MECHANICAL INSTRUMENTS

Sigma type mechanical comparator

The vertical beam is mounted on the flat steel springs it is connected to the fixed members, which is turning are screwed to a back plate. The assembly provides frictional movement with self-restraint from the springs. The shank at the base of the vertical beam is arranged to take the measuring contact and it is selected from the available range.

Sigma type mechanical comparator
Sigma type mechanical comparator

Sigma comparator contains

  1. Slit diaphragm
  2. Screws
  3. Knife edge
  4. Slit diaphragm
  5. Plunger
  6. Bearing block
  7. Moving block
  8. Cross strip hinge
  9. ‘Y’ Arm of length b
  10. Phosphor bronze driving band
  11. Driving drum
  12. Pointer spindle
  13. Pointer length R
  14. Fixed member
  15. Scale

The stop is provided to restrict movement at the lower tail end of the scale. It is mounted on the fixed members, is the hinged assembly substratum (provided with means to adjust the controlling ratio of transmitted motion) operates on the face of a jeweled inserting on the flexible portion of the assembly.

The metal ribbon is attached to the forked arms posses round the spindle causing it to rotate in a magnetic field between permanent magnet and a steel plate. The indicating pointer is secured to the disc. The trigger is used to protect the measuring contact. At the upper end of version beam, adjustment screw for provided for the final zero setting of the scale.

Technical specification of Sigma comparator

The sigma type mechanical comparator technical specifications are the instrument has a linear movement of 12 cm, 25 cm, 50 cm with a magnification of 500, 1000 and 1500 times are respectively. Scales in the metric system with a least count of one division = 25 mm.

Working mechanism of sigma comparator

Working mechanism of sigma comparator is the plunger is mounted on a pair of slit diaphragms in order to allow friction less and linear movement.

A knife edge is mounted on a slit diaphragm and bears upon the face of the moving member of a cross strip hinge.

The cross strip hinge consists of the moving components and a fixed member which is connected to by thin flexible strips, alternatively at right angles to each other.

If an external force is applied to the moving member it’ll pivot, as would a hinge, about the road of intersection of the strips.