Fundamentals of kinematics and dynamic of machines and mechanisms / I have taught kinematics and dynamics of machines and mechanisms for many. This is full text of the report of Satish Chandra Committee (), pages in original Kinematics of machines jbk das pdf. This may not be fully legible due to. Hi friends i just have upload an ebook on Kinematics of machinery. I hope it will help you to guide well. let me know if you need more updates.
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Kinematics of Machines for IV Semester - Mechanical Engineering of Vtu by J.b.k Das, , available at Book Depository with free delivery. KINEMATICS OF echecs16.info - Download as PDF File .pdf), Text File .txt) or read online. KINEMATICS OF echecs16.info Kinematics Of Machines For 4th Sem Mechanical Eng Vtu by JBK Das, P L Srinivasa Murthy. Tags: vtu, local author, mech kinematics, machinesjbk, das, srinivasa, murthysapna, book, house, (m) Theory of Machines and Mechanisms.
Path traced 2 2 2 2 by mid-point of PQ is a circle. Scotch yoke mechanism: This mechanism, the slider P is fixed. When PQ rotates above P, the slider Q reciprocates in the vertical slot. The mechanism is used to convert rotary to reciprocating mechanism. If one block is turning through an angle, the frame and the other block will also turn through the same angle. It is shown in the figure below. An application of the third inversion of the double slider crank mechanism is Oldhams coupling shown in the figure.
It is the escapement which divides the time into equal segments. The balance wheel, the gold wheel, oscillates backwards and forwards on a hairspring not shown as the balance wheel moves the lever is moved allowing the escape wheel green to rotate by one tooth. The power comes through the escape wheel which gives a small 'kick' to the palettes purple at each tick. In the example above the blue gear has eleven teeth and the orange gear has twenty five. Notice that as the blue gear turns clockwise the orange gear turns anti-clockwise.
In the above example the number of teeth on the orange gear is not divisible by the number of teeth on the blue gear. This is deliberate. If the orange gear had thirty three teeth then every three turns of the blue gear the same teeth would mesh together which could cause excessive wear.
By using none divisible numbers the same teeth mesh only every seventeen turns of the blue gear. CAMS: Cams are used to convert rotary motion into reciprocating motion. The motion created can be simple and regular or complex and irregular.
As the cam turns, driven by the circular motion, the cam follower traces the surface of the cam transmitting its motion to the required mechanism. Cam follower design is important in the way the profile of the cam is followed.
A fine pointed follower will more accurately trace the outline of the cam. This more accurate movement is at the expense of the strength of the cam follower. Steam engines were the backbone of the industrial revolution. In this common design high pressure steam is pumped alternately into one side of the piston, then the other forcing it back and forth. The reciprocating motion of the piston is converted to useful rotary motion using a crank.
As the large wheel the fly wheel turns a small crank or cam is used to move the small red control valve back and forth controlling where the steam flows. In this animation the oval crank has been made transparent so that you can see how the control valve crank is attached. Straight line generators, Design of Crank-rocke r Mechanis ms: Straight Line Motion Mechanisms: The easiest way to generate a straight line motion is by using a sliding pair but in precision machines sliding pairs are not preferred because of wear and tear.
Hence in such cases different methods are used to generate straight line motion mechanisms: 1. Exact straight line motion mechanis m. Peaucellier mechanism, b. Hart mechanism, c. Scott Russell mechanism 2. Approximate straight line motion mechanisms a. Watt mechanism, b. Grasshoppers mechanism, c.
Roberts mechanism, d. Tchebicheffs mechanism a. Peaucillier mechanism : The pin Q is constrained to move long the circumference of a circle by means of the link OQ. The link OQ and the fixed link are equal in length. Therefore the point P traces out a straight path normal to AR. Robe rts mechanis m: This is also a four bar chain.
The best position for O may be found by making use of the instantaneous centre of QR. The path of O is clearly approximately horizontal in the Roberts mechanism.
Peaucillier mechanism b. Velocity and acceleration analysis by complex numbers: Analysis of single slider crank mechanism and four bar mechanism by loop closure equations and complex numbers. Displacement, velocity and acceleration analysis in simple mechanis ms : Important Concepts in Velocity Analysis 1. The absolute velocity of any point on a mechanism is the velocity of that point with reference to ground.
Relative velocity describes how one point on a mechanism moves relative to another point on the mechanism. In the direction of sliding. A rotating link will produce normal and tangential acceleration components at any point a distance, r, from the rotational pivot of the link. The total acceleration of that point is the vector sum of the components.
A slider attached to ground experiences only sliding acceleration. A slider attached to a rotating link such that the slider is moving in or out along the link as the link rotates experiences all 4 components of acceleration.
Perhaps the most confusing of these is the coriolis acceleration, though the concept of coriolis acceleration is fairly simple.
Imagine yourself standing at the center of a merry- go-round as it spins at a constant speed. Even though you are walking at a constant speed and the merry-go-round is spinning at a constant speed, your total velocity is increasing because you are moving away from the center of rotation i.
This is the coriolis acceleration. In what direction did your speed increase? This is the direction of the coriolis acceleration. In this way, the x and y components of the total acceleration can be found. Graphical Method, Velocity and Acceleration polygons : Graphical velocity analysis: It is a very short step using basic trigonometry with sines and cosines to convert the graphical results into numerical results.
The basic steps are these: 1. Set up a velocity reference plane with a point of zero velocity designated. Plot your known linkage velocities on the velocity plot. A linkage that is rotating about ground gives an absolute velocity. This is a vector that originates at the zero velocity point and runs perpendicular to the link to show the direction of motion. The vector, VA, gives the velocity of point A. Plot all other velocity vector directions.
