The Brake System Of Moving Machines And Vehicles Engineering Essay

Brake systems are one of the compulsory constituents in a moving machine. Any traveling machine or vehicle needs a brake to slow and halt. As we want the auto to travel fast, we would besides desire the auto to halt rapidly and safely. Not merely for a safety, the vehicle equipped with a good and consistent brake will besides increase the impulsive pleasance.

In this paper we will analyze the rule of brakes. Furthermore, we will discourse current fluctuation of brakes system, brakes type and actuators mechanism. The purpose of this paper is to discourse and understand how different car braking system work. In add-on, we will discourse the hereafter development system and the sustainability of the system.

BRAKES HISTORY

Brake systems were foremost used on Equus caballus drawn waggon, which was a tyre brakes. History of brake is a portion and built-in with the car history. Subsequently, when the autos has been develop, the demand on a proper brake go important as the autos turned heavier and more powerful. Earlier applied scientist has tested and failed many design until they found the design that worked.

In 1902 few brake systems were introduce to the market. Frederick William Lanchester patented disk brake system in 1902. Because of the design create a awful noise, the design does n’t accepted in the market. In 1907, after Herbert Frood improved the tablets with asbestos stuff and solved the noise job it started to catch the market attending ( Puhn, 1985 ) . However, the disc brakes were non become standard in Europe until much subsequently.

The membranophone brakes were foremost tested in 1902, by Ransom E. Olds, which was designed in New York. The design was the external membranophone brakes. It works by wrapping unstained steel set around the membranophone, which attached to the rear axle ( Harris, 2009 ) . The new design by Olds, has allowed the auto to halt faster comparison to the older design on Equus caballus drawn waggon. It becomes popular as most of the auto maker during that clip used the design. Subsequently, the external membranophone brakes were found non wholly dependable particularly on soil route and have on out after 200 stat mis. The solution was the internal membranophone brake ( Harris, 2009 ) .

Malcom Lougheed introduced the fluid mechanicss brakes by utilizing tubings to bring forth hydraulic power to brakes shoe in 1918. In 1921, model A Dusbenberg becomes the first auto to utilize the hydraulic brakes. Most of makers used the hydraulic brake by 1931. Ford started to utilize the hydraulic brake by 1939 ( Harris, 2009 ) .

The early antilock brake system was invented for aeroplane in 1929 by Gabriel Voisin and been applied to automobile in 1950s. Even though the antilock brakes were proven dependable, it had non applied to the autos until Chrysler introduced its “ Certain Brake ” on the 1971 Impala theoretical account ( Harris, 2009 ) . The modern antilock brakes were produced by Mercedes-Benz and Teldix and were used in the 1978 Mercedes Benz S-Class ( Harris, 2009 ) .

BRAKES BASIC

The basic intents of the brake system in motor vehicle are:

To forestall unwanted motion of the resting vehicle with used of parking brakes.

To forestall unwanted acceleration, i.e. while driving downhill with the uninterrupted braking.

To cut down the velocity and if necessary to halt the vehicle with slowing braking

Different types of brake are arranged otherwise with a different method of coercing clash surfaces together. It will besides make a different heat dispersing one time its generated. As a system, brake consists of few constituents. The system includes pedals, levers, lines, brakes constituent and the triping medium ( mechanical, hydraulic, pneumatic and electric ) ( Breuer and Bill, 2008 ) .

Brake Circuit Configuration

It is lawfully compulsory for the auto maker to supply the brakes system with a double circuit transmittal system for safety intent, because the chance of failure is lesser comparison to individual circuit system. They are five available options for the circuit constellation as shown in following figures below:

Figure 1.1 II distributions. One circuit brakes the forepart axle and the other one brakes rear axle

Figure 1.2 Ten distributions. Each circuit brakes one forepart wheel and one diagonally opposite rear wheel.

Figure 1.3 HI distributions. One circuit brakes all wheels on forepart and rear axle and the other circuit brakes on front axle.

Figure 1.4 LL distributions. Each circuit brakes two wheels on forepart axle and one wheel on rear axle.

Figure 1.5 HH distributions. Each circuit brakes all wheels on forepart and rear axles.

