Full complement bearings All free space in the bearing should

Grease nipple

Grease escape hole

Care should be taken when using a grease gun operated by pressurized air. The seals may be damaged by the pressure.

Figure 23. Grease lubrication of CARB toroidal roller bearing

Fig 23 • operating conditions such as

vibration

• bearing type and size • bearing load

• full complement or caged bearing The viscosity of the base oil of a grease partly determines the thickness of the lubricant film in the rolling contact. Applying the grease

On delivery, CARBTM_{toroidal roller} bearings are coated with a rust inhibit- ing compound. There is no need to remove this.

Generally a CARB bearing is first greased when it has been mounted in order to minimize the risk of contami- nation. Only in cases where it is impos- sible to apply the grease evenly to the bearing should the grease be applied before the bearing is mounted.

The application of grease to CARB bearings is shown in figs➔ 21 and .22

2 15000 10000 6000 4000 2000 1000 600 500 400 300 250 200 150 100 80 60 50 40 30 20 15 10 3 d = 10 mm 20 40 60 80 100 120 160 200 280 360 420 500 4 5 6 7 8 9 2 1000 100 10000 20000 3 4 5 6 7 8 9 240 Relubrication Interval t f operationing hours Example C 2220 K

The bearing has a bore diameter of d = 100 mm and is to rotate at 1000 r/min.The operating temperature varies between 50 and 70°C (122° and 160°F). What is the recommended relubrication interval?

A line from 1000 r/min on the x axis is followed until it meets the curve for 100 mm bore. A line at right angles is then followed to the y axis where the value is found to be 2000 h. Thus the relubrication interval is 2000 operating hours.

L01grease life

n r/min

Excess grease is thrown from the rotating disc into a groove in the end cover of the housing Housing end cover

Rotating disc

Fig 26

Figure 26. Grease valve

How to lubricate CARBTM_toroidal roller bearings

Since CARB bearings have one row of rollers they can only be lubricated from the side. The housing should be fitted with a grease nipple at the side opposite to the lock nut (if they are mounted on an adapter sleeve). If they are to be fre- quently relubricated it is advisable for the housing base to have a grease escape hole at the side of the bearing opposite to the grease nipple, see ➔fig .

Experience gained with all roller bear- ings indicates that a first relubrication after a few days of operation is very beneficial, and may even be a prerequi- site if the expected relubrication interval is to be attained when operating speeds are high. For this first relubrication half of the normal quantity recommended for regular relubrication will be sufficient.

Full complement bearings cannot retain grease as well as caged bearings unless the speed is very low. Therefore, full complement bearings should be relu- bricated much more often than caged bearings, and continuous relubrication may be required if speeds are high. Relubrication

The length of time during which a grease lubricated bearing will function satisfacto- rily without relubrication depends on bearing size and speed and on the oper- ating temperature etc., see ➔fig .

The grease used for relubrication should be the same as that used for the original greasing. Certain greases lose their lubricating properties when mixed with other greases. For this reason, greases should never be mixed if it is not known whether they are compatible. Correct amount of grease

The following general rules apply for initial lubrication:

• CARBTM_{with cages should be filled} to approximately 50% except at low speeds when they should be completely filled

• Full complement bearings should be completely filled

• Bearing housings should be partly filled (30% to 50% of the free space)

24 23

Leave some space in the bearing housing for grease which is thrown out of the bearing when starting up.

It is possible with most lithium base greases to fill more than 50% of the free space in the housing.

Figure 25. Grease filling

Fig 25

• Replenishment quantities should be determined using the methods described on page 75.

In non-vibrating applications it is possible when using most lithium base greases of the “full fill” type to apply more grease to the housing than recommended above, without any risk of increasing the temperature, see ➔fig . The increased grease quantity provides greater protection against the penetration of contaminants to the

25

bearing. When a bearing has to be relubricated often, too much grease may collect in the bearing housing. This can be prevented by using a grease valve, see ➔fig26.

SKF Solid Oil™ — The Unique Lubrication Problem Solver

SKF Solid Oil is a mixture of lubricating oil and polymers, thermally cured to a rigid, sponge-like gel. This solid but elastic mass completely fills the bearing cavity but permits free rotation of the rolling elements. While the bearing oper- ates, a thin film of oil is continuously released from the polymer “sponge” through light rubbing contact — only as much as required. When operation stops, excess oil is reabsorbed into the SKF Solid Oil “sponge”, ready to be released again when needed.

