Adjustment mechanism for grading systems

An apparatus for grading sensitive products, comprising:

• a plurality of endless ridge-belts arranged side by side and moved continuously in a forward direction, forming a gap there in-between, the gap being increased in the direction of movement, two adjacent belts receiving, conveying and releasing the products as the gap there between becomes greater than the product thickness into said receiving units, the ridge-belts being longitudinally supported by plurality of guide rails, and
• one or more adjusting device(s) arranged underneath the ridge-belts and supporting guide rails, said adjusting device arranged for adjusting the distance between the ridge-belts, said adjusting device comprising:
• a plurality of support members, said support members comprising a cylindrical central section further comprising a first screwing section, the first screwing section being a double action inner elevated portion of the cylindrical central section forming a screw thread structure extending from the centre of the cylindrical central section and towards each opening,
• a plurality of adjusting screwing members, said adjusting screwing member being having a cylindrical shape and a second screwing section, the second screwing section being a double action outer elevated portion of a cylinder forming a screw thread structure extending from the centre of the cylindrical central section and towards each end, said adjusting screwing member further comprising an inner hollow structure providing a grip for rotation, and
• an adjusting screwing shaft, said adjusting screwing shaft being adapted to rotate said adjusting screwing member by penetrating the inner hollow structure of the adjusting screwing member having a shape providing gripping structure fitting in the circumference of the inner hollow structure of the adjusting screwing member,
• wherein support members and adjusting screwing members are alternately arranged in a perpendicular line, where each adjusting screwing member is screwed into the support member on each side and where each support member is positioned underneath and corresponds to each guide rails,
• wherein said second screwing section of the adjusting screwing member, interacts with said first screwing section of the support members upon rotation of said adjusting screwing shaft for increasing or decreasing the distance between adjacent support members and thereby said guide rails and said rigid belts,
• wherein the first screwing section of the support member is a square screw thread where the corners of the crest rim have been rounded off, and in that the second screw section of the adjusting screwing member is a square screw thread where the corners of the crest rim have been rounded off,
• root corner of the first screw section of the support member and the root corner of the second screw section of the adjusting screwing member are rectangular to provide less friction when the adjusting screwing shaft is being rotated.