Questions and Answers Section 10

Questions and Answers

Question :

91.The diagram which shows the correct crank positions corresponding to the opening and closing of the valves, that is known as

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valve timing diagram

Note:-In a piston engine, the valve timing is the precise timing of the opening and closing of the valves. In an internal combustion engine those are usually poppet valves and in a steam engine they are usually slide valves or piston valves.

Question :

92.The difference between DOT 3 and DOT 4 brake fluids is 

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DOT 4 fluid has a higher boiling point than DOT 3 fluid

Note:-higher grade fluid. Dot 4 and 5.1 also have borate ester to handle higher temperatures. DOT 3, 4, and 5.1 fluids are found in most brake and clutch systems.

Question :

93.The operation of removing trapped air from the hydraulic braking system is known as

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bleeding

Note:-Air-bleed is nothing but the escape of air from a closed system.

Question :

94.The aluminum alloy is used in cylinder blocks because

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it is lighter and have good heat dissipation characteristics

Note:-The typical alloying elements are copper, magnesium, manganese, silicon, tin and zinc.

Question :

95.The tilting of the front wheels away from the vertical, when viewed from the front of the car, that is called

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camber

Note:-Camber angle is the angle made by the wheels of a vehicle; specifically, it is the angle between the vertical axis of the wheels used for steering and the vertical axis of the vehicle when viewed from the front or rear.

Question :

96.The most commonly used supplementary restraint system (SRS) component is

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airbag

note:-Working as a supplemental restraint system to the vehicle's seat-belt systems, airbag module deployments are triggered through a pyrotechnic process that is designed to be used once. Newer side-impact airbag modules consist of compressed air cylinders that are triggered in the event of a side on vehicle impact.

Question :

97.The natural gas is compressed in a CNG cylinder at a pressure of 

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200 bar

Question :

98.The cetane rating of Diesel fuel is in the order of

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45

Note:-Cetane number (or CN) is an inverse function of a fuel's ignition delay, and the time period between the start of injection and the first identifiable pressure increase during combustion of the fuel. In a particular diesel engine, higher cetane fuels will have shorter ignition delay periods than lower Cetane fuels.

Question :

99.The air gap between the central electrode and ground (or side) electrode of a spark plug is around

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1 mm

Question :

100.The cetane number of a Diesel fuel is a measure of

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delay period.

Note:-The ignition delay in a diesel engine is defined as the time interval between the start of injection and the start of combustion. This delay period consists of (a) physical delay, wherein atomisation, vaporization and mixing of air fuel occur and (b) of chemical delay attributed to pre-combustion reactions.