PRESSURE LUBRICATION SYSTEM IN ENGINES :

In this system, lubricating oil id forced under pressure by a pump at a pressure of 2 to 4 MPa. It consists of oil sump, oil pump, oil gallery , pressure release valve, oil filter, oil pressure gauge and oil dipstick. The lubricating oil from the sump or oil pan is sucked by the oil pump and lifted to oil main gallery through oil filter and strainer. The oil pump is driven by camshaft. Oil pump and filter are always immersed in the oil.

From the oil gallery, the oil is distributed under pressure to various parts of the engine to be lubricated by the oil tubes. Oil from gallery enters the crank pin bearing through a taper hole in the crank shaft. A through hole is provided at the center of the connecting rod. Separate oil tubes carry oil for lubricating timing gears, rocker arm assembly, cam shaft etc. Another oil line is connected to the pressure gauge to show the pressure of the oil.

The excess supplied oil drips back into the oil sump. A pressure relief valve is provided to avoid any damage in case of excess oil pressure. An oil dipstick is provided to measure the oil level in sump.

Advantages :

* All the parts of the engine are efficiently lubricated.

* The minute gap between the sliding surfaces can be lubricated since the oil is supplied under pressure.

Engine parts lubricated under pressure : Crank Shaft main Bearings, cam shaft main bearings, big end bearings of the connecting rod, timing gears , chain and sprocket, rocker arm , springs , valve stems, valve guides etc.

Comments

ELECTRICAL COMPARATORS AND ITS WORKING

Electrical Comparators are used as a means of detecting and amplifying small movements of a work contacting elements. An electrical comparator consists essentially of a pick-up head or transducer for converting a displacement into a corresponding change in current and a meter or recorder connected in the circuit to indicate the electrical change, calibrated to show in terms of displacement. Generally, an amplifier is needed to provide the requisite sensitivity and to match the characteristics of different parts of the circuit. Electrical comparators can be classified according to the electrical principle used in the pick-up head. Most of the comparators use either a differential transformer, an inductance bridge, a strain gauge or a capacitor as a means of detecting movement of the gauging element. There are different types of electrical comparators. One kind called an electrolimit gauge is used to check or measure the outside diameter of a roll. The object to be checked is place

THROTTLE GOVERNING OF STEAM TURBINES

Steam Pressure at inlet to a steam turbine is reduced by throttling process to maintain the speed of the turbine constant at part load and hence this method of governing is called "Throttle Governing". Construction : Throttle governing system consists of a centrifugal governor, a lever , an oil pump , a pilot piston , control valve , a relay piston and a throttle valve. The throttle valve is moved by a relay piston. The relay piston is actuated by pilot piston control valve. There are two piston valves covering ports in the pilot piston control valve without any overlap. These piston valves are operated by lubricating oil supplied by a gear pump at 2 to 4 bar. The oil returns to the drain from this chamber. Working : When the turbine works on full rated load, the throttle valve will remain open. When the load is decreased, the energy output of the turbine becomes in excess and the turbine shaft speed increases. Hence, governor sleeve will lift. The upward movement of the

Advantages And Disadvantages Of Air Refrigeration System :

Advantages Of Air Refrigeration : 1. The refrigerant used namely air is cheap and easily available. 2. There is no danger of fire or toxic effects due to leakages. 3. The weight to ton of refrigeration ratio is less as compared to other systems. Disadvantages Of Air Refrigeration : 1. The quantity of Refrigerant used per ton of refrigeration is high as compared to other systems. 2. The COP of the system is very low. Therefore running cost is high. 3. The danger of frosting at the expander valves is more as the air contains moisture content.

Mechinopedia For Mechanical Engineers

Search This Blog