- 22 -
3
27
28
23
25
24
26
Ø
Q
(Ø-Q)
3LD 450, 3LD 451/S
3LD 510, 3LD 510/S
85,00 ÷ 85,02
84,925 ÷ 84,945 0,05 ÷ 0,09
4LD 640
95.00 ÷ 95,02
94.88 ÷ 94.90
0.10 ÷ 0.14
4LD 705
100.00 ÷ 100.02
99.83 ÷ 99.85
0.15 ÷ 0.19
4LD 820
102.00 ÷ 102.02 101.85 ÷ 101.89 0.11 ÷ 0.17
29
Workshop Manual__3 - 4 LD_cod. ED0053025560_
4° ed
_ rev.
03
Disassembly / Reassembly
Cylinder and piston
Set a bore gauge to zero with a calibrated ring. Check the dia.
Ø
at points
A
and
B
at three different heights, see pictures 23 and
24.
In case of wear exceeding 0.06 mm to the maximum value
prescribed, grind the cylinder at the subsequent increased value.
The increases suggested are 0.50 and 1.00 mm.
Measure the piston
Q
dia. (picture 26) at
A
height from the skirt
base:
A
= 17 mm (3LD 450, 3LD 451/S, 4LD 820)
A
= 12 mm (3LD 510, 3LD 510/S)
A
= 22 mm (4LD 640, 4LD 705)
Remove the stop rings and extract the piston pin, picture 25.
Remove the piston rings and clean the slots.
Replace the piston as well as the segments in case the dia. wear
exceeds 0.05 mm as regards to the minimum value prescribed.
Dimensions (mm)
Note:
Even if 3LD 450, 3LD 450/S and 3LD510, 3LD510/S
pistons have the same bore, they differ in other
dimensions, thus they are not interchangeable.
ENGINES
Distance among segment ends (mm)
Insert the piston ring in the lower part of the cylinder, then mea-
sure the distance among the points.
3LD 450, 3LD 451/S, 3LD510, 3LD 510/S
1
st
piston ring (chromium plated)
A
= 0.30 ÷ 0.50
2
nd
piston ring (torsional)
A
= 0.30 ÷ 0.50
3
rd
piston ring (scraper ring)
A
= 0.25 ÷ 0.50
4LD 640, 4LD 705, 4LD 820
1
st
piston ring (chromium plated)
A
= 0.40 ÷ 0.65
2
nd
piston ring (torsional)
A
= 0.40 ÷ 0.65
3
rd
piston ring (torsional)
A
= 0.40 ÷ 0.65
4
th
piston ring (oil scraper ring)
A
= 0.30 ÷ 0.60
Piston ring - Clearances among slots (mm)
3LD 450, 3LD 451/S, 3LD 510, 3LD 510S, picture28
A
= 0.08 ÷ 0.09
B
= 0.06 ÷ 0.07
C
= 0.05 ÷ 0.06
4LD 640, 4LD 705, 4LD 820, picture 29
A
= 0.12 ÷ 0.14
B
= 0.07 ÷ 0.09
C
= 0.07 ÷ 0.09
D
= 0.06 ÷ 0.08
Содержание 3LD 450
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