The new FAG SNS plummer block housing from Schaeffler has been completely redesigned, providing numerous technical advantages to users, including more even load distribution on the bearings, resulting in an extended operating life. Schaeffler has also optimised the design further, resulting in a housing that is not only more cost effective to manufacture, but also easier to mount and dismount.
Manufactured from high quality, spheroidal graphite cast iron as standard, the housing ensures a high level of robustness and operational reliability. Other benefits include improved lubrication and condition monitoring of the bearings, as well as increased application flexibility and a significant reduction in overall cost of ownership.
Also, due to the introduction of new, industry-standard mounting arrangements and dimensions, the housing can be installed as a direct replacement (retrofitted) for a wide variety of conventional plummer block housings.
The unique, patented design of the FAG SNS plummer block housing distributes the load on the bearings more effectively (uniformly) than previous and alternative housings.
Using its in-house developed bearing design, calculation and simulation software, Bearinx®, Schaeffler is able to analyse different housing designs with various combinations of bearings, enabling the optimisation of the complete system (housing and bearings).
By introducing some subtle geometrical changes, including a small arch-shaped cutaway at the bottom centre of the housing, the load on the bottom roller (at the apex, 180 degrees) is now distributed more evenly across two or three rollers. By spreading the load from the shaft across a greater number of rolling elements, the operating life of the bearing is increased by up to 50 percent.
In Fig 1 (see separate attachment), the blue curve represents the rolling element load on a bearing installed in a housing with conventional support. The red curve represents the same load but in a bearing installed in the SNS housing with a cutaway. The red curve has a wider load zone and more even load distribution than the blue curve.
In addition, the load on the roller at the apex is significantly higher in the blue curve. However, the red curve demonstrates that a cutaway in the feet of the housing creates a wider load zone. The maximum load from the shaft is no longer supported by the roller at the apex, but by its two neighbouring rollers.
Other design changes have resulted in improved bearing lubrication, mounting and condition monitoring – which together contribute to a significant reduction in the total cost of ownership.
A lubrication bore with a longer groove has now been added to the inside of the upper section of the housing. This means that different bearing types installed in each bearing position can now be supplied with sufficient lubricant at all times. The lower section of the housing still contains grease outlet bores, which allow for the removal of used or superfluous grease when relubrication is carried out.
To enable improved condition monitoring of the bearings, connections are now provided on both sides of the housing as standard for Schaeffler’s FAG SmartCheck condition monitoring device. However, if these two connections are not accessible, a centre mark in the upper section of the housing indicates the optimum mounting position for condition monitoring.
Schaeffler can also supply the housing with connections for its new Concept 8 automatic lubrication system.
To make mounting even easier, centre marks that indicate the bearing centre line and shaft are provided in the lower section of the housing, which enables fast alignment of the housing. The lower section of the housing also incorporates high precision, machined locating surfaces. These are raised and so allow the use of ledges to achieve precise alignment. Once it has been aligned, the housing can be quickly replaced if required.
Bevels, small surfaces and an upper housing section that covers the lower housing section, eliminate potential collection points for fluid and contaminants, ensuring that these drain off naturally, reducing the amount of cleaning required.
A variety of seals are available, which enable the bearings to operate in harsh environments such as mining, quarrying, mineral processing, food and beverage processing, and applications in which the bearings must perform reliably over extended periods in harsh, remote locations.
Rolling bearings of different diameters and widths can be installed in the new SNS plummer block housing. The bearings are moveable and so function as non-locating bearings. Suitable bearings include the 222, 223, 230, 231, 232, and 240 series. The FAG SNS housings can be used as direct replacements for a wide range of conventional housings.
Schaeffler has also launched two new products that simplify the distribution of power and input/output signals of up to four FAG SmartCheck online condition monitoring devices, resulting in reduced cabling costs and faster, easier installation.
The FAG SmartConnectBox power supply unit enables easy distribution of power supply inputs and outputs to a maximum of four FAG SmartCheck devices. In addition, a standard speed sensor and Schaeffler’s new FAG SmartLamp local alarm indicator unit can also be connected to the FAG SmartConnectBox.
Rather than running separate cables from four FAG SmartCheck devices to a speed sensor, this new system provides a cleaner, more elegant solution for customers, particularly when monitoring the condition of large rotating machines such as electric motors, geared motors and variable speed drives.
FAG SmartCheck is an extremely compact, online condition monitoring device that monitors vibration and temperature, as well as a range of other machine and process-specific parameters such as pressure and flow rate.