Motor shafts of small and medium size sometimes made of ductile cast iron modified with nodular VCH45-5 VCH50-2, etc. The advantages of cast iron rolls: lower production costs, the ability to use of more sustainable forms of design (in terms of reducing the stress concentration), less sensitivity to the stress concentrators (risks, scratches, etc.), increased wear resistance of the necks (due to the presence of graphite in cast iron and good wetting of the necks of oil). Deficiencies of iron shafts: lower stiffness and strength, and the difficulty of detecting internal casting defects. Cranks (knee) made one-piece shaft polusostavnymi and components. In polusostavnyh and built-up crank connection parts supplied with hot or cold trip (no wedges or stoppers). Adequate compression is achieved by interference fit 1/800-1/1000 when heated to 200-250 C.
Polusostavnye cranks and components used primarily for shafts with large diameters of the necks of the MOU. Angle cranks wedges and flares in the order of the cylinders is selected from the conditions of the most uniformly rotating moment, the most complete equilibration, a uniform load on ramovye bearings, optimal use of energy of exhaust gases to boost the least additional stress on the torsional vibration. For provide a uniform rotation of the crankshaft in the cylinder outbreak should occur through the same angles p.k.v.: for four-stroke diesel engines Q> = 720 / i, for two-stroke – cf = 360 / i (where i-number of cylinders). The waters of the condition of the most complete balance is often a critical angle of the neck and connecting rod Ramovye usually have the same diameter, a medium-speed diesel engines and high speed for removing the rod through the cylinder is sometimes reduced by 10-15% crank diameter of the neck. Places necks transitions to the cheeks to reduce stress concentration run smoothly with as large a radius of curvature. Source: The device ships