WEEK 2

BELT AND CHAIN DRIVE

Definition of Belt Drives: Belt drives are simple mechanical devices
used for transmitting motion from one pulley to the other. Belt drives are an
arrangement of pulleys which are either connected to flat or vee-belts.
Types of Belt Drives
a. Vee Belt and Pulley
b. Flat Belt Pulley
c. Variable speed pulley with vee-belts.
The three groups of belts above can be used to:
 Increase or reduce speed from driver to a driven shaft.
 Transmit power over a long distance between shafts.
 Change the direction of motion of both pulleys.
Application of Belt Drives
Belt drives can be used in the following areas:
i. Pepper grinders.
ii. Cassette and video or DVD tape players.
iii. Refrigerating and air-conditioning systems.
iv. Vehicle engines, where motion is transmitted to rotate radiator fan or drive
the alternator.
v. In an alternating current generator, where motion is transmitted from the
petrol engine to the alternator through a belt drive.
vi. The sewing machine-reciprocating rotary motion.
Definition of Chain Drive
This is an arrangement of a chain connected across two sprocket gears. You
can see the application of a chain drive in:
i. A bicycle
ii. Motorcycle
iii. Forklift, etc.

WEEK 3
Advantages of Belt Drives
i. Belt drives need less or no maintenance since it requires no lubrication.
ii. Belt drives can be used to transmit motion over a long distance.
iii. Belt drives can be used to transmit power to shafts inclined at an angle
different from the driven shaft.
Disadvantages of Belt Drives
i. Since energy is lost to friction, the transmission of power in belt drives is not
too efficient, in fact no machine is 100% efficient due to heat.
ii. In belt drives, the belt can get worn-out with time and can break suddenly.
Chain and gear
Advantages of Chain Drives
i. Chain drives can be used between shafts that are at a great distance apart.
ii. Chain drives transmit power more efficiently because it has less friction.
iii. Chain drives do not break so easily like belts.
iv. Chain drives, once greased takes time to dry up. This means less
maintenance.
Disadvantages of Chain Drives
i. Chain drives are limited in their use for distances less than one metre.
ii. Chain drives are not easily reversible.
REVIEW QUESTIONS
1.Define belt drive
2. List at least five machines that make use of belt
3. List at least two types of belts
4. State at least three advantages of belt drives
5. State at least five applications of chain drives
6. State at least four advantages of chain drives
7. State at least three disadvantages of chain drives.
WEEK 4
GEARS
Definition of a Gear: A Gear is a toothed wheel used to transmit motion
from one shaft to another, to change speed and direction in machines. They
can be made of plastics or metals. E.g. Meshing gears
Classification of Gears
i. Internal gear: This is a type of gear that is toothed internally.
ii. External gear: As the name implies, this class of gear is externally toothed.
Types of Gears
i. Wheel gears: These are gears that are used when shafts are arranged in
parallel. E.g. Meshing wheel gears
ii. Bevel gears: These are gears used where shafts are inclined at 900 to each
other and for speed reduction.
iii. Worm gears: Where axis of rotation is inclined at 900 the worm gear is
used.
iv. Sprocket gears: These are the types of gears used on bicycles and
motorcycles. Sprocket gears
Applications of Gear
Can be applied in the following mechanical devices:
i. Wood and metal work machines-lathes.
ii. Used on cranes.
iii. Mechanical clocks.
iv. Bicycle and motorcycles.
v. Hoists.
vi. Cars and automobiles –gear box, rear axle.
Uses of Gears
a. Gear is used for transmitting power.
b. Gear can be used to change the direction of travel by transmitting force of
speed at 900 with the use of bevel gear.
c. Gear can be used to change speed, either to increase or decrease the speed
d. Back movement with the selection of bevel gear is possible in most engines
with the use of gears.
Construction and Uses
Introduction: This lesson is going to be a practical lesson. All hands must
be on deck on this one. I will strongly recommend the video attached to this
lesson be seen first either as a group or as an individual, preferably in the
classroom or workshop.
Take notes and ask questions from your instructor. Obtain the necessary
materials and set to good work.
For the purpose of this lesson, a simple 5mm thick plywood or
modeling board card may be used. In addition, the following tools will be
required:
i. Marker
ii. Ruler
iii. Scissors or cutting knife
iv. Gear template (one can obtain a template online like the one shown below).
 Gear template
Project Procedure:
i. After printing out and cutting out the pattern of the template shown above,
you can use the template to draw out on the plywood outlines of the pair of
gears
ii. Use your cutting knife or fret saw in the case of a plywood, to cut out the
marked outline.
iii. Nail the pair of plywood or modeling board gears on a flat wooden board.
Ensure they are arranged in mesh as shown above.
iv. Turn one of the gears to see:
(a) what direction the other is turning
(b) and how faster or slower it does.

