The following data relate to a single-cylinder reciprocating engine: mass of reciprocating parts = 40 kg, mass of revolving parts = 30 kg at crank radius, speed = 150 rpm, stroke = 350 mm. If 60% of the reciprocating parts and all the revolving parts are to be balanced, what is the balance mass required at a radius of 320 mm ?

Concept:

mrω² = Bbω²

mr = Bb

m = mass to be balanced, B = Mass required for balancing the mass.

r and b are the radius of mass to be balanced and mass required for balancing.

Calculation:

Given:

mass of reciprocating parts = 40 kg, mass of revolving parts = 30 kg at crank radius, speed = 150 rpm, stroke = 350 mm

60% of the reciprocating parts and all the revolving parts are to be balanced

b = 320 mm, Stroke = 2r = 350 mm, ∴ r = 175 mm.

Mass to be balanced

m = m_rot + 0.60m_reci

m = 30 + (0.60)*40 = 54 kg

mr = Bb

54 × 175 = B × 320

B = 29.53 kg