Automobile Engine — Part 1 MCQs with Explanations

A diesel engine operates on the principle of compression ignition , where fuel is injected into highly compressed air inside the cylinder. In a diesel engine, combustion occurs gradually during the early part of the expansion stroke , and the volume change during combustion is relatively small. Because of this characteristic, a diesel engine is also referred to as a low volume combustion engine . A constant volume combustion engine is associated with petrol engines operating on the Otto cycle, not diesel engines. Hence, the correct answer is Option B – Low volume combustion engine .

In an automobile engine, the camshaft is responsible for controlling the opening and closing of the engine valves, which allows fuel-air mixture intake and exhaust gases to be expelled from the engine cylinders.

A cone clutch is a type of mechanical device used in automobiles to engage and disengage power transmission between the engine and transmission system. It consists of two conical surfaces, one attached to the driving shaft (input shaft) and the other to the driven shaft (output shaft). When these conical surfaces are pressed together, friction is generated, allowing torque to be transmitted between the shafts. Now, the disadvantage of the cone clutch, particularly when the cone angle is less than 20°, lies in the difficulty to disengage the clutch. The cone angle refers to the angle formed by the tapering surfaces of the clutch components. When this angle is too small, it reduces the effective diameter of the clutch, making it harder to separate the clutch plates. As a result, more force is required to disengage the clutch, leading to operational difficulties and potential damage to the clutch components over time. Other options are incorrect because: Option B: Being silent in operation is not a disadvantage but rather a desirable characteristic of a clutch system. Option C: The normal force on the contact surface being larger than the axial force is not a typical disadvantage of cone clutches. It's more of a design consideration that needs to be managed to ensure proper functionality. Option D: Transmitting the same torque for the same size as the plate clutch is not a disadvantage. In fact, it can be considered an advantage in terms of efficiency and space-saving design. In summary, the correct answer is Option A because a small cone angle can indeed make it difficult to disengage the clutch, which is a notable disadvantage of cone clutches.

The clutch facing is the friction material (like a special brake pad) on the clutch disc. It's designed to create friction to transmit power from the engine to the gearbox. When you push the clutch pedal, these facings disengage, and when you release it, they engage. Now, let's talk about the ' uniform wear theory '. When a clutch works over time, its friction material starts to wear out. There are different ways to model how this wear happens. The 'uniform wear theory' assumes that the amount of wear is the same everywhere across the clutch facing surface. This is a common and practical assumption, especially for older or worn clutches, because as wear occurs, the pressure distribution changes to keep wear uniform. We need to find the effective mean radius (Rm). This is like an "average" radius that engineers use in calculations to determine things like how much torque the clutch can handle under this uniform wear condition. Let's solve the problem step-by-step: 1. We are given the External diameter (Do) = 120 mm. To find the External radius (Ro) , we divide the diameter by 2: Ro = Do / 2 = 120 mm / 2 = 60 mm . 2. We are told the Inner diameter (Di) is 0.3 times the external diameter. Di = 0.3 * Do = 0.3 * 120 mm = 36 mm . To find the Inner radius (Ri) , we divide this diameter by 2: Ri = Di / 2 = 36 mm / 2 = 18 mm . 3. For uniform wear theory , the formula to calculate the effective mean radius (Rm) is very straightforward: Rm = (Ro + Ri) / 2 This formula effectively takes the average of the outer and inner radii. Now, let's put our calculated radii into the formula: Rm = (60 mm + 18 mm) / 2 Rm = 78 mm / 2 Rm = 39 mm So, the effective mean radius for this clutch facing, according to the uniform wear theory, is 39 mm . Comparing our result with the given options, Option B: 39 is the correct answer.

A torque converter or fluid converter in an automobile performs a function similar to that of a clutch . Both components are part of the transmission system, and they are responsible for transmitting power from the engine to the vehicle's wheels. However, they do so in different ways: Torque Converter (Option B): A torque converter is a type of fluid coupling device used in automatic transmissions. It transmits power from the engine to the transmission using a fluid-based mechanism. It allows for automatic gear shifting without the need for manual clutch operation. Clutch (Option B): A clutch is a mechanical device used in manual transmissions. It engages and disengages the engine from the transmission and wheels. When the driver presses the clutch pedal, it disengages the engine from the transmission, allowing the driver to shift gears manually. Gearbox (Option A): The gearbox, also known as a transmission, is a component that houses multiple gears. It allows the driver to select different gear ratios to control the speed and power of the vehicle. Shock Absorber (Option C): A shock absorber is a suspension component that helps dampen and control the movement of the vehicle's suspension. It is not directly involved in power transmission. Torsion Box (Option D): A torsion box is a type of vehicle chassis design that provides structural rigidity. It is not directly related to power transmission. In summary, the function of a torque converter or fluid converter in an automobile is most similar to that of a clutch , as both are involved in transmitting power from the engine to the vehicle's wheels.

Heat energy into mechanical energy is the correct answer to “Engine is a device, which converts”. This question is standard in competitive examination syllabi for Automobile Engine.

