Page 218 - Rollingbearings

Vibrating screen

C.1 Vibrating screen

Bearing type and
This example shows the bearing selection process applied to an
application case in which a vibrating screen manufacturer is selecting
the bearings for a new machine arrangement
The steps in the example follow the sequence in the bearing se lec-
tion process Refer to sections B.1 – B.8 for a full description of each
process step

A locating/non-locating bearing arrangement is used The bearing
on the drive side is the locating bearing This limits axial displace-
ment of the transmission pulley, which saves energy and increases
Performance and operating belt life The opposite bearing is non-locating to accommodate axial
displacement caused by thermal expansion of the shaft
conditions The distance between the bearings is 3 metres, and the vibrating
screen structure is made of welded and bolted steel parts. Shaft
delection and misalignment of supports under load require bearings
that can compensate for misalignment.
Spherical roller bearings are selected for this new vibrating screen
The new machine is a free circular motion vibrating screen. The (ig. 2), which is the typical solution. They can carry high loads and
vibrator unit is composed of a shaft with two bearings and counter- accommodate misalignment between the inner and outer ring with-
weights. This means the main radial load rotates with the shaft while out any reduction of their service life.
the outer ring is stationary. The application drawing is shown in ig. 1.
The relevant performance requirements, operating conditions and
input parameters for the bearing selection are:

• mass of screen box without charge: G = 6 100 kg
• shaft diameter: 140 mm
• rotational speed: n = 756 r/min
• angular velocity (n × 2π/60): ω = 79,2 rad/s
• radius of vibration: r = 8,1 mm
• distance between the centres of gravity of the counterweights and
shaft axis: R = 80 mm
• distance between the bearings: 3 m
• lubrication method: grease
• operating temperature of the bearings: T = 75 °C (165 °F)
• environment: the screen may be located outdoors, in harsh, dusty
C.1 Vibrating screen
and humid conditions
• required SKF rating life: 20 000 h

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