REVIEW QUESTIONS
1. Define a gear.
2. State at least four types of gears.
3. State at least five uses of gears.
4. State at least four applications of gears in a machine.

WEEK 5
GEARS(II)- Gear Ratio and Speed of Rotation
Introduction: In working with gears in engineering, one must
understand how to calculate gear ratios and the speed of rotation. This is what
this lesson will be exposing to you. You are also going to learn the relationship
between gear ratio and the speed of rotation in a gear system.
 Gear Speed and Ratio
When two or more gears are in a mesh, one will drive the other. As such,
one of the gears will be referred to as a driving gear and a driven gear.
i. Driving gear: This is the gear that transmits power, force or speed to the
other gear.
ii. Driven gear: This is the gear that receives the force, power or speed
transmitted to it.
Gear ratio (GR): Gear ratio is the relationship between two gears in
which one gear has larger speed than the other. For instance, a gear A has 120
teeth and another gear B has 40 teeth. The gear ratio will be 3:1, which means
that there is enlargement of speed. If the ratio were 1:3, it means there is
speed reduction of ratio 1:3.
Simple Calculations Involving Gear Ratios
To carry out calculations involving gears, let use appropriate parameters
to refer to them.
Number of Teeth in Driver Gear = Nd Speed of Rotation for Driver Gear = Sd
(revolution/sec)
Number of Teeth in Driven Gear = ND Speed of Rotation for Driven Gear = SD
(rev/sec)
But Gear Ratio (GR) =
Nd Number of Teeth in Driver Gear
ND Number of Teeth in Driven Gear
NOTE: It is the gear ratio (GR), that determines the speed of the Driven Gear.
As such,
Speed of the Driven Gear is SD = GR x Sd …(1) This implies that SD = Nd x Sd
………………………….(2) ND This implies that Speed Ratio, GR = SD
Sd (I only cross multiplied 1 above)
 This means that Speed Ratio (SR) = Gear ratio(GR). (The two means the
same thing).
Now, let us use an example to drive home the point more clearly:
EXAMPLE
A bicycle has 40 teeth in its driver gear at the pedal of the bicycle which turns
at a speed of 1000rev/min. If the driven gear at the rear of the bicycle has 80
teeth, calculate the speed of the driven gear.
SOLUTON
Speed of Driver Gear, Sd = 1000rev/min Number of teeth in Driver Gear, Nd =
40 Number of teeth in Driven Gear, ND = 80 Speed of revolution of Driven Gear
=?
Recall that SD = GR x Sd
But GR = Nd ND = 40 / 80 = 0.5 or 1:2.
Since Sd = 1000rev/min SD = GR x Sd
Therefore, SD = 0.5 x 1000 = 500rev/min.
Example 2.
A forklift consisting of two gears in a mesh have a speed ratio of 4. If the
driven gear rotates at 600 rev/min and has 60 teeth, determine:
i. The gear ratio
ii. The speed of the driver gear
iii. The number of teeth in the driver gear.
SOLUTION
Given that: GR (speed ratio) = 4
SD = 600 rev/min.
ND = 60 teeth
Sd = ?
Nd = ?
Recall that, Speed Ratio = Gear Ratio, therefore, (i). The gear ratio = 4:1
(ii). The speed of the driver gear GR = SD/Sd
Therefore, Sd = SD/GR = 600/4 = 150 rev/min.
(iii). The number of teeth in the driver gear GR = Nd/ ND
Therefore, Nd = GR x ND Nd = 4 x 60 Nd = 240 teeth.
Functions of Lubricants in Gears
Definition: Lubrication is the process of applying grease or oil on sliding
surfaces in contact. A good lubricant must possess viscosity. Viscosity is the
resistance to flow of a fluid. It shows how thick the lubricant is and its
readiness to flow.
Properties of Good Lubricant
i. A lubricant with proper viscosity must not be corrosive.
ii. It must be chemically stable.
iii. The lubricant must wet the surfaces being lubricated.
iv. A lubricant with proper viscosity must not evaporate easily.
Lubrication and Gears
Whenever two or more gears are in a mesh, friction results. This
force of friction can be reduced with the use of correct grade of gear oil. The
gear wheels of motor vehicles do swim in gear oil inside the gear box so as to
overcome frictional force.
The effects of lubrication of gears can achieve the following:
i. Reduce friction;
ii. Reduce heat;
iii. Reduce corrosion;
iv. Reduce wear and tear.
v. Serves as a cushion for proper movement of the teeth.
REVIEW QUESTIONS
1. Differentiate between driver and driven gear.
2. In two meshing gears, the driver gear has 30 teeth and rotates at 150 r.p.m.
What is the speed of the driven gear with 18 teeth?
3. In a gear box, if the driver gear has 24 teeth and rotates at 120
revolution/minute, what is the speed of the driven gear with 160 teeth?

