Midterm Flashcards
horsepower
the common unit of power; i.e., the rate at which work is done. one horsepower equals 33,000
foot-pounds of work per minute
HP = (Force x Velocity) divided by 33,000 ft-lbs/min
Brake Horsepower (BHP)
the maximum power generated by an engine at a given RPM as determined by the engine manufacturer.
Shaft Horsepower (SHP)
the power delivered along the shaft to the propeller at a given RPM.
Effective Horse Power (EHP)
the power required to overcome a vessel’s total resistance at a given speed, not including the power required to turn the propeller or operate any machinery (this is close to the power required to tow a vessel).
potential energy
stored energy, ie a spring
kinetic energy
energy in motion
internal energy
stored within a body, ie compressed gas
chemical energy
released from chemical reaction, often producing hear
diesel engine theory of operation
reciprocating, compression ignition engines in which the fuel is ignited upon injection by the hot, compressed charged air in the cylinder.
types of roller bearings
straight, tapered, spherical, needle, ball
basic bearing construction
balls or cylinders confined between outer and inner rings (called races). The balls or rollers are usually spaced uniformly by a cage or separator.
bearing uses on diesel engines
Bearings are used to help reduce friction.
4-Stroke Diesel Engine Lube Oil System
Lube oil is pumped into the main bearings, preventing contact between the steel shaft and the white metal bearings.
2-Stroke Diesel Engine Lube Oil System
The oil is being supplied through swivel jointed pipes inside the engine casing, to the crossheads, and guides, piston cooling and bottom end bearings, the oil pressure being increased by a booster pump.
lube oil properties
viscosity, volatility, alkalinity, detergents, oiliness, pour point
grease properties
pump-ability, dropping point, penetration number, operating temperature, water resistance, shear stability
governers
maintains a reasonable constant engine speed, regardless of load, by limiting the fuel delivered to the cylinders.
common rail fuel injection system
a high pressure pump discharges fuel into a common rail, which each fuel injector is connected to by tubing
unit type fuel injection system
pump and fuel spray nozzle are combined into one unit. usually installed in the cylinder head
individual pump (jerk) fuel injection system
high pressure pumps and pressure operated nozzles are separate units
direct fuel injection
fuel is injected into the combustion chamber
indirect fuel injection
fuel is injected into the pre-combustion chamber
