How to install

Here you find the most common and frequently asked questions for installation and set-up of your grapple saw. Please check the user manual for more information.

If the problem you are facing is still not solved, please do not hesitate to send us a short WhatsApp-video which shows the problem you are facing. We will come back to you as soon as possible.

Keep checking our website: This page will be updatet frequently based on new developments and frequently asked questions. If you have any, send us an email: info@gmt-equipment.com.

How to choose carrying vehicle

 Take the following specs as a guidance when choosing your carrying vehicle for GMT grapple saw:

  GMT035 GMT050
(Forestry) crane > 5 ton/metre >10 ton/metre
Excavator >4,5 tons >7,5 tons
Maximum grapple load 1,5 tons 2,5 tons
Maximum operating pressure 250bar/3626psi 250bar/3626psi
Minimum flow 35 l/min 9,2 gal/min 45 l/min 11,9 gal/min


 

Afbeelding: mount1

How to mount the felling grapple to existing rotator

The rotator must be placed on the tilt frame in such a way that the G.O. (grapple open <>) coupling is located on the side of the accumulator. This will mean that the G.C. (grapple close ><) coupling is automatically located on the side of the chain oil reservoir.

Both hydraulic hoses must form a neat loop when attached to the nipples underneath the rotator. The short hose must rest inside the loop created by the long hose.

Afbeelding: hydraulic

How to install drain valve

At all times there should be a return-hose created to tank in order to have the tilt-down function working properly. In order for the felling grapple to perform correctly, a drain valve must be attached to the crane valve block of the carrying vehicle. This valve is supplied in a ready-to-use state in the box containing tools and fittings.

How to install on telehandler

When a rotating telescopic forklift is used which has only one double hydraulic function available a 6/2 valve should be installed on the jib. On this valve a different drain valve is installed (these valves are not supplied standard with the GMT) that will generated the second hydraulic double function. An electric signal will take care of the controls for the second double function that is being created: the rotation of the grapple.

Please contact us directly if you have questions on installing the drain valve or 6/2-valve.

How to adjust pressure settings

Pressure measurements and/or adjustments may only be performed by authorized persons. It is recommended that two persons work on adjusting the valve block. For detailed information please check the user manual.

For basic understanding of the grapple saw we will explain the location and usage of the different valves:

Afbeelding: instructiekaart 1.emf
  • valve 1: This valve determines when the grapple close function switches to saw function, i.e. the cylinder pressure at which the saw function is activated.
  • connection K: Measuring point for grapple close
  • valve 10:This valve determines when the grapple open function switches to tilt up function, i.e. the cylinder pressure at which this function switches to tilt up.
  • connection J: measuring point for grapple open
  • valve 7: This valve determines the speed at which tilt up moves to tilt down, i.e. the tipping speed.
  • valve 6: This valve ensures that the grapple will only drop to the tilt down position once the saw blade has retracted into the saw casing
Afbeelding: instructiekaart 2.emf
  • valve 3: This valve regulates the pressure on the saw bar. If the pressure is too high, the saw motor will not have enough power. If the pressure is too low, the saw motor makes a lot of RPM’s but the saw chain is not cutting.
  • valve 8: This is the pressure safety valve for the tilt cylinder. (factory pre-set, do not adjust!)
  • valve 11: This is the pressure safety valve for the grapple close function. (factory pre-set, do not adjust!
Afbeelding: instructiekaart 3.emf

After valve 3 is set, the ideal cutting speed for soft or hard wood can be adjusted with this restrictor. 

How to adjust pressure settings (video)

How to pressurize accumulator (video)

How to pressurize accumulator

When pressurizing accumulator is needed more frequently during normal operation, please check the following items:

  • check tilt cilinder for possible internal leakage

If this item is ok and the problem still occurs, please contact us directly!

How to solve saw blade extends error

How to solve saw function not activated error

When the saw blade does not extend when grapple close is fully operated, please check the following items:

  • check if ball valve on site of saw casing is open
  • check if saw chain is jammed
  • check valve 1 settings

If all items are ok and the problem still occurs, please contact us directly!

Afbeelding: hydraulic

How to solve grapple saw does not tilt down error

When the grapple saw does not tilt down (grapple is closed and the saw is operated and keeps extended afterwards), please check the following items:

  • check if return oil line is installed in hydraulic line normal grapple-open function

If this item is ok and the problem still occurs, please contact us directly!

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