A small pruning machine, carried on the user's back knapsack style, has been developed by Kasetsart University in Thailand ( Fig. 1). It is expected to be very useful for pruning trees in orchards, private gardens, public parks and along the sides of roads.

Effectiveness of the Technology

• The machine can cut branches from 1 - 10 cm in diameter. An operator standing on the ground, can use the machine to cut branches 1 - 5 meters high. If branches are between 6 cm and 6.5 cm in diameter, it takes between 6 and 15 seconds to cut each branch (depending on how accessible the branch is, and how hard the wood).
• The machine makes it much easier to cut a large branch which is some distance above the ground.
• It reduces the amount of labor needed for pruning.
• If the attachment is changed, the machine can be used as a knapsack lawn mower.

Components of the Machine

The machine includes the following components ( Fig. 2).

• A two-stroke engine of 3-5 HP (horse-power);
• An aluminum handle 0.5 cm in diameter and four meters long;
• A small 90 - degree bevel gear drive unit; and,
• A small chain saw.

Pruning Technique

The operator must be particularly careful when cutting branches which are larger than 0.5 cm in diameter. He should make a deep cut on the underside of the branch first, to keep a clean cross section when he finishes cutting the branch from above.

It is more difficult to cut a vertical branch than a horizontal one. The operator must pay attention to the alignment of the branch before he cuts it. The operator should use the chain saw at a slower speed when he is beginning to cut the branch.

Precautions

The larger model of pruning machine weighs 12 kilograms. It has a handle four meters long ( Fig. 3). The smaller model has a handle two meters long, and weights 7.5 kg ( Fig. 4). Both models are probably too heavy for most women to use.

The main disadvantage of this pruning machine is the chain saw, because the law in Thailand does not allow anyone to use a chain saw to cut trees except with official written permission. (This is part of the regulations for forest conservation).

Index of Images

Figure 1 A Small Chain Saw

Figure 2 The Lawn Mower Handle and the Handle of the Pruning Machine Are Interchangeable

Figure 3 Pruning Machine: The Model with a Handle Four Meters Long

 Figure 4 Pruning Machine: The Model with a Handle Two Meters Long

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