Brochure

Mtd. Ball
Bearings
G-224
®
Mounted Ball Bearing Engineering Section
CASE #1
Drive Load Calculation
P =
HP = horsepower
RPM = revolutions per minute
d = pitch of pulley in inches
K = constant for type of drive used
K = 1.5 for V-belts
K = 2 to 3 for flat transmission belts
K = 1.1 for chain drives
x K = Apply P to Case 2,
3 or 4 if applicable
126,000 x HP
RPM x d
x
z
y
Brg. 1Brg. 2
CASE #2
Cantilever and Drive
4”
9”
a
k
b
2”
Brg. B
Brg. A
P1
200#
P2
80#
Load on Bearing A =
P
1
x (a + k) - (P
2
x b)
k
=
200 x (4 + 9) - (80 x 2)
9
Load on Bearing B =
P
2
x (k + b) - (P
1
x a)
k
=
80 x (9 + 2) - (200 x 4)
9
= 9 lbs.
= 271 lbs.
CASE #3
Straddle, Cantilever Drive
Load on Bearing A =
P
1
x (k + a) + (P
2
x c) - (P
3
x d)
k
=
60 x (12 + 2) + (180 x 6) - (70 x 4)
12
Load on Bearing B =
-(P
1
x a) + (P
2
+ b) +P
3
x (k + d)
k
=
-(60 x 2) + (180 x 6) + 70 x (12 + 4)
12
= 137 lbs.
= 173 lbs.
12”
2”
a
6”
b
k
Brg. B
Brg. A
P1
60#
P2
180#
P3
70#
6”
c
4”
d
CASE #4
Straddle Mount, Cantilever Drive
7”
11”
a
k
4”
b
3”
Brg. BBrg. A
P2
150#
P1
1000#
c
Load on Bearing A =
(P
1
x b) - (P
2
x c)
k
=
(1000 x 4) - (150 x 3)
11
Load on Bearing B =
(P
1
x a) + (c + k) x (P
2
)
k
=
(1000 x 7) + (3 + 11) x (150)
11
= 827 lbs.
= 323 lbs.
CASE #5
Vibrating Drives
Load due to Centrifugal and Inertial Forces - In a shaker or gyrating
screen bearing application, the load on the bearings is increased by
sudden stopping, starting, and reversing of typically large loads.
This can be expressed as a basic physical law:
Force = Mass x Accelerations
In order to use this law, we develop from it the following equation:
F = .000341 x WR(RPM)
2
Where: F = Load of force in lbs.
W = Weight of rotating mass in lbs.
R = Radius of rotation or throw in feet
RPM = Shaft rotation in revolutions per minute
What is the centrifugal bearing load on a shaker screen which weighs
2,500 lbs., has a throw of 1/4 in. and whose shaft speed is 500 RPM?
F = .000341 x 2,500 x x (500)
2
= 4,440 lbs.
.250
12
R
WEIGHT
Load Ratings and Life Continued
Computing Bearing Loads
In the computation of bearing loads in any application
of an Power Transmission Solutions unit, the principal
factor determining the selection of the unit is the
equivalent radial load to which the bearing will be
subjected. These radial loads result from any one or
any combination of the following sources:
1. Weights of machine parts supported by bearings.
2. Tension due to belt or chain pull.
3. Centrifugal force from out of balance, eccentric or
cam action.
The resulting load from any one, or any combination
of the above sources is further determined by know-
ing:
1. The magnitude of the load.
2. Direction of the load.
3. The point of load application.
4. The distance between bearing centers.
Bearing loads are the result of force acting on the
shaft. Direction, magnitude, and location with respect
to the bearings must be considered when calculating
bearing loads. The following cases are typical exam-
ples of loads encountered and methods of calculating
bearing loads.