A point on a grounded link such as point B will produce an absolute velocity vector passing through the ze ro velocity point and perpendicular to the link. A point on a floating link such as B relative to point A will produce a relative velocity vector. This vector will be perpendicular to the link AB and pass through the reference point A on the velocity diagram.
Kinematic analysis by Complex Algebra methods: Analysis of single slider crank mechanism and four bar mechanism by loop closure equations and complex numbers. Vector Approach: Relative velocity and accelerations of particles in a common link, relative velocity and accelerations of coincident particles on separate link Computer applications in the kinematic analysis of simple mechanis ms : Computer programming for simple mechanisms In a direction perpendicular to the link.
Cams are used to convert rotary motion into reciprocating motion. Classifications - Displacement diagrams Cam Terminology: Physical components: Cam, follower, spring Types of cam systems: Oscilllating rotating , translating Types of joint closure: Force closed, form closed Types of followers: Flat-faced, roller, mushroom Types of cams: radial, axial, plate a special class of radial cams.
Types of motion constraints: Critical extreme position the positions of the follower that are of primary concern are the extreme positions, with considerable freedom as to design the cam to move the follower between these positions.
This is the motion constraint type that we will focus upon. Critical path motion The path by which the follower satisfies a given motion is of interest in addition to the extreme positions.
This is a more difficult and less common design problem. Types of motion: rise, fall, dwell Geometric and Kine matic parameters: follower displacement, velocity, acceleration, and jerk; base circle; prime circle; follower radius; eccentricity; pressure angle; radius of curvature.
Parabolic, Simple harmonic and Cycloidal motions: Describing the motion: A cam is designed by considering the desired motion of the follower.
This motion is specified through the use of SVAJ diagrams diagrams that describe the desired displacement-velocity-acceleration and jerk of the follower motion Layout of plate cam profiles: Drawing the displacement diagrams for the different kinds of the motions and the plate cam profiles for these different motions and different followers.
Derivatives of Followe r motion: Velocity and acceleration of the followers for various types of motions. Calculation of Velocity and acceleration of the followers for various types of motions.
High speed cams: High speed cams Circular arc and Tangent cams: Circular arc Tangent cam Standard cam motion: Simple Harmonic Motion Uniform velocity motion Uniform acceleration and retardation motion Cycloidal motion Notice that as the blue gear turns clockwise the orange gear turns anticlockwise. Fundame ntal Law of toothed gearing and Involute gearing: Law of gearing Involutometry and Characteristics of involute action Path of Contact and Arc of Contact Contact Ratio Comparison of involute and cycloidal teeth Inte r changeable gears, gear tooth action, Terminology: Inter changeable gears Gear tooth action Terminology Inte rference and undercutting: Interference in involute gears Methods of avoiding interference Back lash Gear trains: Gear Train Basics The velocity ratio, mV, of a gear train relates the output velocity to the input velocity.
For example, a gear train ratio of means that the output gear velocity is 5 times the input gear velocity. Parallel axis gear trains: Simple Gear Trains A simple gear train is a collection of meshing gears where each gear is on its own axis. The train ratio for a simple gear train is the ratio of the number of teeth on the input gear to the number of teeth on the output gear. A simple gear train will typically have 2 or 3 gears and a gear ratio of or less.
If the train has 3 gears, the intermediate gear has no numerical effect on the train ratio except to change the direction of the output gear. Compound Gear Trains A compound gear train is a train where at least one shaft carries more than one gear. A common approach to the design of compound gear trains is to first determine the number of gear reduction steps needed each step is typically smaller than for size purposes.
Once this is done, determine the desired ratio for each step, select a pinion size, and then calculate the gear size. Reverted Gear Trains A reverted gear train is a special case of a compound gear train.
A reverted gear train has the input and output shafts in line with one another. Assuming no idler gears are used, a reverted gear train can be realized only if the number of teeth on the input side of the train adds up to the same as the number of teeth on the output side of the train. Epicyclic gear trains: If the axis of the shafts over which the gears are mounted are moving relative to a fixed axis , the gear train is called the epicyclic gear train. Problems in epicyclic gear trains.
Differentials: Used in the rear axle of an automobile. To enable the rear wheels to revolve at different speeds when negotiating a curve. To enable the rear wheels to revolve at the same speeds when going straight.
Surface contacts: Basic laws of friction Pivot and collar, introduction and types.
Problem on flat pivot, Problems on conical pivot. Sliding and Rolling friction: Sliding contact bearings Rolling contact bearings Problems in bearings Friction drives: Friction drives Positive drives and Slip drives Speed ratio Friction in scre w threads: Friction in screw and nut Friction in screw jack Problems in screw jack Friction clutches: Single plate clutches and Multi-plate clutches Uniform wear theory and Uniform pressure theory Problems in clutches Belt and rope drives: Belt drives, Open belt drives and Crossed belt drives Length of the belt and Angle of lap Power transmitted by a belt drive Problems in belt drives Friction aspects in Brakes: Brakes, Types Mechanical brakes, band brakes Braking torque calculations Self locking brakes Problems in brakes Friction in vehicle propulsion and braking: Vehicle dynamics Vehicle propulsions Braking aspects in vehicles Related Interests.
Theory of machines R. Gupta , S. Chand publication 2. Theory of machines P. Ballaney , Khanna publication 3. Bansal ,Laxmi publication 7. Marks Time: 3Hrs Note : 1. Question No.
Answer any two full questions from each of the remaining sections 3. Any missing data may be suitably assumed 1.
Give its applications. It is subjected to a load of 30 KN. The angle of the cone is degree and the co-efficient of friction is 0.