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## Engine Speed Governors | Speed Control Governor | Speed Limiters

Proell governor
Watt governor
ii) Spring controlled type Hartnell governor
Hartung governor
2. Inertia and fly-wheel governor 3. Pickering Governor Purpose of governor: 1. To automatically maintain the uniform speed of the engine within the specified limits, whenever there is a variation of the load. 2. To regulate the fuel supply to the engine as per load requirements. 3. To regulate the mean speed of the engines. 4. It works intermittently i.e., only there’s modification within the load 5. Mathematically, it can express as ΔN. Terminology used in the governor: 1. Height of the governor (h): Height of the governor is defined as the vertical distance between the centre of the governor ball and the point of the intersection between the upper arm on the axis of the spindle. The height of the governor is denoted by ‘h’. 2. Radius of rotation ®: Radius of rotation is defined as the centre of the governor balls and the axis of rotation in the spindle. The radius of rotation is denoted by ‘r’. 3. Sleeve lift (X): The sleeve lift of the governor is defined as the vertical distance travelled by the sleeve on spindle due to change in equilibrium in speed. The sleeve lift of the governor is denoted by ‘X’. 4. Equilibrium speed: The equilibrium speed means, the sped at which the governor balls, arms, sleeve, etc, are in complete equilibrium and there is no upward or downward movement of the sleeve on the spindle, is called as equilibrium speed. 5. Mean Equilibrium speed: The mean equilibrium speed is defined as the speed at the mean position of the balls or the sleeve is called as mean equilibrium speed. 6. Maximum speed: The Maximum speed is nothing but the speeds at the maximum radius of rotation of the balls without tending to move either way is called as maximum speed. 7. Minimum speed: The Minimum speed is nothing but the speeds at the minimum radius of rotation of the balls without tending to move either way is called as minimum speed. 8. Governor effort: The mean force working on the sleeve for a given change of speed is termed as the governor effort. 9. Power of the governor: The power of the governor is state that the product of mean effort and lift of the sleeve is called as power of the governor. 10. Controlling force: The controlling force is nothing but an equal and opposite force to the centrifugal force, acting radially (i.e., centripetal force) is termed as controlling force of a governor. In other words, the force acting radially upon the rotating balls to counteract its centrifugal force is called the controlling force.

## India is building world's highest railway bridge.

India is building world's highest railway bridge. Indian engineers are toiling in the Himalayas to build the world's highest railway bridge which is expected to be 35 metres taller than the Eiffel Tower when completed by 2016. The arch-shaped steel structure is being constructed over the Chenab River to link sections of the spectacular mountainous region of India's northern Jammu and Kashmir state. The bridge is expected to be 359 metres (1,177 feet) high when completed -- surpassing the world's current tallest railway bridge over the Beipanjiang River in China's Guizhou province, which stands at 275 metres high. "It is an engineering marvel. We hope to get this bridge ready by December 2016," a senior Indian Railways official told AFP. "The design would ensure that it withstands seismic activities and high wind speeds," he said Wednesday. Work on the bridge started in 2002 but safety and feasibility concerns, including the area's strong winds, saw the project halted in 2008 before being green-lighted again two years later. The estimated cost of the project, which is being handled by Konkan Railway Corporation, a subsidiary of state-owned Indian Railways, is \$92 million. The bridge will connect Baramulla to Jammu in the Himalayan state with a travel time of six-and-a-half hours, almost half the time it currently takes. The main arch is being erected using two cable cranes attached on either side of the river which are secured on enormous steel pylons, according to engineers of the project. The 1,315-metre long bridge will use up to 25,000 tonnes of steel with some material being transported by helicopters due to the tough terrain, they said. "One of the biggest challenges involved was constructing the bridge without obstructing the flow of the river," the railways official said. "Approach roads had to be constructed to reach the foundations of the bridge," he added. Source: Zee News

## HOW DO SUPERCHARGERS WORK?

Superchargers are automotive performance products that may be factory-installed or added as an aftermarket upgrade. The job of a supercharger is to increase engine power and performance by a process known as forced-air induction. This simply means increasing the amount of air flowing into an engine's combustion chambers via the intake manifold. This increase in the amount of air allows for a relative increase in fuel that may be added to the combustion mixture, translating into a bigger bang that produces more horsepower. How A Supercharger Does Its Job A basic, four-stroke internal combustion engine completes four processes per cycle, the first being the intake stroke. During this stroke, air and fuel are drawn into the combustion chamber, where the mixture is then compressed and ignited by the spark plug. The correct ratio of air-to-fuel for optimum efficiency is 14:1. The size of the explosion during the combustion stroke is what determines engine horsepower. One way that engine horsepower can be slightly increased is by enlarging cylinder size, thereby increasing the capacity of the combustion chamber, allowing for a larger volume of air and fuel (still in the 14:1 ratio) to be ignited. To get a greater increase in horsepower without reverting to cylinder boring, one can simply add a supercharger. Normally, air drawn into the combustion chamber is at atmospheric pressure, which, at sea level, is 14.7 psi. A supercharger compresses this air, typically to between six and nine more psi, before sending it to the intake manifold. With this 50 percent increase in pressure, 50 percent more air can be introduced into the combustion chamber, requiring a 50 percent increase in fuel, keeping the 14:1 air/fuel ratio in tact. With more fuel being combusted, more horsepower is produced. Types of Superchargers There are two basic types of , distinguished by the method each employs to compress air.
Positive Displacement – delivers a near constant level of pressure and air volume at any speed. First designed and patented in 1860 by the Roots brothers, Philander and Francis, of Connersville, Indiana, their "air mover" was first used in blast furnaces and mine shafts. The first supercharged production cars, using the Roots supercharger, were two 1921 Mercedes, models 6/25/40 and 10/40/65. These cars were designated "Kompressor" models, a designation that still lives on today to signify Mercedes-Benz automobiles with factory-installed superchargers. Other types of positive displacement superchargers include the twin-screw type and the sliding vane type.

Dynamic compressors – deliver increased air pressure as engine speed increases. More efficient than positive displacement models, they accelerate incoming air to high speed then diffuse that speed to produce high pressure. Examples of this type are centrifugal, pressure wave and axial flow. Centrifugal are the most common and most efficient of air-induction systems. These performance products are fairly easy to install and several manufacturers offer bolt-on kits that allow car owners to supercharge their rides quickly and easily. Some manufacturers of these performance products include: Keene Bell, Vortech, Saleen, ProCharger, MagnaCharger and Whipple.
Efficiency Equals Economy It might seem that adding a supercharger to a vehicle would decrease its fuel efficiency, since more air requires more fuel to burn. In regular engines, however, some of the fuel remains unburned and ends up wasted, going out in the exhaust. Additional air supplied through a supercharger system makes for more complete combustion, which is more efficient. In addition, smaller, lighter engines can be used to generate greater power. This produces a lighter-weight vehicle, which will bolster efficiency. Putting the pedal to the metal, however, will quickly negate any fuel savings that might have otherwise been gained.