FIBRE HARVESTING EQUIPMENT
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3.1 Machine Shearing
3.1.1 The Shearing Stand
There is a vast array of shearing equipment available and information on the correct settings and adjustments on these should be sought from the manufacturers or their representatives.
Wool shed layouts vary tremendously but set out below are some standard measurements providing the relationship of the shearing plant to the catching pen and porthold. Detailed woolshed designs are available from the Wools of New Zealand.
Correct chute construction - Cut-away shows 150 mm indent into shearing board and 150 mm immediate drop.
Figure 3.1 The shearing stand
3.1.2 The Dropper
The dropper contains the gut which provides the driving power for the handpiece. Important features of the dropper are:
The Spring - It provides an automatic return after each blow.
The Elbow - It is important to keep this oiled daily.
The Short Tube - The tube should be set so the gut is just inside the tube. If the handpiece won't stay engaged, slide the tube up a little.
The Long Tube - When assembling the dropper, always lift the long tube approximately 20 mm from where it rests inside the ferrule, otherwise the gut is put under stress while shearing. A well oiled and well maintained down tube is essential for easy shearing.
All parts of the dropper should be checked for excessive wear before shearing ie. cogs, guts, etc.
Always keep spare guts handy at shearing time and hang them to keep them straight. It is crucial that the down tube be at the correct height for easy shearing. The length of the long gut and the mounting of the machine determines this, but as a rule of thumb the bottom of the short tube should be just touching the floor. The dropper should hang 40 cm out from the wall.
Flexible Tubes (Not illustrated) Set the machine up so the bottom of the flexible tube is just clear of the floor. If rigidly mounted the machine should sit out from the wall so the down tube is 40 cm away from the wall.
In some situations, people have to sling the machine on a rope from a rafter. If this is the case, ensure:
1. That the machine is tied to prevent rotation when shearing and;
2. That the electrical connection is sound and secured in such a way that if the machine locks up, the motor cannot tear the electrical cable. If the earth wire in the electrical cable is disconnected and there is an electrical short in the motor, the shearer becomes the earth, with possible fatal consequences!
Figure 3.2 The dropper
3.1.3 The Handpiece
The handpiece has been evolved over the last 85 years as an efficient tool for removing wool from the sheep. A good shearer working with clean sheep can shear for half an hour without the comb getting hot enough to burn the hand when touched.
The handpiece is designed to convert the rotary motion of the driving spindle into a reciprocating (back and forth) action of the cutter. The drive from the gut of the down-tube enters at the back spindle and is transmitted through the two cogs of the back joint to the crane spindle. On the front end of this spindle there is a pin mounted eccentrically. A steel ball fits onto this pin and engages in a race in the back end of the fork. The fork is pivoted on the centre post, and so the rotation of the crank spindle causes the fork to move from side to side.
On the front end of this fork are two fork yokes or "chicken feet" which hold the cutter in contact with the comb. The pressure needed to keep the fork yokes and cutter in close contact with the comb comes from a tension pin. The lower end of this pin presses on the front half of the fork. Its upper end fits into the tension sleeve. Screwing down the tension nuts thus forces the pin down and increases the pressure on the cutter. Since both ends of the tension pin are spherical, equal pressure is exerted in all directions by the cups at each end while the fork moves from side to side.
Similarly, the top of the centre post, on which the fork pivots, is spherical and fits into the fulcrum cup of the fork to take the forward and downward pressure exerted by the tension pin.
Figure 3.3 The handpiece
3.1.4 Combs and Cutters
When purchasing shearing combs, it is important to buy a type of comb that is best suited to the sheep you will be shearing. The important things to consider are the bevel and the consistency of the teeth in length, shape and thickness.
The major shearing equipment manufacturers produce a variety of combs but mostly combs can be put in three categories based on their bevels or tips:
Short Bevel Comb
The short bevel comb is principally used when the shearing is at its best and the stock are in top condition. The bevel is also appropriate on thinner combs when the scallop is ground out.
Medium Bevel Comb
The medium bevel comb is the most widely used comb and is used for the majority of crossbred shearing. Suitable for all types of wool.
Long Bevel Comb
These combs are particularly suited to fine woolled sheep and are used when the wool is sticky or for early shearing.
When using new combs, use them as they come out of the packet to determine how they perform. If they run through the wool easily and don't dig in or cut the sheep then no further work or dressing may need to be done.
However, if the comb does dig in and cut the sheep or if it is hard to push and keeps riding up off the skin, further dressing will be required.
"Experting" is the term used to describe the dressing of combs and grinding of combs and cutters. It is important that every shearer master the basics of experting, for without properly ground and dressed gear, good quality work cannot be achieved.
Figure 3.4 Types of bevel
3.2 Hand Shears (Blades)
Hand Shears (or blades) have never been entirely displaced by machine shearing in many countries around the world. Blades are used extensively where electricity is limited or not available. Blades are also used for dagging and eye wigging.
Blade shears must always be treated with care and should never be dropped on the floor or jammed into a cleft in a post.
Compared to machine shorn sheep the length of wool left on blade shorn sheep after shearing is longer, providing greater protection against sudden adverse weather occurring soon after shearing. A set of blades with the various parts named is given below.
Figure 3.5 Hand shears
3.3.1 Combs - Cashmere
The combs used for harvesting fibre from cashmere goats are made of 16 metal rods, which are curved round at the end and sharpened (see below). Two sizes of combs are used, the first one coarser than the second. Further adjustments are made by means of a metal slide which moves the teeth either closer together or further apart. This slide also assists in removing the hair from the comb.
Figure 3.6 Cashmere comb
3.3.2 The Mongolian Yak Comb
The comb used in Mongolia to harvest down fibre from the yaks is made of steel. The comb fingers are spring steel 1.5 mm in diameter and approximately 100 mm in length. The end of the fingers are curled around and have a radius of 13 mm with the tips being rounded to form a blunt point. The handle is 125 mm in length and 25 mm in diameter. The tube the comb fingers are brazed into is 100 mm long and 15 mm in diameter (see below).
Figure 3.7 Yak comb
Source: R Johnston, Kingston Morrison
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