In contrast to II and X distribution, HI, LL and HH distribution have a failing in the event of overheating at one wheel, could do a failure to a circuit. The Ten distribution is used on vehicle with forward weight prejudice, while the II distribution is a solution for vehicle with rear weight prejudice ( Bosch, 2007 ) .

BRAKE ACTUATING SYSTEM

Between driver ‘s pes and wheel brakes, there are constituents that transmit force from driver ‘s pes into clash force at the brake clash surface. Those constituents act as triping system for the generated force. The system could be mechanical, hydraulic, pneumatic, electric or combination of these. All sort of system will give the same consequence. As the system operated, brakes applied. Brake system application ever begins with driver runing the pedal. Brake pedal are design to find the pes force required to halt the vehicle.

Cable/Linkage Actuated

The simplest brake triping system is a mechanical system. The brake pedal operates rods or overseas telegrams that apply the brake when actuated. The system was widely used in earlier system and still used in modern system for parking brakes. Most of system in modern vehicle are used the hydraulic system. Alternatively of overseas telegrams or rod used to trip the brake, fluid filled line and hosieries are used for propulsion ( Breuer and Bill, 2008 ) . However, overseas telegram and linkage system straight transferred force generated at the pedal without any aid.

Pneumatic

Pneumatic brake actuator systems are by and large used in big commercial vehicles and trucks. The lone advantage of the pneumatic system comparison to hydraulic system is leak safe, where little leak in the system could non do loss in braking due to air invariably supplied by compressor and stored in big reservoir.

However, there are factors that hinder pneumatic brakes. First, air is compressible. Because of that nature, a comparatively big sum of air required to flux from reservoir to brakes chamber before the air is compresses plenty to construct the force per unit area to slow the vehicle ( Ewel, n.d. ) .

The 2nd changeless fact is, air contain wet. While go throughing through the pressure-regulating valve in pneumatic brake system, air expands and go cools. Subsequently, the cool air condenses. In cold environment, this condenses air can stop dead and do the brakes to neglect. In order to get the better of the job, the system must be equipped with drain valve, air drier and intoxicant evaporators ( Ewel, n.d. ) .

Hydraulic

All of rider autos used hydraulic brake system alternatively of pneumatic system because, hydraulic system are smaller and simpler comparison to pneumatic system. In add-on, pneumatic system requires bigger size and more constituents to be installed.

In contrast to pneumatic brakes system, hydraulic brake system require less preventative care such as run outing the reservoir and replenishing the intoxicant evaporator for pneumatic system. Unlike pneumatic system, hydraulic system offers more dependability in term of care cost and downtime over the life of the system ( Ewel, n.d. ) . With all the advantages of hydraulic brakes system, its make it suited and dependable for used in rider auto.

Electro Hydraulic Brakes ( EHB )

In conventional braking system, force from brake pedal transmitted automatically via brake supporter to the wheel cylinder. In contrast to the conventional system, electrohydraulic brakes transmit the brake petition from pedal to wheel cylinder via detectors and ECU ( Bosch, 2007 ) .

Electrohydraulic brakes operate by triping the actuator unit that observing the pedal travel and pedal force per unit area, the information from the actuator unit so transmitted to ECU ( Bosch, 2007 ) . The ECU calculates the signal to be send to wheel force per unit area modulator, which converted the signal into brake force per unit areas for single wheels.The electrical driven hydraulic pump with force per unit area monitoring system provides the hydraulic force per unit area supply to the wheels ( Bosch, 2007 ) .

Since there are no mechanical actuating parts, no quiver felt through the brake pedal, which usually felt in other type of triping system. Other important advantage of the system is it will cut down infinite usage in engine bay.

Antilock Brakes System ( ABS )

The inclination of vehicle maker to increase safety of vehicle has lead to the development of the vehicle intelligent aid system such as ABS. Similar to other intelligent brake aid system such as ESP, EBD and others, the system typically is to help drivers with critical driving state of affairs. In this subdivision, we will merely discourse the ABS system.

ABS brakes were designed to get the better of the job of tyre lock up and uncontrolled spins. Since brakes are most effectual at decelerating the auto at a point merely before wheel lock up, a system that provides wheel braking while forestalling wheel lock up such as ABS is really desirable. The characteristics give ABS a important advantage over conventional brakes system.

