# Machine Design Questions and Answers – Knuckle Joint

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This set of Machine Design Multiple Choice Questions & Answers (MCQs) focuses on “Knuckle Joints”.

1. Knuckle Joint can’t be used to connect two intersecting rods.
a) Yes
b) No, it can’t be used
c) It can be used with some modificatios
d) It is expensive and hence isn’t used

Explanation: Knuckle Joint is used to connect two rods whose axes coincide or intersect and lie in a same plane.

2. A knuckle joint is unsuitable for two rotating shafts, which transmit torque
a) True
b) False

Explanation: Knuckle joint can’t be used for torque transmission.

3. A maximum of how many roads may be connected using a knuckle joint?
a) 2
b) 3
c) 4
d) 5

Explanation: In rare explanation, two rods with forks and one rod with eye is connected.
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4. A knuckle joint is also called socket pin joint.
a) True
b) False

Explanation: A knuckle joint is also called a Forked Pin Joint.

5. Which of the following are important parts of knuckle joint?
a) Eye
b) Pin
c) Fork
d) Each of the mentioned

Explanation: All the mentioned parts are important components of knuckle joint.

6. Calculate the diameter of pin from shear consideration with maximum shear stress allowed is 40NN/mm² and an axial tensile force of 50kN is acting on the rod.
a) 39mm
b) 44mm
c) 49mm
d) 52mm

Explanation: As the pin is subjected to double shear diameter (D) = √(2P/π x τ) = 38.80mm.

7. If knuckle joint is to fail by crushing failure of pin in fork, then determine the diameter of knuckle pin when 50kN axial tensile force act on rods. Given: Max allowable compressive stress=25N/mm², thickness of each eye of fork=25mm.
a) 40mm
b) 50mm
c) 60mm
d) 70mm

Explanation: d=P/2aσ = 40mm.

8. If any cross section is subjected to direct tensile stress and bending stress, then find the dimension of cross section. Given length & breadth are t and 2t respectively. F=25kN acts on the top fibre of the cross section, M=F x t . Also maximum allowable tensile stress =100N/mm².
a) 25.5mm
b) 30.2mm
c) 27.55mm
d) None of the mentioned

Explanation: σ= [P/A] + [My/I], where y=t & I=t(2t)ᴲ/12.

9. A knuckle joint can be used in valve mechanism of a reciprocating engine.
a) Yes
b) No
c) Yes but there are stress probles
d) No as it is very dangerous to use

Explanation: Knuckle joint can be used till the rods coincide or intersect in a plane.