GRADING MACHINES

Grading means the sorting of whole fish into two or more sizes, perhaps to provide fish in the right size range to suit a gutting or filleting machine, or to enable fish in a number of specified size ranges to be offered for sale. Mixed sizes that involve the buyer in further selection may mean a lower sale price or, for herring particularly, no sale at all except for reduction to meal and oil.

A graded machine for ungutted white fish such as cod and haddock is made by Wilson; its main purpose is to select a size range suitable for a gutting machine by removing all fish that are too large or too small. Two pairs of parallel rollers are inclined at a small angle and set one above the other. The gap between the upper pair is wider than the gap between the lower pair. The rollers in each pair rotate in opposite directions so that within the gap their surfaces are moving upwards. Fish are fed from a hopper onto the top pair of rollers; small fish fall through the gaps between both pairs of rollers and are collected at a take off point, while large fish are held between the top rollers and are conveyed to a second take off point. Fish in the required size range fall through the top rollers but are held by the bottom rollers and conveyed to the gutting machine. The principal particulars of the machine are:

Size grading machine for ungutted cod and haddock

Table 1

The same machine can also be used to produce three grades of gutted fish; the tolerance on each length grade is then ±50mm.

Wilson also makes a machine specifically for grading gutted haddocks. The fish are carried along between a pair of rotating inclined rollers and as the tapered gap widens fish fall through into a number of collecting points. The fish are fed to the rollers by chute, and a raised helix on one roller helps to pull the fish into the machine and convey them between the rollers. Within the gap the roller surfaces are moving downwards. The taper of the gap between the rollers can be adjusted to suit the size grades required. The particulars of the machine are:

Size graded machine for gutted haddocks

Table 2

Size grading machines for herring and sprats are made by Arenco, Baader, Holms and Trio. In each of these machines the broad principle is the same; the fish pass over a bed of rods or rollers and fall through the tapered gaps once their thickness permits. The rods or rollers may be oscillated or vibrated to shake the fish and cause them to lie parallel to the slots. Up to four or five size grades can be produced. The principal particulars of the four machines are:

Size grading machines for herring

Table 3

Exercise 2.

a)Give the English equivalents for the following words and phrases:

Сортировка, обеспечивать, ролик, цилиндр, желоб, настраивать, подходить, транспортировать, удалять, параллельный, вращаться

b) Give the Russian equivalents for the following words and phrases:

thickness, slot, to oscillate, the broad principle, a bed of rods, size grading machines, three grades of gutted fish

Exercise 3. Match the parts of the sentences according to the text: