Teikoku USA | Chempump
Instruction Manual NC-Series 0220
6
and is used for circulating the process fluid in the rotor cavity and
heat exchanger.
The shaft is fitted with replaceable shaft sleeves and thrust
bearing collar. These parts are keyed to prevent turning. Axial
movement is restricted by the impeller hub in the front and by a
retaining nut in the rear.
1.4 Bearings
The bearings for the NC-Series are metal sleeved carbon/graphite
and are machined with a special helix groove through the bore
to assure adequate fluid circulation at the journal area. Each
bearing is manufactured to close tolerances for a high degree of
concentricity and is held in a bearing housing by a retaining screw.
Bearings are easily replaced by removing the retaining screw and
sliding the bearing from its housing. See
.
1.5 Thrust Surfaces
The pump is equipped with thrust bearings against which axial
loads can be carried during upset conditions. The shaft is fitted
with a replaceable thrust bearing collar which is keyed to rotate
with the shaft. Axial movement is restricted by two (2) thrust
bearings located on either side of the thrust bearing collar. Each
thrust bearing has a set screw which prevents rotation. This thrust
bearing system prevent metal to metal in the event of abnormal
pump operation such as running dry or cavitation.
1.6 Internal Cooling Flow
Cooling for stator, rotor, and bearings, as well as bearing
lubrication, is provided by circulation of the pumped fluid. A
portion of the fluid circulates through the circulation tube to the
motor adapter, entering the motor section at the front bearing.
A portion of the fluid flows across the front bearing and returns
to the rear of the impeller. The remainder passes over the rotor,
across the rear bearing, and returns to suction through the hollow
shaft. See
Figure 1-1
.
1.7 Automatic Thrust Balance
Based on hydraulic principles, NC-Series automatic thrust balance
is accomplished by the pressure of the pumped fluid itself,
operating in a balance chamber on the front and rear of the
impeller. When a change in load tends to change the position
of the impeller away from the balance condition, there is an
equalizing change of hydraulic pressure in the balance chambers
which immediately returns the impeller - rotor assembly to the
balanced position. See
Figure 1-3. Automatic Thrust Balance, Single Ring
Figure 1-2. Bearings
