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GMT GMT 050 User Manual Download Page 23

 

GMT 050 

 

User manual 

 

 

23 

 

To support the operator in determining if the diameter of the tree or branch to cut is not larger than 
Ø50 cm [Ø19,7”] the following rule can be used: 

 

“When the claws of the grapple are placed around the 
tree or branch and the claws are fully enclosing the 
wood the diameter is smaller than Ø50cm [Ø19,7”].” 

 

Length of wood 

at ≈ 500 kg (1102 lb) 

Type of tree 

with foliage 

(50% red.) 

Ø 19,7"  

[Ø 50cm] 

  

[m] 

[ft] 

Pine 

2 

6 

Spruce 

2 

7 

Larch 

2 

5 

Willow 

1 

5 

Birch 

1 

5 

Beech 

1 

5 

Ash 

1 

5 

Alder 

2 

6 

Oak 

1 

4 

Poplar 

2 

7 

 
Attention! The values in the table are indications only. The load charts of the crane and carrying 
vehicle as well as the maximum allowed length of the hanging load are at all times decisive. 
 

Lifting reference table 

1) 

Lifting reference (Metric system) 

  

Length for 500 kg stem 

Length for 1000 kg stem 

Type of 

tree 

Average 

density of 

1 m3 fresh 

green wood 

Weight 

stem Ø 

19,7" 

[Ø 50cm] 

tree without 

foliage 

Ø 19,7" [Ø 

50cm] 

with 

foliage(50% 

red.) 

Ø 19,7" [Ø 

50cm] 

tree without 

foliage 

Ø 19,7" [Ø 

50cm] 

with 

foliage(50% 

red.) 

Ø 19,7" [Ø 

50cm] 

  

[kg/m3] 

[kg/m] 

[m] 

[m] 

[m] 

[m] 

Pine 

673 

132 

4 

2 

8 

4 

Spruce 

625 

123 

4 

2 

8 

4 

Larch 

769 

151 

3 

2 

7 

3 

Willow 

865 

170 

3 

1 

6 

3 

Birch 

913 

179 

3 

1 

6 

3 

Beech 

865 

170 

3 

1 

6 

3 

Ash 

849 

167 

3 

1 

6 

3 

Alder 

721 

142 

4 

2 

7 

4 

Oak 

1009 

198 

3 

1 

5 

3 

Poplar 

609 

120 

4 

2 

8 

4 

1)

 

Cited: Moisture Content and Weight. [online] Available at: https://www.engineeringtoolbox.com/weigt-wood-d_821.html [Accessed 25 Apr 2019]

 

Summary of Contents for GMT 050

Page 1: ...USER MANUAL GMT 050 FELLING GRAPPLE including GMT050 TTC Serial number 255 and up release date Oct 2020 ...

Page 2: ...or branch with TTC 20 5 4 Supplied tools 22 4 3 Lifting reference for sawing at height 22 6 Maintenance 24 6 1 Safety recommendations 24 6 2 Daily maintenance 24 6 3 Maintenance schedule 25 6 4 Repairs Welding 25 6 5 Replacement of saw bar and chain 26 6 6 Lubricants 27 6 7 Hydraulic fluid 28 6 8 Chain oil 28 6 9 Handle the chainsaw 29 7 Adjusting the felling grapple 30 7 1 Pressure adjustments 30...

Page 3: ...very or repair is not possible you must contact the manufacturer or distributor 1 2 Warnings and warning pictograms Warnings and warning pictograms have been added to certain components These texts and pictograms must be noted in order to prevent injury to persons and damage to the felling grapple This pictogram indicates to the user that mounting maintenance and repairs to and of the felling grap...

Page 4: ...tions can affect use of the felling grapple Such conditions include wind snow and or storms Weather conditions must be taken into account before use of the felling grapple Weather circumstances at the site allow use of the felling grapple must also be determined If this proves to not be the case appropriate precautions must be taken Familiarize yourself with the felling grapple before use Knowledg...

