ENGLISH
Fig. 18
Fig. 21
Fig. 20
Fig. 19
Fig. 25
Fig. 24
Fig. 23
Fig. 22
5.2 DISCS AND KNIVES
Work on irregular ground can damage the knives to a greater
extent (deformation and cracking), consequently increasing
the risk of accidents, giving a poorer quality cut and with the
risk of greater wear on the discs.
After the first time, the discs, knives and relative fastening
components must be periodically checked after every 15-
20 hours service. They must be checked more frequently if
the ground where the mowing work is done is stony and
always after hitting against an obstacle.
The oval discs are mounted on a support fixed by four M10
screws the tightness of which must be periodically checked.
They must be positioned so that the greater axis of each is
perpendicular to that of the adjacent disc (fig. 17).
The knives are fixed by means of a special self-locking screw
and are locked by a spring washer and M10 nut. The con-
cave part of the washer must point downwards and the nut
must be tightened to a 7.5 kgm (75 Nm) torque value, (fig.
18). Make sure that the disc turns in the right direction!
Worn knives must always be replaced or remounted on the
same disc, using the 2nd cutting edge (if the wear is not
excessive).
WARNING
The knives must be replaced when:
- they are worn: if the width of the knife 10 mm / 0.39 inches
- from the disc is ¾ of its original width (fig.19).
- the hole has become ovalized: if ovalizing exceeds 2
mm / 0.078 inches - the size of the original hole (fig.20).
Only use knives manufactured in compliance with ISO
5718.
The knife fastening components must be periodically
checked. In particular, check their condition after they have
hit against obstacles, whenever the knives are replaced and,
generally, at the beginning and end of the season.
WARNING
The fastening components must be replaced when:
- the screw that fixes the knives has become curved or
excessively worn under the head (fig.21).
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