For a shoe brake, the equivalent coefficient of friction is equal to (where μ = Actual coefficient of friction, and θ = Semi-block angle)
2μ sinθ/(θ + sinθ)
μ sinθ/(2θ + sin 2θ)
4μ sinθ/(θ + sinθ)
4μ sinθ/(2θ + sin 2θ)
Correct Answer :
D. 4μ sinθ/(2θ + sin 2θ)
Related Questions
A tapered key which fits in a key way in the hub and the bottom of which is shaped to fit the curved surface of the shaft, is known as,
Hollow saddle key
Hollow key
Soft key
None of these
In case of thick cylinders, the tangential stress across the thickness of cylinder is
Maximum at the outer surface and minimum at the inner surface
Maximum at the inner surface and minimum at the outer surface
Maximum at the inner surface and zero at the outer surface
Maximum at the outer surface and zero at the inner surface
When the fulcrum is in between the load and effort, the lever is said to be of
First type
Second type
Third type
Any one of these
In order to permit the thermal expansion/contraction of tubing, it should be
Crimped
Honed
Flared
Bent
In radial cams, the follower moves
In a direction parallel to the cam axis
In a direction perpendicular to the cam axis
In any direction irrespective of cam axis
Along the cam axis
The rated life of a bearing varies
Directly as load
Inversely as square of load
Inversely as cube of load
Inversely as fourth power of load
Which is correct statement?
A member made of steel will generally be more rigid than a member of equal load carrying ability made of cast iron
A member made of cast iron will generally be more rigid than a member of equal load carrying ability made of steel
Both will be equally rigid
Which one is rigid will depend on several other factors
A key made from a cylindrical disc having segmental cross-section, is known as
Woodruff key
Feather key
Flat saddle key
Gib head key
The washer is generally specified by its
Outer diameter
Hole diameter
Thickness
Mean diameter
According to Indian standard specifications, a grey cast iron designated by 'FG 200' means that the
Carbon content is 2%
Maximum compressive strength is 200 N/mm²
Minimum tensile strength is 200 N/mm²
Maximum shear strength is 200 N/mm²
A tap bolt
Has a head on one end and a nut fitted to the other
Has head at one end and other end fits into a tapped hole in the other part to be joined
Has both the ends threaded
Has pointed threads
Which process will increase the fatigue duration of parts?
Finishing and polishing
Shotpeening
De-carburisation
Electroplating
Resistance to fatigue of a material is measured by
Young's modulus
Coefficient of elasticity
Elastic limit
Endurance limit
When screw threads are to be used in a situation where power is being transmitted in one direction only, then the screw threads suitable for this will be
Knuckle threads
Square threads
Acme threads
Buttress threads
The size of a cam depends upon
Base circle
Pitch circle
Prime circle
Pitch curve
Two shafts will have equal strength, if
Diameter of both the shafts is same
Angle of twist of both the shafts is same
Material of both the shafts is same
Twisting moment of both the shafts is same
The flank of the tooth is the
Surface of the top of the tooth
Surface of the tooth above the pitch surface
Width of the tooth measured along the pitch circle
Surface of the tooth below the pitch surface
An open belt drive is used when
Shafts are arranged at right angles and rotate in one definite direction
Shafts are arranged parallel and rotate in the opposite directions
Shafts are arranged parallel and rotate in the same directions
Driven shaft is to be started or stopped whenever desired without interfering with the driving shaft
The width of the pulley should be __________ width of the belt.
Equal to
Less than
Greater than
None of these
A hot short metal is
Brittle when cold
Brittle when hot
Brittle under all conditions
Ductile at high temperature
A triple riveted butt joint with double straps of unequal width is to be designed for a boiler shell. The pitch of the rivets in the outer row is double the pitch in the inner row and zigzag riveting is proposed. Which of the following statement is correct?
There are four rivets per pitch length, all in double shear
There are four rivets per pitch length, out of which two are in single shear and two are in double shear
There are five rivets per pitch length, all in double shear
There are five rivets per pitch length, out of which four are in double shear and one is in single shear
The centrifugal tension in belts
Decreases the power transmitted
Increases the power transmitted
Increase the wrap angle
Increases the belt tension without increasing power transmission
Which of the following statement is correct?
The stress concentration in static loading is more serious in ductile materials and less serious in brittle materials
The stress concentration in static loading is more serious in brittle materials and less serious in ductile materials
The toughness of a material increases when it is heated
The shear stress in a beam varies from zero at the neutral surface and maximum at the outer fibres
In helical gears, the distance between similar faces of adjacent teeth along a helix on the pitch cylinders normal to the teeth, is called
Normal pitch
Axial pitch
Diametral pitch
Module
The shock absorbing capacity of a bolt can be increased by
Tightening it properly
Increasing shank diameter
Grinding the shank
Making shank diameter equal to core diameter of thread.
The effective stress in wire ropes during normal working is equal to the stress due to
Axial load plus stress due to bending
Acceleration/retardation of masses plus stress due to bending
Axial load plus stress due to acceleration/retardation
Bending plus stress due to acceleration/retardation
The size of a gear is usually specified by
Pressure angle
Pitch circle diameter
Circular pitch
Diametral pitch
An alien bolt is
Self locking bolt
Same as stud
Provided with hexagonal depression in head
Used in high speed components
The ratio of circumferential stress to longitudinal stress in a thin cylinder subjected to an internal pressure is
½
1
2
4
The resultant axial load on a bolt depends on
Initial tension
External load applied
Relative elastic yielding (springness) of the bolt and the connected member
All of the above