# Machine Kinematics Questions and Answers – Straight Line Mechanism

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This set of Machine Kinematics Multiple Choice Questions & Answers (MCQs) focuses on ” Straight Line Mechanism”.

1. A double universal joint is used to connect two shafts in the same plane. The intermediate shaft is inclined at an angle of 20° to the driving shaft as well as the driven shaft. Find the maximum speed of the intermediate shaft if the driving shaft has a constant speed of 500 r.p.m.
a) 532.1 r.p.m
b) 469.85 r.p.m
c) 566.25 r.p.m
d) 441.5 r.p.m.

Explanation: Given α = 20° ; NA = 500 r.p.m.
Let A, B and C are the driving shaft, intermediate shaft and driven shaft respectively. We know that for the driving shaft (A) and intermediate shaft (B),
Maximum speed of the intermediate shaft,

NB(max) = NA/cosα = 500/cos 20°= 532.1 r.p.m.

2. A double universal joint is used to connect two shafts in the same plane. The intermediate shaft is inclined at an angle of 20° to the driving shaft as well as the driven shaft. Find the minimum speed of the intermediate shaft if the driving shaft has a constant speed of 500 r.p.m.
a) 532.1 r.p.m
b) 469.85 r.p.m.
c) 566.25 r.p.m.
d) 441.5 r.p.m.

Explanation: Given α = 20° ; NA = 500 r.p.m.
Let A, B and C are the driving shaft, intermediate shaft and driven shaft respectively. We know that for the driving shaft (A) and intermediate shaft (B),
minimum speed of the intermediate shaft,

NB(min) = NAcosα = 500 × cos 20° = 469.85 r.p.m.

3. A double universal joint is used to connect two shafts in the same plane. The intermediate shaft is inclined at an angle of 20° to the driving shaft as well as the driven shaft. Find the maximum speed of the driven shaft if the driving shaft has a constant speed of 500 r.p.m.
a) 532.1 r.p.m
b) 469.85 r.p.m.
c) 566.25 r.p.m.
d) 441.5 r.p.m.

Explanation: Given α = 20° ; NA = 500 r.p.m.
Let A, B and C are the driving shaft, intermediate shaft and driven shaft respectively. We know that for the driving shaft (A) and intermediate shaft (B),
Maximum speed of the driven shaft,

NC(max) = NB(max)/cosα = NA/cos2α = 566.25 r.p.m.

4. A double universal joint is used to connect two shafts in the same plane. The intermediate shaft is inclined at an angle of 20° to the driving shaft as well as the driven shaft. Find the minimum speed of the driven shaft if the driving shaft has a constant speed of 500 r.p.m.
a) 532.1 r.p.m
b) 469.85 r.p.m.
c) 566.25 r.p.m.
d) 441.5 r.p.m.

Explanation: Given α = 20° ; NA = 500 r.p.m.
Let A, B and C are the driving shaft, intermediate shaft and driven shaft respectively. We know that for the driving shaft (A) and intermediate shaft (B),
minimum speed of the driven shaft,
NC(min) = NB(min)× cos α = NAcos2α = 441.5 r.p.m.

5. In a pantograph, all the pairs are
a) turning pairs
b) sliding pairs
c) spherical pairs
d) self-closed pairs

Explanation: In a pantograph, all the pairs are turning pairs. It has 4 links.

6. Which of the following mechanism is made up of turning pairs ?
a) Scott Russel’s mechanism
b) Peaucellier’s mechanism
c) Hart’s mechanism
d) Both (a) and (b)

Explanation: None.

7. Which of the following mechanism is used to enlarge or reduce the size of a drawing ?
a) Grasshopper mechanism
b) Watt mechanism
c) Pantograph
d) none of the mentioned

Explanation: A pantograph is an instrument used to reproduce to an enlarged or a reduced scale and as exactly as possible the path described by a given point.

8. The Ackerman steering gear mechanism is preferred to the Davis steering gear mechanism, because
a) whole of the mechanism in the Ackerman steering gear is on the back of the front wheels
b) the Ackerman steering gear consists of turning pairs
c) the Ackerman steering gear is most economical
d) both (a) and (b)

Explanation: The Ackerman steering gear mechanism is much simpler than Davis gear. The difference between the Ackerman and Davis steering gears are :
1. The whole mechanism of the Ackerman steering gear is on back of the front wheels; whereas in Davis steering gear, it is in front of the wheels.
2. The Ackerman steering gear consists of turning pairs, whereas Davis steering gear consists of sliding members.

9. The driving and driven shafts connected by a Hooke’s joint will have equal speeds, if
a) cos θ = sin α
b) sinθ = ±√tanα
c) tanθ = ±√cosα
d) cot θ = cos α

Explanation: None.

10. In a Davis steering gear, the distance between the pivots of the front axle is 1.2 metres and the wheel base is 2.7 metres. Find the inclination of the track arm to the longitudinal axis of the car, when it is moving along a straight path.
a) 12.5°
b) 13.5°
c) 14.5°
d) 15.5°

Explanation: c = 1.2 m ; b = 2.7 m
Let α = Inclination of the track arm to the longitudinal axis.
We know that tan α = c/2b = 1.2/2 x 2.7
or, α = 12.5°.

Sanfoundry Global Education & Learning Series – Machine Kinematics.
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