Brochure

400
500
300
200
100
0 10 3020 7040 50 60
Force [N]
Q [m
3
/h]
80
100
60
40
20
0 10 3020 70
Q [m
3
/h]
40 50 60
Force [N]
4444
2.11 Axial thrust
Axial thrust is the sum of forces acting on the shaft in axial direction,
see figure 2.14. Axial thrust is mainly caused by forces from the pressure
dierence between the impeller’s hub plate and shroud plate, see section
1.2.5.
The size and direction of the axial thrust can be used to specify the size of
the bearings and the design of the motor. Pumps with up-thrust require
locked bearings. In addition to the axial thrust, consideration must be taken
to forces from the system pressure acting on the shaft. Figure 2.15 shows an
example of an axial thrust curve.
The axial thrust is related to the head and therefore it scales with the speed
ratio squared, see sections 3.4.4 and 4.5.
2.12 Radial thrust
Radial thrust is the sum of forces acting on the shaft in radial direction
as shown in figure 2.16. Hydraulic radial thrust is a result of the pressure
dierence in a volute casing. Size and direction vary with the flow. The
forces are minimum in the design point, see figure 2.17. To size the bearings
correctly, it is important to know the size of the radial thrust.
Figure 2.15: Example of a axial thrust curve
for a TP65-410 pump.
Figure 2.14: Axial thrust
work in the bearing’s
direction.
Figure 2.17: Example of a radial thrust curve
for a TP65-410 pump.
Figure 2.16: Radial thrust
work perpendicular on
the bearing.
2. Performance curves