Balancing of rotating and reciprocating parts of an engine is necessary when it runs at
Slow speed
Moderate speed
Highs peed
Any one of these
Correct Answer :
C. Highs peed
Related Questions
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
Cross head and guides form a
Lower pair
Higher pair
Turning pair
Sliding pair
The frictional torque transmitted in a flat pivot bearing, assuming uniform wear, is (Where μ = Coefficient of friction, W=Load over the bearing, R=Radius of bearing)
μwr
¾μWR
(2/3) μWR
½μWR
A pulley and belt in a belt drive form a
Cylindrical pair
Turning pair
Rolling pair
Sliding pair
The frictional torque transmitted in a flat collar bearing, considering uniform wear, is (where r₁ and r₂ = External and internal radii of collar respectively)
(1/2) μ W (r₁ + r₂)
(2/3) μ W (r₁ + r₂)
(1/2) μ W [(r₁³ - r₂³)/(r₁² - r₂²)]
(2/3) μ W [(r₁³ - r₂³)/(r₁² - r₂²)]
The primary unbalanced force is maximum when the angle of inclination of the crank with the line of stroke is
0° and 90°
0° and 180°
90° and 180°
180° and 360°
A disc is a spinning with an angular velocity ω rad/s about the axis of spin. The couple applied to the disc causing precession will be (where I = Mass moment of inertia of the disc, and ωP = Angular velocity of precession of the axis of spin)
(1/2).Iω²
Iω²
(1/2). I ω ωP
I ω ωP
If two moving elements have surface contact in motion, such pair is known as
Sliding pair
Rolling pair
Surface pair
Higher pair
A circle passing through the pitch point with its center at the center of cam axis is known as
Pitch circle
Base circle
Prime circle
Outer circle
In Meyer's expansion valve, the expansion valve is driven by an eccentric having an angle of advance from
50°-60°
60°-70°
70°-80°
80°-90°
A mechanism consisting of four links is called a __________ mechanism.
Simple
Compound
Binary
None of these
Which of the following is false statement in respect of differences between machine and structure?
Machines transmit mechanical work, whereas structures transmit forces
In machines, relative motion exists between its members, whereas same does not exist in case of structures
Machines modify movement and work, whereas structures modify forces
Efficiency of machines as well as structures is below 100%
The pressure angle of a cam depends upon
Offset between centre lines of cam and follower
Lift of follower
Angle of ascent
All of the above
When the sleeve of a Porter governor moves downwards, the governor speed
Increases
Decreases
Remain unaffected
First increases and then decreases
The maximum fluctuation of speed is the
Difference of minimum fluctuation of speed and the mean speed
Difference of the maximum and minimum speeds
Sum of maximum and minimum speeds
Variations of speed above and below the mean resisting torque line
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
Which of the following is an example of a higher pair?
Toothed gearing
Belt and rope drive
Ball and roller bearing
All of these
The frictional torque transmitted in a conical pivot bearing with assumption of uniform pressure is __________ as compared to uniform wear.
Less
More
Same
None of these
The Klein's method of construction for reciprocating engine mechanism
Is a simplified version of instantaneous centre method
Utilises a quadrilateral similar to the diagram of mechanism for reciprocating engine
Enables determination of coriolis component
Is based on the acceleration diagram
The primary unbalanced force due to inertia of reciprocating parts in a reciprocating engine is given by (where m = Mass of reciprocating parts, ω = Angular speed of crank, r = Radius of crank, θ = Angle of inclination of crank with the line of stroke, and n = Ratio of the length of connecting rod to radius of crank)
m.ω².r sinθ
m.ω².r cosθ
m.ω².r (sin 2θ/n)
m.ω².r (cos 2θ/n)
Elements of pairs held together mechanically is known as
Closed pair
Open pair
Mechanical pair
Rolling pair
Angle of ascent of cam is defined as the angle
During which the follower returns to its initial position
Of rotation of the cam for a definite displacement of the follower
Through which the cam rotates during the period in which the follower remains in highest position
Moved by the cam from the instant the follower begins to rise, till it reaches its highest position
The coefficient of fluctuation of speed is __________ of maximum fluctuation of speed and the mean speed.
Sum
Difference
Product
Ratio
The periodic time is given by (where ω = Angular velocity of the particle in rad/s)
ω/2π
2π/ω
ω × 2π
π/ω
A body is said to be under forced vibrations, when
There is a reduction in amplitude after every cycle of vibration
No external force acts on a body, after giving it an initial displacement
A body vibrates under the influence of external force
None of the above
The lower pair is a
Open pair
Closed pair
Sliding pair
Point contact pair
In S.H.M., the velocity vector w.r.t. displacement vector
Leads by 90°
Lags by 90°
Leads by 180°
Are in phase
An automobile steering gear is an example of
Sliding pair
Rolling pair
Lower pair
Higher pair
A shaft carrying two rotors at its ends will have
No node
One node
Two nodes
Three nodes
In a cone pulley, if the sum of radii of the pulleys on the driving and driven shafts is Constant, then
Open belt drive is recommended
Crossed belt drive is recommended
Both open belt drive and crossed belt drive is recommended
The drive is recommended depending upon the torque transmitted