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PVOC Grade 2 > Engineering > Flashcards

Engineering Flashcards

1
Q

What is a seacock?

A

water inlet for the water pump

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2
Q

Purpose of oil sump

A

collect and cool oil collect collect and cool oil

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3
Q

Crankcase

A

House for the crankshaft

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4
Q

Cooling circuit

A

Green Square - Water, Red Circle - Oil

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5
Q

Signs of burnt head gasket

A

Running engine to hot, Oil stains, bubbling cooling water tank, EMULSION (higher reading on dipstick due to water in oil sump)

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6
Q

Torque Wrench

A

Tighten screws/nuts with equal force ACCORDING TO SPECIFICATION OF THE ENGINE

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7
Q

Blue Smoke

A

Oil entering compression chamber

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8
Q

White Smoke

A

Water entering compression chamber

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9
Q

List Items connected to Cam Shaft

1.

2.

3.

4.

5.

A
  1. Cam Shaft
  2. Cam
  3. Push rod
  4. Valve Spring - (USED TO CLOSE THE VALVE)
  5. Rocker Arm
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10
Q

Timing Gears & chain?

Ratio Crankshaft : Camshaft in a 4 stroke engine

A

Used to transfer rotation of crankshaft to camshaft which moves push rods and rocker arms to OPEN the valves

SPRING - Closes the valves

2:1

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11
Q

Where is the Tappet valve (Cam follower) located

A

Between the cam and the push rod

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12
Q

What does rocker arm do?

What does valve spring do?

A

Rocker Arm - Opens the Valve

Spring - Closes the valve

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13
Q

Valve clearance

A

Located between rocker arm and valve STEM which ensures VALVE CLOSES FULLY AFTER ENGINE WARMS UP

0.025 inches in the normal clearance OR REFER TO ENGINE MANUAL

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14
Q

Which valve normally has a larger diameter

A

INTAKE

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15
Q

What happens if the valve clearance is to small after the engine warms up?

A

Valve wont close properly leading to engine COMPRESSION LOSS

Engine wont run smoothly

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16
Q

What happens if the valve clearance is to BIG after the engine warms up?

A

Valve become NOISY - TAPPING SOUND

Engine wont run smoothly

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17
Q

What does Feeler gauge tool do?

A

Hand tool for adjusting valve clearance

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18
Q

Gudgeon Pin?

A

Connects piston to the con rod

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19
Q

Big end bearing?

Small end bearing?

A

Con rods join the crankshaft

Gugdgeon pin joins the con rod

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20
Q

Main Bearing?

Symtoms of warn out bearing?

A

Supports crankshaft on the engine block

knocking noise and low engine oil pressure in a running engine

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21
Q

Engine speed?

A

Number of rotations equivalent to the rotation of the crankshaft

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22
Q

Flywheel

A

Stores engery during expansion and releases it during the other 3 three strokes to make the engine run SMOOTHLY

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23
Q

Stroke

A

Distance travelled between TDC and BDC

1 stroke - Camshaft turns 180 degrees (4 stroke engine 720 degrees)

2:1 ratio

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24
Q

Power stroke Piston movement

A

CLOSE TO TDC, spark which ignites fue/air

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25
Q

4 stroke engine 1000rpm - calculation of power strokes?

A

1000/2 = 500 power strokes X no. of cyliners =

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26
Q

Valve timing - Overlap

A

Both valves open together in order to clear the exhaust gases completely from the cyliner

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27
Q

Lead (Advance) - Valve

Lag (Retard) - Valve

A

Valve opens before TDC or BDC

Valve opens after TDC or BDC

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28
Q

Firing order of Pistons

A

1,3,4,2

Induction

Compression

Expansion

Exhuast

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29
Q

What is timing light gun used for

A

Checking ignition timing

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30
Q

Petrol engine compression ratio?

Diesel engine compression ratio?

Calculate the above?

A

10: 1
20: 1

Piston working volume (X) + Clearance Volume (Y) = Clearnance Volume (Y)

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31
Q

Red diesel fuel

A

Dye fuel - cheaper due to lower tax, intended for industrial use

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32
Q

Density/Flashpoint Petrol?

Density/flashpoint Diesel?

A

-44 degrees / 0.73g

+65 degrees / 0.84g

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33
Q

Safety when refueling

A

Close all windows and doors

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34
Q

Diesel fuel in petrol Engine?

Petrol in Diesel Engine?

A

PRETOL ENGINE WILL STOP AFTER STARTING

OVERSPEED DIESEL ENGINE

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35
Q

What operates the fuel pump?

A

Camshaft

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36
Q

STEPS before reufing boat

1.

2.

3.

4.

5.

