The condition that causes vapour locking in a brake system is
A. overheating of the fluid due to frequent brake application
B. overcooling of the brakes during high speed driving
C. keeping the vehicle without use for an extended period
D. an excessively high engine speed on a downhill road
Answer A
Pre-ignition is caused by the spontantaneous combustion of the mixture before the end of the compression stroke, and is due to
A. Cylinder walls being too hot
B. overheated spark plug points
C. red hot carbon deposits on cylinder walls
D. any one of these
Answer D
The brake power of a diesel engine, keeping other parameters constant, can be increased by
A. decreasing the density of intake air
B. increasing the temperature of intake air
C. increasing the pressure of intake air
D. decreasing the pressure of intake air
Answer C
The exhaust valve in a four stroke cycle petrol engine
A. opens at 50° before bottom dead centre and closes at 15° after top dead centre
B. opens at bottom dead centre and closes at top dead centre
C. opens at 50° after bottom dead centre and closes at 15° before top dead centre
D. may open and close anywhere
The ratio of the volume of charge admitted at N.T.P. to the swept volume of the piston is called
A. mechanical efficiency
B. overall efficiency
C. volumetric efficiency
D. relative efficiency
