Engineering Technology

Engine Strip Down

What is the petrol four stroke engine?

A four-stroke engine, also known as four-cycle, is an internal combustion engine in which the piston completes four separate strokes—intake, compression, power, and exhaust—during two separate revolutions of the engine's crankshaft, and one single thermodynamic cycle. (From Google Engine)

Describe what you have done to date and mention the health and safety.

Note: Turn off the engine and keep it cold, and shut off the power. PPE equipments(overall and safety boot)  must be wear any time when working.

Work in date: 07/08/2012

Petrol four stroke engine all parts of name and photo

Take some parts off and describe what it is for

Cylinder block: 

Cylinder block is a rigid frame that holds the cylinders in proper alignment. If the engine is liquid cooled, the block is jacketed, so that it can be surrounded by the liquid, or has passages for the liquid around each cylinder. In automotive engines, the cylinder block and crankcase form a single unit. Most cylinder blocks are made of cast iron or aluminium.

Cylinders 

Cylinders are rigid tubes that serve as a bearing for the pistons that move up and down inside them. They have highly polished surfaces. This permits a close fit between piston and cylinder and prevents gases from leaking past the piston. The cylinders in most car engines are part of the block. Some engines have a cylinder sleeve made of specially hardened steel or cast iron pressed into the cylinder block.

Cylinder head:

Cylinder head is a casting bolted to the top of the cylinder block. The cylinder head, together with the upper end of the cylinder and the top of the piston, form the combustion chamber where the fuel-air mixture burns. A cylinder head and block may be one unit.

Piston and Connecting rods

There is a piston fitted in the cylinder. This piston is connected to a connecting rod which in turn is connected to the crank shaft. When the fuel-air mixture burns, the expanding gases exert a force on the piston. This force is then transmitted through a connecting rod to the crankshaft. The piston has two to six rings to prevent the gases from escaping and to keep lubricating oil from getting into the combustion chamber. 

Work in 08/08/2012

Take some parts off and describe what it is for

Crankcase

Crankcase is a rigid frame that holds the crankshaft and the crankshaft bearings. In small engines, all or part of the crankcase may be a part of the cylinder block.

Crank shaft

Crankshaft changes the reciprocating motion of the pistons into rotary motion. The crankshaft has a number of cranks, or throws. These cranks are displaced at angles to each other. For example, in a six-cylinder, in-line, four-stroke cycle engine, the cranks are displaced at 120° angles to each other. As a result, the engine delivers three equally spaced power strokes in each revolution of the crankshaft to assure smooth operation.

Flywheel

Flywheel stores energy during a piston's power stroke and releases it during other strokes. This helps to keep the crankshaft turning at a constant speed.

Valves

In a four-stroke cycle engine, each cylinder has one or two intake valves, to let the air-fuel mixture into the combustion chamber, and one or two exhaust valves, to let the burned gases escape. These are called poppet valves, because they pop up and down as they open and close. The opening in the cylinder block or head uncovered by the valve is called the port. In many two-stroke cycle engines, the movement of the piston takes the place of separate valves. As the piston moves, it covers and uncovers the ports.

Camshaft

Camshaft opens and closes the valves at the proper point in the engine cycle. It runs the length of the engine and has one cam (lobe) at each intake and exhaust valve. In a four-stroke cycle engine, the camshaft is geared to the crankshaft so that it runs at half the crankshaft's speed. The camshaft may be located in the head of an overhead valve engine, or in the crankcase.

Micrometer

METRIC MICROMETER READING EXERCISES

Jacking up a vehicle in the workshop

Tools List as below:

1. Trolley Jack

2. Axle stands

3. Wheel brace

4. Torque wrench

Jacking up a vehicle processing video from YouTube



Tips & Warnings

• Use a trolley jack designed to support the weight of your vehicle. Trolley jacks are not "one size fits all."
• Long-handled trolley jacks allow for more leverage and may be more effective when lifting vehicles that are lower to the ground, as a short handle will only allow for smaller strokes when lifting.
• Consult the owner's manual for your vehicle prior to using a trolley jack.
• Do not use the oil pan or areas of the car unsupported by the frame as a lift point when using a trolley jack.
• Do not work underneath a car supported by a trolley jack alone. Always use jack stands.

(From Google How to Lift a Car Using a Trolley Jack)