Mechanical Guru's

LINEARITY THE WORKING RANGE OF MOST OF THE INSTRUMENT PROVIDES A LINEAR RELATIONSHIP BETWEEN THE OUTPUT (READING TAKEN FROM THE SCALE OF THE INSTRUMENT) AND INPUT (MEASURED, SIGNAL PRESENTED TO THE MEASURING SYSTEM). THE ASPECT TENDS TO FACILITATE A MORE ACCURATE DATA REDUCTION. LINEARITY IS DEFINED AS THE ABILITY TO REPRODUCE THE INPUT CHARACTERISTICS SYMMETRICALLY, AND THIS CAN BE EXPRESSED BY THE STRAIGHT LINE EQUATION  Y=MX+C WHERE Y IS THE OUTPUT, X IS THE INPUT, M IS THE SLOPE AND C IS THE INTERCEPT.APPARENTLY, THE CLOSENESS OF THE CALIBRATION CURVE TO A SPECIFIED STRAIGHT LINE IS THE LINEARITY OR THE INSTRUMENT. ANY DEPARTURE FROM THE STRAIGHT-LINE RELATIONSHIP IS NON-LINEARITY. THE NON-LINEARITY MAY BE DUE TO: * NON-LINEARITY ELEMENTS IN THE MECHANICAL DEVICE * MECHANICAL HYSTERESIS * VISCOUS FLOW OR CREEP, AND * ELASTIC AFTER EFFECTS IN THE MECHANICAL SYSTEM IN A NOMINALLY LINEAR MEASUREMENT DEVICE, THE NON-LINEARITY MAY TAKE DIFFERENT FORM...

ERROR DESPITE UTMOST CARE AND PRECAUTIONS AN EXPERIMENTER MAY TAKE TO ELIMINATE ALL POSSIBLE ERRORS, THE HAPPY GOAL IS SELDOM ATTAINED AND CERTAIN ERRORS ARE BOUND TO CREEP IN FOR EXAMPLE, EVEN IN AN APPARENTLY   SIMPLE MEASUREMENT OF FLOW VELOCITY WITH A PITOT TUBE ANY MISALIGNMENT OF THE PROBE, LEAKS IN THE PRESSURE TUBING, CHANGES IN THE BORE AND SURFACE CONDITIONS OF THE MANOMETER, ANY FLUCTUATIONS IN THE ATMOSPHERIC AND STREAM PRESSURE ARE LIKELY TO AFFECT THE PROBE READINGS AND GIVE RISE TO UNCERTAINTIES .ERRORS AND UNCERTAINTIES ARE INHERENT IN THE PROCESS OF MAKING ANY MEASUREMENT AND IN THE INSTRUMENT WITH WHICH THE MEASUREMENT ARE MADE. A STUDY OF ERROR IS IMPORTANT AS A STEP IN FINDING WAYS OF REDUCING THEM, AND ALSO AS MEANS OF ESTIMATING THE RELIABILITY OF FINAL RESULTS. THIS CHAPTER PROVIDES A BRIEF DISCUSSION ABOUT THE NATURE OF ERRORS AND STATISTICAL ACCURACY OF TEST RESULTS.

HYDRAULIC CONTROL VALVES THESE ELEMENTS OF A HYDRAULIC CONTROL SYSTEM FUNCTION TO REGULATE THE FLOW OF HYDRAULIC FLUID FROM THE HIGH PRESSURE SIDE TO THE ACTUATOR, I.E. THE HYDRAULIC MOTOR. THERE ARE THREE MAIN TYPES OF VALVES. ·          THE PISTON OR SPOOL TYPE ·          THE FLAPPER AND NOZZLE TYPE ·          THE JET PIPE VALVE IN ALL CASES, THE MECHANICAL INPUT MOTION CAN BE CONTROLLED BY MANUAL OPERATION, OR BY A LIMITED MOTION CAN BE CONTROLLED BY MANUAL OPERATION, OR BY A LIMITED MOTION ELECTRIC MOTOR, OR BY HYDRAULIC PILOT METHOD. THE OUTPUT RESULTS IN A CHANGE OF HYDRAULIC PRESSURE. PISTON OR SPOOL VALVE:   THE COMMONLY USED SPOOL VALVE IS CONSTRUCTED IN EITHER A THREE-WAY OR A FOUR-WAY VALVE ARRANGEMENT WHEN THE SPOOL IS IN THE NEUTRAL POSITION, THE OIL FLOW TO THE ACTUATOR IS COMPLETELY BLOCKED. DISPLACEMENT OF THE SPOOL TO RIGHT...

