module1 Flashcards
treats of the designing and construction of machinery.
Science of Mechanism
is a device that transforms input forces and movement into a desired set of output forces and movement.
mechanism
moving components of Mechanisms
Gears and gear trains; Belt and chain drives; Cam and
followers;
Friction devices
brakes and clutches
Various machine elements,
splines, pins, and keys.
is a combination
of resistant bodies so arranged that by their means the mechanical forces of nature can
be compelled to do work accompanied by certain determinate motion.
machine
defined as the two links or elements of a machine when in contact
with each other are said to form a pair. If the relative motion between them is completely
or successfully constrained in a definite direction,
Kinematic pair
three types of Kinematic pair
Types of relative motion; Types of Contact; and Types of mechanical constraint or Type of closure.
Relative Motion types categorized into 5 parts what are they
Sliding, Turning, Rolling,
Screw and Spherical Pair.
This consists of two elements connected in such a manner that one is constrained to have a sliding motion relative to another. Example: Rectangular
bar in a rectangular hole; Square bar in the square hole; Piston and cylinder of an IC engine; Tail-stock and lathe bed, etc.
Sliding Pair
This consists of two elements connected in such a manner that one is constrained to turn or revolve about a fixed axis of another element. Example: Shaft with a collar at both ends revolving in a circular hole; the crankshaft of an IC engine turning in a bearing; Cycle wheel revolving about their axles.
Turning Pair
This consists of two elements connected in such a manner that one
is constrained to roll in another element which is fixed. Example: Ball and roller
bearings; Wheel rolling on a flat surface; Marble rolling on a flat surface.
Rolling Pair:
This consists of two elements connected in such a manner that one element turns about the other element by means of threads. The motion, in this
case, is a combination of sliding and turning. Example: The lead screw of a lathe and nut; Nut and bolt combination; Screw with nut of screw jack.
Screw Pair
This consists of two elements connected in such a manner that one element in the form of a sphere turns about the other fixed element. Example: Ball and socket joint; Pen stand; Minor attachment of vehicles.
Spherical Pair
Types of contact is classified as
Lower pair and Higher Pair
When the two elements of a pair have surface contact when relative motion takes place and the surface of one element slides over the surface of another element
Lower pair
When the two elements of a pair have line contact or point contact when relative motion takes place and the motion between the two elements is partly turning, sliding then the pair is known as
Higher Pair
Types of Mechanical Constraint classified into two types what are they
Self-closed pair and
Force closed pair.
whenever two elements of pair are held together
mechanically in such a way that only required the type of relative motion occurs is called.
Self-closed pair or closed pair:
whenever two elements of pair are not held
together mechanically but are kept in contact by the action of external forces the pair is said to be.
Force closed pair or Unclosed pair:
scheme illustrates the connectivity of links and
joints of a mechanism or machine rather than the dimensions or shape of the parts. Often links are presented as geometric objects, such as lines, triangles or squares, that support schematic versions of the joints of the mechanism or machine.
kinematic diagram
Elements of kinematics diagrams
include the frame, which is the frame of
reference for all the moving components, as well as links (kinematic pairs), and joints.
Primary Joints include
pins, sliders and other elements that allow pure rotation or pure
linear motion.
also exist that allow a combination of rotation or linear
motion.
Higher order joints
