FIELD: engine manufacture. SUBSTANCE: given exhaust mechanism has double tube exhaust collector with connection branch pipe and expansion chamber formed by two perforated tubes with acoustic windows-cuts in end placed inside enclosure. One tube is 
-shaped and is linked to exhaust pipe-line. Chamber enclosure is three-layer fixture with outer layer made of sheet metal, middle layer produced from sound- absorbing material and inner layer fabricated from fine-mesh gauze. Exhaust mechanism is characterized by following relation of geometric parameters: A=(20- 35)din; l=(6-9)din; b= (3-5)din; δ2= (1,5-2,5)din; δ1= (3-5)din; where A is length of tubes of exhaust collector ( distance from exhaust branch pipes to connection branch pipe); l is length of expansion chamber; b is width of expansion chamber; δ1 is length of acoustic window-cut in end of 
-shaped perforated tube; δ2 is length of acoustic window-cut in end of straight perforated tube; din is inner diameter of tubes of exhaust collector equal to inner diameter of perforated tubes of expansion chamber. EFFECT: increased efficiency of noise silencing. 1 cl, 2 dwg
