Dynamics of Machines - Unit II-Balancing of Reciprocating Masses
Download as PPTX, PDF1 like251 views
This document discusses balancing of reciprocating masses in machines like engines. It states that the purpose of balancing is to eliminate unbalanced forces and couples caused by reciprocating masses. These include shaking forces from inertia, and shaking couples from imbalanced distribution of mass. The document notes that complete balancing is usually not practical, so reciprocating masses are often only partially balanced to reduce unbalanced forces and couples. It defines primary and secondary unbalanced forces and describes other effects like tractive force along the stroke, swaying couple causing side-to-side motion, and hammer blow from the maximum perpendicular force.
Dynamics of Machines - Unit II-Balancing of Reciprocating Masses
- 1. ME8594 - DYNAMICS OF MACHINES UNIT-II-BALANCING (BALANCING OF RECIPROCATING MASSES) By, Dr.S.SURESH, Assistant Professor, Department of Mechanical Engineering Jayalakshmi Institute of Technology.
- 2. The various forces are acting on the reciprocating parts of an engine. The resultant of all the forces acting on the body of the engine due to inertia forces only is known as unbalanced force or shaking force. Thus if the resultant of all the forces due to inertia effects is zero, then there will be no unbalanced force, but even then an unbalanced couple or shaking couple will be present. BALANCING OF RECIPROCATING MASSES
- 3. 8 Balanced Balanced Vertical Component of FB (FBV) Need to be properly Balanced Need to be properly Balanced
- 4. Thus the purpose of balancing the reciprocating masses is to eliminate the shaking force and a shaking couple. In most of the mechanisms, we can reduce the shaking force and a shaking couple by adding appropriate mass, but it is usually not practical to eliminate them completely. In other words, the reciprocating masses are only partially balanced.
- 5. PRIMARY AND SECONDARY UNBALANCED FORCES OF RECIPROCATING MASSES
- 6. Primary unbalance force = FP = Secondary unbalance force = Fs = unbalance force FU
- 7. NOTE:
- 12. 1. VARIATION OF TRACTIVE FORCE The resultant unbalanced force due to the two cylinders, along the line of stroke, is known as tractive force.
- 13. 2. SWAYING COUPLE This couple has swaying effect about a vertical axis, and tends to sway the engine alternately in clockwise and anticlockwise directions. Hence the couple is known as swaying couple.
- 14. 3. HAMMER BLOW The maximum magnitude of the unbalanced force along the perpendicular to the line of stroke is known as hammer blow.