Maintenance
3303−1/A1
Winterthur Gas & Diesel Ltd.
5/ 5
5. Tensioning the stud of top end bearing
Note: For tensioning the studs always follow the sequence shown in Fig. 4 i.e.
a+a and b+b for each step.
1) Clean the threads of studs 1 as well as the area around nuts 2.
2) Apply oil to the stud threads and screw on the nuts.
3) Tighten the nuts with round bar ’RS’ and equally distribute clearance ’y’ between
the bearing halves (bearing protrusion) as shown in Fig. 4.
4) Open the vent screw 7.
5) Put the pre-tensioning jacks 94315 diagonally on studs as shown in Fig. 4, and
completely screw them on until there is only little or no clearance at ’x’ (Fig. 5).
6) Connect the pre-tensioning jacks to hydraulic unit 94942 as shown in Fig. 4.
7) Actuate the hydraulic unit until bubble-free oil flows out through the vent screws.
Close vent screws.
8) Actuate the hydraulic unit and set pressure to 1000 bar (1
st
step) and keep
pressure constant.
Pistons 8 of the pre-tensioning jacks must never exceed the red limiting
grooves ’BN’ (Fig. 5).
Tighten the nuts with round bar ’RS’ and check with the feeler gauge through
slot ’KO’ (Fig. 5) that no clearance remains between nut and supporting
surface.
Check with the feeler gauge that no clearance remains between bearing cover and
connecting rod.
(Should clearance remain, loosen the fastening and compare the bearing protrusion with
the nominal value as indicated in 3303−3).
9) Do the same procedure for the second
pair of the connecting rod studs.
10) After tensioning to the 1
st
step mark the
position of the nuts against bearing
cover as shown in Fig. ’a’.
11) Raise the pressure to 1500 bar (2
nd
step) and keep constant.
Tighten the nuts down and check correct
seating with the feeler gauge.
Check from the markings applied by how
much the nuts were turned after
pre-tightening (1
st
step).
Tightening angle to be about 15_ (Fig. ’b’).
Should considerable differences to these
nominal values be encountered then repeat
the tensioning process.
12) Release the pressure to ’0’ at the
hydraulic unit and remove
pre-tensioning jacks.
Finally check the vertical bearing
clearance, refer to Clearance Table
0330−1 ’Top and bottom end bearings to
connecting rod’.
2016
Loosening and Tensioning the Connecting Rod Studs
TIGHTENING
Fig. ’a’
Fig. ’b’
x
013.432/05
y
x
009.758/02
y
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