Engine Parts Flashcards
intake valve
only on a 4-stroke engine. valves are poppet shaped with beveled edges and seats for self centering action. made of low alloy Steel because not subjected to corrosive action of hot exhaust gas
camshaft
a shaft with eccentric projections, called cams. They are designed to control the operation of valves.
provide proper firing order of cylinders. Shape determines the point of opening and closing, the speed of opening and closing, and the amount of valve lift. Driven by crankshaft.
the most common method is by gears or buy a chain and sprocket. Camshaft for 4-stroke engine is 1/2 speed. two stroke engine is same speed.
location varies
exhaust valve
on both two-stroke and four-stroke engines. Made of steel alloy to resist corrosion caused by high temperature gases. a hard alloy welded to seating surface increases wearing qualities of the exhaust valve surfaces
rocker arm
part of valve actuated mechanism. Pivot on a pivot pin or shaft secured to a bracket mounted on the cylinder head. One end contacts top of valve stem and other is actuated by the camshaft.
if camshaft is near cylinder head, the rocker arm may be actuated from the cam by hardened steel rollers.
if camshaft is below cylinder head the rocker arm is actuated by pushrods.
1 rocker arm and a bridge may be used in some installations to open two valves simultaneously
push rod
a rod that pushes rocker arm to actuate valves when a camshaft is located below the cylinder head
cam follower
changes the rotary motion of the camshaft to reciprocating motion. This action opens the valves
can followers ride the flat of the cam and are raised as the cam rotates by the high side of the cam and lowered by tension from the valve
lash adjuster
also called a hydraulic valve lifter, they are used to avoid the necessity of a clearance otherwise needed in the valve gear to allow for expansion resulting from temperature changes.
they also eliminate the need for manual adjustment to take care of the we’re at various points of the valve gear. They may be on the rocker arm, valve Bridge, or Cam follower
Cylinder Block
The part of the engine frame which supports the engine’s cylinder liners and heads.
Crankcase
The part of the engine frame which houses the crankshaft
Bedplate
The bedplate supports the engine and ensures alignment of the shaft. In large engines the crankcase and bedplate come in one piece.
sump
a reservoir at the bottom of the engine, like an oil pan
entablature
the cylinder block which incorporates the scavenge air space and the cooling water spaces. It forms the housing required to fit the cylinder liners.
Tie rods
long strong rods that hold the three
major engine components (cylinder block or entablature, “A” frame, and crankcase) in compression and transmit the firing load to the bedplate.
end plate
add rigidity to the engine block and provide a surface to which housings may be bolted to for gears, blowers, pumps, filters, etc.
Access Openings and Covers
Permit access to internal parts and spaces within the engine for inspection and maintenance.
