MEOclassIIexamnotes

When hydraulic jack is pressurised, the bolt is elongated and the load is taken by the jack to loosen the nut, and the nut is turned back up.  On releasing the pressure, the bolt will go back to its original size, thereby causing the loosened nut to get jammed with the moving piston of the jack.

 Pneumatic quick couplers (also referred to as air couplers, or pneumatic quick disconnects),  are primarily used for pneumatic applications, connecting air tools, hoses, or other implements to compressed air supplies.  The coupler half contains a shut-off valve that is automatically opened when a mating nipple is  inserted and automatically closes when the nipple is removed.   Parker pneumatic couplings come in three basic designs: general purpose/manual connect,  general purpose/push-to-connect, and special purpose.   The standard seal material for shut-off couplers is Nitrile.

The alloy nature of Stainless Steel and its thin, transparent layer on the surface provides a self   healing feature. When activated by oxygen within the air or water then it is this layer which   repairs lightly scratched or any damage to the surface.  Stainless steels contain a significant amount of chromium, which forms Chromium Oxide   when it oxidizes (rusts).  In contrast to a simple carbon steel, which forms iron oxide when it   rusts, (the flaky reddish brown oxide we typically associate with rust).  Iron oxide is brittle and  permeable, doing little to prevent further oxidation of the steel surface. In contrast, chromium  oxide does not have an objectionable appearance, being the same effective color as the base  metal, just a bit duller, and is hard and resilient.  When you scratch or mar stainless, the   exposed chromium just forms a new oxide layer, protecting the underlying metal.

Pressure = Force / Area  So Force = Pressure x Area  We know that Pressure = 120 bar, Lets take cylinder bore = 60 cm  So area of head = ㄫ r x r = 3.14 x 30 x 30 = 2826 cm2   There for Force acting on cylinder head = 120 x 2826 = 339120 Ncm   In order to keep cylinder head in place we need to apply a force that is greater than 330120   Now cylinder head is tighten with 8 hydraulic nuts and assume area of one nuts as 100 cm2   For safety we take the force needed to keep head in place as 800000 Ncm  Now There are 8 nuts so total area = 8 x 100 = 800 cm2   Pressure = 800000 / 800 = 1000 bar   So we need to tight nuts around 1200 bar

 

To  make  small  adjustments  to  each  unit  make  uniform power  generation in every unit. Pmax  by  timing  of  fuel  pump(vit  or  by  shims  to  pump  or  cam  floating and readjusting) Pcomp in ME engines by exh valve timing change. Pmax- Pcomp not more than 35 bar to avoid piston ring failure. Pi adjusted by fuel index. (But limits are The peak pressure difference can't be more than 3 to 5 for AE And max 10 for ME. Exhaust gas temp diff 40deg C. Fuel  rack  should  not  be  adjusted  more  than  10% Otherwise  we  have  to change the plunger and barrel)