Efficient Plant April 2018 - 17

feature | maintenance solutions
Table: Relative Thrust Capacities
Bearing Configuration

Thrust Classification

Percentage of Normal Thrust

Normal

100

Tandem angular-contact ball bearings

High thrust

175

Tandem angular-contact ball bearings

Extra high thrust

250

Spherical roller bearing

Extra high thrust

300 to 500

Kingsbury, tilting-pad, or plate bearing

Very high thrust

1,000+

Angular-contact ball bearing

VERTICAL-MOTOR-BEARING
CONSTRUCTION
Vertical motors commonly have a thrust bearing
and a guide bearing. The thrust bearing is usually
at the top of the motor and may consist of one or
more angular contact bearings, a spherical roller
bearing, or a hydrodynamic plate bearing. The
force and direction (upward, downward, or balanced) of the applied axial load dictate the type
and number of thrust bearings needed to obtain
optimum performance and service life.
Fig. 1, on page 16, shows a typical vertical
motor with the thrust bearings at the top. If the
upper bracket and bearing in the illustration were
replaced with a Conrad deep-groove ball bearing,
the motor would look very similar to a horizontal
motor. The bearing opposite the thrust bearing
(usually the lower one) is called a guide bearing
(Fig. 2). Typically a Conrad bearing, this guide
bearing locates the lower end of the motor shaft.
It's often grease-lubricated, even though the load
of the thrust bearing requires oil lubrication.
Although the guide bearing has little or no
load applied under normal operation, it may be
called upon to handle momentary thrust in the
direction opposite the thrust bearing (upthrust).
Momentary thrust is defined as no more than
30% of standard high thrust for no more than 10
seconds.

THRUST CLASSIFICATIONS
Vertical motors are classified as normal thrust,
in-line thrust, or high thrust. Normal thrust loads

APRIL 2018

can be determined from tables based on the motor's speed and horsepower rating. High thrust is
a multiple of normal thrust, such as 175%, 250%,
and 300%.
We will see, later in this article, how bearings
are arranged to accommodate each of these thrust
levels. (Note: Single-stage, close-coupled pump
motors have limited external thrust, so the usual
Fig. 2. Guide bearing

Shaft
Bottom-bearing
cap
Stabilizing
bushing
Gasket
Labyrinth seal
Bottom-bearing
cap bold
Bottom bearing
Bottom-bearing
retention ring
Bottom-bearing
bracket
Bottom-bearing lock washer
Bottom-bearing lock nut

EFFICIENTPLANTMAG.COM |

17


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Table of Contents for the Digital Edition of Efficient Plant April 2018

Editorial
Implementations
What's Wrong With My Bolts?
Understand Vertical Motor Bearings
Bourbon Boom Drives Distillery Expansion
Lubricant Myths That Can Cost You
IIoT
SAP: When To Update SAP Master Data
Give Your Chain A 'Hand'
Why Do Hackers Hack?
Why Compressor Size Matters
Equipment-Rental Considerations
On The Floor
Microgrids Are On The Rise
Solution Focus
Products
Index
Showcase
Seeking Reliability
Efficient Plant April 2018 - Cover1
Efficient Plant April 2018 - Cover2
Efficient Plant April 2018 - 1
Efficient Plant April 2018 - 2
Efficient Plant April 2018 - 3
Efficient Plant April 2018 - 4
Efficient Plant April 2018 - 5
Efficient Plant April 2018 - Editorial
Efficient Plant April 2018 - 7
Efficient Plant April 2018 - Implementations
Efficient Plant April 2018 - 9
Efficient Plant April 2018 - What's Wrong With My Bolts?
Efficient Plant April 2018 - 11
Efficient Plant April 2018 - 12
Efficient Plant April 2018 - 13
Efficient Plant April 2018 - 14
Efficient Plant April 2018 - 15
Efficient Plant April 2018 - Understand Vertical Motor Bearings
Efficient Plant April 2018 - 19
Efficient Plant April 2018 - 20
Efficient Plant April 2018 - Bourbon Boom Drives Distillery Expansion
Efficient Plant April 2018 - 22
Efficient Plant April 2018 - 17
Efficient Plant April 2018 - 18
Efficient Plant April 2018 - 19
Efficient Plant April 2018 - 20
Efficient Plant April 2018 - Bourbon Boom Drives Distillery Expansion
Efficient Plant April 2018 - 22
Efficient Plant April 2018 - 23
Efficient Plant April 2018 - 24
Efficient Plant April 2018 - Lubricant Myths That Can Cost You
Efficient Plant April 2018 - 26
Efficient Plant April 2018 - 27
Efficient Plant April 2018 - 28
Efficient Plant April 2018 - IIoT
Efficient Plant April 2018 - SAP: When To Update SAP Master Data
Efficient Plant April 2018 - Give Your Chain A 'Hand'
Efficient Plant April 2018 - Why Do Hackers Hack?
Efficient Plant April 2018 - Why Compressor Size Matters
Efficient Plant April 2018 - Equipment-Rental Considerations
Efficient Plant April 2018 - On The Floor
Efficient Plant April 2018 - 36
Efficient Plant April 2018 - Solution Focus
Efficient Plant April 2018 - 38
Efficient Plant April 2018 - 39
Efficient Plant April 2018 - 40
Efficient Plant April 2018 - Products
Efficient Plant April 2018 - 42
Efficient Plant April 2018 - 43
Efficient Plant April 2018 - 44
Efficient Plant April 2018 - 45
Efficient Plant April 2018 - Index
Efficient Plant April 2018 - Showcase
Efficient Plant April 2018 - Seeking Reliability
Efficient Plant April 2018 - Cover3
Efficient Plant April 2018 - Cover4
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