MOUNTING OF FK BALL BEARING UNITS

9.1 Setscrew method

This method is to mount the bearing unit to the shaft with two set screws located at two places on one side of wide inner ring which makes 120⁰ each other.

FK setscrews are of self-locking knurled cup point types. This self-locking knurled cup point type setscrew has peculiar edge points as shown in the figure and counter-clockwise knurl to prevent loosing back. The material is special alloyed steel (Nickel chromium molybdenum steels) which has high tensile Fords can stanle. The head is never broken nor deformed.

Installation to the shaft can be sufficiently made, if the grub screws are tightened by application of the tightening torque as shown in the following table.

In case either the vibration is caused to the insert bearing, the reciprocal movement takes place, the load charged on the insert bearing is large, or the shaft revolution speed is rapid, then it is desired to provide with the filed seat or concave section at the part where the setscrews with the shaft. If the thrust load is large, it is more effective to use joggling tightened with nuts.

9.2 Adapter assembly method

According to this system, the inner ring diameter of bearing has the taper of 1:12. Prior to the bearing installation the sleeve is installed to an arbitrary position as shown in the right drawing. After the shake-proof washer is inserted, the nut is tighted.

“The proper nut tightening condition can be obtained if it is tightened enough by a hand and is then rotated by 2/5 ~ 3/5 revolution with a spanner”.

After the nut is tightened, bend the shake proof washer within the slot. If not, the nut may be loosened and the creep may be caused between the shaft and sleeve.

If tightened too hard, the clearance between the shaft and the sleeve may be reduced, and the exothermic and burning phenomenon may be caused.

9.3 Eccentric Locking Collar Method

The bearing installation to the shaft by using the eccentric locking collar is one of the methods. The eccentric part of the collar mates with section of inner ring, and in this way, the bearing is Locked to the shaft.

In the normal hexagonal hollow setscrew or adapter assembly case, the shaft and inner ring are simply locked. Different from such a method, the revolving force of shaft is utilized as the tightening force in this case.

The assembly to the shaft is done only by tightening the eccentric locking collar to the shaft by use of the setscrew.

The tightening force of the setscrew can be the same level as that of common setscrew type. Since the shaft revolution force or load does not directly act on the setscrew, the setscrew is not loosened.

9.4 Concentric Locking Collar Method

The concentric locking collar, with a single standard hex head cap screw and relief slot, provides great holding power. The collar, installed over the slotted inner ring, locks the bearing on the shaft concentrically without marring or burring and provides a 360 degrees clamping force to the shaft. The roundness of ball path on concentric locking bearings results in better operation and longer life. Concentric locking bearings can replace either setscrew or eccentric locking collar bearings.

9.5 Axial movement due to expansion and shrinkage

It is often that under some driving conditions the shaft expands or shrinks, the bearing is moved.

The wheel shafts of truck, for example, must be moved in thrust direction while to some extent. When the shaft is used at high temperature, the thermal expansion of shaft becomes larger as the shaft is longer. If the all bearing are fixed to the shaft in this case, an extraordinary thrust load is applied to the bearings due to thermal expansion and it may cause failure of the bearings.

For this reason, if there exist expansion and shrinkage of shaft or movement of bearing, a fixed type unit must be used at one and a moving type unit at the other.

9.6 Mounting of the housing

It is desired to install the unit in the order of mounting housing firstly, and then mounting the shaft and bearing. The bearing unit can be installed in principle at any place in an easy way. However:

A. The mounting surface must be sufficiently rigid, the surface on which the housing is mounted should be as flat as possible, normally the requested flatness is 0.10-0. 15mm or less.

B. It is desirable that the angle between the surface on which the pillow block or flange unit housing is mounted and the shaft be maintained to a tolerance less than ±2°. When the housing is installed with a open cover, the tolerance should be less than ±1°.

C. Cartridge unit is installed on the cylindrical hole of body as a free-end. H7 tolerance is applied for normal operation conditions. When working temperature is too high, G7 tolerance is suggested. If shocking load is applied, then special tolerance is necessary to be used. Please refer to following table :

9.7 Maintenance of bearing unit

9.7.1 After mounting the bearing unit, check that it has been done correctly :

A. Turn the shaft by hand to make certain that it rotates smoothly.

B. Run the machine at low speed under 0 load, check there are no abnormalities.

C. Run the machine at normal operation conditions, check working temperature rising trend and stable working temperature.

9.7.2 Inspection during operation

In order to have the long service life, it is necessary to inspect the bearing units regularly during operation. While the interval between inspections varies from case to case, according to the degree of importance and the rate of operation, it is usually some time between two weeks and a month. Main regular inspections:

A. Bolt

B. Setscrews

C. Noise or vibration

D. Working temperature

E. Relubrication

2025 October 4th Week FK Product Recommendation:

722500 DA/DB:

The 722500 DA/DB is a type of Plummer Block (bearing housing) designed to support rotating shafts with rolling bearings. It features:

Robust cast iron or steel housing, suitable for heavy-duty applications.

DA/DB variations may refer to different sealing or mounting designs (e.g., DA with set screws, DB with double seals).

Easy installation and maintenance, ideal for industries like conveyors, motors, fans, and mining equipment.