CONTROL  SYSTEMS INTRODUCTION THE KEY CHARACTERISTIC OF CONTROL IS TO INTERFERE, TO INFLUENCE OR TO MODIFY THE PROCESS. THIS CONTROL FUNCTION OR THE INTERFERENCE TO THE PROCESS IS INTRODUCED BY AN ORGANIZATION OF PARTS (INCLUDING OPERATORS IN MANUAL CONTROL) THAT, WHEN CONNECTED   TOGETHER IS CALLED THE  CONTROL SYSTEM .  DEPENDING ON   WHETHER A HUMAN   BODY (THE OPERATOR) IS PHYSICALLY INVOLVED IN THE CONTROL SYSTEM, THEY ARE DIVIDED INTO    MANUAL CONTROL  AND  AUTOMATIC CONTROL . DUE TO ITS EFFICIENCY, ACCURACY AND RELIABILITY, AUTOMATIC CONTROL IS WIDELY USED IN CHEMICAL PROCESSED. THE AIM OF THIS SECTION IS TO INTRODUCE THE CONCEPT OF CONTROL SYSTEMS, WHAT THEIR FUNCTION IS AND WHAT HARDWARE AND SOFTWARE IS REQUIRED BY THEM. MANUAL  CONTROL SYSTEM FIRST START WITH A SIMPLE MANUAL CONTROL SYSTEM, TO EXAMINE HOW CONTROL IS INTRODUCED, HOW THE CONT...

REGULATOR REGULATOR: -  A REGULATOR IS A FEED BACK CONTROL SYSTEM IN WHICH THE OUTPUT IS MAINTAINED AT A PRESET VALUE IRRESPECTIVE OF EXTERNAL LOAD ON THE PLANT. THE REFERENCE INPUT OR COMMAND SIGNAL, ALTHOUGH ADJUSTABLE, IS HELD CONSTANT FOR LONG PERIODS OF TIME. THE PRIMARY TASK IS THEN TO MAINTAIN THE OUTPUT AT THE DESIRED VALUE IN THE PRESENCE OF DISTURBANCES. EXAMPLES OF AN AUTOMATIC REGULATOR ARE; REGULATION OF STEAM SUPPLY IN STEAM ENGINES BY THE FLY BALL GOVERNOR; THERMOSTAT CONTROL OF HOME HEATING SYSTEM; CONTROL OF PRESSURE AND OF ELECTRICAL QUANTITIES SUCH AS VOLTAGE, CURRENT AND FREQUENCY. IN GENERAL, A CONTROL SYSTEM THAT REGULATES A VARIABLE IN RESPONSE TO A FIXED COMMAND SIGNAL IS KNOWN AS A REGULATOR SYSTEM WHEREAS CONTROL SYSTEM THAT ACCURATELY FOLLOWS CHANGES IN THE COMMAND SIGNAL IS REFERRED TO AS FOLLOW UP SYSTEM.

