Basic mechanical engineering :friction

clutch.Clutch is a transmission device of an automobile which is used to engage anddisengage the power from the engine to the rest of the system.
the types of friction clutches
Types of friction clutches are:
*Disc or plate clutches.
*Cone clutches.
*Centrifugal clutches.
centrifugal clutch.Centrifugal clutch is being increasingly used in automobile and machinesobviously it works on the principle of centrifugal force.
the types of flat drives The types of flat drives are:
*Compound belt drive.
*Stepped or cone pulley drive.
*Fast and loose pulley.

slip.Slip is defined as the relative motion between the belt and pulley.

law of belting.Law of belting states that the centre line of the belt, as if approaches the pulley liein a plane perpendicular to the axis of that pulley or must lie in the plane of the pulleyotherwise the belt will run off the pulley.

Rope drive: Utility.The rope drives are widely used when large power is to be transmittedcontinuously from one pulley to another over a considerable distance. One advantage ofrope drives is that a number of separate driver may be from the driving pulley

Belt drive: Utility.Belt drive is commonly used for transmission of power when exact velocity ratiois not required. Generally, belt drives are used to transmit power from one pulley toanother, when the two pulleys are not more than 10 meters apart.

the types of ropes The types of ropes are:*Fiber ropes.*Wire ropes.
Quarter turn left drive. The quarter turn left drive is used with shafts arranged at right angles and rotatingin one definite direction.

the velocity ratio of the belt drive.The velocity ratio of the belt drive is defined as the ratio between the velocities ofthe driver and the follower or the driven.

Advantages of V-belt.*Power transmitted is more due to wedging action in the grooved pulleys.*V-belt is more compact, quite and shock absorbing.*The V-belt drive is positive because of negligible slip between the belt and thegroove.*High velocity ratio may be obtained.

Disadvantages of V-belt.*It cannot be used with large center distances.*It is not as durable as flat belt.*It is a costlier system.

Circular belts or ropes.*Ropes are circular in cross section.*It is used to transmit more power.*Distance between two pulleys is more than 8metres.

Belt materials.BELT TYPES BELT MATERIALSFlat belts Leather, canvas, cotton & rubber.V-belts Rubberized fabric & rubber.Ropes Cotton, hemp & manila.

Name the types of friction.*Static friction.*Dynamic friction.

frictional force Force of friction is always acting in the direction opposite to the direction ofmotion.

self locking screws have lesser efficiency Self locking needs some friction on the thread surface of the screw and hence itneeds higher effort to lift a body and hence automatically the efficiency decreases.

static friction It is the friction experienced by a body, when at rest.

dynamic friction It is the friction experienced by the body, when in motion. The dynamic friction isalso called as kinematic friction.

screw jack.The screw jack is the device used to lift the heavy loads by applying acomparatively small effort at its handle. The working principle of screw jack is similar tothat of an inclined plane.

Square thread vs V-thread.*V-thread is stronger and often moves frictional to the motion than squarethreads.*A given load may be lifted by applying lesser force by square thread ascompared to V-threads.*V-threads are capable of taking more loads as compared to square threads