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GEK-95352
4
I. INTRODUCTION
General Electric high-thrust vertical mo-
tors covered by these instructions are
carefully constructed of high-quality ma-
terials and are designed to give long and
trouble-free service when properly in-
stalled and maintained. These motors are
generally used to drive pumps.
Both HOLLOW-SHAFT and SOLID-
SHAFT motors are described in this in-
struction book. Figure 1 shows a typical
hollow-shaft high-thrust motor. The solid-
shaft construction is similar except that
the top half-coupling is omitted, and the
motor shaft extends out the bottom of the
motor. See Figure 2. Solid-shaft high-
thrust motors are not suitable for driving
loads that impose significant radial load
on the motor shaft; they should not, for
example, be used for belt-drive applica-
tions.
Motors may be supplied with different
bearing arrangements for various external
thrust conditions imposed by the pump,
such as different magnitudes of down-
thrust and either momentary or continu-
ous up-thrust. A typical high-thrust motor
with angular-contact ball bearings is
shown in Figure l. This standard con-
struction is for high continuous down-
thrust and is suitable for momentary up-
thrust equal to 30% of the rated down-
thrust capacity of a high-thrust motor.
NOTE THAT ANGULAR-CONTACT
BEARINGS CAN ONLY CARRY
THRUST IN ONE DIRECTION.
Figure 3 shows a typical solid-shaft high-
thrust construction (on right side) for ap-
plications requiring continuous up-and-
down thrust capability. In this type of
motor, two or three angular-contact ball
bearings are mounted in opposed mount-
ing with one bearing oriented to carry up-
thrust and one or two oriented to carry
down-thrust. If greater down-thrust ca-
pacity is required, motors may use one or
two standard angular-contact ball bear-
ings and one split-race bearing which
gives the capacity of two or three bear-
ings down and one bearing up. This does,
however, give more end-play than nor-
mal.
IN-LINE motors (designed to be mounted
on pumps which are directly in the pipe-
line, and hence called IN-LINE motors)
are also covered by this instruction book.
These motors have two opposed-mounted
angular-contact ball thrust bearings at the
top end of the motor so they can carry
either up or down thrust. The lower guide
bearing is a radial-ball type and also car-
ries any radial load imposed by the pump.
IN-LINE motors are always of the solid-
shaft type. This construction is shown on
the left side of Figure 3.
Spherical-roller bearings are sometimes
used for applications requiring extra high
down-thrust capacity and/or extra bearing
life; these bearings may require water-
cooling. See Figure 2. Motors with
spherical-roller thrust bearings also re-
quire certain minimum down-thrust dur-
ing all continuous operation.
Since overloading greatly reduces bearing
life, the amount of thrust applied should
not exceed the recommended values.
This instruction book applies to motors
with either Weather-Protected I or
Weather-Protected II enclosures as de-
fined by NEMA. Both of these are “open"
motors. (WP-II enclosure is not available
in 440 frame series.)
Weather-Protected I motor construction is
shown in Figure 1 for 500 frame motors
and in Figure 3 for 440 frame motors.