Air cooled is the correct answer to “Two-stroke engine is . . . . . . . . engine.”. This question is standard in competitive examination syllabi for Automobile Engine.

1 : 4 - 1 : 10 is the correct answer to “Engines are:”. This question is standard in competitive examination syllabi for Automobile Engine.

BDC to TDC is the correct answer to “In compression stroke piston move”. This question is standard in competitive examination syllabi for Automobile Engine.

25 mm is the correct answer to “Free pedal play in car clutches is about”. This question is standard in competitive examination syllabi for Automobile Engine.

Fuel injector is the correct answer to “The diesel engine, is identified by the presence of . . . . . . . .”. This question is standard in competitive examination syllabi for Automobile Engine.

Ignition warning bulb is the correct answer to “Which of the following bulb in a car will have the least watt”. This question is standard in competitive examination syllabi for Automobile Engine.

Steam separator is the correct answer to “Which of the following does not relate to steam engine”. This question is standard in competitive examination syllabi for Automobile Engine.

All are correct is the correct answer to “Which of the following system (circuits) is in the carburettor”. This question is standard in competitive examination syllabi for Automobile Engine.

Brake drum is the correct answer to “During braking, the brake shoe is moved outward to force the lining against the”. This question is standard in competitive examination syllabi for Automobile Engine.

Reduces noise is the correct answer to “The silencer of an IC engine”. This question is standard in competitive examination syllabi for Automobile Engine.

230 is the correct answer to “Power to weight ratio for high performance cars can range upto”. This question is standard in competitive examination syllabi for Automobile Engine.

2400 is the correct answer to “RPM of Perkins P6 is-”. This question is standard in competitive examination syllabi for Automobile Engine.

Absorbs vibration and impact forces from the road surface is the correct answer to “The basic function of the suspension is to”. This question is standard in competitive examination syllabi for Automobile Engine.

Both A and B is the correct answer to “Which of the following is the function of piston”. This question is standard in competitive examination syllabi for Automobile Engine.

Increased dwell is the correct answer to “The spark occurs when the”. This question is standard in competitive examination syllabi for Automobile Engine.

Toe is the correct answer to “Which of the following parameter can be adjusted by modifying the tie rod attachment length”. This question is standard in competitive examination syllabi for Automobile Engine.

Both are correct is the correct answer to “What is the cause of poor braking”. This question is standard in competitive examination syllabi for Automobile Engine.

Both are correct is the correct answer to “What is the function of brake lining”. This question is standard in competitive examination syllabi for Automobile Engine.

93 - 94 is the correct answer to “At present the average octane rating of regular grade gasoline is-”. This question is standard in competitive examination syllabi for Automobile Engine.

Flywheel is the correct answer to “When the clutch is engaged, spring pressure clamps the friction disc between the pressure plate and the”. This question is standard in competitive examination syllabi for Automobile Engine.

Facilitate moulding and curing of brake linings is the correct answer to “In the case of brake linings saturants and bonding materials are used to”. This question is standard in competitive examination syllabi for Automobile Engine.

Exactly four electrons in its outermost orbit is the correct answer to “A semi conductor is a material with”. This question is standard in competitive examination syllabi for Automobile Engine.

Both is the correct answer to “Which is one of the types of liners”. This question is standard in competitive examination syllabi for Automobile Engine.

0.4 is the correct answer to “Which of the following is the coefficient of friction of the clutch plate”. This question is standard in competitive examination syllabi for Automobile Engine.

80% is the correct answer to “The brake efficiency of a new vehicle is about”. This question is standard in competitive examination syllabi for Automobile Engine.

Differential case assembly is the correct answer to “If a noise is present in a differential only when the car moves past a curve, the chances are that the trouble is due to some fault in”. This question is standard in competitive examination syllabi for Automobile Engine.

6.5 : 1 is the correct answer to “Compression Ratio of Royal Enfield is-”. This question is standard in competitive examination syllabi for Automobile Engine.

$$N = {{R\,P\,M} \over 2}$$ is the correct answer to “In four stroke engine the number of revolutions is”. This question is standard in competitive examination syllabi for Automobile Engine.

Pascal's law is the correct answer to “The formula F/A = constant (A = Area, F = weight) is called-”. This question is standard in competitive examination syllabi for Automobile Engine.

Sulphuric acid is the correct answer to “The acid used in automobile battery is”. This question is standard in competitive examination syllabi for Automobile Engine.

Volumetric efficiency is the correct answer to “The ratio of the volume of charge admitted at N. T. P. to the swept volume of the piston is called”. This question is standard in competitive examination syllabi for Automobile Engine.

Petrol engines is the correct answer to “The quantity control method of governing is used in”. This question is standard in competitive examination syllabi for Automobile Engine.

Radius of brake drum is the correct answer to “Factor effecting retardation is-”. This question is standard in competitive examination syllabi for Automobile Engine.

Front end of the spring is shackled and rear end is pin jointed is the correct answer to “With a leaf spring type of suspension, interference between steering and suspension system can be reduced to minimum when”. This question is standard in competitive examination syllabi for Automobile Engine.