Class Room

Keys A key can be defined as a machine element which is used to connect the transmission shaft to rotating machine elements like pulleys, gears, sprockets or flywheels. A keyed joint consisting of shaft, hub and key.    There are two basic functions of the key. i)                  The primary function of the key is to transmit the torque from the shaft to the hub of the mating element and vice versa. ii)                 The second function of the key is to prevent relative rotational motion between the shaft and the joined machine element like gear or pulley. In most of the cases, the key also prevents axial motion between two elements, except in case of feather key or splined connection. There are different ways to classify key the keys. Some of them are as follow: ·         Saddle key and sunk key ·         Square key and flat key ·         Taper key and parallel key ·         Key with and without Gib-head   The selection of the type of key for a given

Introduction Performance of the boiler, like efficiency and evaporation ratio reduces with time, due to poor combustion, heat transfer fouling and poor operation and maintenance. Deterioration of fuel quality and water quality also leads to poor performance of boiler. Efficiency test- ing helps us to find out how far the boiler efficiency drifts away from the best efficiency. Any observed abnormal deviations could therefore be investigated to pinpoint the problem area for necessary corrective action. Hence it is necessary to find out the current level of efficiency for performance evaluation, which is a pre requisite for energy conservation action in industry.         Purpose of the Performance Test •            To find out the efficiency of the boiler •            To find out the Evaporation ratio The purpose of the performance test is to determine actual performance and efficien- cy of the boiler and compare it with design values or norms. It is an indicator for trac