CBSE Class 12 Engineering Machine Drawing

Read and download CBSE Class 12 Engineering Machine Drawing chapter in NCERT book for Class 12 Other Subjects. You can download latest NCERT eBooks for 2021 chapter wise in PDF format free from Studiestoday.com. This Other Subjects textbook for Class 12 is designed by NCERT and is very useful for students. Please also refer to the NCERT solutions for Class 12 Other Subjects to understand the answers of the exercise questions given at the end of this chapter

 

MACHINE DRAWING

2.1 INTRODUCTION

2.2 SCREW THREAD

In our day to day life, we come across many objects where bolts and nuts are used to join two pieces together. For example we use wooden furnitures like desks, stools, tables etc. in school, showing bolts, nuts and screws. Such machine parts which are used to connect two pieces together are called as fasteners. There are two types of fasteners, viz, temporary fasteners and permanent fasteners. Threaded fasteners like bolt and nut are temporary fasteners. The process of joining different machine parts of machine or engineering products is called as fastening.Permanent fastening such as welding, riveting etc. join two parts together permanently and they cannot be separated without breaking the fastening, but in the case of temporary fastening, the parts are joined together temporarily and can be separated easily without breaking the fastening.

MACHINE DRAWING

(i) EXTERNAL THREAD

It is a continuous helical groove or ridge cut along the external surface of the cylinder, e.g. threads on bolts studs, screws etc. FIG 2.2(a) shows an external thread.

(ii) INTERNAL THREAD

It is a thread on the internal surface of a hollow cylinder. FIG 2.2(b) shows the internal threads, e.g. threads of a nut.

(iii) SCREW PAIR

The bolt and nut together called as screw pair. One or more such pairs are used to join two parts.

(iv) PARALLEL AND TAPER THREAD

A thread formed on the surface of a cylinder is called as parallel or straight thread. A thread formed on the surface of a cone called as taper thread. Refer FIG 2.3(b)

(B) TAPER THREAD

(A) PARALLEL THREAD

(v) RIGHT HAND AND LEFT HAND THREADS

Consider any nut and bolt. Hold the bolt firmly in left hand and rotate the nut clockwise by the right hand, the nut will screw on the bolt of the threads are right handed. It is abbreviated as RH thread. A left hand screws thread when assembled with a stationary mating bolt, screws off the bolt for clockwise rotation. It is abbreviated as LH thread.

Observe that mostly the bolts and nuts that we use in daily life have RH thread. Also we can observe that all the jewellery mating pieces have LH thread.

(vi) PITCH, P

It is "the distance between the corresponding points on the adjacent threads, measured parallel to the axis". Refer FIG2.2 (a)

(vii) LEAD,L

It is "the distance moved by a nut or bolt in the axial direction in one complete rotation".

(viii) SINGLE START AND MULTI START THREADS

When only one helix, forming the thread runs on a cylinder, it is called as single start thread. If more then one helices run on a cylinder, it is called as multi start threads.

i.e. L=P in the case of single start

L=2P in the case of double start

L=3P for triple start and so on.

(ix) CREST

It is the edge of the thread surface farthest from the axis, in case of external thread and nearest to the axis, in case of internal thread

(x) ROOT

It is the edge of the thread surface nearest to the axis in case of external thread and farthest from the axis, in case of internal thread.

(xi) FLANK

The surface connecting crest and root is called as flank.

(xii) THREAD ANGLE

It is "the angle between the flanks measured in an axial plane".

(xiii) MAJOR DIAMETER OR OUTSIDE DIAMETER

It is the diameter of an imaginary coaxial cylinder just touching the crest of external threads or roots of internal threads. It is the largest diameter of a screw thread.

(xiv) MINOR DIAMETER OR ROOT DIAMETER OR CORE DIAMETER

It is the diameter of an imaginary co-axial cylinder just touching the roots of external threads or crest of internal threads.

(xv) NOMINAL DIAMETER


Please refer to the link below for - CBSE Class 12 Engineering Machine Drawing

Tags: 

 