The unique characteristics of SKF Solid Oil provide excellent oil lubrica- tion without the problems normally associated with keeping oil or grease in contact with the rolling elements. The thin film of oil released by the sur- face during rubbing contact with the metal surfaces provides efficient lubri- cation. There’s no waste and no bleed- ing of excess lubricant from the bear- ing which could contaminate processes or mechanisms. When operation stops, any excess oil is reabsorbed.

With SKF Solid Oil, environmental restrictions requiring users to account for the greases that have been consumed are more easily met. SKF Solid Oil is most beneficial in applications with

● _{Low to moderate speeds} SKF Solid Oil

Formulations Approximate Oil Viscosity

W64B/W64C 140 cSt at 40°C 19 cSt at 100°C

(Standard Product) 735 SUS at 100°F 96 SUS at 210°F

W64E 385 cSt at 40°C 39 cSt at 100°C

2000 SUS at 100°F 189 SUS at 210°F

W64H 1056 cSt at 40°C 97 cSt at 100°C

5600 SUS at 100°F 470 SUS at 210°F

Food Grade W64 (USDA H1)

W64F 62 cSt at 40°C 10.1 cSt at 100°C

315 SUS at 100°F 64 SUS at 210°F

W64G 208 cSt at 40°C 25 cSt at 100°C

1050 SUS at 100°F 130 SUS at 210°F

● _{Short service life due to:}

—Orbital centrifugal force throwing grease out

—High pressure liquids washing out grease

—Particle contamination where fre- quent regreasing cannot be done ● _{Where relubrication is inconvenient}

or in a hazardous area or environ- ment.

In general, the advantages are most cost beneficial in those applications where the current bearing service life is only a few months due to the causes listed above. In these cases, it may substantially increase the bearing ser- vice life (and reduce overall costs) even though the (much longer) calculated L10life may still not

be achieved.

Consult with your SKF representative especially if one or more of the follow- ing conditions apply:

● _{Bearing service life with grease} is three years or longer (without relubrication)

● _{High moisture levels/condensation} is causing internal bearing corrosion ● _{Speeds and/or ambient tempera-}

tures are high

● _{Grease relubrication at proper inter-} vals is easily done at little extra cost (for example — other parts of the machine are regreased anyway)

Maximum Ndm* SKF bearing type with Solid Oil Single row deep

groove ball 300,000

Angular contact ball 150,000 Self-aligning ball 150,000 Cylindrical roller 150,000 Spherical roller-radial

Excluding “E” type 85,000

“E” type 42,500

Tapered roller 45,000

Ball bearings

with nylon cages 40,000

(including Y-range unit ball bearings)

(Bore + O.D.) in mm Ndm= RPM x —————————————

2

*Maximum Ndmvalues are for open

Troubleshooting

Bearings that are not operating properly usually exhibit identifiable symptoms. This section presents some useful hints so you can help prevent it from happening again. The listed caus- es are the most common for the symp- toms. Practical solutions are presented wherever possible. Depending on the degree of bearing damage, many mis- leading symptoms may be present. In most cases these symptoms are the result of secondary damage. To effec- tively troubleshoot bearing problems, it is necessary to analyze the symptoms according to those first observed in the applications. Additional solutions appear throughout this guide.

Common Symptoms

A — Overheated bearing B — Noisy bearing

C — Replacements are too fre- quent

D — Vibration

E — Unsatisfactory performance of equipment

F — Bearing is loose on shaft G — Shaft is difficult to turn

Symptoms of bearing trouble can usually be reduced to a few classifica- tions, listed in the chart below.

The following table shows:

● _{The alphabetical codes for symp-} toms

● _{Typical conditions that result in bear-} ing failure

● _{The numerical codes for solutions} NOTE:

Troubleshooting information shown on these pages should be used as guide- lines only. Consult your SKF represen- tative or machine manufacturer for specific maintenance information.