A
  1. TIED
  2. Passengers ashore
  3. CLOSE windows/doors
  4. GROUND fuel nozzle
  5. READY FOAM extinguisher
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37
Q

3 purposes of Air filter

A
  1. Clean
  2. Silencer
  3. Flame trap
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38
Q

Needle Valve

A

Float chamber of the Carb, cuts off fuel supply

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39
Q

Pilot Jets

A

Main Jet - Fast Speed

Slow Jet - Idle speed

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40
Q

Mixture control screw

A

operate 1/4 of the throttle for 10 minuts to warm up the engine

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41
Q

Mixture in the carb

Normal operation?

Flooded?

Petrol/Air?

A

50: 50
80: 20
60: 40

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42
Q

Causes of Engine flooding

A

Needle valve not closing

Can’t start engine because mixture is to rich

temp fix - turn off fuel from tank and crank the cylinders dry

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43
Q

Choke plate closed

A

Richens mixture for cold starting

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44
Q
A
  1. Choke
  2. Main Jet
  3. Throttle Valve
  4. Slow speed Jet
  5. Float
  6. Needle Valve

B - Fastmmoving air

A/C - Slow moving Air

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45
Q

LEAN MIXTURE symtoms/causes

A

Leaking intake manifold, wrong adjustment

WHITE spark plug

pre ignition

cyliner knocking

engine vibration and lack of power

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46
Q

RICH MIXTURE symtoms/causes

A

Wong adjustment,dirty air filter, fuel flooding engine, OVERLOADING engine

Black emmisions

Black colour spark plug tip

Engine stop after warm up

Carbon buit up in the exhaust manifold

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47
Q

Igntion - Lobbed cam?

A

Operates contact breaker (open/close)

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48
Q

Distribuor /cam shaft ratio

4 stroke -

2 stroke -

A

4 stroke - 1 : 0.5 (half speed)

2 stroke - 1 : 1

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49
Q

Induction Coil?

A

Primary and secondary windings - 12v to 20 000v

High voltage jumps the gap on the spark plug to which makes a spark

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50
Q

Contact Breaker

A

Connected to primary windings, when it opens high voltage is produced in the secondary windings

CLEARANCE CONTACT BREAKER - 0.25mm - 0.50mm (10-20/1000 inches)

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51
Q

Purpose of the condensor?

A

Connecting to the contact beaker to prevent sparks from jumping across the contact breaker, thus protecting CONTACT POINT

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52
Q

Distributor shaft speed?

A

Driven by the Camshaft at HALF the engine speed

enables firing order 1,3,4,2

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53
Q
A

A,B,C,D,F - HIGH Voltage

I,E,H,H - Low voltage

  1. Lobed Cam
  2. Battery
  3. Rotor Arm
  4. Contact breaker
  5. Condenser
  6. Induction coil
54
Q

Spark plug gap clearance

A

0.63 - 1.26mm (25-50/1000 inches)

55
Q

Sprak plug gap to large

A

Use FEELER GAUGE to adjsut earth electrode

56
Q

Spark plug colours

Grey

White

Balck

Oily

A
  1. Engine running normally
  2. Mixture to lean
  3. Mixture to rich
  4. Engine needs to be overhauled
57
Q

HOT ENGINE (9000rpm) - What type of plug?

COLD ENGINE (4000 rpm) - What type of Plug?

A

OPPOSITE!!

HOT - Cold plug (Shorter)

COLD - Hot plug (Longer)

58
Q

What Spare should be kept on the boat?

A

SPARK PLUGs

59
Q

Oil pump speed

A

Half the speed on a 4 stroke engine

60
Q

When do you check oil levels?

A

Engine is cold - Always topup oil with the same oil type

61
Q

Sea water cooling (Direct cooling system)

A

Wet exhaust (with rubber tubing)

IMPRELLER (plastic pump)

62
Q

Fresh water cooling system( Indirect cooling system)

A

Heat exchanger (sea water cools fresh water which is circulated)

CENTRIFUGAL PUMP (metal)

63
Q

Direct Cooling

A

Sea water, less efficient due to salt

Thermostat enabes engine to warm up quickly

Thermostat stuck open - engine will take longer to warm up

Stuck closed - Engine will overheat

64
Q

Indirect cooling

A

Sea water through heat exchanger

BRONZA seacock - must be turned on before starting and turned off after shutdown

More efficient and less corrosion in the engine, coolant is deeivered more evenly inside the circuit

Fresh water pump driven by the engine V-belt

65
Q

Common causes of engine overheating

A

Sea cock blocked up

heat exchanger dirty or cooling ccircuit blocked

water pump (impellor or V-blet broken)

Stuck thermostat

running engine slowly for to long

66
Q

What do you do if your engine overheats?

