3.
Is the study of fluids such as liquids and
gases and the ways in which they interact
with forces applied to them. Fluids deform to
take the shapes of their surroundings; the
diagram below illustrates what would happen
when a force is applied to a toothpaste tube
with four holes in it. The force is transferred
equally in every direction to all parts of the
container.
4.
5. Blaise Pascal who was a French
mathematician, physicist and
inventor, established that “pressure applied
to an enclosed liquid is transmitted
undiminished to every point in the fluid and
to the walls of the container.”
6. Pascal’s principle is applied in sealed
hydraulics systems such as the operation of a
four wheeled hydraulic automobile braking
system. This is illustrated in the diagram
below, when pressure is applied to a brake
pedal this forces the piston in the master
cylinder against the fluid in that cylinder and
transfers equal force to all other brake
shoes, thus stopping the vehicle.
7.
8. There are many industries that use hydraulics
such automobiles, petrol
pumps, cranes, robotic and aircrafts.
9. The following two digital resources
demonstrate how Pascal’s law and hydraulic
brakes
http://www.youtube.com/watch?v=VxLTDtaR
CZk
http://www.youtube.com/watch?v=d66EiKwy
St4&feature=related
10. Archimedes was a Greek philosopher and
discovered that the level of water in a tub
rose when he sat in it, he found that “a body
wholly or partially submerged in a fluid is
buoyed up by a force equal to the weight of
the fluid displaced by the body.”
(Writing)
12. Hydraulic brakes are commonly used in the
automobile industry, they work on the principle
of Pascal law, Hydraulic brakes consists of a
master cylinder, four wheel cylinder and pipes
carrying a brake fluid from the master cylinder to
the wheel cylinder. The pressure of the brake
fluid forces out the two pistons in the wheel
cylinders, pistons are connected to brake shoes.
The brake shoes expand out against drums due
to friction between the brake linings and drum
the wheels slow down.
14. There are many advantages of hydraulic
brakes such as the equal braking action of all
wheels, increased braking force, simple
construction, low wear rate of brake lining
and a mechanical advantage. The
disadvantages are that when a leakage occurs
or there is air inside the tubing’s the whole
braking systems fails.
15. A Motorcycle hydraulic brakes work similar to
car brakes, in the same way they deliver
brake fluid under pressure from the master
cylinder to the brakes. The difference is on a
motorcycle the rider controls the front and
rear brakes manually.
16. The front brake is operated by the rider’s
right hand, and the rear brakes are operated
by the rider’s right foot. This requires the
rider’s skill in determining the appropriate
amount of pressure to both front and rear
brakes. Generally brake lines are visible on
motorcycles than cars, brake lines usually run
along the motorcycles frame.
(Works, 2011)
17.
18. Buses
Hydraulic Antilock Braking systems (HABS)
operated on buses since March 1 1999, HABS
help maintain control and stability of a bus in
extreme braking circumstances. The unit is
an electronic system with four solenoid valves
and two or more electric hydraulic pumps.
The four solenoids pressure valves control
brake fluid pressure for each wheel and slow
bus down.
19. Railway air brakes is a straight air system where
compressed air pushes on a piston in a
cylinder, the piston is connected to a brake shoe
that uses friction to slow a train down. One
pressurized air cylinder can evenly distribute the
force to 8 – 12 wheels. The pressurized air comes
from a air compressor inside the train and sent
by pipes and hoses beneath each of the
carriages. The problem with railway air brakes is
that any breakage or separation between hoses
and pipes can cause a loss of air pressure, this
affects the force applied to the brakes.
(Wikipedia, 2012)
21. The Electronic Wedge Brake (EWB) bypasses
any hydraulic system that works on a similar
principle with the brakes of horse drawn
carriages, where a wedge is used to bring a
wheel to a stop. The EWB is simply powered
by a 12-volt power system in which already
exists in cars. The EWB is proven to react
faster and works about a third quicker than
conventional breaks, only requiring 100ms to
reach full braking power compared to a
hydraulic brake’s 170ms.
22. The design of the EWB is basically a wedge
connected to a brake pad that is pressed
between the rod and disc. The electric motor
pushes the pad onto the disc, the use of the
wedge means braking power is multiplied
with minimal energy and the faster the car is
going the stronger the brake force is. The
cars kinetic energy is being converted into
breaking energy. The EWB has a back up
power source in case power supply is
disrupted.
23. The highly
sophisticated sensor
technology prevents
brakes from locking up
and guarantees highly
efficient and controlled
braking.
24. When released, the brake disk runs freely
(left). A sight amount of pressure from the
wedge on the disk (right) applies the brake.
Enhanced braking results because the disk’s
rotation drags the wedge with it, thereby
generating drag
(Siemens, 2005)
27. One of the first hydraulic lift devices were
invented by William Armstrong in 1845, the
crane was water powered. Armstrong used
water in cylinders to create a force to lift and
move loads vertically and horizontally.
28. The hydraulic crane was
significant in the growth
and development of
North East of
England, the sea port
imported and exported
goods and the hydraulic
crane enable greater
efficiency, safety and a
reduction in labour
costs, as a result it
became one of the most
important cities of the
time.
29. In 1970 hydraulic elevators were quite common
generally used for low level building with 2- 5
floors, cylinders were underground. Further
development introduced a Rope hydraulic
elevator this allowed the elevator to travel further
than the piston had to move. The impact of
these elevators were that they used less
energy, as a pump worked against gravity to
push the elevator upwards, a greater capacity to
lift more people and faster travelling time. The
negative was the possibility of cylinders leaking
fluid into the ground and causes damage the
environment.
30. Forklifts are design to
move objects or loads
up and down, the
operator uses a
hydraulic system to
move forks. Pressure is
applied to a bar with
rolling chains that are
located in the forklift.
32. An incline platform lift enables disabled
people access places where before were not
possible due to stairs. The incline lift can be
installed to straight and curved
stairways, they can travel 50m, are fully
automated and have load capacity of 225kg.
33.
34. The forest timber harvester is a forestry
vehicle that cuts timber to length, delimbs
and transports the tree. The harvester is a
diesel powered vehicle that is wheel or
tracked the harvester has a hydraulic drive
arm that maneuvers out to the harvester
head. The harvester is operated by a single
person who can fell, process and transport
the trees. The impact that the harvesters has
is efficiency, safety and productivity.
37. Aircraft hydraulics enables energy to from
one place to another safely and efficiently. A
hydraulic system takes engine power and
converts it to hydraulic power by a hydraulic
pump. This power is transported throughout
the plane by tubing through the aircraft.
Hydraulic power can be reconverted to
mechanical power by an actuating cylinder or
turbine.
38. The following are devices operated by
hydraulic systems in an aircraft, primary
control boosters, landing gear, sweep back
and forth of wings, opening and closing of
doors and hatchways, shock absorbing
systems, dive, landing, speed, and flap
brakes.
39. The advantages of a hydraulic system
are, that it is lighter in weight, reliable, easily
maintained and it can develop practically
unlimited force or torque.
(Aeronautics Learning Laboratory for
science, 2004)
