AJAY KUMAR GARG ENGINEERING COLLEGE 27, DELHI-HAPUR BYPASS ROAD A PROJECT PROGRESS REPORT ON AUTOMATIC LIFT BRAKING SYSTEM

AJAY KUMAR GARG ENGINEERING COLLEGE

27, DELHI-HAPUR BYPASS ROAD

GHAZIABAD-201009

A

PROJECT PROGRESS REPORT

ON

AUTOMATIC LIFT BRAKING SYSTEM

Under the guidance ofSubmitted by: GROUP NO. 1

Mr. H.S.CHAURASIYARITESH KUMAR (1102740092) PRAKASHKHUSHWHA(1102721066)

SURAJPANDEY(1102740112) PRAVEEN KUMAR GAUTAM(1102740077)

CONTENT:

DESIGN AND SPECIFICATION OF COMPONENTS USED:

I. LIFT CHAMBER II. ELEVATOR CAR

III. ELECTRIC MOTOR IV. ROPE V. PULLEY VI. RECTIFIER CIRCUIT

VII. OVERSPEED GOVERNOR

LIFTCHAMBERDIMENSIONS:

BASE AREA : 1.5 ft x 1.5ft

HEIGHT : 4.0 ft

MATERIAL : Medium-density fibreboard (MDF)

MDF: It is an engineered wood product formed bybreaking down hardwood or softwood residualsinto wood fibres, combining it with wax anda resin binder, and forming panels by applying hightemperature and pressure. MDF is denser than plywood.MDF density is typically between 500 kg/m3 and1000 kg/m3 .

Physical propertiesOver time, the word "MDF" has become a generic namefor any dry process fiber board. MDF density istypically between 500 kg/m3 (31 lbs/ft3) and

1000 kg/m3 (62 lbs/ft3). The range of density andclassification as Light or Standard or High densityboard is a misnomer and confusing. Density of boardwhen evaluated in relation to density of the fiberthat goes in to making of the panel is important. Athick MDF panel at 700-720 density in case ofsoftwood fiber panels may be considered as highdensity whereas a panel of same density when made ofhard wood fibers is not so. The evolution of varioustypes of different MDF was driven by the differingneeds of specific applications.

Comparison to natural woodsMDF does not contain knots or rings, making it moreuniform than natural woods during cutting and inservice. However, MDF is not entirely isotropic,since the fibres are pressed tightly together throughthe sheet. Like natural wood, MDF may split whenwoodscrews are installed without pilot holes, and MDFmay be glued, doweled or laminated, but smooth-shanknails do not hold well. Typical fasteners are T-nuts and pan-head machine screws. Fine-pitch screwsdo not hold well in MDF and screw retention in theedge is particularly poor. Special screws areavailable with a coarse thread pitch but sheet-metalscrews also work well. Typical MDF has a hard, flat,smooth surface that makes it ideal for veneering, asthere is no underlying grain to telegraph through thethin veneer as with plywood. A so-called "Premium"MDF is available that features more uniform densitythroughout the thickness of the panel.

Safety concerns

When MDF is cut a large quantity of dust particlesare released into the air. It is important thata respirator be worn and the material be cut in acontrolled and ventilated environment. It is a goodpractice to seal the exposed edges to limit theemissions from the binders contained in thismaterial.

ELEVATOR CAR

DIMENSIONS:

BASE AREA : 1.0 ft x 1.0 ft

HEIGHT : 0.5 ft

MATERIAL : Medium-density fibreboard (MDF)

MASS : 6.0 Kg

COUNTER MASS : 2.5 Kg

ELECTRIC MOTORSPECIFICATION:

TYPE : DC Geared Motor

VOLTAGE : 12 V

CURRENT : 1.2 A

RPM : 300 rpm

A gear motor is a specific type of electrical motorthat is designed to produce high torque whilemaintaining a low horsepower, or low speed, motoroutput. Gear motors can be found in many differentapplications, and are probably used in many devicesin your home.Gear motors are commonly used in devices such as canopeners, garage door openers, washing machine timecontrol knobs and even electric alarm clocks. Commoncommercial applications of a gear motor includehospital beds, commercial jacks, cranes and manyother applications that are too many to list.

Basic Principles of OperationA gear motor can be either an AC (alternatingcurrent) or a DC (direct current) electric motor.Most gear motors have an output of between about1,200 to 3,600 revolutions per minute (RPMs). Thesetypes of motors also have two different speed

specifications: normal speed and the stall-speedtorque specifications.Gear motors are primarily used to reduce speed in aseries of gears, which in turn creates more torque.This is accomplished by an integrated series of gearsor a gear box being attached to the main motor rotorand shaft via a second reduction shaft. The secondshaft is then connected to the series of gears orgearbox to create what is known as a series ofreduction gears. Generally speaking, the longer thetrain of reduction gears, the lower the output of theend, or final, gear will be.

