Four Bar Mechanism
It has 4 links (3 moving links, 1 fixed link) and 4 joints (pinned).
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Inversion : Crank and Lever Mechanism (Beam Engine)
Lever oscillates about a fixed center.
Inversion : Double Crank Mechanism (Locomotive Coupling Rod)
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Fig: Connecting rod and coupling rods attached to a small locomotive driving wheel
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Inversion : Double Lever Mechanism (Watt's Indicator, Stream Engine)
- Watt's linkage (also known as the parallel linkage) : In which the central moving point of the linkage is constrained to travel on an approximation to a straight line. It is also used in automobile suspensions, allowing the axle of a vehicle to travel vertically while preventing sideways motion.
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Slider Crank Mechanism
This is a kinematic chain having four links (i.e., modification of the basic four bar mechansim). It has one sliding pair and three turning pairs.
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1st Inversion : Ground body is fixed (Reciprocating Engine, Reciprocating Compressor, etc)
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2nd Inversion : Crank is fixed (Whitworth Quick Return Motion Mechanism, Rotary Internal Combustion (IC) Engine or Gnome Engine, etc)
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3rd Inversion : Connecting Rod is fixed (Slotted crank mechanism or Crank and Slotted Lever Quick Return Mechanism, Oscillating Cylinder Engine, etc)
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Fig: Oscillating Cylinder
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4th Inversion : Slider is fixed (Hand Pump, Pendulum Pump or Bull Engine, Radial Engine, etc)
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Double Slider Crank Mechanism
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Inversion : Elliptical Trammels
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Inversion : Scotch Yoke Mechanism
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Above Fig Only: Needle Bar Slot Cam (Modified Scotch Yoke Mechanism)
Inversion : Oldham's Coupling
It is used to connect two parallel shafts whose axes are at a small distance apart. Two flanges, each having a rectangular slot, are keyed, one on each shaft. The two flanges are positioned such that, the slot in one is at right angle to the slot in the other.
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