The condition that causes vapour locking in a brake system is
Overheating of the fluid due to frequent brake application
Overcooling of the brakes during high speed driving
Keeping the vehicle without use for an extended period
An excessively high engine speed on a downhill road
Correct Answer :
A. Overheating of the fluid due to frequent brake application
Related Questions
What type of bearing is used for main bearings and connecting rod bearings?
Ball bearings
Plain bearings
Needle roller bearing
Taper roller bearing
The main function of a master cylinder is to
Adjust the extent of brake pedal free play
Boost the force applied to brake pedal
Convert brake pedal force into hydraulic pressure
Ensure that all the wheel brakes are supplied with the same amount of fluid pressure
In a forced feed lubrication system, the device used to guard against excessive oil pressure, is known as
Release chamber
Balancer
Relief valve
Stop valve
The function of an oil control orifice is that it
Returns cylinder head lubricating oil to the oil pan at high speed
Turns oil into fine mist for spray lubrication
Regulates the pressure of engine oil supplied by the oil pump for the lubrication of cylinder head mechanism and other purposes
Removes impurities from cylinder head lubricating oil
The basic characteristics of a brake fluid is
A high boiling point
Low viscosity
Compatibility with rubber and metal parts
All of these
The indicated power of a four stroke engine (in watts) is equal to (where P = Mean effective pressure in N/m², L = Length of stroke in metres, A = Cross-sectional area of the piston in m², and N = Speed of the engine in revolutions per second (r.p.s)
P.L.A.N/2
P.L.A.N
2 × P.L.A.N
P.L.A.N/4
The main cause for the change in engine oil viscosity is
Humidity
Temperature
Vibration
Contamination
An overinflated tyre will wear the tread most near the
Edges
Corners
Centre
None of these
A front stabilizer bar is used to
Increase vehicle load carrying capacity
Provide a softer ride
Control suspension movement and body roll
All of the above
The acid used in automobile battery is
Hydrochloric acid
Hydrofluoric acid
Nitric acid
Sulphuric acid
The heat transfer from coolant to air in the radiator of an automobile engine takes place by
Radiation only
Convention only
Convection and radiation
Conduction, convection and radiation
Which part of the automobile tyre is subjected to greatest flexing action?
Bead
Side wall
Shoulder
Tread
The diagram which shows the correct crank positions corresponding to the opening and closing of the valves, is known as
Indicator diagram
Axial force diagram
Valve timing diagram
None of these
The power source for a brake booster is
Exhaust manifold pressure
Electricity
The pressure difference between the atmospheric pressure and the vacuum pressure in the intake manifold
Hydraulic pump
With the increase of battery temperature, the specific gravity of electrolyte
Increases
Decreases
Remains the same
None of these
Instead of valves, the ports are used in case of
Four stroke I.C. engines
Two stroke I.C. engines
V6 engines
None of these
The purpose of a balancer shaft is to
Balance the timing in the movement of the two groups of pistons
Increase inertia force of the rotating crankshaft
Reduce vibrations caused by the crankshaft rotation
Adjusts the timing of the intake and exhaust valve openings
The most commonly used supplementary restraint system (SRS) component is
Seat belt
Brake
Airbag
Steering
In a four wheel drive (4WD), the numbers of gear boxes are
1
2
3
4
Damper is also known as
Shock absorber
Torsion bar
Spring
Radius rod
The main function of an exhaust muffler is the
Optimisation of exhaust efficiency
Reduction of exhaust noise
Reduction of nitrogen oxide in the exhaust gases
Reduction of the exhaust gas volume
How many cells are used in a 12 volt car battery?
2
4
6
8
When a gear box has four forward speeds and one reverse speed, it is said to be a
3-speed gear box
4-speed gear box
5-speed gear box
6-speed gear box
The aspect ratio (expressed in percentage) of the tyre is defined as the ratio of
Section width to section height
Section height to section width
Wheel diameter to section height
Wheel diameter to section width
For the same maximum pressure and temperature
Diesel cycle is more efficient than Otto cycle
Otto cycle is more efficient than Diesel cycle
Both Otto cycle and Diesel cycle are equally efficient
None of the above
The compression ratio in petrol engine is kept less than in Diesel engine because
It makes petrol engines lighter
Higher or equivalent compression ratio in petrol engines is not possible due to pre-ignition
Less compression ratio gives better performance
It is just customary to have less compression ratio in petrol engines
The valve overlap in four stroke petrol engines is approximately
30°
60°
90°
120°
The camshaft of a four stroke Diesel engine running at 1000 rpm will run at
500 rpm
1000 rpm
2000 rpm
4000 rpm
Valve overlap is the number of degrees of camshaft rotation during which
Both valves are closed
Both valves are open
Both 'A' and 'B'
None of these
The mechanical efficiency (ηm) of an I.C. engine is equal to (where I.P. = Indicated power, B.P. = Brake power and F.P. = Frictional power)
I.P/B.P.
B.P/I.P.
B.P/F.P.
F.P/B.P.