The maximum efficiency of spiral gears is (where θ = Shaft angle, and φ = Friction angle)
sin (θ + φ) + 1/ cos (θ - φ) + 1
cos (θ - φ) + 1/ sin (θ + φ) + 1
cos (θ + φ) + 1/ cos (θ - φ) + 1
cos (θ - φ) + 1/ cos (θ + φ) + 1
Correct Answer :
C. cos (θ + φ) + 1/ cos (θ - φ) + 1
Related Questions
To obviate axial thrust, following gear drive is used
Double helical gears having opposite teeth
Double helical gears having identical teeth
Single helical gear in which one of the teeth of helix angle a is more
Mutter gears
Length of arc of contact is given by
Arc of approach - Arc of recess
Arc of approach + Arc of recess
Arc of approach / Arc of recess
Arc of approach × Arc of recess
When a rigid body is suspended vertically and it oscillates with a small amplitude under the action of the force of gravity, the body is known as
Simple pendulum
Compound pendulum
Torsional pendulum
Second's pendulum
A point B on a rigid link AB moves with respect to A with angular velocity ω rad/s. The total acceleration of B with respect to A will be equal to
Vector sum of radial component and coriolis component
Vector sum of tangential component and coriolis component
Vector sum of radial component and tangential component
Vector difference of radial component and tangential component
A machine mounted on a single coil spring has a period of free vibration of tp . If the spring is cut into four equal parts and placed in parallel and the machine is mounted on them, then the period of free vibration of the new system will become
tp /16
tp /4
4 tp
16 tp
The two elements of a pair are said to form a higher pair, when they
Have a surface contact when in motion
Have a line or point contact when in motion
Are kept in contact by the action of external forces, when in motion
Permit relative motion
When the speed of the engine fluctuates continuously above and below the mean speed, the governor is said to be
Stable
Unstable
Isochronous
Hunt
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 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
For low and moderate speed engines, the cam follower should move with
Uniform velocity
Simple harmonic motion
Uniform acceleration and retardation
Cycloidal motion
Lower pairs are those which have
Point or line contact between the two elements when in motion
Surface contact between the two elements when in motion
Elements of pairs not held together mechanically
Two elements that permit relative motion
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 cam and follower is an example of
Sliding pair
Rolling pair
Lower pair
Higher pair
The product of the diametral pitch and circular pitch is equal to
1
1/π
π
2 π
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
When the crank is at the inner dead centre, in a reciprocating steam engine, then the velocity of the piston will be
Minimum
Zero
Maximum
None of these
With usual notations for different parameters involved, the maximum fluctuations of energy for a flywheel is given by
2ECS
ECS/2
2ECS²
2E²CS
The maximum or minimum value of the swaying couple is
± c.m.ω².r
± a (1 - c) m.ω².r
± (a/√2) (1 - c) m.ω².r
± 2a (1 - c) m.ω².r
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 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 partial balancing means
Balancing partially revolving masses
Balancing partially reciprocating masses
Best balancing of engines
All of these
In a multiple V-belt drive, if one of the belts is broken, then we should replace
The broken belt only
All the belts
The broken belt and the belts on either side of it
None of the above
If two moving elements have surface contact in motion, such pair is known as
Sliding pair
Rolling pair
Surface pair
Higher pair
Which of the following would constitute a link?
Piston, piston rod and cross head
Piston and piston rod
Piston rod and cross head
Piston, crank pin and crank shaft
The unbalanced force due to revolving masses
Varies in magnitude but constant in direction
Varies in direction but constant in magnitude
Varies in magnitude and direction both
Constant in magnitude and direction both
The instantaneous centre of a rigid thin disc rolling on a plane rigid surface is located at
The centre of the disc
The point of contact
An infinite distance on the plane surface
The point on the circumference situated vertically opposite to the contact point
A spring controlled governor is found unstable. It can be made stable by
Increasing the spring stiffness
Decreasing the spring stiffness
Increasing the ball mass
Decreasing the ball mass
The total number of instantaneous centres for a mechanism consisting of n links are
n/2
n
n - 1
n(n - 1)/2
Elements of pairs held together mechanically is known as
Closed pair
Open pair
Mechanical pair
Rolling pair
In a shaper mechanism, the Coriolis component of acceleration will
Not exist
Exist
Depend on position of crank
None of the above