Siemens 580 用户手册

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At the first sign of oil discoloration or contamination, 
replace with new oil. Rapid discoloration is caused by 
bearing wear, often from vibration or thrust. Change 
oil as required to keep clean. 
 
When assembling the bearing, it is possible to foul 
the rings so that they will not turn freely. Check ring 
operation by rotating shaft by hand after assembly 
 
Oil Seals 

580 frame motors use fixed, labyrinth oil seals to 
close off the bearing cavity.  The 500, 880, SH400, 
SH450, and SH560 frame motors utilize floating type 
oil seals to close off the bearing cavity.  The primary 
purposes of the oil seal are: 
1.  To prevent the entrance of dirt in to the bearing 

cavity. 

2.  To retain the oil in the bearing cavity. 
3.  To provide pressure regulation in the bearing 

cavity. 

 
To achieve these purposes it is necessary that a 
specific diametrical clearance of oil seal to shaft be 
held.  The cooling fans of the motor tend to create a 
suction or a pressure in the bearing cavity, which, if 
large enough, will push or draw oil out along the 
shaft.  The close fitting oil seal gives a pressure drop 
across it and minimizes the differential pressure. 
 

 
Besides using close clearances to correct differential 
pressures, some oil seals are vented to the 
atmosphere.  It is important that the piping and 
venting for these oil seals be kept clean. 
 
The clearance between the journal and the bearing 
will permit the journal center to be slightly below the 
bearing center.  With the motor operating, the 
presence of the oil film between the journal and the 
bearing will cause the shaft to rise slightly. 
 

When a sleeve bearing becomes worn and requires 
replacement, the labyrinth oil seal should also be 
replaced. 

 
Bearing Clearance Too Large 
Too large a bearing clearance or clogged oil return 
holes in the bearing will permit excessive oil to seep 
out the ends of the bearing.  This seepage, combined 
with the rotation of the shaft, will create an oil mist 
inside the bearing cavity which will tend to leak 
through the oil seals.  Excessive pressure in a force 
feed lubrication system can also cause an oil mist to 
build up. 
 
Cavity Pressures 
Motors are sensitive to the amount of pressure or 
vacuum existing in the bearing cavity.  The table 
below shows the maximum allowable oil cavity 
pressure or vacuum in terms of plus or minus inches 
of water: 
 

 
For the correction of a high or low reading it is 
important that: 
1.  The parts and joints around the bearing cavity 

and oil seals are sealed. 

2.  Condensation drains, piping, sight gauges and 

breathers are functioning properly. 

3.  Auxiliary equipment extending into the motor 

must be sealed to prevent a transfer of air from 
inside to outside the motor.