The tractive force is maximum or minimum when the angle of inclination of crank with the line of stroke (θ) is equal to
0° and 90°
90° and 180°
135° and 315°
270° and 360°
Correct Answer :
B. 90° and 180°
Related Questions
Which of the following statement is correct for involute gears?
The interference is inherently absent.
The variation in centre distance of shafts increases radial force.
A convex flank is always in contact with concave flank.
The pressure angle is constant throughout the teeth engagement.
The minimum number of teeth on the pinion which will mesh with any gear without interference for 20° full depth involute teeth will be
12
14
18
24
The two links OA and OB are connected by a pin joint at O. If the link OA turns with angular velocity ω₁ rad/s in the clockwise direction and the link OB turns with angular velocity ω₂ rad/s in the clockwise direction, then the rubbing velocity at the pin joint O is (where r = Radius of the pin at O)
ω₁.ω₂.r
(ω₁ - ω₂)r
(ω₁ + ω₂)r
(ω₁ - ω₂)2r
A rotor which is balanced statically but not dynamically is supported on two bearings L apart and at high speed of the rotor, reaction on the left bearing is R. The right side of the bearing is shifted to a new position 2L apart from the left bearing. At the same rotor speed, dynamic reaction on the left bearing in the new arrangement will
Remain same as before
Become equal to 2R
Become equal to R/2
Become equal to R/4
Pulley in a belt drive acts as
Cylindrical pair
Turning pair
Rolling pair
Sliding pair
Which one of the following can completely balance several masses revolving in different planes on a shaft?
A single mass in different planes
Two masses in any two planes
A single mass in one of the planes of the revolving masses
Two equal masses in any two planes
A mechanism is an assemblage of
Two links
Three links
Four or more than four links
All of these
In a band and block brake, the ratio of tensions on tight side and slack side of the band is (where μ = Coefficient of friction between the blocks and the drum, θ = Semi-angle of each block subtending at the centre of drum, and n = Number of blocks)
T₁/T₂ = μ. θ. n
T₁/T₂ = [(1 - μ tanθ)/(1 + μ tanθ)]n
T₁/T₂ = (μ θ)n
T₁/T₂ = [(1 + μ tanθ)/(1 - μ tanθ)]n
Sense of tangential acceleration of a link
Is same as that of velocity
Is opposite to that of velocity
Could be either same or opposite to velocity
Is perpendicular to that of velocity
A circular bar moving in a round hole is an example of
Incompletely constrained motion
Partially constrained motion
Completely constrained motion
Successfully constrained motion
The condition for correct steering of a Davis steering gear is (where α = Angle of inclination of the links to the vertical)
sinα = b/c
cosα = c/b
tanα = c/2b
cotα = c/2b
The height of a Watt's governor is
Directly proportional to speed
Directly proportional to (speed)²
Inversely proportional to speed
Inversely proportional to (speed)²
The velocity of any point in mechanism relative to any other point on the mechanism on velocity polygon is represented by the line
Joining the corresponding points
Perpendicular to line as per (A)
Not possible to determine with these data
At 45° to line as per (A)
The frictional torque transmitted in a conical pivot bearing, considering uniform wear, is
(1/2) μ W R cosec α
(2/3) μ W R cosec α
(3/4) μ W R cosec α
μ W R cosec α
The velocity of a body moving with simple harmonic motion is __________ at the mean position.
Zero
Minimum
Maximum
None of these
The frequency of oscillation of a torsional pendulum is
2πk/r. √(g/l)
r/2πk. √(l/g)
2πr/k. √(g/l)
r/2πk. √(g/l)
The secondary unbalanced force is __________ the primary unbalanced force.
One-half
Two-third
n times
1/n times
The Hooke's joint consists of:
Two forks
One fork
Three forks
Four forks
The maximum frictional force, which comes into play, when a body just begins to slide over the surface of the other body, is known as
Static friction
Dynamic friction
Limiting friction
Coefficient of friction
The contact ratio is the ratio of
Length of pair of contact to the circular pitch
Length of arc of contact to the circular pitch
Length of arc of approach to the circular pitch
Length of arc of recess to the circular pitch
In involute gears, the pressure angle is
Dependent on the size of teeth
Dependent on the size of gears
Always constant
Always variable
Which of the following is an inversion of a single slider crank chain?
Pendulum pump
Oscillating cylinder engine
Rotary internal combustion engine
All of these
The example of spherical pair is
Bolt and nut
Lead screw of a lathe
Ball and socket joint
Ball bearing and roller bearing
When two pulleys of different diameters are connected by means of an open belt, the angle of contact at the ________ pulley must be taken into consideration.
Smaller
Larger
Either A or B
None of these
In a spring controlled governor, when the controlling force ________ as the radius of rotation increases, it is said to be a stable governor.
Remains constant
Decreases
Increases
None of these
The essential condition of placing the two masses, so that the system becomes dynamically equivalent, is (where l₁ and l₂ = Distance of two masses from the centre of gravity of the body, and kG = Radius of gyration of the body)
l₁ = kG
l₂ = kG
l₁l₂ = kG
l₁l₂ = kG²
The velocity of the rubbing surface __________ with the distance from the axis of the bearing.
Increases
Decreases
Remain same
None of these
Which of the following governor is used to drive a gramophone?
Watt governor
Porter governor
Pickering governor
Hartnell governor
For dynamic balancing of a shaft
The net dynamic force acting on the shaft is equal to zero
The net couple due to the dynamic forces acting on the shaft is equal to zero
Both (A) and (B)
None of the above
In Meyer's expansion valve, the main valve is driven by an eccentric having an angle of advance from
10°-15°
15°-25°
25°-30°
30°-40°