Page 5: ... Maintenance and or repairs must be carried out slowly and carefully If replacement or spare parts are needed these must be ordered from the felling grapple manufacturer or distributor This is the only way of obtaining original parts Make sure that the hydraulic hoses of the felling grapple are in good condition Whenever necessary replace damaged hoses or couplings in good time Pressurized jets of...

Page 6: ...r instructions please provide the manufacturer or distributor with the details found on the serial plate This will ensure faster processing of your order or service 3 2 Carrying vehicle The cabin of the carrying vehicle must be fitted with safety glass The saw chain operates at extremely high revolutions If this chain breaks or splits apart the resulting flying fragments can cause serious injury F...

Page 7: ... the felling grapple is supplied by GMT Equipment Transport to the pallet Due to transport requirements the chain lubrication hose is not allowed to loose oil This hose is connected between the oil pump and the saw bracket and has been left empty for transport Before the unit can be put into service please ensure the hose is filled with oil again Instruction Use an air compressor to carefully pres...

Page 8: ... close coupling G C underneath the rotator Connection of the hoses to the manifold 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 Connection of the hoses to the rotator Both hydraulic hoses must f...

Page 9: ...are done from factory A drain valve needs to be installed to ensure correct function of the tilt down similar as done with the GMT050 product A signal device needs to be installed in the carrying vehicle to activate the brake functionality This can be a remote control button or an additional button on the joystick Even a foot pedal signal can used Whatever the operator prefers Connection of the ho...

Page 10: ...ed with the Grapple The T coupling needs to be mounted in the hydraulic line for grapple open near to the crane valve block of the carrying vehicle This new connection that has been created needs to go to the hydraulic tank of the carrying vehicle In this new line the ball valve and leaking oil valve must be mounted with the T side of the drain valve facing the hydraulic tank When a main manifold ...

Page 11: ...ced in tilt up position position for vertical felling and no functions are activated it must lower itself when grapple open input stops This allows the user to check whether the leaking oil valve has been attached correctly and or whether the ball valve has been opened 4 5 Installation on Telehandler When a rotating telescopic forklift is used which has only 1 double hydraulic function available a...

Page 12: ...maximum permissible operating pressure for the felling grapple is 250 bar 4 6 1 Hydraulic schematic for mounting Simplified schematic for mounting The ball valve must be closed when work is done with a regular timber grapple Please note for testing purposes When the felling grapple is placed in tilt up position position for vertical felling it must lower itself when grapple open input stops This a...

Page 13: ...TTC brakes by activating the TTC control box When an electrical signal is already present at the tip of the crane like with a telehandler the remote control option can be replaced by another activation option Simplified schematic for mounting For example on a telehandler an electrical signal is normally present at the mounting board An additional activation signal can be used for the brakes The re...

Page 14: ...GMT 050 User manual 14 4 6 3 Hydraulic schematic Hydraulic schematic GMT050 and drain valve ...

Page 15: ... made before starting the cuts Using the proper techniques and understanding how to apply them to individual trees is the key to felling any tree safely After the limb or branch has been cut free high up in the tree it becomes a hanging load and will slowly tilt down The maximum length which may be cut is limited to 6 meter 20 feet or shorter when the maximal allowed weight has been reached first ...

Page 16: ...ioned 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 th...

Page 17: ... pedal the felling grapple will simply function as a regular timber grapple for the loading and or relocating of sawn wood Grapple open function If maximum grapple open input is applied pressure in the grapple cylinder increases This brings the felling grapple into the tilt up position the position for sawing vertical timber As long as this input continues the felling grapple will stay in the tilt...

Page 18: ...tree conditions such as a frozen state can reduce the maximum sawing diameter Take note of the pitch of the target tree and take the direction of the wind into account If a remote controlled carrying vehicle is used the operator must be positioned at right angles to the drop trajectory of the felling grapple Watch the load and the felling grapple at all times Maneuver the grapple towards a tree or...

Page 19: ...evere overhang or other factors affect the action such as strong wind etc A sawed tree in the grapple Once a tree has been sawed through it must be lowered slowly The grapple frame will start to drop to the tilt down position because maximum grapple close input is no longer being applied Before sawing make sure that the area onto which the tree or branch will be lowered has been considered lowered...

