
The main functions of oil ring are to scratch down lubricant splashing on
cylinder walls, return it to oil pan through the upside and downside gaps of oil
ring and the oil feed-back hole on spring gasket drain pan, as well as distrib-
ute lubricant on cylinder wall evenly to reduce fiction and strengthen seal
property. The oil ring is a combination steel ring, consisting of two scraper
rings and one backing ring. The combination oil ring is 3 in height and
2.7±0.15 in thickness. The barrel-shaped scraper rings, which have chroming
surfaces and small contact surface, are made of tool steel. The tangential
elasticity of scraper rings is 34-51N and the backing ring is made of nickel-
chrome steel. The cross section of the oil ring is illustrated as Fig. 177.The
structure of piston,piston pin and piston ring about JL481Q/ MR481QA are
the same principle and have a little differences in dimension.
II. Structural Characteristics of the Con-
necting Rod and its Bearing Shell
Fig. 178 Structural diagram of
Fig. 179 Structural diagram of
+0.024
0
-0.15
-0.20
Fig. 177 Cross section of combination oil ring
-0.05
-0.13
+0.018
0
1. Connecting rod
The connecting rod connects the piston pin and the crank pin to convert the reciprocating
inertial movement of the piston into rotational movement of the crankshaft. The connecting rod
includes the connecting-rod body, cap, bolts and nut. The connecting-rod body is shown in Fig.
178. The small end and big end of the connecting-rod bear rectilinear load with varying
strength and direction, while on each section of the body there exists adverse loads such as
alternating bending moment, shear, normal force and rectilinear load. The connecting rod of
engine, mould-forged with No. 40 fine steel, has its surface stress peened. The truncated
connecting rod structure, connecting-rod body and connecting-rod cap are fastened through
bolts. The center distance of the MR479Q connecting rod = 122±0.031mm, center distance
between the two bolt holes is 54±0.1mm, diameter of the big end is 43 The section of the
rod body is I-shaped, the big end of the connecting-rod cap has a thickness of 22 .
The center distance of the JL481Q connecting rod = 132.5±0.050mm, center distance between
the two bolt holes is 62±0.1mm, diameter of the big end is 51 .They will be processed
after it is assembled with the connecting-rod body. The connecting-rod body and connecting-
rod cap have a recess respectively for positioning of the bearing shell of the connecting rod
during installation. In the big end hole of the connecting-rod body, there is an oblique oil hole
of 3mm in diameter, from which the injected lubricant cools and lubricates the piston. In the
meanwhile, the outlet of the oil hole is made in the form of a load relieving recess. For the
convenience in assembly, the connecting-rod body and cap carry a front end marking. The
connecting-rod cap is also marked with the grouping. For re-assembly, the parts need to be
assembled according to the numbers. The connection between connecting –rod and
connecting-rod cap of JL481Q is different from the MR479Q in that nut tightens to screw hole
directly.
2. Connecting-rod bearing shell
Engine has a double layer bearing shell, using 08F as the steel back and aluminum-based alloy
as the anti-friction layer. The total thickness at the middle of the bearing shell is 1.5 whereby
the thickness of the steel back layer is 1.22mm and that of the anti-friction layer is 0.28mm. To
avoid retreating or bulging of the bearing shell during assembly, on both sides of it there are
partial thin areas. The internal diameter of the JL481Q bearing shell d=48mm, and its width
b=17 . The proper width/diameter ratio (b/d=3/8) can prevent lubricant from flowing out from
both ends, and excessive load is avoided on the fringe as well. A positioning tongue and oil
reservoir ditch are punched at the orifice of the bearing shell. The thickness of the connecting-
rod bearing shell is achieved by assembling in 3 groups in order to have a reasonable clearance
of the oil film.
-0.002
-0.014
0
-0.2
71
Содержание JL481Q
Страница 1: ......
Страница 9: ...5 Fig 3 Components Assembly Drawing of MR479Q MR479QA Engine ...
Страница 10: ...6 Fig 4 MR479Q MR479QA Engine and Its Power System ...
Страница 11: ...7 Fig 5 Assembly Drawing of Engine and Its Auxiliaries MR479Q MR479QA ...
Страница 12: ...8 Fig 6 Electronic Control Fuel Injection System in Engine MR479Q MR479QA ...
Страница 13: ...9 Fig 7 Front view of Engine JL481Q MR481QA ...
Страница 14: ...10 Fig 8 Sectional elevation of Engine JL481Q MR481QA ...
Страница 15: ...11 Fig 9 Electronic Control Fuel Injection System in Engine JL481Q MR481QA ...
Страница 21: ...17 Fig 13 Exterior Feature of JL481Q Engine Power Me N m Torque Pe Kw ge g kwh Fuel Consumption Ratio ...