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A.0500.551 – IM-TGMAG/02.00 EN (02/2008)
TG MAG pump size K.hyd
15-50 6250
23-65 4000
58-80 3750
86-100 3600
185-125 2500
3.10.3 Operation under hydrodynamic lubrication conditions
Hydrodynamic lubrication could be important criteria for bush material selection.
If the bush bearings are running under the condition of hydrodynamic lubrication there is no more
material contact between bush and pin or shaft and the lifetime cycle is increased significantly.
If there is no condition for hydrodynamic lubrication, the bush bearings make material contact with
pin or shaft and the wear of these parts is to be considered.
The condition of hydrodynamic lubrication is fulfilled
with the following equation:
Viscosity * shaft speed / diff.pressure ≥ K.hyd
with: viscosity [mPa.s]
shaft speed [rpm]
diff.pressure [bar]
K.hyd = design constant for each pump size.
3.10.4 Maximum torque of pump shaft and rotor material combination
The maximum torque is limited by the maxium transmittable torque of the magnetic coupling.
This means the magnetic coupling will slip through before the rotor shaft or pump shaft reach
their mechanical limitations.
3.10.2 Maximum temperature of internals
For some material combinations the general temperature performances must be limited. The
maximum allowable working temperature of internals depends on the combination of materials used
and their thermal expansions and the interference fit to hold the bearing bush fixed.
• Somebushbearingshaveanextralockingscrew.Inthiscasethemaximumallowabletempera-
ture is based on the most probable interference fit.
• Incasethebearingbushhasnolockingscrewbecausematerialandconstructiondonot
allow concentrated stress the maximum allowable temperature is based on the minimum inter-
ference fit.
Maximum temperature (°C) of idler bush bearing material and
idler material combinations
TG MAG pump
size
Bush and Idler materials (°C)
Cast iron idler G Steel idler S Stainless steel idler R
SG*) CG BG HG SS*) CS BS HS US BR CR HR UR
15-50 300 280 240 240 300 250 300 200 240 300 250 200 240
23-65 300 300 250 240 300 280 300 200 240 300 280 200 240
58-80 300 300 250 240 300 280 300 200 240 300 280 200 240
86-100 300 300 250 280 300 280 300 240 240 300 280 240 240
185-125 300 300 250 300 300 280 300 260 240 300 280 260 240
*) Remark: Hardness diminishment of steel bush (S) and hardened steel pin (2) above 260°C
The maximum allowable temperature of the rotor shaft bearing assembly is 280°C.