Yaroslavl Engine Plant YMZ-536 Operation Manual page 69

Fig. 17b Accessory drive belts (third option):
1 – crankshaft pulley and damper; 2 – tension roller;
3 – water pump pulley; 4 – belt; 8 – generator pulley
The belts are tensioned by automatic rollers with springs
inside; during operation no additional adjustment is required. All
rollers are the same, with a smooth pulley, operating on the outer
smooth belts surface.
The roller pulley incorporates a press-fitted ball bearing with
shields. The bearing is filled with grease for the whole period of the
engine lifetime.
The fixed base of the roller has a special area with three marks,
and there is one mark on the rotating part (Fig. 18). The marks are
used to check belt stretch elongation.
In the operating position, the mark on the rotating part must be
within the area of the three marks on the fixed part. If it is outside the
area, the belt must be replaced. To remove the belt, compress the
spring of the automatic belt tensioning system by turning the roller
relative to the fixed base.
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