1. Why do bearings have thrust clearance and expansion clearance?

A) Metal materials have the properties of thermal expansion and cold contraction. When the shaft is operated at different temperature conditions, the length and diameter of the shaft will also change.

Therefore, in order to ensure the formation of pressure oil film of thrust bearing, thrust clearance must be left.

B) In order to ensure that the shaft will not be hindered or restricted in the expansion process, resulting in great stress and damage to the bearing, an expansion gap must be left.

2. How to measure the top clearance between split bearing cover and bearing with lead wire method?

A) Place the lead wire near the bolt hole and along the arc length direction of the bearing top in the joint surface of the bearing seat and bearing cover.

B) Install the upper cover and tighten the bolts evenly diagonally.

Remove the bearing cover and use the outside diameter micrometer to measure the thickness of each wire.

C) Subtract the average thickness of the lead wire at the outer ring of the bearing from the average thickness of the bonding plane of the bearing seat. If the difference is positive, it is the clearance, and the negative value is the tightening force.

Click here for more information about KOYO 32218JR.

3. What is the harm of too low or too high bearing oil level?

A) If the oil level is too high, the oil ring movement resistance will increase and skid or stop. The mutual friction of oil molecules will increase the bearing temperature, increase the leakage of oil at the gap and the friction power loss of oil.

B) If the oil level is too low, the ball or oil ring of the bearing will not have oil, resulting in the bearing not being lubricated and the temperature rising, and the bearing will burn out.

4. What is the reason for the high temperature of rotating mechanical bearing?

A) Low oil level, lack or no oil.

B) The oil level is too high and the oil quantity is too much.

C) The oil quality is unqualified or bad (there are impurities in the oil).

D) Insufficient or interrupted cooling water.

E) The oil ring does not carry oil or does not rotate.

F) Defective or damaged bearings.

G) Equipment vibration.