Kinematic Inversions of Four Bar Chain, Slider Crank and Double Slider Crank Mechanism

Kinematic Inversions of Four Bar Chain, Slider Crank and Double Slider Crank Mechanism

KINEMATIC INVERSION

Inversions of mechanism: A mechanism is one in which one of the links of a kinematic chain is fixed. Different mechanisms can be obtained by fixing different links of the same kinematic chain. These are called as inversions of the mechanism. By changing the fixed link, the number of mechanisms which can be obtained is equal to the number of links. Excepting the original mechanism, all other mechanisms will be known as inversions of original mechanism. The inversion of a mechanism does not change the motion of its links relative to each other.

Four bar chain:

Four bar chain

Fig 1.22 Four bar chain

One of the most useful and most common mechanisms is the four-bar linkage. In this mechanism, the link which can make complete rotation is known as crank (link 2). The link which oscillates is known as rocker or lever (link 4). And the link connecting these two is known as coupler (link 3). Link 1 is the frame.


Inversions of four bar chain:

Inversions of four bar chain.

Fig.1.23 Inversions of four bar chain.

Crank-rocker mechanism: In this mechanism, either link 1 or link 3 is fixed. Link 2 (crank) rotates completely and link 4 (rocker) oscillates. It is similar to (a) or (b) of fig.1.23.

Crank-rocker mechanism

Fig.1.24

Drag link mechanism. Here link 2 is fixed and both links 1 and 4 make complete rotation but with different velocities. This is similar to 1.23(c).

Drag link mechanism

Fig.1.25

Double crank mechanism. This is one type of drag link mechanism, where, links 1& 3 are equal and parallel and links 2 & 4 are equal and parallel.

Double crank mechanism

Fig.1.26

Double rocker mechanism. In this mechanism, link 4 is fixed. Link 2 makes complete rotation, whereas links 3 & 4 oscillate (Fig.1.23d)

Slider crank chain: This is a kinematic chain having four links. It has one sliding pair and three turning pairs. Link 2 has rotary motion and is called crank. Link 3 has got combined rotary and reciprocating motion and is called connecting rod. Link 4 has reciprocating motion and is called slider. Link 1 is frame (fixed). This mechanism is used to convert rotary motion to reciprocating and vice versa.

Slider crank chain

Fig1.27

Inversions of slider crank chain: Inversions of slider crank mechanism is obtained by fixing links 2, 3 and 4.

Inversions of slider crank chain:

(a) crank fixed

Inversions of slider crank chain:

(b) connecting rod fixed

Inversions of slider crank chain:

(c) slider fixed

Fig.1.28

Rotary engine – I inversion of slider crank mechanism. (crank fixed)

Rotary engine – I inversion of slider crank mechanism.

Fig.1.29

Whitworth quick return motion mechanism–I inversion of slider crank mechanism.

Whitworth quick return motion mechanism

Fig.1.30

Crank and slotted lever quick return motion mechanism – II inversion of slider crank mechanism (connecting rod fixed).

Crank and slotted lever quick return motion mechanism

Fig.1.31

Oscillating cylinder engine–II inversion of slider crank mechanism (connecting rod fixed).

Oscillating cylinder engine–II inversion of slider crank mechanism

Fig.1.32

Pendulum pump or bull engine–III inversion of slider crank mechanism (slider fixed).

Pendulum pump or bull engine–III inversion of slider crank mechanism

Fig.1.33

Double slider crank chain: It is a kinematic chain consisting of two turning pairs and two sliding pairs.

Scotch –Yoke mechanism.

Turning pairs – 1&2, 2&3; Sliding pairs – 3&4, 4&1.

Scotch –Yoke mechanism.

Fig.1.34: Scotch –Yoke mechanism.

Inversions of double slider crank mechanism:

Elliptical trammel. This is a device which is used for generating an elliptical profile.

Elliptical trammel

Fig.1.35: Elliptical trammel

In fig. 1.35, if AC = p and BC = q, then, x = q.cosθ and y = p.sinθ.

Rearranging,clip_image034.

This is the equation of an ellipse. The path traced by point C is an ellipse, with major axis and minor axis equal to 2p and 2q respectively.

Oldham coupling. This is an inversion of double slider crank mechanism, which is used to connect two parallel shafts, whose axes are offset by a small amount.

Oldham coupling

32 Responses to “Kinematic Inversions of Four Bar Chain, Slider Crank and Double Slider Crank Mechanism”

  1. kishore

    superb

  2. vel

    thank you so much of valuable notes

  3. Dev

    read the. topics……..

  4. admin

    Thanks

  5. admin

    Thanks for the appreciation.

  6. admin

    Thanks

  7. shidesh manjare

    that were be the nice one thankx for it

  8. admin

    Thanks, I will upload more like this.

  9. manoj kumar

    thank you a lot

  10. admin

    Thanks for linking it.

  11. Engg

    Please provide fourth inversion of this mechanism.
    It is a kinematic chain consisting of two turning pairs and two sliding pairs.

  12. admin

    Thanks for the suggestion.. We will include for sure..

  13. bhautik

    thnaksssssssss

  14. Gokul

    Thanks

  15. Robin Sebastian

    thanks a lot..

  16. venkat

    Its clear thank you

  17. Akash

    awesome bcz of avoiding unuse of net n use of time ….
    figure help full…

  18. Yeshwanth Kumar

    It s really simple & effective way of depiction.. Have bookmarked the page for future doubts….

  19. lalit

    Thanks

  20. Mayank

    Easy understand on consumption of less time…. Thanks

  21. Md saquib

    Thanks

  22. Harish L&T

    Very useful and summarised and easily can be understand the concept of mechanism.

  23. singhrbalraj

    This is nice…….and please add quick return mechanism also

  24. aditya mohan shuryabanshi

    this is best concept of mechenical
    Engginering department

  25. RAM AVATAR CHAURASIYA

    me thankfull for such information in short and effective way.

  26. mah

    you are very good

  27. admin

    Thanks

  28. ВалокБоровичи

    RE:Kinematic Inversions of Four Bar Chain, Slider Crank and Double Slider Crank Mechanism – Engineering Tutorials Валок КПС Звенигово

  29. gaurav

    sir, is the degree of freedom a mechanism and its inversions is equal?

  30. Ravi

    Sir,, i need to know.. How double crank third inversion works

  31. pradip

    Its very important topics cover ……

  32. Chandan

    Thanks

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