The method of determining the efforts of the pre-tightening of bolts to a bearing of the crankshaft, automobile and tractor engines

The increase of power density of automotive and tractor engines leads to increased loads on parts of the crank mechanism. To ensure the specified reliability indicators, it is necessary to give an accurate analysis of the loads. There was studied currently used technique for calculating the pre-tightening force of rod bolts or mounting bolts of main bearing caps to ensure that the density of the junction of the threaded connections. It is shown that, first when the bolt is tightened, the liner shrinks by the amount of its protrusion and only then the joint is closed between the cover and the crank head of the connecting rod. This reduces the effort to ensure a given margin of safety of the joint density. The calculation of the force for deformation of the insert on the amount of its protrusion is carried out, which ensures the fit of the inserts when they are inserted into the bearing bore. It can be seen from the calculation that the force to deform the liner is not less than 30 ... 40 % of the value of the force of the tightening, which ensures the tightness of the joint between the components to be tightened. A procedure is proposed for determining the pre-tightening force of the connecting rod bolts or bolts for attaching the main bearings of the piston engine crankshaft, in case of providing the specified margin of joint density as a standard threaded joint. An example of calculating the torque settings connecting rod bolt for diesel engine D-245 when operating on the maximum idle speed.

connecting rod bolt tightening force, the density of the joint, ledge of the plain bearing, the coefficient basic load