Yanmar 1GM User Manual page 27

20
CHAPTE R ONE
I I I
Bea ring
r---
pl,lller ~
100 0
00 0 1
+----1-1-
Shaft
F,t~~;;;;---11-
Spacer
Irp:1'l~~~~l"'f>=~tt-
Beaarlng
3. Step 1 describes how 10 insta ll a bearing in a case half
and over a sha ft. However, when installing a beari ng over
a shaft and into a housing at the same time , a snug
fit
wi ll
be requ ired for both outer and inne r beari ng races. In this
situation, a spacer must be insta lled unde rneath the driver
tool so that pressure is appl ied evenly across both races.
Sec Figur e 56. If the oute r race is not supported as shown
in Ffgu re 56, the ball s will push against the outer bearing
trac k and damage it.
Sh r ink Fit
1. Ins/a iling a bearing over a shaft- If
a
tight
fit is re-
quired. the beari ng inside d
iamete r will be smaller than
the sha ft. In this case, driving the beari ng on the shaft us-
ing norm al methods may cause beari ng damage. Instead ,
the beari ng: shou ld be heated before installation. Note the
followi ng:
a. Secure the shaft so that it can be ready for bearin g
installat ion.
b. Clean the bearing surface on the shaft of all residue.
Remove burrs with a file or sandpaper.
c. Fill a suitable pot or bea ker with clean minera l oil.
Place a thennomctcr (rated highe r than 120
0
C
[248
0
F]) in the oil. Support the thermome ter so it
does not rest on the bottom or side of the pot.
d. Remove the bearing from its wrap per and secu re it
with a piece of heavy wi re bent to hold it in the pot.
Hang the bearing in the pot so that it does not touch
the bottom or sides of the pot.
e . Tum the heat on and monitor the thermo meter.
When the oil temperature rises to approxi matel y
120 0 C (248 0 F), remove the bearing from the pot
and quickly install it. l f'nccessary, place a socket on
the inner bearing race and tap the beari ng into place.
As the bearing cools, it will tighten on the sha ft so
work quick ly when installing it. Make sure the bear-
ing is insta lled all the way.
2. Installing a bea ring in a housing-Bearings are gener-
ally installed in a hou sing with a slight interference fit.
Driving the bearing into the hou sing using normal meth -
ods may damage the housing or cause bearing damage. In-
stead, the housing should be heated before the bearing is
insta lled. Note the following:
CAUTION
Before heating the housing in this procedure
to remove the bearings, wash the housing
thoroughly with dete rgent and water. Rinse