Question

Match List-I with List-II

List-I (Link)	List-II (Type of load)
(A) Rock shaft	(I) Bending and shear
(B) Lower link	(II) Axial
(C) Upper link	(III) Axial, bending and shear
(D) Lift arm	(IV) Torsion, bending and shear

Choose the correct answer from the options given below:

• A. (A)-(IV), (B)-(III), (C)-(II), (D)-(I)
• B. (A)-(III), (B)-(II), (C)-(I), (D)-(IV)
• C. (A)-(II), (B)-(I), (C)-(IV), (D)-(III)
• D. (A)-(I), (B)-(IV), (C)-(III), (D)-(II)

Hint:

Ask which of these parts only pushes or pulls in a straight line, and which one has to twist to do its job.

Answer 1

The Correct Option is A

Step 1: The upper link of a tractor's three point hitch is connected at both ends by simple pin joints, one to the tractor body and one to the implement. A two pin link like this can only push or pull along its own length, so it carries a purely axial load. That matches (II) Axial, so C-(II).

Step 2: The two lower links carry the draft force from the implement, which is axial, but they also help support part of the implement's weight and resist its swaying, which adds bending, and the pin joints see shear too. So the lower link carries axial, bending and shear together, matching (III), giving B-(III).

Step 3: The lift arms stick out from the rock shaft like small cantilever arms and connect down to the lift rods. When the hydraulic system raises the implement, these arms are bent and their pins are sheared, so they see bending and shear, matching (I), giving D-(I).

Step 4: The rock shaft (cross shaft) is what the hydraulic ram actually turns. It has to twist to swing both lift arms together, so on top of its own bending and shear from supporting the arms, it also carries torsion. That is torsion, bending and shear together, matching (IV), giving A-(IV).

Step 5: Putting it together: (A)-(IV), (B)-(III), (C)-(II), (D)-(I), which is option 1.