FIG. 1: DC GEARED MOTOR

An excellent example of this principle would be anelectric time clock (the type that uses hour, minuteand second hands). The synchronous AC motor that isused to power the time clock will usually spin therotor at around 1500 revolutions per minute. However,

a series of reduction gears is used to slow themovement of the hands on the clock.For example, while the rotor spins at about 1500revolutions per minute, the reduction gears allow thefinal second hand gear to spin at only one revolutionper minute. This is what allows the second hand tomake one complete revolution per minute on the faceof the clock.Gear Motors and Increased ForceGear motors are commonly used in commercialapplications where a piece of equipment needs to beable to exert a high amount of force in order to movea very heavy object. Examples of these types ofequipment would include a crane or lift Jack.If you've ever seen a crane in action, you've seen agreat example of how a gear motor works. As you haveprobably noticed, a crane can be used to lift andmove very heavy objects. The electric motor used inmost cranes is a type of gear motor that uses thebasic principles of speed reduction to increasetorque or force.Gear motors used in cranes are usually specialtytypes that use a very low rotational output speed tocreate incredible amounts of torque. However, theprinciples of the gear motor used in a crane areexactly the same as those used in the exampleelectric time clock. The output speed of the rotor isreduced through a series of large gears until therotating, RPM speed, of the final gear is very low.The low RPM speed helps to create a high amount offorce which can be used to lift and move the heavyobjects.

ROPE ANDPULLEY

Dimensions: ROPE

SIZE : 6 x 19LENGTH : 1.2 mMATERIAL : Steel WireDIAMETER : 0.5 inch

PULLEY DIAMETER : 6.0 cmMATERIAL : Mild Steel

PulleyA pulley is a wheel on an axle that is designed tosupport movement and change of direction of a cableor belt along its circumference. Pulleys are used ina variety of ways to lift loads, apply forces, and totransmit power. In nautical contexts, the assembly ofwheel, axle, and supporting shell is referred to as a"block."A pulley is also called a sheave or drum and may havea groove between two flanges aroundits circumference. The drive element of a pulleysystem can be a rope, cable, belt, or chain that runsover the pulley inside the groove.

FIG.2: BLOCKAND TACKLE ASSEMBLIES

Hero of Alexandria identified the pulley as one ofsix simple machines used to lift weights. Pulleys areassembled to form a block and tackle in order toprovide mechanical advantage to apply large forces.Pulleys are also assembled as part of belt and chaindrives in order to transmit power from one rotatingshaft to another.A set of pulleys assembled so that they rotateindependently on the same axle form a block. Twoblocks with a rope attached to one of the blocks andthreaded through the two sets of pulleys form a blockand tackle. A block and tackle is assembled so one block isattached to fixed mounting point and the other isattached to the moving load. The mechanicaladvantage of the block and tackle is equal to thenumber of parts of the rope that support the movingblock.In the diagram on the right the mechanical advantageof each of the block and tackle assemblies shown is asfollows:

Gun Tackle: 2 Luff Tackle: 3 Double Tackle: 4 Gyn Tackle: 5 Threefold purchase: 6

RECTIFIER CIRCUIT

COMPONENTS USED

DIODE

Quantity : 4

Voltage : 12 V

Current : 30 mA

TRANSFORMER

220 V mains to 12 V lower supply.

CAPACITOR

Type : Cylindrical

Capacity : 50 µF

TransformersFor electronic devices to function it is necessary to have aDC power supply. Batteries and rechargeable cells can fulfillthe role, but a much more efficient way is to use a POWERSUPPLY. The basic component of a power supplyr is atransformer to transform the 220V "mains" to a lower value,say 12V. A common type of transformer has one primary windingwhich connects to the 220V and one (or several) secondarywindings for the lower voltages. Most commonly, cores are madeof E and I laminations, but some are made of ferromagneticmaterial. There are also iron core transformers used forhigher frequencies. Various types of transformers are shown onthe picture below.

FIG.3:VARIOUS TYPES OF TRANSFORMERS

Symbols for a transformer are shown on the figure 3.6   Twovertical lines indicate that primary and secondary windingsshare the same core.

FIG.4:TRANSFORMER SYMBLE

With the transformer, manufacturers usually supply a diagramcontaining information about the primary and secondarywindings, the voltages and maximal currents. In the case wherethe diagram is missing, there is a simple method fordetermining which winding is the primary and which is thesecondary: a primary winding consists of thinner wire and moreturns than the secondary. It has a higher resistance  - andcan be easily be tested by ohmmeter. Figure 3.6d shows thesymbol for a transformer with two independent secondarywindings, one of them has three tappings, giving a total of 4different output voltages. The 5v secondary is made of thinnerwire with a maximal current of 0.3A, while the other windingis made of thicker wire with a maximal current of 1.5A.Maximum voltage on the larger secondary is 48V, as shown onthe figure. Note that voltages other than those marked on thediagram can be produced - for example, a voltage betweentappings marked 27V and 36V equals 9V, voltage betweentappings marked 27V and 42V equals 15V, etc.

Working principles and basic characteristics As already stated, transformers consist of two windings,primary and the secondary (figure 3.7). When the voltage Up isconnected to the primary winding (in our case the "mains" is220V), AC current Ip flows through it. This current creates amagnetic field which passes to the secondary winding via the

core of the transformer, inducing voltage Us (24V in ourexample). The "load" is connected to the secondary winding,shown in the diagram as Rp (30Ω in our example). A typicalload could be an electric bulb working at 24V with aconsumption of 19.2W.

