For the brake to be self locking, the force P at C shown in the below figure, should 
Be zero
Act in upward direction
Act in downward direction
None of these
Correct Answer :
A. Be zero
Related Questions
Oldham's coupling is the
Second inversion of double slider crank chain
Third inversion of double slider crank chain
Second inversion of single slider crank chain
Third inversion of slider crank chain
The length of a simple pendulum which gives the same frequency as the compound pendulum, is
kG + l₁
kG² + l₁
(kG² + l₁²)/ l₁
(kG + l₁²)/ l₁
When two links are connected by a pin joint, their instantaneous centre lies
On their point of contact
At the centre of curvature
At the centre of circle
At the pin joint
A system of masses rotating in different parallel planes is in dynamic balance if the
Resultant force is equal to zero
Resultant couple is equal to zero
Resultant force and resultant couple are both equal to zero
Resultant force is numerically equal to the resultant couple, but neither of them need necessarily be zero
In a system subjected to damped forced vibrations, the ratio of maximum displacement to the static deflection is known as
Critical damping ratio
Damping factor
Logarithmic decrement
Magnification factor
Davis steering gear consists of
Sliding pairs
Turning pairs
Rolling pairs
Higher pairs
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 anticlockwise 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
For a twin cylinder V-engine, the crank positions for primary reverse cranks and secondary direct cranks are shown in the below figure. The engine is a 
30° V-engine
60° V-engine
120° V-engine
150° V-engine
A reed type tachometer use the principle of
Longitudinal vibration
Torsional vibration
Transverse vibration
Damped free vibration
When the speed of the engine fluctuates continuously above and below the mean speed, the governor is said to be
Stable
Unstable
Isochronous
Hunt
The working depth of a gear is the radial distance from the
Pitch circle to the bottom of a tooth
Pitch circle to the top of a tooth
Top of a tooth to the bottom of a tooth
Addendum circle to the clearance circle
The motion between a pair which takes place in __________ is known as incompletely constrained motion.
One direction only
Two directions only
More than one direction
None of these
A point on a link connecting double slider crank chain traces a
Ellipse
Circle
Parabola
Hyperbola
An imaginary circle which by pure rolling action, gives the same motion as the actual gear, is called
Addendum circle
Dedendum circle
Pitch circle
Clearance circle
For a kinematic chain to be considered as mechanism
Two links should be fixed
One link should be fixed
None of the links should be fixed
There is no such criterion
In a steam engine, the link constitutes a
Piston, piston rod and crosshead
Connecting rod with big and small end brasses, caps and bolts
Crank pin, crankshaft and flywheel
All of the above
Idler pulley is used
For changing the direction of motion of the belt
For applying tension
For increasing velocity ratio
All of the above
If the number of links in a mechanism is equal to l, then the numbers of possible inversions are equal to
l - 2
l - 1
l
l + 1
The two parallel and coplanar shafts are connected by gears having teeth parallel to the axis of the shaft. This arrangement is known as
Spur gearing
Helical gearing
Bevel gearing
Spiral gearing
In elliptical trammels
All four pairs are turning
Three pairs turning and one pair sliding
Two pairs turning and two pairs sliding
One pair turning and three pairs sliding
Hammer blow
Is the maximum horizontal unbalanced force caused by the mass provided to balance the reciprocating masses.
Is the maximum vertical unbalanced force caused by the mass added to balance the reciprocating masses
Varies as the square root of the speed
Varies inversely with the square of the speed
If the rotating mass of a rim type flywheel is distributed on another rim type flywheel whose mean radius is half the mean radius of the former, then energy stored in the latter at the same speed will be
Four times the first one
Same as the first one
One fourth of the first one
One and a half times the first one
A completely constrained motion can be transmitted with.
1 link with pin joints
2 links with pin joints
3 links with pin joints
4 links with pin joints
The efficiency of a screw jack is maximum, when (where α = Helix angle, and φ = Angle of friction)
α = 45° + φ/2
α = 45° - φ/2
α = 90° + φ
α = 90° - φ
In a Hartnell governor, the lift of the sleeve is given by (where r₁ and r₂ = Max. and min. radii of rotation, x = Length of ball arm of the lever, and y = Length of sleeve arm of the lever)
(r₁ + r₂) (y/x)
(r₁ + r₂) (x/y)
(r₁ - r₂) (y/x)
(r₁ - r₂) (x/y)
The rotating shafts tend to vibrate violently at whirling speeds because
The system is unbalanced
Bearing centre line coincides with the axis
The shafts are rotating at very high speeds
Resonance is caused due to the heavy mass of the rotor
If the controlling force line for a spring controlled governor when produced intersects the Y-axis at the origin, then the governor is said to be
Stable
Unstable
Isochronous
None of these
The secondary unbalanced force is __________ the primary unbalanced force.
One-half
Two-third
n times
1/n times
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
Elements of pairs held together mechanically is known as
Closed pair
Open pair
Mechanical pair
Rolling pair