WEEK 6
HYDRAULIC AND PNEUMATIC MACHINES (I)
Introduction: In the last lesson, you learned about belt and chain drives.
In this lesson, you are going to be learning about hydraulic and pneumatic
machines. You will be exposed to some examples of these machines and how
they function.
HYDRAULIC MACHINES
Definition of Hydraulic: An Hydraulic can be defined as the flow of fluid
through pipes under pressure in machines to be able to do work.
Hydraulic fluid: The liquid or fluid used in any hydraulic system is referred
to as hydraulic fluid. Examples are water and oil.
Hydraulics: Hydraulics are machines that work on the principle of
hydraulic. E.g. Forklift.
It is important to note that both hydraulic and pneumatic devices are used
for the following purposes:
 For pushing
 For pulling and
 For lifting.
Hydraulic Components: Some of the components that make use of
hydraulic include the following:
i. Hydraulic brake
ii. Lifting and crushing mechanisms
iii. Hydraulic pallet
iv. pump driven hydraulics
v. Truck mounted trains vi. Hydraulic jack.
Hydraulic Devices Bottle Jack: This is the simplest form of an hydraulic
jack. It has two main parts – the handle and the lever which is connected by
two pistons which raises the lever that raises the load (car). E.g.
External and Internal Structure of a Bottle Jack
1. Suction and Double Acting Pump: These are manually operated pumps used
for lifting liquids and gases from reservoirs. E.g. Double Acting pump
2. 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.
3. 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 include:
(a) Reaction turbine (at dams) and
(b) Brakes – used in cars to control motion, etc.
PNEUMATIC MACHINES
Definition of Pneumatic: The use of compressed air in machines to do
work is called pneumatic.
Compressed Air: When ordinary air is forced under pressure into a small
space it is called compressed air. As such, when air is under pressure it
possesses energy which can be released to do important work for man’s
enjoyment.
Pneumatic Components: Pneumatic components include the following:
i. The single acting cylinder
ii. The shuttle valve
iii. A double-acting cylinder
iv. A three-port valve
v. The five-port valve
vi. A flow regulator
Pneumatic devices include the following:
1. Hand Pump: These are of different types, they are used to inflate tires,
balloons, balls etc. the hand pump has a plunger which sucks in and pushes out
air at the barrel cylinder.
2. Compressor Machine: This machine is used by vulcanizers. The modified one
is used as a spray machine on several products. E.g.
REVIEW QUESTIONS
1. Define hydraulic
2. Identify four hydraulic devices
3. Define pneumatic
4. Identify at least two pneumatic devices.
OPERATIONS ON HYDRAULIC AND PNEUMATIC MACHINES
HYDRAULIC MACHINES
1. Hydraulic Jacks
Hydraulic jacks are used to lift heavy loads like cars, heavy-duty trucks, etc.
Hydraulic jacks work on the principle of hydraulic press. In an hydraulic press
there are two cylindrical drums, one with smaller area (A1) and the other with
a larger area (A2).
The surface area of a piston in A2 supports the load why the surface area of a
piston in A1 forms where an effort is applied.
In the hydraulic press, as force is applied at the smaller cylinder drum (A1),
force is transmitted throughout the body of the liquid contained in the cylinder
drum to the opposite larger cylinder drum (A2), which lifts any load resting on
it.
2. Bottle Jack: This is the simplest form of hydraulic jacks. It contains a lever
arm, vertical inner cylinder containing mineral oil and a bearing pad which is in
direct contact with the load. When pressure is applied through the lever arm
to lift any heavy load, the bearing pad reciprocates by lifting the load attaché
to it. This type of jack is best suited for vehicles with a good clearance above
the ground. For cars with a low base, the bottle jack is not an ideal jack for
them.
3. Bottle jack.
3. Turbines: There are different types of turbines namely:
i. Water turbine
ii. Gas turbine and
iii. Steam turbine
Water turbine for instance is also referred to as reaction turbine. Usually
water turbines are located at the base of dams where river or lagoon water
can be controlled through a gate and channeled towards the turbine.
A water turbine is made up of a rotor shaft with an adjoining blades called
buckets. All these are arranged in an enclosed casing.
Mechanical energy from the flowing water pushes against the buckets or
blades to turn the rotor shaft. In turn, this energy drives an hydropower
generator to generate electricity. It should be noted that the pressure in a
water turbine changes as the water flows in and out of the turbine. E.g.
4. Hydraulic Brakes: Brakes rely on the human body to provide the force to
create pressure in the hydraulic system. By the time the brake pedal is pressed,
a small piston in the master cylinder creates pressure in the brake fluid which
is transmitted to the wheel cylinder. The piston in the wheel cylinders exerts a
force on the brake pad which rubs against the rotating disc. Therefore, this
slows down and finally stops the vehicle. In cars with drum brakes, the
arrangement is a little different but the same principles, especially on cars
where all four wheels have either a disc or drum brake.
PNEUMATIC MACHINES
Generally speaking, pneumatic machines are mostly pumps for moving
air to inflate a container, to move water or waste from one point to another
through changes in air pressure within a cylinder or system.
1. The Hand Pump: This is the one generally known as the bicycle pump. It is
often referred to as a positive displacement pump. Positive displacement
pumps have a plunger and a cylinder. The plunger is enclosed within the
cylindrical barrel and at one end of the barrel, there is a nozzle. In using the
pump, all you need do is to pull and push the plunger. The displacement of the
piston (plunger) results is massive suction of air into the designed cylindrical
container. At the forward stroke, air is pushed out through the nozzle thereby
inflating any material it was attached to such as football, balloon or tires. E.g.
2. Compressed Air Pumps: Compressed air pumps, centrifugal pumps and
vacuum cleaners belong to the group of pumps known as rotary pumps. Their
principle of operation is quite different. The compressed air machine has two
parts. There is the petrol or diesel engine part and
the rotary pump section. Internally, the compressed pump contains a rotary
device in the form of a fan which draws in air from the immediate surrounding
and directs it through a nozzle. The air compressor machine is used by most
tire repairers (vulcanizers) to inflate automobile and vehicle tires. In some
other cases, some compressed air pumps have a cylindrical metal tank, called
the receiver, into which sucked air is directed by passing through a regulator.
This device makes it possible to build up air at constant pressure. Such stored
air can also be used to direct a jet of spray of polish or paint on furniture and
bodies of metallic materials.

