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electrical and steering > electrical circuits part A > Flashcards

electrical circuits part A Flashcards

1
Q

equipment lighting is used to provide

A

vision during night operation. machine operator safety . operator convenience . unit appearance

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2
Q

battery group disconnect switch

A

will prevent accidental slow discharge of battery group when unit is in park and not operating . can be connected in series with negative or positive battery leads

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3
Q

circuit protection devices

A

fuses and breaker panels . prevent machines electrical components from being destroyed by large current flows

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4
Q

main circuit protection device

A

usually 60 to 80 amps . protect entire machines electrical circuits . connected in series to machine fuse breaker box

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5
Q

type 1 circuit breaker

A

used when electrical current flow needs to be restored quickly . circuit opens and closes when a bimetal strip heats up and cools down . headlight circuits would use this type

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6
Q

type 2 circuit breaker

A

come equipped with a heat -producing resistor . this resistor holds the circuit breaker in the off ( open) position while the breaker rating is exceeded . used in non critical circuits like interior cab lighting

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7
Q

type 3 circuit breaker

A

have a manual reset button . can be used in non critical circuits that can remain non energized until the circuit is manually reset . used in equipment mounted signage

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8
Q

how do you properly size a circuit protection device

A

P = I x E or watts = amps x volts

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9
Q

high beam head lamps produce what for wattage

A

high wattage usually 80 watts

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10
Q

low beam lights produce what for wattage

A

low wattage usually 60 watts

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11
Q

flood / working lamps are connected where in the electrical circuit

A

connected into the key switch controlled circuits

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12
Q

why do you want flood / working lamps to be connected into the key switch control circuit

A

so you wont drain your battery when the unit is shut off

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13
Q

tail lamps are used for

A

used to outline a machines perimeter in poor visibility conditions . always red in color

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14
Q

clearance lamps are used for what

A

used to indicate the outer sides of a unit . usually amber in color

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15
Q

panel lighting

A

assists the operator in viewing the panel gauges . controlled by the master switch . able to alter the intensity of the light with the use of a lamp dimming solid state module

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16
Q

another way to dim panel lights other than a solid state module is by using a

A

series connected rheostat

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17
Q

why is it important to mount a rheostat away from flammable material

A

because the heat developed from the rheostat may start a fire

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18
Q

what is pulse width modulation

A

a digital signal that turns the circuit voltage on and off

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19
Q

what is duty cycle

A

the period of time a pulse width modulating signal is on compared to off

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20
Q

fiber optic cable is made out of what

A

plastic core surrounded by a polymer optical cladding sheath

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21
Q

when fiber optical cables fail what is the most likely source of the problem

A

the light source has malfunctioned

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22
Q

if the fiber optic cable is damaged you must

A

replace the cable . it cannot be repaired

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23
Q

when retrofitting break lights to LED you must also change

A

electromechanical flasher must be changed to a solid state electronic flasher

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24
Q

if you are going to use a electromechanical flasher with LED lights you must

A

install a series connected resistor

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25
Q

what are warning beacons

A

safety devices mounted at the highest point of the unit

26
Q

when warning beacons fail they must be replaced as

A

a unit

27
Q

what circuit is the warning beacon connected into

A

the key switch control . beacon will operate when the engine is operating

28
Q

if the ECU is the control device for back up warning lights the relay must be

A

grounded through the ECU

29
Q

what does it mean to have multiple switches control your cab lights

A

it means that any one switch can turn your lights on or off . ex both doors or switch on the dash

30
Q

what is the normal state of a door switch that controls the cab lights

A

normally closed

31
Q

LED lamps require approximately how much of the electrical current to that of a normal incandescent bulb

A

1/10

32
Q

what is the advantage of LED stop lights

A

to provides a quicker reaction time for drivers to respond

33
Q

DC motors use electricity and magnetism to produce

A

rotary mechanical motion

34
Q

what are the two types of DC motor configurations

A

permanent magnet . parallel wound

35
Q

what is the only factor that limits a PM motors armature speed

A

counter electromagnetic force ( CEMF )

36
Q

if an equipment demads a slower slower rotation that the rated speed of the PM motor can provide you must

A

install a gear box reduction to the motors armature

37
Q

the direction a PM motor turns depends on

A

the interaction between the magnetic lines of force around the field coils and the direction lines of force around the armature windings

38
Q

how can you protect the wiring harness if the engine is cranked with the battery disconnect in the open position in accessory that requires constant power memory

A

install positive and negative leads uses in both

39
Q

when testing electrical circuits you should always use

A

high impedance meter . ( 10m ohms )

40
Q

when replacing speakers you should always

A

match the replacement speaker two the output of the systems amplifier

41
Q

when cutting speaker wires with side cutters what may happen to the output amplifier

A

you may cause a short between the two lines through the side cutters

42
Q

what is one way to reduce static noise or interference

A

install a series coil ( filter choke ) or a parallel capacitor to the machines power lead or at the source

43
Q

when connecting intermediate grounds what should you make sure they are all connected to

A

the main ground ( cab must have a ground strap to the units main frame

44
Q

what is the park position on the widow wipers circuit

A

park contacts supply current to the motor after the wiper switch has been turned off . this allows the wipers to keep running until park position has been reached

45
Q

windshield wiper motors are

A

two speed DC motors

46
Q

are the internal components of windshield wiper and washer systems serviceable

A

no . they must be replaced

47
Q

what would use an armature connected to a diaphragm that causes a column of air to vibrate at a frequency

A

a horn

48
Q

in a relay what contacts are normally open

A

30 to 87

49
Q

in a relay what contacts are normally closed

A

30 to 87A

50
Q

in a relay what contacts carry large current

A

85 to 86

51
Q

what would happen to a warning light if the voltage on both sides of the light were the same

A

the light would be electrically balanced and not illuminate

52
Q

why do some manufactures install a resistor in parallel on a warning light

A

because if the bulb were to burn out and go open it would not shut down the entire circuit

53
Q

what is EEPROM

A

electronically erasable programable read only memory

54
Q

if a temp gauge uses a negative temperature coefficient thermistor . the resistance of the thermistor would read high when

A

the temp was cold . resistance lowers when temperature increases

55
Q

what are the two types of gauges that can be used to determine the condition of the equipments electrical condition

A

ammeter or voltmeter

56
Q

the intensity of the insterment panel lamps can be controlled by the use of

A

series connected rheostat or pulse width modulated signal

57
Q

the turn signal light circuit has a turn signal flasher connected in its circuit . how would the flasher be connected

A

series with the turn signal lamp connection

58
Q

what other electrical accessory can be controlled by the same switching system that controls the back up lamp circuit

A

the backup alarm

59
Q

equipment tracking systems are comprised of what two distinct components

A

GPS and digital satellite uplink

60
Q

anti theft systems can be classed as either

A

alarm or theft deterrent

electrical and steering (8 decks)

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