Click to View or Download pdf file
Click for more Other Subjects Study Material
CBSE Class 12 Accounting for Business Cost Sheet
CBSE Class 12 An Introduction to Creativity
CBSE Class 12 Application of Computer in Library
CBSE Class 12 Banking Operations
CBSE Class 12 Business Process Outsourcing Part 1
CBSE Class 12 Business Process Outsourcing Part 2
CBSE Class 12 Clearing Reports Downloads
CBSE Class 12 Contents of Balance Sheet
CBSE Class 12 Economics Capital receipts
CBSE Class 12 Economics Consumers Equilibrium
CBSE Class 12 Economics Determination of Income
CBSE Class 12 Economics Evolution of Money
CBSE Class 12 Economics Features of Perfect Competition
CBSE Class 12 Economics Foriegn Exchange Rates
CBSE Class 12 Economics National Income
CBSE Class 12 Economics Producers Behaviour and Supply
CBSE Class 12 Economics Production Possibilities Curve
CBSE Class 12 Elements of Drama
CBSE Class 12 Elements of Fiction
CBSE Class 12 Engineering Bearings
CBSE Class 12 Engineering Isometric Projection
CBSE Class 12 Engineering Machine Drawing
CBSE Class 12 Engineering Pulleys
CBSE Class 12 Engineering Rod Joints
CBSE Class 12 Engineering Shaft Couplings
CBSE Class 12 Engineering Tie Rod and Pipe Joints
CBSE Class 12 Entering the Transactions in Tally
CBSE Class 12 Fashion Studies Basics of Garment Making
CBSE Class 12 Fashion Studies Pattern Making
CBSE Class 12 Feature Writing
CBSE Class 12 Features of Technical Registers
CBSE Class 12 FMM Banking Operations
CBSE Class 12 FMM Financial Statements
CBSE Class 12 Forms of Business Translation
CBSE Class 12 Forms of Drama
CBSE Class 12 Forms of Prose
CBSE Class 12 Forms of Technical Translations
CBSE Class 12 Functions of Different Sections of Library
CBSE Class 12 Getting Familiar to NEET Screen
CBSE Class 12 Introducing and Understanding Transaction Cycle
CBSE Class 12 Introduction to Article Writing
CBSE Class 12 Introduction to the Writing of Drama
CBSE Class 12 Learning How to Write the Short Story
CBSE Class 12 Library Cataloguing
CBSE Class 12 Library Classification
CBSE Class 12 Macroeconomics in Hindi Part 1
CBSE Class 12 Macroeconomics in Hindi Part 2
CBSE Class 12 Macroeconomics in Hindi Part 3
CBSE Class 12 Macroeconomics in Hindi Part 4
CBSE Class 12 Modern Library and Information Services
CBSE Class 12 Modes of Theatrical Presentation
CBSE Class 12 Operations of Depository
CBSE Class 12 Order and Trade Management
CBSE Class 12 Philosophy Education For Character Development
CBSE Class 12 Philosophy Of Education
CBSE Class 12 Physics Lens and Mirror
CBSE Class 12 Practical Handbook BPO Manual
CBSE Class 12 Problems of Translation
CBSE Class 12 Procedure for doing enteries in payroll software
CBSE Class 12 Process of Translation
CBSE Class 12 Punjabi Kaav Jatra
CBSE Class 12 Punjabi Katha Jagat
CBSE Class 12 Resources and Human Resource Management
CBSE Class 12 Risk Containment Measures
CBSE Class 12 Talks and Speeches
CBSE Class 12 Technical Processing of Documents
CBSE Class 12 Trading Reports Download
CBSE Class 12 Traditional Library and Information Services
CBSE Class 12 Translating Technical and Business Registers
CBSE Class 12 Translation and the Translator
CBSE Class 12 Translations of Business Registers
CBSE Class 12 Understanding NEAT System
CBSE Class 12 Understanding Short Stories
CBSE Class 12 Understanding the Rolling Settlement
CBSE Class 12 Web Based Search
CBSE Class 12 Writing Essays
CBSE Class 12 Writing Reviews
CBSE Class 12 Writing Short Stories
CBSE Classs 12 Fashion Studies Book
NCERT Class 12 Heritabe Craft Colonial Rule and Crafts
NCERT Class 12 Heritage Craft Craft In the Age of Tourism
NCERT Class 12 Heritage Craft Craft In The Past
NCERT Class 12 Heritage Craft Design and Development
NCERT Class 12 Heritage Craft Mahatma Gandhi and Self Sufficiency
NCERT Class 12 Heritage Craft The Crafts Community Today
NCERT Class 12 Heritage CraftProduction and Marketing
NCERT Class 12 Heritage Crafts Craft Tradition Of India Carfts In The Age Of Tourism
NCERT Class 12 Heritage Crafts Craft Tradition Of India Design and Development
NCERT Class 12 Heritage Crafts Craft Tradition Of India The Crafts Community Today
NCERT Class 12 Heritage Crafts Tradition Of India Colonial Rule and Crafts
NCERT Class 12 Heritage Crafts Tradition Of India Crafts Bazaars
NCERT Class 12 Heritage Crafts Tradition Of India Crafts In Past
NCERT Class 12 Heritage Crafts Tradition Of India Handloom and Handicrafts Revival
NCERT Class 12 Heritage Crafts Tradition Of India Mahatma Gandhi and Self Sufficiency
NCERT Class 12 Heritage Crafts Tradition Of India Production and Marketing

Latest NCERT & CBSE News

Read the latest news and announcements from NCERT and CBSE below. Important updates relating to your studies which will help you to keep yourself updated with latest happenings in school level education. Keep yourself updated with all latest news and also read articles from teachers which will help you to improve your studies, increase motivation level and promote faster learning

CBSE asks schools to load Class 12 Internal Assessment Marks

This has a reference to the letter no CBSE/COORD/2021 dated 11.02.2021 regarding conduct of the School-Based Assessment (Internal Assessment/Practical/ Project) of Class-XII and uploading the marks by 11.06.2021. It has been observed that some schools have not been...

CBSE Class 12 Evaluation Criteria 2021

SUMMARY OF THE POLICY FOR TABULATION OF MARKS FOR CLASS XII BOARD EXAMINATIONS 2021   1(a) Due to cancellation of the Board examinations, the assessment of theory portion of 80/70/60/50/30 marks will be done by the school based on the following:     Class...

Moderation of Marks Class 11 and 12 Board Exams

The portal for moderation and finalization of results for Class-12 is being opened from 16.07.2021 to 22.07.2021. As Board has to declare the result latest by 31.07.2021, schools have been requested to follow the schedule strictly and complete the moderation within...

CBSE Board Examination Scheme of Assessment 2021 2022

A. Academic session to be divided into 2 Terms with approximately 50% syllabus in each term: The syllabus for the Academic session 2021-22 will be divided into 2 terms by following a systematic approach by looking into the interconnectivity of concepts and topics by...

FAQs on Policy for Tabulation of Marks for Class 10 Board Exams

ON POLICY Question.1 How CBSE will declare the result of Class-X? Answer. Results of Class X Board will be declared on the basis of an objective criterion developed by the Board vide Notification no.CBSE/CE/2021 dated 01.05.2021. Question.2. If any candidate is not...

×
Studies Today