Transcript Document
LESSON EIGHT
VALVE OPERATING GEAR
1. DEFINITION
A mechanism for actuating & controlling the inlet & exhaust valves . It may also open & close starting valves & fuel pumps .
1. DEFINITION
A mechanism for actuating & controlling the inlet also open & close starting valves & fuel pumps .
& exhaust valves . It may
2. OPERATION OF VALVES*
Mechanical ( valve operating gear )
1. DEFINITION
A mechanism for actuating & controlling the inlet also open & close starting valves & fuel pumps .
& exhaust valves . It may
2. OPERATION OF VALVES*
Mechanical ( valve operating gear ) Hydraulic . There are neither pushrods nor rocker arms but a piston pump . The oil pressure is led by means of a high pressure pipe to a working cylinder & hydraulic piston placed on top of the exhaust valve cage.
1. DEFINITION
A mechanism for actuating & controlling the inlet also open & close starting valves & fuel pumps .
& exhaust valves . It may
2. OPERATION OF VALVES*
Mechanical ( valve operating gear ) Hydraulic . There are neither pushrods nor rocker arms but a piston pump . The oil pressure is led by means of a high pressure pipe to a working cylinder & hydraulic piston placed on top of the exhaust valve cage.
3. CAMSHAFT
3.1 CONSTRUCTION* Integral camshaft is made in a single piece of forged steel; Separate cams of forged steel or cast iron are:
1. DEFINITION
A mechanism for actuating & controlling the inlet also open & close starting valves & fuel pumps .
& exhaust valves . It may
2. OPERATION OF VALVES*
Mechanical ( valve operating gear ) Hydraulic . There are neither pushrods nor rocker arms but a piston pump . The oil pressure is led by means of a high pressure pipe to a working cylinder & hydraulic piston placed on top of the exhaust valve cage.
3. CAMSHAFT
3.1 CONSTRUCTION* Integral camshaft is made in a single piece of forged steel; Separate cams of forged steel or cast iron are:
keyed on the shaft;
hyraulicaly shrunk on or press fitted ;
fitted to the shaft by SKF oil injection pressure method .
3.2 CAM DESIGN
3.2 CAM DESIGN 3.3 CAMSHAFT ROTATION 4-stroke = ½ speed of the crankshaft 2-stroke = same speed as the crankshaft 3.4 CAMSHAFT DRIVE
Train of gears
Chain drive
3.2 CAM DESIGN 3.3 CAMSHAFT ROTATION 4-stroke = ½ speed of the crankshaft 2-stroke = same speed as the crankshaft 3.4 CAMSHAFT DRIVE
Train of gears
Chain drive 3.5 REVERSING The camshaft slides axially ( in 4-stroke engines ) thus bringing a different set of cams for reverse direction .