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CF-2-SB
Инструкция Страница: 4

McGill CF-2-SB Инструкция онлайн [4/132] 828615

GENERAL ENGINEERING SECTION

Introduction

The following general information will serve the purpose of

aiding the machine designer or bearing user when apply-

ing CAMROL

, CAGEROL

, GUIDEROL

, and SPHERE-

ROL

bearings covered by this catalog. Additional data

dealing solely with each type of bearing is found in each

respective section. Cross references are made whenever

necessary. Engineering data should be carefully consid-

ered in selecting the proper design and size bearing.

For those applications where unusual or abnormal operat-

ing conditions exist, it is advisable to consult the McGill

Engineering Department for recommendations. Examples

of such conditions requiring special consideration are

those involving high or low temperatures, misalignment,

shaft and housing fits that might cause the bearing to be

too tightly fitted internally after mounting, vibration, mois-

ture, contamination, etc.

Nuclear applications

GOODS AND/OR SERVICES SOLD HEREUNDER ARE

NOT FOR USE IN ANY NUCLEAR AND RELATED AP-

PLICATIONS. Buyer accepts goods and/or services with

the foregoing understanding, agrees to communicate the

same in writing to any subsequent purchaser or users and

to defend, indemnify and hold harmless Seller from any

claims, losses, suits, judgments and damages, including

incidental and consequential damages, arising from such

use, whether the cause of action be based in tort, contract

or otherwise, including allegations that the Seller's liability

is based on negligence or strict liability.

Bearing life

Bearings which have been properly mounted, lubricated,

and protected will operate with minimal, if any, internal

wear until fatigue of the rings or rolling elements takes

place. Fatigue is the first evidence of spalling of the rolling

contact surfaces of these parts, and occurs because of the

repeated stressing of the contacts.

The "life" of an individual roller bearing is defined as the

number of revolutions (or hours at a given constant speed)

which the bearing runs before the first evidence of fatigue

develops in the material of either ring or of any of the rolling

elements. The L

or "rating life" of a group of apparently

identical roller bearings is defined as the number of revo-

lutions (or hours at some given constant speed) that 90%

of the group of bearings will complete or exceed before the

first evidence of fatigue develops.

FACTORS INFLUENCING ROLLER BEARING SELECTION

Load ratings

The basic load rating or Basic Dynamic Rating as defined

by the American Bearing Manufacturers Association

(ABMA) is that calculated, constant radial load which 90%

of a group of apparently identical bearings with stationary

outer ring can theoretically endure for a Rating Life of 1

million revolutions. (33

/3 rpm for 500 hours.) The basic

load rating is a reference value only, the base value of 1

million revolutions rating life having been chosen for ease

of calculation.

It is not anticipated that such bearing loading would nor-

mally be applied while the bearing is rotating. Bearings in

this catalog should not normally be subjected to dynamic

loads greater than 50 percent of the Basic Dynamic Rating.

Consult the McGill Engineering Department if such condi-

tions exist. Applications involving reversing radial loads on

stud type cam follower bearings should be reviewed by the

McGill Engineering Department.

Life calculations

The L

(rating) life for any given application and bearing

selection can be calculated in terms of millions of revolu-

tions by using the bearing Basic Dynamic Rating and

applied radial load (or, equivalent radial load in the case of

applications having combined radial and thrust loads or

outer ring rotation). It has been shown by laboratory and

field tests that rating life for roller bearings is normally

inversely proportional to the

10/3

power of the load.

Therefore, L

BDR

10/3

million revolutions, where

is the rating life in millions of revolutions with a constant

bearing load P, and BDR is the load which will give a

theoretical rating life of one million revolutions and is

referred to as Basic Dynamic Rating in this catalog.

The L

life for any given application can be calculated in

terms of hours, using the bearing Basic Dynamic Rating,

applied load (or equivalent radial load) and suitable speed

factors, by the following equation:

16,666 BDR

10/3

where,

=rating life, hours

BDR = Basic Dynamic Rating

P = Constant equivalent radial load

N = speed (RPM)

To determine the Basic Dynamic Rating required for a

given application, use the following formula:

BDR = .054 x P x (L

x N)

()

McGill CF-2-SB Инструкция онлайн [4/132] 828615

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