Naarva Single Grip Harvester

The Naarva Stroke Harvester fells, delimbs, and cuts the stems to length. The Naarva is an one-grip harvester, which is mounted in the place of the grapple of log loaders. No additional hydraulic lines are needed. The harvester is controlled from the cab, by means of electric wires, that control. the felling, tilting, de-limbing and cross-cut functions. The stroke harvester has an internal system which diverts the oil to the machines functions.

The Naarva Stroke Harvester has a strong guillotine type cutter, and requires very little servicing of the machine. The guillotine design is not easily damaged by sand or stones, so trees can be cut close to the ground. One can even cut trees that are under snow or moss. The Naarva Stroke Harvester has no chains to sharpen or bars to replace.

The guillotine frame surrounds the tree completely before the blade starts cutting. The guillotine leaves a clean and smooth cutting surface. The stumps are short, so they do not cause damage to the tires of the harvesting machinery.

The Naarva Stroke Harvester is installed in the place of the grapple. It only requires oil flow from the same two hoses that opened and closed the grapple. The oil flow is directed to the different functions by the means of electrically controlled solenoid valves. A five wire cable runs from the stroke harvester to the cab. The electric buttons that control the stroke harvester are fastened in the left-hand joystick lever which runs the knuckleboom. The three electric switches enable the operator to fell, tilt, delimb and cross cut. The controls run either off of 12 volt or 24 volt DC.

With the gripper arms fully open, the Naarva stroke harvester's width is only 31 1/2 inches. This makes it well suited for first thinning of young forests. The time that it takes for the guillotine to cut the tree depends upon the oil flow, pressure and the hardness of the tree. At 18 GPM, the cutting time is approximately 1 1/2 seconds. At 13 GPM, the cutting time is approximately 2 seconds. At 11 GPM, the cutting time is approximately 2 1/2 seconds. The above cutting times assume an oil pressure of 2400 psi.

The delimbing stroke is 39 3/8" (100 cm). The operator has control over the stroke, and it can be stopped at any time before the strokes full extension. The maximum delimbing diameter is 11 13/16". The delimbing knives can be opened during the delimbing process, which allows for delimbing trees that are not completely straight. The delimbing starts from a height of 40" from the ground. The delimbing force is 20,900 lbs. at 2200 psi. The delimbing stroke speed at 18 GPM is 1.1 seconds. The return stroke takes half a second. The processor has two speeds for delimbing. The faster speed is used when, for example, delimbing pine, where there often is just a few branches in the lower part of the trunk. The operator can put the delimber immediately in the lower "gear" when thicker branches so require.

Technical specifications Naarva Stroke Harvester 2000-25
Max. Felling Diameter:	9 13/16"
Weight:	616 lbs.
Oil Flow Recommendation	8-18 ½ gallons per minute
Oil Hose Recommendation:	1/2"
Oil Pressure Recommendation:	2400-2900 psi
Electrical Requirements:	12 or 24 volts DC
Minimum Height	68"
Maximum Width	31 ½"

The Naarva Stroke Harvester has been field tested by the Work Efficiency Institute in Finland. Click here for the report.