REVIEW QUESTIONS
1. Identify both three hydraulic machines you learned about in this lesson.
2. State at least two components in the hydraulic machines identified above.
3. State one principle of operation in a hydraulic jack machine.
4. State at least one use each of the machines that identified during this lesson.
5. Identify two pneumatic machines you just learned about.
6. State at least one component of the pneumatic machines.
7. State at least one principle of operation in an identified pneumatic machine.
8. State at least one outstanding use of an identified pneumatic machine.
WEEK 7
SITE PREPARATION
Site preparation can be defined as the preliminary work that must be
carried out to bring the site to a ready status for construction to be carried out
on. Prior to building or farming on a piece of land, there is need to clear the
land of trees, bushes, vegetables soil or level the site in case of undulating
surfaces in order to make the site ideal for the intended use. Both hands and
mechanical tools are involved
HAND TOOLS
1. Spades: This is a tool that can be used for digging loose or soft earth
2. Shovel: Spade like tool used for lifting and throwing loose material or soft
earth or aggregates (broken stones) into another position and for spreading
excavated materials
3. Matchets: For cutting grasses or wood like trees or shrubs
4. Hoe: used for digging usually the surface of the ground. It is also used for
uprooting weeds among growing crops and for loosening the soil
5. Axe: sometimes called Ax. It is used for felling trees, splitting wood and for
cutting bigger branches of trees
6. Pick axe: used for breaking up hard surfaces. The mattock shown is also used
as a pick axe
7. Chain saw: is a portable diesel or petrol operated machine used in felling
bigger trees and for cutting tree trunks into smaller sizes
MECHANICAL TOOLS
Preparing some site manually can be almost an impossible task within
the use of mechanical plants. Three most commonly used plants for site
preparations are:
1. Bulldozers: This plant has an hydraulically operated powerful blade which
can be used to push against any obstacle on site. The plant can be used to fell
trees and clear the vegetable soil and to push large amounts of soil
2. The tractor shovel: Also called the payloader, this mechanical plant has a
flipping shovel which can be used to scoop, dig and lift large mass of earth to
load in a truck. The metallic body is usually mounted on wheel
3. Graders: Site preparation work will not be complete without levelling the
site. The grader is best suited for this work. It has a wheeled frame under
which a long powerful blade is mounted with the blade, levelling of the ground
can be easily achieved by manoeuvering it at different angles.

