All SDAF pillow blocks can accommodate grease, oil bath or circulating oil lubrication systems. Any sealing solution can be used with grease lubrication, while for oil lubrication SKF does not recommend using labyrinth rings in the LER series.
The lubricant should be selected based on the operating conditions of the bearing. For additional information, refer to Lubricant selection
Initial grease fill
If no other requirements exist, the free space in the bearing should be completely filled with grease and the free space in the housing should be filled 20 to 40% of its volume. A 40% grease fill is required when bearings have to be relubricated from the side, while a 20% grease fill is used when bearings are relubricated via the outer ring.
For highly contaminated environments and slow speeds, fill the housing to 70 to 80%. For additional information, contact the SKF application engineering service.
Quantities for 20 and 40% fills are listed in table 1
and table 2
. The values are valid for a typical lithium grease (about 0.57 oz/in3
). The grease to fill labyrinth seals or taconite heavy-duty seals is not included.
In most applications, the initial grease fill will adequately lubricate the bearing until the grease is exchanged during the next planned maintenance interval.
All SDAF housings have one drilled and tapped lubrication hole in the centre of the cap (fig. 1
). The hole is plugged on delivery.
All housing bases are equipped with a drain plug on each side to purge or drain old lubricant or to serve as an outlet for circulating oil (fig. 2
). The sump in the housing base is large enough to accommodate a sufficient quantity of lubricant to provide reliable long-term operation.
Relubrication via the outer ring
The hole in the centre of the cap should be used to relubricate spherical roller bearings with a relubrication feature (a lubrication groove and holes in the outer ring) (fig. 3). When applying grease via the relubrication feature, the shaft should be rotating.
Oil bath lubrication
The level of oil should be at about the centre of the lowermost rolling element when the bearing is stationary. For more information about oil levels, contact the SKF application engineering service. For higher speeds, the level should be slightly lower to reduce the effects of lubricant churning – about 1/8 inch above the corner of the outer ring raceway of the bearing.
An oil sight glass should be used to monitor the oil level during operation. It can be mounted into one of the drain holes in the housing base. The static oil level should be marked on the sight glass prior to operation and a running level should be marked after start up. Depending on the type of bearing and the speed and direction of rotation, the running level will either rise or fall from the static level.
Circulating oil lubrication system
When using a circulating oil lubrication system with any SDAF housing, oil is introduced through the inlet holes in the housing cap and drained from one or both sides of the base.
Drains should lead downward immediately outside of the housing to prevent oil from accumulating in the housing. Too high an oil level can result in higher operating temperatures due to churning of the lubricant. The drain pipes must be adequately sized and arranged to allow oil to drain from the housing. Additional considerations may be necessary when using a circulating oil system. These can include special housing seals, cross drilling the housing sump, wet sump requirements, flow rates, and drain hole dimensions. For more information, contact the SKF application engineering service.