Automatic control by relays

for Naarva S25, S23 and S23C harvesting heads


  • Automatic drive for harvesting head
  • Enables continuous delimbing when grapple close-function is pressed

Suitable for

  • Naarva S25, S23C or S23 stroke harvester heads.


Automatic control for Naarva S25, S23 and S23C harvesting heads. Sensor detects when stroke movement is in the far end. It commands a directional valve to change the direction of delimbing movement. Driver can delimb the trunk to desired length by just pressing grapple close-function. When the desired length is reached, driver uses grapple open-function to cut the tree. Sensors and the directional valve for automatic control are battery powered. Control package includes a charger and two batteries. Driver can always disconnect the battery and operate stroke harvester head manually if necessary. Control system does not prevent normal manual drive in any way.

There will be no wires in the crane boom or additional controlling buttons in the tractor cab. The stroke harvester head repeats strokes automatically when you hold the “grapple closed” function on. Cutting and dropping the top is done with the “grapple open” function. If the pruning head collides with a curve or a thick branch, the direction changes automatically. You can also make changes of direction and partially open the grip with “open” and “close”.

Technical information

Product Automatic control by relays
Contents Control system in protective casing, directional valve, two batteries and a charger, inverter for charger, 3 pcs. inductive sensors
Voltage 12 V (12 Ah battery)
Control system 2 pcs. relays, 3 pcs. inductive sensors and a directional valve