Cables Cables

The selection of cable and type of The selection of cable and type of insulation required for motor vehicle insulation required for motor vehicle

use depends on two main factorsuse depends on two main factors

These are;These are;

1 The amount of voltage to be carried 1 The amount of voltage to be carried

2 The amount of current to be carried2 The amount of current to be carried

Cables are often bunched together Cables are often bunched together In a harness or loom. This In a harness or loom. This

simplifies fitting and ensures less simplifies fitting and ensures less chance of breakage or short chance of breakage or short

circuits. Each cable within the circuits. Each cable within the harness is colour coded. harness is colour coded.

What is the reason for colour What is the reason for colour coding?coding?

To identify the cables as they enter and To identify the cables as they enter and leave the loomleave the loom

The main feed cable to a specific The main feed cable to a specific switch may have a single colour switch may have a single colour and past the switch the lead has and past the switch the lead has

the same colour but with a different the same colour but with a different colour trace line going through it.colour trace line going through it.

Typical main colours for circuits Typical main colours for circuits are;are;

Ignition…GreenIgnition…Green

Headlamp…WhiteHeadlamp…White

Sidelamp…GreySidelamp…Grey

Flasher…BlueFlasher…Blue

The amount of current a cable can The amount of current a cable can pass is determined by its size. How pass is determined by its size. How

are these classified?are these classified?

By the number of strands and their By the number of strands and their individual thicknessindividual thickness

What does a cable having a size of What does a cable having a size of 28/0.30 indicate?28/0.30 indicate?

28 strands each of 0.30 mm thickness 28 strands each of 0.30 mm thickness

What is the recognised safe current What is the recognised safe current capacity for each strand of cable capacity for each strand of cable

0.30mm thick?0.30mm thick?

0.5 amps0.5 amps

Examine cables of various Examine cables of various thicknesses obtained from or still thicknesses obtained from or still

held in a wiring harness.held in a wiring harness.

From what material are the wires From what material are the wires made?made?

Copper Copper

To crank the engine with sufficient speed To crank the engine with sufficient speed for it to start, by converting electrical for it to start, by converting electrical energy into mechanical energy energy into mechanical energy

Starter motorStarter motor

starter motors fitted to cars are starter motors fitted to cars are usually one of the two types usually one of the two types

shown. What is the purpose of shown. What is the purpose of the starter motor and what type the starter motor and what type

of energy occurs?of energy occurs?

Examine starter motors of the two Examine starter motors of the two types shown and identify the types shown and identify the

arrowed partsarrowed parts

Inertia Pre-engagedInertia Pre-engaged

Examine the mechanical operation Examine the mechanical operation of type (ll) which is also shown of type (ll) which is also shown

oppositeoppositeSolenoid on actuating Solenoid on actuating lever to force pinion lever to force pinion drive into mesh with drive into mesh with flywheel, while the flywheel, while the starter begins to starter begins to rotate slowly. When rotate slowly. When fully meshed main fully meshed main contacts close and contacts close and the starter motor the starter motor works on full power.works on full power.

The clutch in the starter motorThe clutch in the starter motor

Re-capRe-cap

We have looked at cables and how they We have looked at cables and how they are made upare made up

We have seen how cables are classifiedWe have seen how cables are classified

We stated that the capacity for each We stated that the capacity for each strand of cable 0.30mm thick is 0.5 amps strand of cable 0.30mm thick is 0.5 amps

We have labeled the two main types of We have labeled the two main types of starter motor starter motor