When creating the machinery most common challenge for designers is to transfer torque from one part to another.We solve it in different ways.Toothed gears, driving belts and even electromagnetic fields drive the wheels, and in each case, the use of a particular method is motivated by technical requirements.Friction transmission is used when you want a smooth change in speed.
When there was no gears
frictio word in Latin means "friction".Until not been invented gear friction gear has major transportation torque.Thus already in antiquity mechanics revealed the dependence of the angular velocity of the ratio of diameters of the driving and driven rollers, learning to speed up or slow down your mills or water stations.This invention is applicable today.
smooth acceleration - merit clutch
serious engineering study of the site began in the late XIX century, the need for it arose during the rapid development of mechanical engineering, especially with the advent of the first cars.Transmission built on gears, not stand sharply varying load during the transition from one speed to another gear broke, required complex and expensive repairs.Disc friction transfer provided a soft contact between the motor shaft and the cardan, giving time for a smooth change of speed, which is much improved the reliability of vehicles.
and other mechanical systems that require smooth acceleration or deceleration, mechanical engineers use this important element.The design of any tape necessarily includes special counter wheels to change the angular velocity of the take-up unit, because the more receiving coil is wound, so it has to spin more slowly.Friction transmission provides the speed change per unit of time: at the beginning of playback tape or coil receiving node is spinning fast, and in the end - slowly.
variety of forms
between the gear and the clutch has a lot in common.Firstly, the ratio of the diameters of the wheels in both cases forms a gear ratio.Second, the direction of movement of the receiver and output shafts may have varied spatial orientation from parallel to perpendicular.When experimenting with the first samples of rail transport even tried to create a gear pair "rail-wheel", but soon abandoned the thought, making it smooth, with the possibility of slippage and smooth increase friction.Types of friction gears correspond to the types of gear kinematic schemes, they are tapered, cylindrical and disk (frontal).The smooth shape of the contacting surfaces, and creates the conditions for solving more complex technical problems that require Spherical Torus geometry or parts, such as editable vector output shaft.Thus the choice of a method of kinematics affect the task.The cylindrical friction gear is used for parallel transmission and bevel - for the perpendicular.
Despite the great age of the invention, the method for transmitting rotational mechanical torque is widely used in modern technology.But he has and disadvantages.Clutch discs and brake pads need to be replaced periodically in all vehicles - from the elegant "Bentley" to humble "Lada".
main efforts of technologists, materials scientists engaged clutch, designed to increase the life of the contacting surfaces, because they are constantly rubbing against each other, and hence wear.