WEEK 8
SETTING OUT
This is the process by which the building plan (drawn by the architect) is
transferred to the ground by the builder of the building engineer. It refers to
transferring actual measurements on the building plan, called also the blue
print, physically to the ground techniques, materials and tools
TOOLS AND MATERIALS REQUIRED FOR SETTING OUT A BUILDING PLAN
Setting out a building foundation requires the use of the following
materials and tools, with their uses as stated below
Materials
i. Building plan: Also referred to as the blue print is to be read and interpreted
before setting out the foundation. The building plan is used to obtain
information about the building line, the position and widths of the foundation
and walls on ground
ii. Pegs: These are cut pieces of wood, fairly sharpened at the lower tip to make
it easy driving into the ground
iii. Lines: Linen, rubber or cotton rope can be used as lines to demarcate the
path, width and direction for the foundations and walls before excavation is
carried out
iv. Profiles: Wood materials of thin width and breadth used in setting out are
called profile boards. These small sized planks are nailed on pegs and are used
to mark the positions of trenches and walls
v. Nails: Nails are hammered on the pegs and profile boards in order to run the
lines

Tools
i. Measuring tape: The steel tape is a measuring tool in setting out. It is
graduated in centimeters and meters
ii. Sledge hammer: A driving tool used in driving pegs into the wood
iii. Builders square: This is a triangular wooden tool for setting out squareness
at the corners of the building space. The wooden triangle is built to have a
right angle which is placed at the corner to check for angle 90 0
iv. Steel square: The steel square is a substitute tool for the builders square,
when the latter is not available
v. The plumb: The plumb is a setting out tool in building work. It comes in form
of lead ball tied to a string and suspended vertically to set walls in a vertical
position
vi. The Theodolite: A special measuring and setting out instrument which has a
tripod stand for its legs (or support). It can be used to measure a number of
things (e.g. angles of elevation and depression), especially setting out corners
of massive complex structures

