FAQs
Naarva Stroke harvesters hydraulic
The recommended hydraulic specifications are:
S23C 40 – 60 L/min and 170 – 200 bar
S35C 50 – 70 L/min and 180 – 210 bar
Feeding hose 1/2″. Return hose min 1/2″ but to avoid excessive back pressure, return hose of 3/4″ is recommended.
It is recommended that the Grapple CLOSE / OPEN function is controlled by 2 buttons. Pedal should be avoided.
On the S35C model, the tilt holding force is adjustable.
Adjustment instructions can be found in the operator manual.
Delimbing force
Delimbing force is determined by the cylinder piston size and the oil pressure.
Refer to the technical table for calculated forces based on cylinder dimensions and pressure
| Delimbing force in kN | ||
| Stroke cylinder piston diameter | ||
| Oil pressure | 40mm | 50mm |
| 170 bar | 21 | 32.7 |
| 180 bar | 22.2 | 34.7 |
| 190 bar | 23.4 | 36.6 |
| 200 bar | 24.7 | 38.5 |
| 210 bar | 25.9 | 40.4 |
Delimbing speed (forward stroke)
Within the specified delimbing diameter range: Higher oil flow results in faster forward stroke motion
Delimbing speed (return stroke)
During the return stroke, oil exits the cylinder:
– Excessive back pressure slows down the movement
– A sufficiently large return hose is essential to ensure efficient cylinder emptying and fast return speed
Sawing performance depends on several factors, including tree type. However, higher oil flow and pressure increase sawing speed and cutting power
The performance of the harvester is directly affected by the hydraulic characteristics of the base machine:
- Oil flow (L/min) determines the operating speed
- Pressure (bar) determines the available force/power
- Back pressure reduces the effective working force
For optimal performance, it is important to minimise back pressure. This is achieved by using a sufficiently large return line.