cameroon gce A level chassis systems and transmission 2

cameroon gce A level chassis systems and transmission 2

cameroon gce A level chassis systems and transmission 2

ANSWER ONLY THREE (03) QUESTIONS FROM THIS SECTION

QUESTION 1.   STEERING SYSTEM

The steering mechanism has two main purposes. It must enable the driver to:

• easily maintain the straight-ahead direction of the vehicle even when bumps are encountered at high speeds;
• change the direction of the vehicle with the minimum amount of effort at the steering wheel.

To ensure easy, as well as safe handling, the front wheels of a car must be properly aligned. There are several angles that must be considered. These angles include: Camber, Caster, Toe in, Toe out etc.

1. What is Ackermann principle as applied to steering?                  (3marks)
2. Draw a simple diagram of the steering layout to conform to the Ackermann principle. Show the position of the front and rear wheels, point of turn and approximate angles of the outer and inner front wheels. Use “A” and “B” to represent the angles of the outer and inner front wheels respectively.                  (4marks)
3. With the aid of a simple diagram explain what is Camber, Castor and Toe-in.                  (6marks)
4. Of what particular use is toe-in?                   (2marks)
5. State TWO checks to be done before carrying out vehicle wheel alignment test.                    (2marks)
6. Give one effect in the steering system if the scrub radius is 0.                                                  (1.5mark)
7. What name is given to this type of steering with a scrub radius of 0?                         (1.5mark)

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QUESTION 2.   AUTOMOBILE AC SYSTEM (HEATING AND VENTILATION)

Heating and ventilation system in collaboration with the air condition system help in maintaining a comfortable

interior temperature of the vehicle. As trained technicians, proper understanding on the construction and operation of these systems is important so as to successfully carry out diagnostics and repair on this system.

`Figure 1of the Appendix I illustrates the diagram of a heating and ventilation system.

1. Name the following parts; 1,2 and 3 respectively.                                (1.5mark)
2. Give the functions of parts 1,2 and 3 respectively.  (1.5mark)
3. Describe the operation of the heating and ventilation system illustrated in figure 1 of Appendix I. On the diagram, use a blue pen to indicate the flow of air when the system is set to the hot position and a pencil to indicate when the system is set to cold.                                                                          (2marks)
4. Explain how a defective cooling system thermostat can result to the lack of heat produced by the heater in the heating and ventilation system. (1mark)
5. Figure 2 of Appendix I illustrates the layout of an air conditioning system. Use a table to answer the following questions.                                                                                                 (3marks)
6. Give the names of the numbered parts 1,2,3,4, and 5.
7. What are the functions of parts numbered 1,2,3,4 and 5.
8. During the operation of the air conditioning system, refrigerant in the circuit undergoes different phase changes (states). These different states include; high pressure vapour, high pressure liquid,

low pressure vapour and low pressure liquid/Vapour. Use the letters A, B, C and D to identify each change of state as shown on the diagram in Appendix I.                                                                                                              (2marks)

1. Describe the operation of the typical automotive air-conditioning system.                               (2marks)State the role of the electromagnetic clutch used on the air condition compressor                           (1mark)
2. Some air conditioning systems are designed to prevent the compressor from being engaged when the level of refrigerant in the system is low. Explain how this is achieved. (1mark)
3. List four sensors used by the climate control system (automatic temperature control system) to accurately maintain or regulate the interior temperature of the vehicle.                               (2marks)
4. Analyse and give the possible causes of faults associated with the heating, ventilation and air conditioning system.                (3marks)

NB: one cause each.

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QUESTION3.             SUSPENSION SYSTEM

1. State two functions of the suspension system.   (1.5mark)
2. Regardless the type of suspension system, components of the suspension system can be grouped into three main groups i.e. suspension springs, dampers and suspension linkages. (6marks)

Give the function of the following parts;

1. Suspension Springs
2. Dampers

• Suspension Linkages

2. Name FIVE different types of used on vertical suspension system.   (2.5marks)

For each of the suspension spring given above state one main advantage                                (5marks)

1. Calculate the deflection of a front suspension coil spring with a spring constant of 10000N/m if it is loaded with a compressive force of 6000N.                                 (2marks)