DEPARTMENT OF MECHANICAL ENGINEERING

  Need Engine valves are used in engines to allow air or air-fuel mixture to enter into the cylinder (through inlet valve) and also to push exhaust gases (through outlet valve) from the cylinder at a specific time during the engine cycle. To have complete contact between the valve and engine surface (head), an accurately faced surface is provided which is known as valve seat. For inlet valves. the seat surface is directly machined on the engine head and are also known as integral seats. However, special seat inserts are used for exhaust valves as these are continuously exposed high temperature and thermal stress. The stem of the valve needs to move up and down without any deviation from its axis. Since, these stems are subjected to side thrust also, the valve guides are provided to maintain its alignment. Sometimes, these guides are the direct holes in the engine block. However, separate valve guides have also been used as inserts which are cylindrical in shape. The clearance between t

  Mechanical Comparator: It is self controlled and no power or any other form of energy is required. It employs mechanical means for magnifying the small movement of the measuring stylus. The movement is due to the difference between the standard and the actual dimension being checked. The method for magnifying the small stylus movement in all the mechanical comparators is by means of levers, gear trains or combination of these. They are available of different make and each has it's own characteristic. The various types of mechanical comparators are dial indicator, rack and pinion, sigma comparator, Johansson mikrokator Sigma Comparator: The plunger is attached to a bar which is supported between the bending plates at the top and bottom portion as shown in Figure (a) The bar is restricted to move in the vertical direction. A knife edge is fixed to the bar. The knife edge is attached to the sapphire plate which is attached to the moving block. The knife edge extorts a force on the m

Comparators - uses - application - classification Definition of a Comparator  A comparator is an instrument used in metrology to compare the size of one object to another. It is widely employed in production and inspection to guarantee that finished goods are of high quality and conform to industry standards. In metrology, we use a wide variety of comparators, such as: The most basic comparators are those that use mechanical means to compare an object’s dimensions to a standard. Dial indicators, plug gauges, snap gauges, and bore gauges are all types of measuring instruments. Comparators can give precision measurements, with consistent accuracy by eliminating human error. They are employed to find out, by how much the dimensions of the given component differ from that of a known datum. If the indicated difference is small, a suitable magnification device is selected to obtain the desired accuracy of measurements. It is an indirect type of instrument and used for linear measurement. If

  Autocollimator An autocollimator is an optical instrument for non-contact measurement of angles. They are typically used to align components and measure deflections in optical or mechanical systems. An autocollimator works by projecting an image onto a target mirror and measuring the deflection of the returned image against a scale, either visually or by means of an electronic detector. A visual autocollimator can measure angles as small as 1 arcsecond (4.85 microradians), while an electronic autocollimator can have up to 100 times more resolution. Visual autocollimators are often used for aligning laser rod ends and checking the face parallelism of optical windows and wedges. Electronic and digital autocollimators are used as angle measurement standards, for monitoring angular movement over long periods of time and for checking angular position repeatability in mechanical systems. Servo autocollimators are specialized compact forms of electronic autocollimators that are used in high

  Sine bar - types - uses and limitations - working principle of clinometer A sine bar is a precision measuring instrument used in machining and metrology. It consists of two parallel bars with accurately angled surfaces, typically 5°, 10°, or 15° apart. Machinists use it to measure angles with high accuracy, aiding in precise machining and inspection processes. What is a Sine Bar? A sine bar, augmented with slip gauge blocks, serves as a precision angular measurement tool renowned for its accuracy in assessing angles for various machining, grinding, and inspection purposes. This instrument excels in both precise angle measurement and workpiece alignment. Crafted from high-quality, corrosion-resistant steel, sine bars are specifically engineered to withstand wear and maintain accuracy during usage, making them indispensable in tasks requiring meticulous angle measurements and alignments. Construction of Sine Bar The sine bar is constructed with a rigid steel gauge body featuring two eq