Typical Conditions Resulting in Bearing Failures

Common Solution

Symptoms Typical Conditions Code

A B C G Inadequate lubrication (Wrong type of grease or oil) . . . 1 A B C G Insufficient lubrication (Low oil level — loss of lubricant through seals) . . . 2 A G Excessive lubrication (Housing oil level is too high or housing is packed with grease) . . . 3 A B C E G Insufficient bearing clearance (Wrong fit selection) . . . 4 B C D E G Foreign matter acting as an abrasive (Sand, carbon etc.) . . . 5 B C D E G Foreign matter acting as a corrosive (Water, acids, paints etc.) . . . 6 A B C D E G Bearing is pinched in the housing (Bore out of round) . . . 7 A B C D E G Bearing is pinched in the housing (Warped housing) . . . 8 A B C D E G Uneven shimming of housing base (Distorted housing bore — possible cracking of the base) . . . 9 B C D E G Foreign matter in bearing housing (Chips, turnings, or dirt left in housing) . . . 10

C High air velocity over bearings causing pressure differentials (Oil leakage) . . . 11 A G Seals are too tight (Distorted seals) . . . 12 A B G Misaligned seals (Rubbing against stationary parts) . . . 13 A Oil return holes are plugged (Oil leakage) . . . 14 A B C E G Preloaded bearings (Cross location) . . . 15 A B C G Preloaded bearings (Two locating bearings on one shaft) . . . 16 B C D E F Bearing is loose on the shaft (Shaft diameter is too small) . . . 17

Common Solution

Symptoms Typical Conditions Code

B C D E F Bearing is loose on shaft (Adapter sleeve is not tightened sufficiently) . . . 18 A B C E G Bearing is too tight internally (Adapter sleeve is tightened excessively) . . . 19 C Split plummer (pillow) block with uneven surfaces (Oil leakage) . . . 20 A B C D E Outer ring spins in housing (Unbalanced load) . . . 21 B D E Noisy bearing (Flattened surface on rolling element due to skidding) . . . 22 C D E Tapered shaft seating (Concentration of load in the bearing) . . . 23 C D E Tapered housing bore (Concentration of load in the bearing) . . . 24 B C D E G Shaft shoulder is too small (Inadequate shoulder support — bending of shaft) . . . 25 A B C G Shaft shoulder is too large (Rubbing against bearing seals) . . . 26 B C D E G Housing shoulder too small (Inadequate shoulder support) . . . 27 B C G Housing shoulder is too large (Bearing seals are distorted) . . . 28 B C D E G Shaft fillet is too large (Bending of shaft, bearing not properly seated) . . . 29 B C D E G Housing fillet is too large (Inadequate support) . . . 30 A B C G Insufficient clearance in labyrinth seals (Rubbing) . . . 31 A C Oil gauge breather hole is clogged (Indicates incorrect oil level) . . . 32 A C D E G Linear misalignment of shaft . . . 33 A C D E G Angular misalignment of shaft . . . 34 A C Constant oil level cups (Incorrect level) . . . 35 A C Constant oil level cups (Incorrect location) . . . 36 A B E G Lock washer prongs are bent (Rubbing against the bearing) . . . 37 A B C G Incorrect positioning of flingers (Rubbing against covers) . . . 38 A B C D E G Supporting surface is uneven (Bent housing is causing the bearing to be pinched) . . . 39 B C D E Rolling element is dented (Caused by blows to the bearing) . . . 40 B Bearing noise (Caused by other components) . . . 41 A B C Lubricant leakage and entry of dirt into the bearing (Worn out seals) . . . 42 B D E Vibration (Excessive clearance in the bearing) . . . 43 B D E Vibration (Unbalanced load) . . . 44 C E G Hard-turning shaft (Shaft or housing shoulders are out of square with the bearing seating) . . . 45 B Bearing is discolored (Blow torch was used to remove the bearing) . . . 46 A B C E G Oversized shaft (Bearing overheats) . . . 47 A B C E G Undersized housing bore (Bearing overheats) . . . 48 A B C D E Oversized housing bore (Outer ring spins; Bearing overheats) . . . 49 A B C D E Enlarged housing bore (Excessive peening of non-ferrous housing) . . . 50 B E Bearing noise (False brinelling) . . . 51

“Symptoms” refers back to the table on page 84.

“Typical conditions” provides the causes of each symptom. “Solution code” provides the practical solution.