Noe Only one question will be randomly selected for marking

Noe: Only one question will be randomly selected for marking. 1. The length of the four links of a four-bar linkage are Lu 53.0, La 9.5. L 48.0 and 25.5. (a) Determine the type of linkage, (b) evaluate the range of transmission angle, (c) find the limits of rotation of link 2, and (d) find the limits of rotation of link 4 The six-bar pin-jointed linkage, shown in Figure 1, consists of two sub-four-bar pin- jointed linkages: O2ABO4 and O4 CDOs. Note that the links are not drawn to scale in Figure 1. The lengths of the links for the first sub-four-bar pin-jointed linkage are: Lu O,04 3.98, L2 0,A 0.69, L AB 3.63, and La Bou 1.82. The lengths of the links for the second sub-four-bar pin-jointed linkage are: La OOo 6.23, Los aa OC 3.56, Ls CD 2.48, and L6 Doe 4.30. For each sub-four-bar linkage, (a) check whether it is Grashoff, (b) specify the type of the linkage (eg. Grashoff double-rocker, non-Grashoff double rocker, etc.), (c) determine the two toggle positions and show the results graphically by the angle between respective ground link and input link), and (d) evaluate the maximum transmission angle, also draw the corresponding configuration. ground link 1b round link la Figure 1.

Solution

Link

A link is defined as a rigid body having two or more pairing elements which connect it to other bodies for the purpose of transmitting forces or motion.

Linkages

A mechanism composed of rigid bodies and lower pairs is called linkages.

Four - bar Linkage

It is the simplest of all closed loop linkage

Have three moving link. 1 fixed link and 4 pin joints

There is only one constraint on the linkage, which defines a definite motion.

1 a) Non Grashof : No link completes a full 360 degree rotation relative to another link

             s+l>p+q

s= smallest link length

l= longest link length

p, q= other two length