GMT 050
User manual
16
5.2
Application GMT050 TTC
Besides the already proven concept of GMT felling grapples the GMT050 TTC is an addition to the
functionality. With the TTC it is possible to hold each branch in any position by means of activating the
hydraulic brake for the rotation of the link between the crane head and the rotator. At the same time
the tilt-cylinder will be hold in position as well. Basically there is no limit in holding the cut branches
therefore GMT has limited the braking capacity and will be always lower than the maximum allowable
forces on the crane beams.
The TTC has been developed to be used in situations when:
-
dead or sick trees needs to be removed and there is no room for branches to break off and
fall down
-
the felling grapple is not allowed to swing down after cutting because the branch could:
o
get tangled in other tree parts
o
damage below situated obstacles
o
get in touch with overhanging electrical cables
At all times the maximum load mentioned in the load chart of the crane is decisive!
A common used method to determine the maximum load that can be cut is:
Find the maximum load mentioned in the load chart of the crane and subtract
o
The weight of the felling grapple (± 530 kg) ≈ (± 1168 lb)
o
The TTC control box (± 20 kg) ≈ (± 44 lb)
o
Sometimes a crane boom-end connection piece (± 80 kg) ≈ (± 176 lb)
o
Or a telehandler extension boom (± 300 kg) ≈ (± 661 lb)
Then 50% of the weight that is left will be the maximum load of the limb or branch which is allowed to
be removed when the load becomes a hanging load for the crane after cutting.
Note when a TTC is used:
The TTC will allow to hold a tree branch in any position. The maximal tree
weight and length that can be hold in its position is limited by the braking capacity. Factory set braking
capacity is limited to 500 kgf
m (4903 Nm).
When the cut tree or branch is hold in a position like below the tree weight and length will
reduce the crane capacity. The longer the branch the more it will influence the load
capacity of the carrying vehicle. The center of gravity (COG) will move further
out of the crane end point when the branch is longer.
GMT050 TTC holding a tree
COG of the weight of the tree or branch
