Husqvarna PG 680 Operator's Manual page 18

The machine will 'pull" to one direction during operation.
The direction of pull is determined by the planetary head
direction of rotation. The head of the machine will pull to
the right (and therefore, will be felt on the right hip of the
operator) when the planetary head is set in the REVERSE
direction.
This sideways pull can be very useful when grinding,
particularly along a wall. Set the machine so that it pulls
towards the wall, and then control the machine so it can
just touch the wall. This will ensure a grind close to the
wall or object.
NOTICE! Planetary head and grinding heads are set to
both turn in the same direction (i.e. both in clockwise
rotation or both in counter-clockwise rotation).
A more powerful grinding force is created when both
planetary head and grinding discs heads are running in
the same direction. The end result is higher productivity
than when the discs are set to run in opposite directions.
It is here that you will also experience the beneift of Dual
Drive Technology™.
To improve the cutting efficiency of diamonds, change
directions on a regular basis. This will work both sides of
the diamond crystals, keeping the abrasives as sharp as
possible by creating maximal exposure of the diamond
crystal.
18 – English
OPERATING