Page 684 - SKF-bearing-housings

Metric roller bearing units SYNT and FYNT series (SKF ConCentra)

Grease life for the relubrication-free Based on the shaft diameter provided and
variant the plummer block housing requirement, the
The grease used in relubrication-free bearing SYNT 60 bearing unit is selected. As the appli-
units can adequately lubricate the bearing cation is an industrial air handling unit in a rel-
throughout its service life provided the bearing atively clean environment, the relubrication-
unit is suitable for the operating conditions. free variant would be a suitable choice.
The relationship between operating conditions From the product table, the basic dynamic
and grease service life is shown in diagram 4 load rating C = 156 kN and
and is a function of:
when C/P = 156/7 = 22,3
• the operating temperature [°C]
then P = 0,045 C
• the speed factor A = n d m
where Therefore, the bearing unit meets the con-
A = speed factor [mm/min] ditions of use for relubrication-free variants,
n = rotational speed [r/min] where P ≤ 0,05 C.
d m = bearing mean diameter [mm]
(† table 9, page 678) For d m = 85 mm († table 9, page 678)
A = n d m = 1 800 ¥ 85 = 153 000 mm/min
Provided the operating range of the bearing
unit falls within the shaded area of diagram 4, Using diagram 4, the intersection point of the
the bearing unit can attain a grease life of calculated speed factor and expected operat-
L 50h = 100 000 hours or more. L 50h is the time ing temperature of 55 °C is located in the
period at the end of which 50% of the units are shaded area.
still reliably lubricated. The SYNT 60 FW (or SYNT 60 LW) bearing
unit meets the grease life requirement and is
Calculation example therefore suitable for the application.
An SKF ConCentra roller bearing unit with
a plummer block housing is required for an
industrial air handling unit. The following
application information is known:
• required grease life L 50h = 100 000 hours
• equivalent dynamic bearing load P = 7 kN
• rotational speed n = 1 800 r/min
• shaft diameter d a = 60 mm
• environmental conditions: relatively clean
• expected operating temperature: 55 °C

680