Pruning shears and branch loppers

Among the maintenance procedures to perform in agriculture and groundskeeping lopping off branches and pruning are those done most frequently. Traditional tools for performing manual operations have been extended to models run by vacuum and electric and hydraulic equipment. The choice of a model depends on the type of work and the thickness of branches to cut

Scissors or shears for pruning trees and bushes go back a long time and are still in widespread use today in spite of the arrival of new instruments such as hedge trimmers and chainsaws. The most traditional tool is the shear operated manually. Other than the traditional type worked with one hand, capable of pruning branches of up to 20 mm in diameter, there are those equipped with two long handles operated by both hands for cutting through branches with diameters of 30-35 mm thanks to greater leverage. These items, also worked manually, are also called loppers and can come with telescopic extensions of the blade. These are used to lop off branches up to a certain height. Cutting is performed by a blade with a deep jaw and deep onset blade working like a guillotine to prevent the blade from slipping off the branch. This type of equipment is used almost exclusively by hobbyists. On the other hand, vacuum, electric and hydraulic operated shears and loppers have been on the market enabling the pruning of branches of greater diameters with no special strain for the operator. Among these three types of equipment, those most in use are those driven by vacuum and electricity.     

 

Vacuum, electric and hydraulic shears and loppers

Aside from electric motors, pruning shears can be divided into two categories: those with a cutting blade and a counter non-cutting blade; those with two cutting blades. There are various models in each of these categories.

The first time is the most common. The cutting blade makes the cut and the  counter blade is a fixed stop. The trouble here is that the cut is not clear because the moving blade causes a small degree of damage to the section of he branch left behind. Some pole models have handles of 1 to 2.5 m long. Use of these poles reduces the cutting power.

Those in the second category are anvil loppers which have a single sharpened blade, with a straight or sometimes curved edge, that closes against a similarly contoured flat anvil like surface on the other side of the jaws, usually made of a softer metal than the blade.

Anvil loppers have the disadvantage of tending to crush rather than cut, sometimes leaving an untidy wound. Their use with extensions is not advised because the quality of the cut is lost, a feature which is a strong point.

Independent of the category, the blades for pruning can be steel or hardened carbon steel. The latter type is obviously lighter and more maneuverable.

Then there is another category of shears mounted on fixed or telescopic poles and these are called loppers. These are used for pruning up to a certain height off the ground and enable greater precision and stability for the cut. There are various models of loppers available also in this category.

The most common model is equipped with a fixed jaw blade, curved like a hook, and a mobile cutting blade. The former blade anchors the branch and the second makes the cut. There are also models with straight blades.

 

The vacuum system

Vacuum or compressed air shears require a compressor equipped with a high-pressure tube connection.

The generator can be run off an independent motor or the PTO of a tractor.

The movement of the blade is controlled by a pneumatic cylinder and a spring and the flow is regulated by a control lever.

Some models are equipped with two levers enabling the strength of the cut to be reduced.

According to the model, mass is between 500 and 800 grams and pressure averages 10 bar with highs and lows at 15 to 5 bar.

These loppers are capable of pruning branches of up to 40 mm and beyond if the blade is especially robust.

 

The electric battery powered system

These loppers are run by an electric motor inside the grip powered by lithium-ion batteries carried in a backpack or a belt worn by the operator.

There are various models of these electric machines differentiated by cutting methods. In detail, there are various openings of the mobile blade.

That is: 100% opening of the blade which automatically makes the cut when this maximum opening is reached; 70% to 40% opening for automatic cutting also with partial opening when the desired opening is reached. This model is ideal for operating in thick foliage.

With maximum opening branches of up to 35-45 mm can be pruned.

Another option is so-called proportional cutting done by the movement of the blade by regulating pressure applied to the power lever.

The mass of these tools are from 500 to 1000 grams and electric motor power is from 100 to 200 watts. For safety reasons, the machine is blocked in case of overheating. 

Hydraulic systems

Hydraulic shears are usually used only for pruning branches of a certain size, with diameters of up to 70-75 mm or branches which are especially tough. They are run off a hydraulic jack located in the grip powered by a hydraulic pump connected to an independent motor which can be carried in a backpack or on trolley. Another option is to work directly off a tractor PTO. The pump compresses the oil in the cylinder at pressures of a minimum of 100 bar to a maximum of 300 bar, depending on the model.

There is one particular model of a lopper mounted on a pole which makes a guillotine cut as described above. The working part is a fixed L-shaped blade and a mobile cutting blade which operates in the angle of the fixed blade for making the cut inside this anchor angle.

Hydraulic shears are in widespread use mainly for typical professional jobs. Their mass can reach more than 1,500 grams.

 

Maintenance and safety in use

Maintenance operations are very simple. They involve cleaning and sharpening the blades and regulating and registering them. The purpose of this work is to avoid lateral blade play which lowers the quality of the cut.

When registering the blades, they must not be set overly tight together because this would lessen the force of the cut and increase blade wear. Work performed with vacuum, electric or hydraulic equipment requires the use of individual safety devices. In relation to the work environment and type of pruning, these consist of hardhats, visors, protective glasses, cuffs, gloves and safety boots.