A

DO NOT SWTICH IT OFF - Run it at idle

67
Q

Swan neck pipe?

A

loop pipe to ensure seawater does not travel up the exhaust and into the engine

68
Q

Advantages/Disadvantages of wet exhaust pipe (Rubber)

A

Rubber hose

lowers engine noise, exhaust pipe temp, lower risk of fire.

Corrosion, cooling water leaking into bilge causing low water pressure in the system, water entering engine cylinders damaging them

69
Q

12v battery formed?

A

6 units of 2volt celss are connected in series to form 12v

70
Q

Specific Gravity of batterys

Discharged?

Half charged?

Fully charged?

A
  1. 12
  2. 2
  3. 28
71
Q

Alternator…..

A

Use same rating fuse for replacement or install a circuit breaker for the electrical system

Output unit of a generator is measured in KW

When battery is low, running generaotr will power the ignition and electrical system

72
Q

what do you do if a generator overspeeds?

A

Turn it off!!

73
Q

First thing you do when connecting to shore power?

A

Turn off the main switch and the power supply of the boat!

74
Q

Earth lamp (ground lamp)

A

Lights equal color - circut is healthly

Logihts not equal colour - problem with insulation or circuit grounded and should be check or rectified

75
Q

Starter - What happens when battery power is turned on?

A

Solenoid connection Pinion (small wheel) to the flywheel teath - Starter motor driver flywheel and crankshaft

76
Q

What wiring should you connect to the starter?

A

Short thick wiring for maximum current

77
Q

Purpose of gearbox?

A

Reduce prop shaft speed increasing thrust (torque)

78
Q

How is gearbox cooled?

A

By WATER to maintain proper viscosity

79
Q

Thrust Bearing?

A

Withstand the axial movement of the propeller shaft

80
Q

Coupling?

A

System connector, alignment adjuster, shock absorber for the prop shaft

81
Q

Sterntube?

A

Located under the engine and goes through the bottom of the hull, holds prop shaft which rotates inside it adn prevents the engine room from flooding

82
Q

Gland???

A

Loosen when the boat is running, tighen when the boat is not in use

83
Q

Zinc??

A

Saccrificial zinc is fitted underwater as to protect the submerged metals from galvanic corrosion

84
Q

what type of prop gives higher top end speed/Low speed?

A

Large pitch with bigger blade - Fast (speed boat)

Small pitch prop with smaller blade - Slow (junk boat)

85
Q

What if engine speed is unchanged but vessel speed reduces?

Floating rope ahead of the vessel in the water?

A

prop may be fouled by obstruction

Reduce engine speed to neutral

86
Q

Difference between Diesel and petrol ignition?

A

Petrol - Spark Plug

Diesel - High temp air

87
Q

Rubber Hose Diesel engine?

A

Low pressure fuel back to the tank

88
Q

What increases diesel fuel pressure?

A

Injector pump (1000 psi)

89
Q

When will Diesel engine stop?

A

Air is present in the fuel system - You have to bleed the system

90
Q

Diesel engine - plunger is down/up?

A

Diesel flows from the inlet port - DOWN

No fuel flows - UP

91
Q

How to control throttle diesel engine?

A

HELICAL EDGE plunger adjsuts the timing of the connection between the spill port and helical egdge. This controls teh quantity of diesel fuel delivered to tthe fuel injector, thus controlling engine speed

92
Q

What does the spring on diesel engine do?

A

When diesel pressure is greater than pre set spring pressure, needle valve opens and diesel fuel sprays through tiny holes at the nozzle to the cylinder

93
Q

Special features in DIESEL engine only?

1.

2.

3.

A
  1. Governor - reduces fuel supply if engine overspeeds
  2. Decompressor - easy cranking and starting (manual valve opener/manual vacuum releaser)

DO NOT USE IT FOR ENGINE STOPPING or fuel may leak into the exhuast pipe and cause fire

  1. Low voltage glow plug - device to preheat air, located at the top of the combustion chamber or intake manifold
94
Q

turbocharger - Damaged intercooler (heat exchanger)

A

Casue engine lack power, surge, KNOCKING NOISE and cylinder temp to overheat

95
Q

Signs of a mulfucntioning turbocharger

A

KNOCKING NOISE with BLUE EXHAUST smoke, lack of engine power

96
Q

Bypass valve do on hydraulic steering?

A

prevents hoses from bursting

97
Q

What if the rudder angle gauge is out?

A

Check rudder stock and bearing should be checked adn rectified

98
Q

Defintion of confined space?

What to do before entering confiend space?