 CLASSIFICATION OF INSTRUMENTS THE CLASSIFICATIONS OF INSTRUMENTS ARE GIVEN BELOW   AUTOMATIC AND MANUAL INSTRUMENTS: THE MANUAL INSTRUMENTS REQUIRE THE SERVICES OF AN OPERATOR WHILE THE AUTOMATIC TYPES DO NOT. FOR EXAMPLE, THE TEMPERATURE MEASUREMENTS BY MERCURY-IN-GLASS THERMOMETER IS AUTOMATIC AS THE INSTRUMENT INDICATES THE TEMPERATURE WITHOUT REQUIRING ANY MANUAL ASSISTANCE. HOWEVER, THE MEASUREMENT OF TEMPERATURE BY A RESISTANCE THERMOMETER INCORPORATING A WHEATSTONE BRIDGE IN ITS CIRCUIT IS MANUAL IN OPERATION AS IT NEEDS AN OPERATOR FOR OBTAINING THE NULL POSITION. AUTOMATIC INSTRUMENTS ARE PROFFERED BECAUSE OF THEIR FAST DYNAMIC RESPONSE AND LOW OPERATIONAL COST. SELF-GENERATING AND POWER-OPERATED INSTRUMENTS: IN A SELF-GENERATING INSTRUMENT, THE OUTPUT ENTIRELY OR ALMOST ENTIRELY BY THE INPUT SIGNAL. THE INSTRUMENT DOES NOT REQUIRE ANY OUTSIDE POWER IN PERFORMING ITS FUNCTION. FOR EXAMPLE, THE MOTIVE POWER IN A MERCURY-IN-GLASS THERMOMETER IS ...

CONTROL SYSTEM INTRODUCTION         A SYSTEM IS AN ASSEMBLAGE OF DEVICES AND COMPONENTS CONNECTED OR RELATED BY SOME FORM OF REGULAR INTERACTION OR INTERDEPENDENCE TO FORM AN ORGANIZED WHOLE AND PERFORM SPECIFIED TASKS. THE SYSTEM PRODUCES AN OUTPUT CORRESPONDING TO A GIVEN INPUT. THE THERMOMETER AND THE MASS SPRING DAMPER SYSTEM CAN BE IDENTIFIED AS SYSTEMS.                A THERMOMETER HAS THE INPUT X=Q(TEMP) ANT THE OUTPUT Y= L(LENGTH OF THE MERCURY COLUMN IN THE CAPILLARY).IN THE MASS SPRING ARRANGEMENT ,THE FORCE AND THE POSITION OF THE MASS CONSTITUTE THE INPUT TO AND   OUTPUT FROM THE SYSTEM , RESPECTIVELY IN A ROTATIONAL GENERATOR OF AN ELECTRICITY, THE INPUT WOULD BE ROTATIONAL SPEED OF THE PRIME - MOVER SHAFT AND THE OUTPUT WOULD EITHER BE THE INDUCED VOLTAGE AT THE TERMINALS( WITH NO LOAD ATTACHED TO THE GENERATOR) OR THE UNIT OF ELECTRICAL POWER (WITH LOAD...

QUESTION PAPER – 5 DYNAMICS OF MACHINES    QUE NO 1:-     (A) EXPLAIN THE IMPORTANCE OF FREE BODY DIAGRAMS IN CASE OF STATIC FORCE ANALYSIS.     (B) HOW IS THE INERTIA TORQUE ON THE CRANK SHAFT OF A VERTICAL I.C. ENGINE DETERMINED ANALYTICALLY? STATE CLEARLY THE VARIOUS LOADS ACTING ON THE ENGINE.    QUE NO 2:-            (A) EXPLAIN CLEARLY THE USES OF CRANK EFFORT DIAGRAM.      (B) A CAST IRON FLY WHEEL USED FOR A FOUR STROKE I.C. ENGINE IS DEVELOPING 18.75 KW AT 250 RPM.THE TANGENTIAL STRESSES DEVELOPED IN THE FLY WHEEL IS 5.2 MPA. THE TOTAL FLUCTUATION OF SPEED IS TO BE LIMITED TO 3% OF THE MEAN SPEED. IF THE WORK DONE DURING THE POWER STROKE IS 1/3 TIMES MORE THAN THE AVERAGE WORK DONE DURING WHOLE CYCLE, FIND THE MEAN DIAMETER AND MASS OF THE FLYWHEEL. THE DENSITY OF CAST IRON MAY BE TAKEN AS 7220 KG/M 3 .    QUE NO 3:- ...