FIG.5:Transformer: a Working principles, b. Symbol

Capacitors

Capacitors are common components of electronic circuits,used almost as frequently as resistors. The basicdifference between the two is the fact that capacitorresistance (called reactance) depends on the frequency ofthe signal passing through the item. The symbol forreactance is Xc and it can be calculated using thefollowing formula:

f representing the frequency in Hz and C representing thecapacitance in Farads.

Capacitors come in various shapes and sizes, depending ontheir capacity, working voltage, type of insulation,temperature coefficient and other factors. All capacitorscan divided in two groups: those with changeable capacityvalues and those with fixed capacity values. These willcovered in the following chapters.

2.1 Block-capacitors (Fixed value):

Capacitors with fixed values (the so called block-capacitors)consist of two thin metal plates (these are called"electrodes" or sometimes called the "foil"), separated bya thin insulating material such as plastic. The mostcommonly used material for the "plates" is aluminum, whilethe common materials used for insulator include paper,ceramic, mica, etc after which the capacitors get named. Anumber of different block-capacitors are shown in thephoto below. A symbol for a capacitor is in the upperright corner of the image.

FIG.6:Block capacitors

Most of the capacitors, block-capacitors included, arenon-polarized components, meaning that their leads areequivalent in respect of the way the capacitor can beplaced in a circuit. Electrolytic capacitors represent theexception as their polarity is important. This will becovered in the following chapters.

Electrolytic capacitors

Aluminum is used for the electrodes by using a thinoxidization membrane.Large values of capacitance can be obtained in comparisonwith the size of the capacitor, because the dielectricused is very thin.

Electrolytic capacitors represent the special type ofcapacitors with fixed capacity value. Thanks to specialconstruction, they can have exceptionally high capacity,ranging from one to several thousand µF. They are mostfrequently used in circuits for filtering; however theyalso have other purposes.

Electrolytic capacitors are polarized components, meaningthey have positive and negative leads, which is very

important when connecting it to a circuit. The positivelead or pin has to be connected to the point with a higherpositive voltage than the negative lead. If it isconnected in reverse the insulating layer inside thecapacitor will be "dissolved" and the capacitor will bepermanently damaged.

Tantalum Capacitors

Tantalum Capacitors are electrolytic capacitors that areuse a material called tantalum for the electrodes. Largevalues of capacitance similar to aluminum electrolyticcapacitors can be obtained. Also, tantalum capacitors aresuperior to aluminum electrolytic capacitors intemperature and frequency characteristics. When tantalumpowder is baked in order to solidify it, a crack formsinside. An electric charge can be stored on this crack.

Diode

A diode is a semiconductor device which allows current toflow through it in only one direction. Although atransistor is also a semiconductor device, it does notoperate the way a diode does. A diode is specifically made

to allow current to flow through it in only one direction.Some ways in which the diode can be used are listed here.

A diode can be used as a rectifier that converts AC(Alternating Current) to DC (Direct Current) for a power supply device.

Diodes can be used to separate the signal from radiofrequencies. Diodes can be used as an on/off switch that controlscurrent.

FIG.7:VARIOUS TYPES OF DIODE

This symbol is used to indicate a diode in a circuitdiagram. The meaning of the symbol is (Anode) (Cathode). Current flows from the anode side to thecathode side.Although all diodes operate with the same generalprinciple, there are different types suited to different

applications. For example, the following devices are bestused for the applications noted.

FIG.8:Diode symbols

a - standard diode, b - LED, c, d - Zener, e - photo,f,g - tunnel, h - Schottky, i - breakdown, j -capacitative

V-I characteristics:

FIG.9:The graph on the right shows the electricalcharacteristics of a typical diode.

When a small voltage is applied to the diode in theforward direction, current flows easily. Because the diodehas a certain amount of resistance, the voltage will dropslightly as current flows through the diode. A typicaldiode causes a voltage drop of about 0.6 - 1V (VF) (In thecase of silicon diode, almost

CALCULATION

Fc : Centrifugal Force

Fs : Spring Force

When Fc > Fs → Lockedposition

Therefore,

mv² > kx--------- ①

r

k < mv2

rx

where, m : mass of flyweights

r : radius of rotation

x : displacement of spring

k : stiffness of spring

v : critical speed

= 110% of rated speed i.e. (1.1Vr )

Hence, ‘K’ of spring can be determined.

After the governor is locked,

T = Mg+(mv2/r)

Where, T : Tension in rope

M: Mass of lift and passenger

g : acceleration due to gravity

FIG.10: FREE BODY DIAGRAM

Now,

R = normal reaction force on wedge block

= T cosα

where, α : wedge angle

N = Normal force on the rail guide by the brakepad

= R cos(90- α)

= R sin α

N = (T/2)sin 2α

Friction Force , f = μN

where, μ : coefficient of friction between pad andsteel plate

Braking force, Fb = nf

where, n= number of contacting surfaces