
A (max) R (max) A (max) R (max)

Lubricated Lubricated

NL NL NL Nm L
A (max) R (max) A (max) R (max) L
A (max) R (max) A (max) R (max)

...J 13...22.54560120...J 18...4590125200 ...J 25...100200320600 ...J 34...2004008001400 ...J 54...45090018003200

NL NL NL N
*6 NL NL NL N

...J 18 DR...4590190600...J 25 DR...1002004001500 ...J 34 DR...2004009003000 ...J 54 DR...45090025005000 ...J 195...4590100240...J 265...100200235575 ...J 360...2004005001200 ...J 580...45090010602600 The above figures assume that bearings are used with slides equal to or larger than the preferred slide selection for that bearing size. For details of the preferred sizes, see tables on pages 28-31. For loading of bearings with smaller slides, please contact Bishop-Wisecarver Corporation.

Calculating the System Load Factor

To calculate the system life, the load factor L

F

should first be calculated using the equation below.

L

A R F

= + L L L

A(max)

L

R(max)

L

F

should not exceed 1 for any combination of loads.Once L

F

has been determined for each bearing, the life can be caculated as follows:

BearingsBasic Life DryBasic Life Lubricated

Calculating System Life

With L

...J 13...4050...J 18...50100...J 18 DR...50100...J 25...7050...J 25 DR...7070...J 34...100100...J 34 DR...100250...J 54...150250...J 54 DR...150500...J 195...50100 ...J 265...7050 ...J 360...100250 ...J 580...150200

F

determined for either a 4 bearing carriage or for an individual bearing, the life in km can be calculated using one of the two equations below. In these equations, the Basic Life is taken from the table (right) in respect of the bearing and the lubrication condition applicable.

Dry System Lubricated System

Life (km) =Basic Life(0.03 + 0.97L

2

Life (km) =Basic Life(0.03 + 0.97L

3 F

)

F

)

* Notes:

1. The maximum values of M
R , M
P , M
Y , L
A and L
R , and the magnitudes of the system Basic Life for each bearing type relate to the performance of complete systems. Tests have shown these figures to be more reliable than working from the theoretical static and dynamic load capacities ( C and Co) of the bearings. Values of C and Co have been included in tabulated data on the relevant bearing pages as a means of comparison with other systems.2. The calculations within this section assume that the linear stroke involves a number of complete bearing revolutions. If the stroke of any application is less than five times the bearing outside diameter, then please calculate the distance travelled as if it moves five bearing diameters per stroke. Systems operating at speeds in excess of 8 m/s may require additional calculation. Please contact Bishop-Wisecarver Corporation for assistance.3. For the purposes of the load/life calculations on this page, the axial load L
A is that load in the axial direction which the bearing can accept from a ‘V’ slide engaged in its outer ring. Since the line of force is some distance removed from the axis of the bearing, this value is much less than the theoretical axial load capacity which is quoted on the relevant bearing page.4. In the above calculations, the term lubricated refers to the contact between the slide and bearing ‘V’s. This lubrication may best be achieved using lubricators, cap seals or cap wipers, however other methods which ensure the presence of a suitable grease or oil in the critical area are acceptable.5. When a system consists of more than 4 bearings per carriage (e.g. see application examples on pages 9 & 12) it cannot always be guaranteed that the load will share equally between all bearings. In such cases it is recommended that controlled height bearings are specified (where available) and that the system is derated to allow for the life of the most heavily laden bearing.6. For some sizes of DR bearing, the actual life for applications with mainly L
R /radial loads may be higher than the calculations indicate. This is because the calculations are simplified for easy use. Please contact Bishop-Wisecarver Corporation for details in instances where a higher system life is required.

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