A

Only one entrance and exit - only certified persons may be allowed to work inside

  1. Suggicient lighting
  2. Good ventilation
  3. No existance of pousonous or flammable gases

Watcher to be at the entrance of a confined space

99
Q

What does the reed valve do in a 2 stroke piston engine?

A

Air-Fuel mixture is transferred into the crankcase through the REED valve

100
Q

Transfer Port 2 stroke engine?

A

Compressed air/fuel mixture in the crankcase is transferred under pressure to the cylinder through the TRANSFER PORT as the piston moves down

101
Q

2 stroke power calculation?

A

2:1

1000rpm/2 = 500

102
Q

2 stroke Diesel crankshaft : Camshaft ratio?

A

1 : 1

103
Q

What does Blower do?

A

Air compressed in cylinder bny the blower on 2 stroke diesel engine

104
Q

What is scavenging on 2 stroke diesel engine?

A

Exhaust gases are futher forced out when the piston is at BDC by fresh compressed air from the blower

105
Q

revolutions on a 100 000 HP diesel 2 stroke engine?

A

50 - 100 rpm - SLOW REVOLUTION ENGINE

106
Q

Outboard engine - Ignition?

A

Magneto under the flywheel, replaces the battery

107
Q

Mixture ratio of 2 stroke oil fuel?

A

50 :1

108
Q

Outboard engine - Cooling?

A

Direct cooling by seawater, discharged through prop hub abd exhaust

STEADY STREAM of discharging water as an indicator for the proper function of the cooling system

109
Q

Outboard engine - Transmission system?

A

Bevel gears and a dog clutch. transmission oil should be filled in from the OIL HOLES at the gearbox casing which is located in the leg of an outboard motor

110
Q

Shear Pin/Rubber Bellow?

A

Metal pin installed on the prop hub to prop shaft and will break on impact, protects the engine, RUBBER BELLOW serves the same purpose on big horse outboard engines

111
Q

How to place an outboard engine to avoid fuel spillage from the carb?

A

PISTONS HIGHER than prop // CARB FACING UPWARDS

112
Q

Procedure to start outboard engine

A
  1. lower leg of the engine and TIGHTEN
  2. Pump fuel to carb
  3. Shift gears to neutral
  4. Open the choke
  5. Open 1/4 of the throttle
  6. Pull manual rope starter
  7. Check cooling indicator
113
Q

position of outboard engine underway?

A

leg of the outboard should be at right angles to water surface, prop shaft PARALLEL/180 degrees

114
Q

Stem out engine overheating ***

A
  1. Move out of channel
  2. Reduce to idle speed, DONT STOP ENGINE
115
Q

Does a 2 stroke or 4 stroke engine have a gas tight crankcase?

A

2 stroke engine only!!!!

116
Q

Distance between pump and sea level for manual bilge pump?

A

7m (due to atmospjeric pressure limitation)

117
Q

What vessels should be fitted with an oily water seperator int he bilge pump system?

A

Vessel gross weight over 400 tonnes

118
Q

Where should you store LPG gas cylinders on board?

A

Full or empty, kept in a lockable compartment having gas tight boundries with the hull

119
Q

What material should a long length gas tube be made of?

A

Metal, only ends should be rubber

120
Q

In case LPG gas escapes?

A

Vigorous flapping of blanket, large towel or canvas will assist in diffusing gas in air via opened windows and doors, soapy water can be used to locate a gas leak

121
Q

How often does LPG gas cyclinder require to be pressure tested?

A

5 years

122
Q

check co2 fire extinguishe for leak?

A

weight, looses more than 10% replace it

123
Q

What fire extinguisher is hazardeous to humans in a confined space?

A

CO2 and HALON

124
Q

what happens in LPG leak is drawn into running cylinders?

A

SPEED UP engine

125
Q

How do fires spread?

A

Conduction, convection, radiation

126
Q

what information does the exhuast temp reading provide you?

A

Engine loading

127
Q

volt meter range?

A

12.5v - 15v

128
Q

Causes of excessive engine vibration

A

Sterntube bearing/prop shaft bearing worn out, valve vlearance needed to be adjsuted or transmission system problem

129
Q

Manual Bilge Pump - Distance between pump and sea level?

A

Limited to 7m due to atmospheric pressure

130
Q

Manual Bilge Pump - Made of what?

A

SOLID and RIGID material

131
Q

4 types manual bilge pumps

A

Diapham - HIGHER DISCHARGE CAPACITY, DOES NOT CLOG

Piston Pump - LOWER DISCHRGE CAPACITY, CLOGS

Semi Rotarty Pump - PRIMING REQUIRED

Piston Pump (to and For type)

PVOC Grade 2 (6 decks)

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