Questions set 73

Lubrication Systems

1.      Which type of lubrication system is used in two-stroke engine?
a) Mist lubrication system
b) Wet sump lubrication system
c) Dry sump lubrication system
d) Splash lubrication system
Answer: a
Explanation: The mist lubrication system is used where crankcase lubrication is not suitable. In a two-stroke engine, as the charge is compressed in the crankcase, it is not possible to have the lubricating oil in the sump.

2.      In most automobiles, which lubrication system is commonly used?
a) Splash system
b) Pressure system
c) Petrol system
d) Gravity system
Answer: b
Explanation: Pressure type lubrication is used commonly in most automobiles. In this system, oil is drawn in from the sump and forced to all the main bearings of the crankshaft through distributing channels.

3.      The pressure inside the lubrication system is controlled by ______
a) Oil pump
b) Oil filter
c) Relief valve
d) Supply voltage
Answer: c
Explanation: The pressure inside the lubrication system is controlled by a relief valve. In the dry-sump lubrication system, if the filter is clogged, the pressure relief valve opens permitting oil to bypass the filter and reaches the supply tank.

4.      What is the need for crankcase ventilation?
a) To cool cylinder
b) To cool crankcase
c) To cool piston
d) To remove blow-by
Answer: d
Explanation: The gas inside the cylinder gets past the piston rings and then it enters the crankcase. It contains water and sulphuric acid (H₂SO₄).

5.      Why are the detergents used as oil additives?
a) To increase fire point
b) To prevent foaming
c) To prevent sludge formation
d) To reduce viscosity
Answer: c
Explanation: The detergents are added to the oil as additives to increase the detergency. Detergency means property of an oil to clean the engine deposits.

6.      Which of the following is the most important property of the lubricant?
a) Density
b) Thermal conductivity
c) Viscosity
d) Melting point
Answer: c
Explanation: Viscosity is the most important property of the lubricant. The viscosity of the oil at a given temperature and pressure must be compatible to ensure the hydrodynamic lubrication.

7.      Which of the following viscosity indices shows the larger changes in viscosity with temperature?
a) 50
b) 100
c) 45
d) 10
Answer: d
Explanation: The high viscosity index number indicates relatively a smaller change in viscosity with temperature. A low viscosity number for given oil indicates a relatively large change of viscosity.

8.      Which of the following of oils is multi-grade oil?
a) SAE 10W 30
b) SAE 25W
c) SAE 10
d) SAE 20W
Answer: a
Explanation: The SAE designation for multi-grade oils includes two viscosity. The first number indicates the relative flowability and the second number indicates the resistances to film break down.

9.      Which of the following oils has the highest viscosity?
a) SAE 20
b) SAE 10
c) SAE 50
d) SAE 45
Answer: c
Explanation: Higher the SAE grade, higher the viscosity. Since SAE 50 has 50 grade hence it as highest viscosity amongst the other oils. SAE 50 is single non -winter-grade oil as there is no ‘W’ in the designation.

10.  The vegetable oils are used as lubricants in the automobiles.
a) True
b) False
Answer: b
Explanation: The mineral oils are used as lubricants in the automobiles. The mineral oils are having properties such as to reduce the friction and wear between two metal contact and moving parts, to provide the sealing the action.