Firing Order The firing order is the sequence of power delivery of each cylinder in a multi- cylinder reciprocating engine. This is achieved by sparking of the spark plugs in a gasoline engine in the correct order, or by the sequence of fuel injection in a Diesel engine. When designing an engine, choosing an appropriate firing order is critical to minimizing vibration, to improve engine balance and achieving smooth running, for long engine fatigue life and user comfort, and heavily influences crankshaft design. A camshaft is a shaft to which a cam is fastened or of which a cam forms an integral part. This allows the camshaft to be in direct contact with the valve, thus aiding in the efficiency and overall power output of the engine itself and eliminating the need for push rods. Objectives: To find the arrangement and firing order of a camshaft Materials: Camshaft, measuring device Experimental work: Hold and center the camshaft by using the tailstock Rotate the carriage hand wheel until the plunger touch the cam Rotate the shaft until the contact touch the highest point Take the reading Go for the next cam and take the reading (angle) of highest point and so on Reading: cam no. 1 2 3 4 5 6 7 8 Angle (degree) 220 330 245 125 307 60 150 37
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Firing Order
The firing order is the sequence of power delivery of each cylinder in a multi-cylinder reciprocating engine.
This is achieved by sparking of the spark plugs in a gasoline engine in the correct order, or by the sequence of fuel injection in a Diesel engine. When designing an engine, choosing an appropriate firing order is critical to minimizing vibration, to improve engine balance and achieving smooth running, for long engine fatigue life and user comfort, and heavily influences crankshaft design.
A camshaft is a shaft to which a cam is fastened or of which a cam forms an integral part. This allows the camshaft to be in direct contact with the valve, thus aiding in the efficiency and overall power output of the engine itself and eliminating the need for push rods.
Objectives: To find the arrangement and firing order of a camshaft
Hold and center the camshaft by using the tailstock
Rotate the carriage hand wheel until the plunger touch the cam
Rotate the shaft until the contact touch the highest point
Take the reading
Go for the next cam and take the reading (angle) of highest point and so on
Reading:
cam no. 1 2 3 4 5 6 7 8
Angle (degree) 220 330 245 125 307 60 150 37
Apparatus:
Firing order:
8, 6, 4, 7, 1, 3, 5, 2
cam 8
cam 6
cam 4
cam 7
cam 1
cam 3
cam 5
cam 2
Cam Profile
A cam is a rotating or sliding piece in a mechanical linkage used especially in
transforming rotary motion into linear motion or vice-versa.
The cam can be seen as a device that rotates from circular to reciprocating (or sometimes oscillating) motion. A common example is the camshaft of an automobile, which takes the rotary motion of the engine and translates it into the reciprocating motion necessary to operate the intake and exhaust valves of the cylinders.
Cam profile terms
RAMPS: The parts of a camshaft lobe that actually initiate the lifting and descending movement of the lifter are called "ramps". Ramps include the lash ramp, the opening ramp, and the closing ramp. Camshaft lobe ramps are ground to have different rates of lifter movement in terms of velocity and degrees of duration, as measured in degrees of crankshaft rotation. The "lash ramp" of a camshaft lobe is a mid-point location between the opening ramp and closing ramp. The "opening ramp" of a camshaft lobe is the point where the lifter just begins to lift until the point that it reaches the nose of the lobe. The "closing ramp" is the point of the camshaft lobe from the nose back down to the lash ramp. NOSE The "nose" of a camshaft lobe is the top or the highest maximum lift point for the valve. It is where valves are kept open for as long as possible before making the transition to the closing ramp. BASE CIRCLE The "base circle", also known as the "heel", is the lowest point of the camshaft lobe and is the place where the valve is in the closed position. The "base circle" is the point where all valve lash settings are made.
Objectives: Drawing and identifying the cam profile terms
Materials: Camshaft, measuring device
Experimental work:
Hold and center the camshaft by using the tailstock
Rotate the carriage hand wheel until the plunger touch the cam
Error of circularity (out of roundness) is the radial distance between the minimum circumscribing circle and the maximum inscribing circle which contain the profile of the surface
Objectives: To find the get the maximum out of roundness of a shaft