Setting out involves

1. Setting out the building line which is usually the frontage line of the building
and must be at a particular distance from the ends of the road (given by the
town planning authority)
2. From the building line which is marked with nails on pegs on the site, the
lengths and width of the building are marked out using measuring tapes
3. The external angles of the building are then set at right angles using the
builder’s square or the 3:4:5 method
4. Setting up profile boards which are wooden planks mounted on wooden
pegs
Excavation and Timbering: After the foundation trench has been marked
on the profile board, digging commences. This can be done manually using
shovel, spade, pick axe etc, or mechanically (using excavator). The process of
digging and removing the earth to create space for the foundation is called
Excavation while Timbering is the method of using planks to line the vertical
sides of foundation trench to prevent the wall from caving in or collapsing
during digging or concreting
Battering: in foundation trench is the process of sloping the sides of
trench at an angle called angle of inclination during excavation so that there
will be no need for timbering
The types of soil as well as its load bearing capacity determines the type of
foundation to be used. The load bearing capacity of a soil is the maximum load
per unit of area (KN/m2) which the ground will support without displacement,
settlement or ground movement. Soil is formed by the weathering and
disintegration of solid rock. There are fine grained soil (silts and clay) and
coarse grained soil (gravel and sand).
WEEK 9
BUILDING SERVICES
PLUMBING AND DOMESTIC WATER SUPPLY
Definition: The system of pipes that supply water to a building is called
plumbing. A plumber is the person whose job is to fit and repair water pipes,
toilets, baths, W.Cs, etc.
Most building in Nigeria today get their water supply from wells and
boreholes. Others get theirs from various water corporations
Terms used in water supply and distribution
1. Main pipes (or street mains): These are major pipes which carry water from
water corporation depots or reservoir to various outlets like homes, factories,
offices, general public etc.
2. Service pipes: These are pipes which takes water from the mains in the road
to private premises and they are made up of
(a) Communication pipe: This is the part of the service pipe which takes
water from the mains up to the boundary of the compound
(b) Supply pipe: Part of the service pipe continuing from the boundary of
the compound
(c) Rising main: Part of the service pipe that takes water up to the storage
tank in the compound
(d) Distribution pipe: Take water from the storage tank in the compound to
various fittings such as kitchen sinks, wash-hand basins, water closets, baths
etc.
Fittings for domestic pipeline and their uses
1. Gate value: To control the flow of water in the pipe. A gate value allows the
flow in both directions
2. Tap: Outlets for water usually fixed at the end of a supply or distribution
pipe. We have 2 types of pillar tap and bib tape
3. Elbows: Used for changing the direction of water flow through pipes
4. Tees: Used for joining 3 pipes which meet at a junction
5. Drain cock: This is a tap which is opened or closed with a spanner. It is used
for draining the pipes
6. Stop cock: A tap which enables water supply to be cut off
7. Tank: This is used for storing water
8. Traps: provides a seal of water against foul smell entering the house through
the appliance or ware it is fitted to
PLUMBING TOOLS
These are tools used by the plumber to carry out plumbing fittings. They
include:
a. Mallet
b. Yarn
c. Screw driver
d. Wrench
e. Hacksaw
f. Coldchisel
g. Trowel etc.
SANITARY APPLIANCES
Sanitary appliances include:
1. Water Closets (W.C): A water closet suite comprises of a W.C, pan, seat,
flushing appliance and any necessary flush pipe. It can be made of ceramic,
plastic or metal. Its purpose (use) is to take solid and liquid excrement with an
inlet for flushing and trapped outlet
2. Urinals: Urinals are installed in building to accept urine
3. Bidets: Bidets are used for cleansing the lower excretory organs of the body
in a thorough and convenient manner by sitting astride the appliance. It can
also be used as a foot bath
4. Wash basins: Wash basin provides facilities for personal ablutions in
bathrooms, dressing rooms, bedrooms and cloak rooms. They are designed for
washing the upper part of the body
5. Baths: Also called bath tubs is a large long container that you put water in
and then get into, to wash your whole body
6. Shower: This is an equipment for producing a spray of water that you stand
under to wash yourself quickly while standing on the shower using a minimum
quantity of water
7. Sinks: Sinks are installed in kitchens for washing dishes and other domestic
purposes