slider crank mechanism Experiment Engineering Dynamics

Experiment No.1

Objective:

To perform experiment of slider crank mechanism

Apparatus:

Theory:

Slider-Crank Mechanim:

A crank is an arm attached at right angle to a rotating shaft by which reciprocating motion is imparted to or received from the shaft. It is used to convert circular motion into reciprocating motion, or sometimes reciprocating motion into circular. The arm may be a bent portion of the shaft, or a separate arm attached to it. Attached to the end of the crank by a pivot is a rod, usually called a connected rod. The end of the rod attached to the crank moves in a circular motion,

While the other end is usually constrained to move in a linear sliding motion, in and out.

                                        

The term often refers to a human-powered which is used to manually turn an axle, as in a bicycle crank set or a brace and bit drill. In this case a person’s arm or leg serves as the connecting rod, applying reciprocating force to the crank. Often there is a bar perpendicular to the other end of the arm, often with a freely rotatable handle on it to hold in the hand, or in the case of operation by a foot (usually with a second arm for the other foot), with a freely rotatable pedal.

Stroke:

Reciprocating motion, used in reciprocating engine and other mechanism, is back-and forth motion. Each cycle of reciprocating consists of two opposite motions: there is a motion one direction and than a motion back in the opposite direction. Each of these is called a stroke. The term is also used to means the length of the stroke.

The stroke length is determined by the cranks on the crankshaft. Stroke can alo refer to the distance the piston travels. Bore is diameter of the cylinder, which means that engine displacement is dependent on both the bore and the stroke of  the cylinder.

Parts:

The principal parts of slider are as follows:

·         Crank: In mechanical engineering, a bent portion of an axle, or

shaft, or an arm keyed at right angles to the engd of a shaft,by which motion is imparted to or received from it.

·         Crank Pin: in a reciprocating engine, the crank pins, also known as crank journals are the journals of the big end bearings, at the ends of the connecting rods opposite to the pistons.

·         Connecting Rod: In a reciprocating piston engine, the connecting rod or condor connects te piston to the crank or crankshaft. Together with the crank, they form a simple mechanism that converts linear motion into rotating motion and vice versa.

·         Guide Frame: A frame held rigidly in place by roof jacks or timbers, with provisions for attaching a shaker conveyor pan line to the movable portion of the frame; prevents jumping or side movement of  the pan line.

·         Slider or Sliding Block: In reciprocating engine, the slider is actual the piston that moves in the cylinder.

·         Wrist Pin: In internal combustion engines, the gudge on pin or wrist pin is that which connects the piston to the connect rod and provides a bearing for the connecting rod to pivot upon as piston moves.

·         Crank Shaft: The crankshaft, sometimes causually abbreviated to crank, is the part of an engine that translates reciprocating linear pista motion into rotation.

Simple Harmonic Motion:

In mechanics and physics, simple harmonic motion is a type of periodic motion where the restoring force is directly proportional to the displacement. It can serve as a mathematical modal of a variety of motion, such as the oscillation of a spring. In addition, other phenomena can be approximated by simple harmonic motion, including the motion of a simple pendulum as well as molecular vibration. Simple harmonic motion is typified by the motion of a mass on a spring. When it is subject to the linear elastic restoring force given by hook’s Law. The motion is sinusoidal in time and demonmonst a single resonat frequency.

Procedure:

 In this mechanism, there is a link wire and a connecting rod. The connecting rod connect the crank to the block. If the crank moves, the block also moves. The motion of the block is like a piston which moves upward and downward.

 It is called a stroke.

When crank moves from 0 to 180. This means that the block also move with it.

When crank moves from 180 to 360, block movs back toward the crank block.

This mechanism also behaves like simple harmonic motion. So it is also called a SHM.

Application:

            Reciprocating Engine         A reciprocating engine, also often known as a piston engine, is a heat engine that uses one or more reciprocating pistons to convert pressure into a rotating motion. This particle describes the common feacture of all types. The main types are: the internal combustion engine, used extensively in motor vehicles: the steam engine, the mainstay of industrial revolution: and the niche application stirling engine.

            Reciprocating pump         Utilize pump

           Reciprocating Compressor          A reciprocating compressor or piston compressor is a positive displacement compressor that uses pistons driven by a crankshaft to deliver gases at high pressure.

Table:

Crank Angle(◦)	Linear Position (mm)

Graph:

Conclusion:

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