Gears and Gear Trains - Theory of Machines
Subject and UNIT: Theory of Machines: Unit II: Gears and Gear Trains
Before proceeding to numerical problems, the various formulae required are summarised in Table 4.4 below for easy reference.
Gears and Gear Trains - Theory of Machines
Subject and UNIT: Theory of Machines: Unit II: Gears and Gear Trains
The contact ratio is the average number of teeth that are in contact at any instant.
Gears and Gear Trains - Theory of Machines
Subject and UNIT: Theory of Machines: Unit II: Gears and Gear Trains
The length of arc of contact is the length of arc made by a point on the pitch circle from beginning to the end of engagement of both pair.
Gears and Gear Trains - Theory of Machines
Subject and UNIT: Theory of Machines: Unit II: Gears and Gear Trains
Fig.4.23 shows two involute gears i.e., pinion and wheel in mesh.
Gears and Gear Trains - Theory of Machines
Subject and UNIT: Theory of Machines: Unit II: Gears and Gear Trains
The three standard pressure angles generally used are 14 ½°, 20%, and 25°
Gears and Gear Trains - Theory of Machines
Subject and UNIT: Theory of Machines: Unit II: Gears and Gear Trains
A set of gears is called interchangeable or standard gears when any two gears of the set will mesh satisfying the law of gearing.
Gears and Gear Trains - Theory of Machines
Subject and UNIT: Theory of Machines: Unit II: Gears and Gear Trains
Two curves of any shape that fulfill the law of gearing can be used as the profiles of teeth.
Gears and Gear Trains - Theory of Machines
Subject and UNIT: Theory of Machines: Unit II: Gears and Gear Trains
The law of gearing states the condition which must be fulfilled by the gear tooth profiles to maintain a constant angular velocity ratio between two meshing gears throughout the mesh.
Gears and Gear Trains - Theory of Machines
Subject and UNIT: Theory of Machines: Unit II: Gears and Gear Trains
The two modes of gear tooth failure are:
Gears and Gear Trains - Theory of Machines
Subject and UNIT: Theory of Machines: Unit II: Gears and Gear Trains
Gears can be manufactured by various processes such as
Gears and Gear Trains - Theory of Machines
Subject and UNIT: Theory of Machines: Unit II: Gears and Gear Trains
The material for pinion should always be better than the material of the mating gear.
Gears and Gear Trains - Theory of Machines
Subject and UNIT: Theory of Machines: Unit II: Gears and Gear Trains
A pinion is the smallest of two mating gears. The larger one is called the gear or the wheel.