Air Compressor Using Crank and Slotted Link Mechanism

AIR COMPRESSOR USING CRANK & SLOTTED LINK MECHANISM

SYNOPSIS

The objective of this experiment is to investigate the kinematics motion of a Crank and Slotted Lever Quick Return mechanism. The investigation is to show that it is indeed a uick return mechanism and to evaluate the increase in efficienc! that this would offer if applied to a machine tool.

INTRODUCTION

Definition of a Mechanism

" mechanism is a simplified model# usuall! in the form of a line diagram# which is used to reproduce the motion occurring in a machine. The purpose of this reproduction is to enable the nature of the machine. The purpose of this reproduction is to enable the nature of the motion to be investigated without the encumbrance of the various solid bodies which form the machine elements The various parts of the mechanism are called links or elements. $here two links are in contact and a relative motion is possible# then the! are known as a pair. "n arbitrar! set of a links which form a closed chain that is capable of relative motion# and that can be made into a rigid structure b! the addition of a single link# is known as a kinematics chain. To form a mechanism from a kinematics chain one of the links must be fixed. %owever as an! of the links can be fixed# it follows that there are as man! mechanism as there are links in the chain. The techniue obtaining different mechanism b! fixing the various links in turn is known as inversion.

ORKING PRINCIPLE Kinematics Pai!s

The relative motion between two links of a pair can take different form. Three t!pes of a pairs are known as lower pairs and these are the freuentl! occurring ones&Sliding & such as occurs between a piston and a c!linder Turning & such as occurs with a wheel on an axle Screw motion & such as occurs between a nut and a bolt "ll other cases are considered to be combinations of sliding and rolling are called higher pairs. Strictl! screw motion is a higher pair as it combines turning and sliding. Slider ' Crank (echanism The slider) crank mechanism is well known as the basis of a reciprocating engine. "s shown in the diagram below it consists of three turning pairs and one sliding pair

*n the above diagram# the link + is fixed. *f we now fix link ,# that is consider an inversion of the mechanism# we obtain the mechanism shown below. This is known as $hiworth-s Quick Return (echanism.