MECHANICAL TRANSMISSION SYSTEM (AIR FLOW, PNEUMATICS AND HYDRAULIC)

OBJECTIVES: At the end of this lesson, the student should be able to:
1. Define air flow
2. Identify at least 3 ways of generating air flow
3. Name two types of air flow
4. Define hydraulic
5. Identify four hydraulic devices
6. Define pneumatics
7. Identify four pneumatic devices.

Definition: Airflow can be defined as the continuous and steady movement of air in a particular direction or at random movement.

Generation of Air: Air can be generated in various ways. Some of these ways include:
i. Fan
ii. Mouth
iii. Air pump
iv. Bellow

Mechanical Properties Of Air

The mechanical properties of air are weight, atmospheric pressure and the relationship between pressure, temperature and speed.

Weight:  That air weighs something can be experimented with an empty balloon. If filled with air, the balloons original weight increases.
Again, since cold air has weight more than hot air, it is found useful in hot-air-balloon, in which the heavier air, which is below, pushes up the hot-air balloon.

Atmospheric Pressure: This is the same thing as air pressure. This pressure is defined as the force per unit area, written mathematically as P = F/A. e.g siphoning, etc.
This is found useful in vacuum cleaner, that sucks in dust particles on the rug and store in the dust bag.
The instrument used in measuring air pressure is called barometer.

Sound: Air produces sound as it passes through a narrow path, as it is found in trumpets and flutes.

Others: Other application of air-flow is in air crafts. The  high speed that discharges at the rear of the engine and thus pushes the aircraft forward.
Again, since air pressure decreases with increase in height, aircrafts are able to travel at a higher altitude.

Extremes of Air flow

There are two extremes of air flow, namely:

Laminar Air Flow: This is a steady flow of air . It is also called streamline flow.

Turbulent Flow: This is the unsteady speed flow of air. Sometimes it is a forced
air flow.  E.g.    

        

Pneumatics Devices

Pneumatics is a device that makes use of compressed air to do useful work. Such devices make use of cylinders to produce force or linear motion at changing speeds. Generally, both pneumatics and hydraulic devices are used for the following purposes.

·        For pushing

·        For pulling and

·        For lifting

Pneumatic devices include the following:

Hand Pump: These are of different types, they are used to inflate tyres, balloons, balls etc. the hand pump has a plunger which sucks in and pushes out air at the barrel cylinder.

Hand pump

Compressor Machine: This is used by vulcanizers, while the modified one is used as a spray machine on several products. E.g.

Compressor machine

Hydraulic Devices

Hydraulics are devices that make use of fluids orliquids to push, pull and lift materials in a machine. They include the following:

Hydraulic Jack: This jack has two main parts – the handle and the lever which is connected by two pistons which raises the lever that raises the load (car).

Suction And Double Acting Pumps: These are locally manually operated pumps used for lifting liquids and gases from reservoirs. e.g.

Double Acting pump

Garden Sprinkler: The sprinkler is used in water gardens. It has jets which issues out water at a given speed about an axis. e.g.

Water sprinklers.

Water Wheel: This wheel can be used to create mechanical energy in grinding, milling and electric power machines. E.g.

Water wheel

Others:  Other devices that make use of hydraulic system includes-(a) Reaction turbine (at dams) and (b) Brakes – used in cars to control motion, etc.

REVIEW QUESTIONS

1.     What is pneumatics?

2.     What is hydraulic?

3.     Name 2 devices that use pneumatics

4.     Name 4 devices that make use of hydraulic

5.     Using the sketches shown on your text book sketch the following

6.     Hand pump

7.     Suction and double acting pump

8.     Garden sprinkler

9.     Water wheel
      


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