Basic systems & diesel engines

Question 1

Describe Open & Close loop systems

(Mechanical systems)

Answer 1

• Open Loop working fluid is consumed
• Closed Loop working fluid is reused

Question 2

Name 3 types of tanks & their uses

Answer 2

• Header tank- resevoir to top up system
• Service tank-water free supply of fuel
• Drain tank-collect oil returning from a system

Question 3

Name 3 tank gauges & their uses

Answer 3

• Contents gauge-indicates how much liquid remains in tank
• Sounding tube-Measure depth
• Gauge glass-visual indication of how much liquid in tank

Question 4

Manometer

Answer 4

Gives a visual indication of pressure or vacuum

Question 5

Tachometer

Answer 5

A device that measure speed of a substance or moving body

Question 6

Rod gearing

Answer 6

Allows a valve to be closed manually from a remote location

Question 7

Uses for Diesel engines

Answer 7

• Generators
• Main engines & motor boats
• Air compressers
• Fire pumps

Question 8

Cylinder block

Answer 8

The structure that holds all other engine components

Question 9

Cylinder head

Answer 9

• Closes the top of the cylinders
• Has the intake & exhaust ports & valves

Question 10

Cylinder head joint

Answer 10

A water,oil,gas & air tight seal between cylinder block & head

Question 11

Sump

Answer 11

Resevoir at the bottom of engine to collect oil

Question 12

Piston

Answer 12

• Moves up & down in the cylinder
• Enables compression

Question 13

Piston rings

Answer 13

• Provides a seal between piston & cylinder
• Prevent fuel from leaking into sump
• Prevents oil from the sump leaking into cylinder
• Transfer heat from piston to cylinder

Question 14

Connecting Rod

Answer 14

• Connects piston to crankshaft
• Bearing around gudgeon pin is small end
• Bearing around crankshaft is big end

Question 15

Gudgeon pin

Answer 15

Connects piston to con rod through small end bearing

Question 16

Crankshaft

Answer 16

• Changes reciprocating motion from pistons to rotary motion

Question 17

Flywheel

Answer 17

• Used for smooth running during non power strokes
• Stores energy & returns it to piston

Question 18

Camshaft

Answer 18

• Controls opening & closing of valves
• Driven at half speed of the crankshaft

Question 19

Pushrod & cam follower

Answer 19

Transfers motion from camshaft to the rocker arm

Question 20

Rocker arm

Answer 20

Transfers motion from pushrod to activate valves

Question 21

Diesel engine fresh water cooling system

Answer 21

• Cools cylinder block & cylinder head
• Closed loop system
• AL39 mixed with water 50:50
• Contains corrosion inhibitor & antifreeze

Question 22

Engine block water passages

Answer 22

• Allow water to circulate thorugh engine for removal of heat
• Known as ‘Water jacket’

Question 23

Diesel engines Salt water cooling circuit

Answer 23

• Open loop system
• Fitted to cool the fresh water & lub oil as they pass through the heat exchangers

Question 24

What is Valve overlap?

Answer 24

• When the intake and exhaust valves are open at the same time
• Occurs towards the end of the exhaust stroke
• Provides more time for air to enter cylinder

Question 25

Why is valve overlap needed?

Answer 25

Because as the speed of the engine increases there is less time spent on the induction stroke,so the intake valve opens sooner

Question 26

Why does Camshaft run at halfspeed of Crankshaft?

Answer 26

In a four-stroke engine, the piston travels up and down the cylinder twice during each complete engine cycle, which corresponds to two full turns of the crankshaft. During that time, we only want the intake and exhaust valves to open and close once, so we only want the camshaft to turn once during the same cycle.