Page 20: ...ke activation device and simultaneously all 3 brakes are activated Both movements in the link and the tilt cylinder will be hold by the brakes Grapple grabs the branch and activating the brakes As long as the operator activates the button of the brake activation device the brakes will be holding the load in position At all times the brake signal must be of a make and hold principle to ensure that ...

Page 21: ...ting damaged When the tree piece to be cut is of considerable weight or length and aiming upright more than 30 degrees the TTC system must be activated during cutting Following work sequence must be followed with TTC system activated 1 Take tree piece out of the canopy 2 Rotate tree piece in front of the crane 3 Tilt down crane extension arm 4 Release the brake 5 Open grapple to drop tree piece lo...

Page 22: ...mulator pressurizing kit Increasing or decreasing pressure in both accumulators Toolset supplied with the GMT050 4 3Lifting reference for sawing at height This section should be used as reference when sawing branches at height using a rotating telescopic forklift or a truck mobile loader crane The greatest danger involves underestimating the weight of the tree or branch being cut Once it has been ...

Page 23: ...carrying vehicle as well as the maximum allowed length of the hanging load are at all times decisive Lifting reference table 1 Lifting reference Metric system Length for 500 kg stem Length for 1000 kg stem Type of tree Average density of 1 m3 fresh green wood Weight stem Ø 19 7 Ø 50cm tree without foliage Ø 19 7 Ø 50cm with foliage 50 red Ø 19 7 Ø 50cm tree without foliage Ø 19 7 Ø 50cm with folia...

Page 24: ...lasses It is also compulsory to always wear safety shoes when working with equipment and machinery 6 2 Daily maintenance The felling grapple must be lubricated in the morning before work commences or at the end of the day when work is complete Please note There are 12 grease nipples 6 greasing nipples on the 3 cylinders 2 greasing nipples on the reaction arm 3 greasing nipples on the Grapple claws...

Page 25: ...or wear X Check hydraulic hoses X Check for possible leaks X Check accumulator pressure X Check brake pad wear Maintenance schedule If any one of the above points does not pass the check the part in question must be repaired before any further work is done with the felling grapple 6 4 Repairs Welding If the felling grapple requires repair or modification please contact the manufacturer or distribu...

Page 26: ...aced the indicated ball valve be must closed completely Then when the saw function is activated again the saw bar will stay in its extended position and will not return into the saw casing Now the machine can be turned off in order to exchange the saw chain and or saw bar Locknuts for chain tensioner saw blade ...

Page 27: ...ping plate once again holds the saw blade Saw blade exchange Replacing the saw bar works according to the same principle Loosen the nuts and remove the chain In this case the nuts must be loosened somewhat more to create enough play between the chain tensioner and the saw bar so that the tensioner pin can be removed from the notch in the saw bar The saw bar can now be pulled out When inserting the...

Page 28: ...luid please consult the base appliance user manual Make sure that the fluid is clean and prevent dirt from entering the system Work in a clean environment 6 8 Chain oil Seen from the front the chain oil reservoir is located on the right side of the tilt frame This oil should be replenished when work commences or ends This small reservoir has a volume of approximately 2 liters The chain is lubricat...

Page 29: ...new chain When an inspected and sharpened chain is installed the risk of breakage is considerably lower than when a blunt chain is used A broken chain must be thoroughly inspected for breaks bends cracks etc before a new link is added Check the saw unit every two hours Rotate the saw blade 1800 if the felling grapple is used throughout the entire day This will ensure that both sides of the blade a...

Page 30: ...ns work on adjusting the valve block 7 1 Pressure adjustments Make sure that the pressure of the base carrying vehicle does not exceed the 25 MPa 250bar maximum Excessive pressure can damage the valve block 7 1 1 Adjusting the valve block The felling grapple is adjusted and supplied in a ready to use state by GMT Equipment Adjusting of valves 1 6 7 and 10 on the manifold ...

