Feller buncher

A feller buncher is a type of harvester used in logging. It is a motorized vehicle with an attachment that can rapidly gather and cut a tree before felling it.

Feller is a traditional name for someone who cuts down trees,

In cut-to-length logging a harvester performs the tasks of a feller buncher and additionally does delimbing and bucking.

Components and Felling attachment

Feller buncher is either tracked or wheeled and has self-levelling cabin and matches with different felling heads. For steep terrain, tracked feller buncher is being used because it provides high level of traction to the steep slope and also has high level of stability.^[3][4] For flat terrain, wheeled feller buncher is more efficient compared to tracked feller buncher.^[5] It is common that levelling cabins are matched with both wheeled and tracked feller buncher for steep terrain as it provides operator comfort and helps keeping the standard of tree felling production.^[6] The size and type of trees determine which type of felling heads being used.

Types of felling heads

Disc Saw Head – It can provide a high speed of cutting when the head is pushed against the tree.^[7] Then, the clamp arms will hold the tree when the tree is almost completed cutting. It is able to cut and gather multiple trees in the felling head. The disc saw head with good ground speed provides high production, which allows it to keep more than one skidder working continuously.^[5][8]

Shear Blade Head -  It is placed against the tree and the clamp arms will hold the tree firmly. Then, the blade will activate and start cutting the tree. Same as disc saw head, it can hold multiple trees before they are placed on the ground.^[7]

Chain Saw Head – The floppy head provides minimal control to place the trees on the ground. It might not suit to collect the cut trees or gather the cut stems in the felling head.

Cost-effectiveness

The purchase cost of a feller buncher is around $180,000 USD and its fuel consumption and lubricant consumption is high among other mechanical harvesting equipment.^[9] The feller buncher also has the highest hourly cost which is around $99.5 when comparing other equipment such as a harvesters and grapple skidders.^[9][10] Although the total cost of feller buncher is high in overall, the unit production price is the lowest which explains why feller buncher is considered the most cost-effective harvesting equipment. The average unit cost of the feller buncher is $12.1/m3 while the unit cost of the harvesters is $16.5/m3.^[5] The unit cost of the feller buncher is primary affected by the tree size and the tree volume.^[10] The unit felling cost is lower when the tree size increased. For example, tree with 5 inches at DBH has the unit cost of $70 while tree with 15 inches at DBH has the unit cost of $12. As the cost of feller buncher is high, only large tree volume can produce more profit to cover the high average cost. In terms of stump height, lower stump height can maximise the use of natural resources and prevent wood waste.^[5] Mechanical felling such as using feller buncher can prevent 30% of value loss caused by the high stumps.^[11]

Maintenance

Feller buncher requires daily maintenance before operation and some components only require periodic maintenance. It could ensure the safety of operators and all the workers around the operation. If damaged or faulty machine is operated, it could result in further damage to the machine which can be more expensive to repair.^[12]

Daily or Every 8 hours

Lubrication

The felling head is considered one of the hardest part of the feller buncher and it is necessary to apply lubricant to every joint for daily maintenance. It is suggested to apply lubricant to saw head clamps, wrist attachment and driveshaft bearings during every maintenance.^[13] The use of grease should meet the extreme pressure performance standard and contains 3% of molybdenum disulphide (MoS₂).^[14] MoS₂ can prevent the wear takes place where the metal to metal contact exists.^[14]

Fuel

It is also important to check if there is enough

engine oil and filter.^[15]

During maintenance, there are common working hazards related to two main areas: working environment and exhaust system.^[19] When working on the exhaust system, be aware of the hot components around the engine. Workers could wear personal protective equipment such as safety spectacles, heat-proof gloves and safety boots. When feller buncher is elevated for service or maintenance, falls from height might happen. Related injuries could be avoided by ensuring dryness of all the walking surface, wiping any oils or other liquid substances on the floor.^[20] Also, ensure the feller buncher is parked on a level and stable ground during maintenance.^[12] When getting in and out of the machinery, workers are suggested to use three point of contact with two hands holding the handrails and one foot on a step.^[19] It is also important to provide sufficient lighting for all the working sites at all time of service.

Safety