Engineering Studies
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Personal and Public Transport
This unit addresses aspects of the following syllabus outcomes:
Outcomes:
H1.2 differentiates between properties of materials and justifies the selection of materials, components and processing in engineering.
H3.1 demonstrates proficiency in the use of mathematical, scientific and graphical methods to analyse and solve problems of engineering practice.
H3.3 develops and uses specialised techniques in the application of graphics as a communication tool.
H5.1 works individually and in teams to solve specific engineering problems and in the preparation of engineering reports.
Source: Board of Studies (1999) Stage 6 engineering studies syllabus preliminary and HSC courses. Sydney: Board of Studies
Background
Many forms of transport are controlled by and interact with various control systems or control mechanisms. These controls may be mechanical, electrical, chemical or human. This section identifies some of the components that may be used, their operation and application. The interaction of physical quantities to digital control is considered. The calculation of electrical quantities, such as resistance, questions on materials and a CAD drawing iare also included.
Activity 1
Typical control systems are made up of sensors, actuators and a processing system.
Describe a sensor and two actuators that could be part of a control system at automatic railway crossing gates.
Activity 2
The doors of this monorail close with precision and accuracy.
Describe a control mechanism that could be used to operate the doors safely.
Activity 3
Many of the control systems in a family car are controlled by a microprocessor using digital data.
Clarify the relationship between a microprocessor and digital data.
Activity 4
A car's central locking system is activated by a solenoid.
With the aid of a sketch describe the operation of a solenoid.
Activity 5
Name a suitable sensor and a possible application in a transport vehicle for the devices used to measure the following quantities.
| Quantity | Sensor | Application |
|---|---|---|
| Temperature | Thermistor | |
| Pressure | ||
| Rotation | ABS  system in a vehicle |
|
| Motion | Air
Bag system in motor vehicles |
|
| Flow | ||
| Change in temperature |
Printable version of this form.
Activity 6
State some advantages and disadvantages of the following types of sensors.
| Sensor | Advantage | Disadvantage |
|---|---|---|
| Thermostat | ||
| Manometer | ||
| Photoelectric cell | ||
| Wheel rotation | ||
| Pitot tube |
Printable version of a form to help with this activity.
Activity 7
What control system could be used in these examples of public transport?
Activity 8
A small part of a control circuit is shown below; calculate the total resistance of the arrangement.
All resistor values A-D are rated at 10 ohms.
Printable version of this circuit.
Activity 9
In another part of the circuit the LED shown is only to draw 200mA.
Calculate the value of the resistor R1.
Printable version of this circuit.
Activity 10
An exploded pictorial drawing of a bicycle brake mounting assembly is shown below. The shape and size of its components are given.
Printable version of the above image
Use a CAD program you are familiar with to complete the following:
Draw a front view of the assembled components when viewed from the direction of the arrow. The assembled components are to be fixed in position through the centre of the brake caliper arm.
The collar and brake caliper arm are to be fully sectioned. The special bolt, washer and nut should not be sectioned.
Do not show the brake block holder or brake block. Do not show any hidden detail.
Activity 11
Define the term CAD.
List four advantages of a CAD
system when compared to manual drawing methods. You may gain some clues
by viewing a typical CAD drawing at Robo
Systems
Activity 12
Suggest a number of reasons why a sketch is a valuable communication tool for an engineer.
Make a neat freehand sketch of a solenoid actuator suitable for the application described in question 4.
Activity 13
What do you consider the frame of the scooter to be made from?
Activity 14
Give three reasons why you consider the material in your previous answer to be the best material for this application.
Activity 15
Give one disadvantage of your suggested material for this application.
Activity 16
What properties do you consider essential for the material from which the tyre is made?
Activity 17
The bicycle brake system is operated by a flexible steel cable acting on two levers.
Which order of levers is this?
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