Page 31: ...e manometer will now indicate the cylinder pressure at which the saw function is activated Lock the adjuster bolt with the locknut by hand is sufficient and detach the manometer 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 Because the tilt up function can only be activated by maximum ...

Page 32: ...hin wood Lower speed for heavier wood 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 If this valve is turned in too far the grapple will tilt down during the sawing process If it is turned out too far the grapple will not tilt down at all Adjust as follows Make sure that valve 7 has already been adjusted Sli...

Page 33: ... clock wise Grab a piece of wood with minimum Ø30 centimeters and try to make a cut Screw valve 3 so far in that the saw speed is optimum Note that if the pressure on the saw bar is too high you will shorten the life time of the chain and saw bar Basic setting is completely out and then 1 5 turn in Fine wood chips during cutting are indicating a to low pressure on the saw blade huge wood chips are...

Page 34: ...do not adjust This is the pressure safety valve for the tilt cylinder If the load is too heavy and the grapple drops too slowly this valve protects the tilt cylinder by allowing the grapple to tilt down immediately If this valve is set too high the felling grapple may strike the crane boom Valve 11 factory pre set do not adjust This is the pressure safety valve for the grapple close function If se...

Page 35: ...lt up position horizontal grapple position the pressure in the accumulator may be too high Measuring the pressure in the accumulator In case of one of the aforementioned problems the pressure in the accumulator must be checked This can be done using the supplied manometer kit Measuring the pressure in the accumulator Use the side of the manometer with no regulator valve See Figure 25 Screw the tes...

Page 36: ...en function can be operated As soon as the grapple reaches tilt up position the 2nd person must slowly open the regulator valve for at least 30 seconds The accumulator will now be pressurized Excess pressure Leave the regulator valve on the accumulator filling kit closed When the grapple is in the default position grapple open and tilt down read the manometer value The final value should be in thi...

Page 37: ... force is set from factory The brake pressure size of brake cylinders and the accumulator are designed and set in such a way that the tilt cylinder is protected against overloading Never increased the hydraulic pressure on the brake system it can result in high torsional forces on the crane end beam When the brake is holding the load but the tilt cylinder is still tilting down then the load that h...

Page 38: ...d to always install a new chain The groove of the saw blade must be in line with the chain sprocket If necessary the chain sprocket must be repositioned with washers to realign it with the groove The chain lubrication system must be checked frequently The saw function should be operated for a maximum of 15 seconds Prolonged use of this function can possibly cause a problem with o Burn the saw bar ...

Page 39: ...hicle Has maintenance been done correctly Have valve block settings been changed Have parts been replaced or removed 3 Operate the machine and the felling grapple Try to trace possible errors malfunctions Check whether the carrying vehicle actually meets the required specifications Operate at work with different speeds in order to trace the potential problem 4 Inspect the machine as a whole First ...

Page 40: ...t up position Pressure in the accumulator on the side of the tilt frame is too high use the accumulator test kit to release the pressure Saw blade sticks and does not cut straight Chain incorrectly sharpened left and right chain links uneven The saw blade is not flush with the saw bracket turn the long saw bolt further into the saw bracket by adding one rotation The saw blade is bended replace the...

Page 41: ... GMT050 Grapple open maximum 122 cm 48 inch Grapple close minimum 7 5 cm 2 9 inch Maximum saw diameter Ø50 cm 19 7 inch Minimum saw diameter Ø8 cm 3 inch Maximum operating pressure 25 MPa 250 bar 3625 9 psi Hydraulic flowrate 45 80 l min 11 9 21 1 gallons min Weight 395 kg 870 8 lbs ...

Page 42: ...22 cm 48 inch Grapple close minimum 7 5 cm 2 9 inch Maximum saw diameter Ø50 cm 19 7 inch Minimum saw diameter Ø8 cm 3 inch Maximum operating pressure 25 MPa 250 bar 3625 9 psi Hydraulic flowrate 45 80 l min 11 9 21 1 gallons min Weight 530 kg 1168 lbs Includes rotator link and headplate ...

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