In contrast to conventional braking system, ABS can supply a shorter controlled braking distance on a slippery route status. In add-on, ABS will besides heighten the guidance ability, as it will let the driver to safely manoeuvres the vehicle while cornering, as illustrated in figure 1.6.

With electrical interface, the ABS characteristics could be activated utilizing package and detectors, alternatively of extra hydraulic or mechanical constituents.

Figure 1.6 Comparison of ABS braking and Non-ABS braking ( NAZA Wheels, 2010 )

BRAKES TYPE

Most of production auto equipped either with one or both type of braking assemblies. They are drum brakes and phonograph record brakes. Each type offers built-in advantage over the other. However, the operation and map of those brakes will non be discussed, as they are beyond the range of treatment in this paper.

Unlike phonograph records brake, drum brake is more complicated. There are two types of membranophone brakes, individual taking border and dual taking border. Leading border refers to portion of brake shoe that really contact with membranophone relation to beat rotary motion while braking. In contrast to individual taking border, dual taking border have two actuators alternatively of one. Therefore, it will give maximal point of membranophone contact.

Disc brakes already known as better in public presentation comparison to its drum opposite number. As a consequence, they usually fitted to athleticss or high public presentation autos. Standard phonograph record brakes usually have one or two cylinders in them, besides know as one or two pot caliper. Those autos that required more braking ability will utilize three or more cylinders. However, major disadvantage of disc brake is they are intolerant of uneven disc surface, which will do quiver during braking.

Part of phonograph record brake system is rotor. Unlike older type of rotors, new design of brake rotors has come with many characteristics to get the better of the job of heat dissipation every bit good as trapped gas between tablets and rotors. Those design characteristics produced several types of brake rotors such as grooved rotor, grooved drilled rotor, and double vented rotor.

FRICTIONAL MATERIAL

They are several types of stuff being used for clash stuff in brakes besides known as brake tablets. Most of tablets used to utilize asbestos, but the usage of asbestos become lesser as its dust is harmful to wellness and environment. Today, all sort of combinations of stuffs used for tablets. They are several typical stuffs combination for tablets.

Organic tablets are the parks used in barroom auto. These tablets are suited for street drive because they wear good, less noise, soft and less dust. This type of tablets function good in cold status, but less efficient at higher temperature status ( Car Bible, 2010 ) .

Semi metallic or sintered tablets is a better pick for sportier auto as its compromised between street and path usage. However, the drawback in this type of tablets compare to organic tablets is they are noisier ( Car Bible, 2010 ) .

While for metallic tablets, they are typically used in rushing or public presentation auto. Even though the braking efficiency is really good at high scope of temperature, metallic tablets squeals and comparatively produces tonss of dust comparison to other type of tablets. Furthermore, the metallic compound is difficult on rotor and will masticate the rotor up.

Ceramic tablets used about 15 % of metal fibre in its compound. Copper fibre is used alternatively of steel and therefore causes less wear and better heat dissipation. Ceramic tablets have many advantages over other type of tablets. They do n’t easy melt, cool faster, longer lasting and efficaciously soundless. In add-on, they create a minimal dust ( Car Bible, 2010 ) .

BRAKE PRINCIPLES AND ANALYSIS

Nowadays the construction of brake systems has become progressively standardised. The most widely used constellation dwell a pedal incorporated with vacuity assisted brake supporter ( Breuer and Bill, 2008 ) . The brake pedal linked to force rod will make an input force into the supporter. Then the force generated in the brake supporter transmitted to brakes maestro cylinder. The force per unit area from maestro cylinder provides the hydraulic force per unit area that acts on the brake Pistons of the wheel brake, which is transmitted via hydraulic line.

Pedal Unit

The pedal operation is based on basic rule of purchase, which covered by rule of minutes ( figure 1.7 ) .

Turning minute

Figure 1.7

Clockwise Moment = Anticlockwise minutes

F1 ( N ) . Y ( m ) = F2 ( N ) . ten ( m )

Example 1.1: A footbrake lever is 350mm long from pivot to footpad centre. The push rod attached 60mm below pivot point. If force applied to footbrake tablet is 300N, how much force is applied to get the hang cylinder.

Solution:

F1. y = F2. ten

300N Ten 0.35m = F2 X 0.2m

F2 = 300 N X 0.35 m

0.06 m

F2 = 1750 N

The minute of force in brake pedal is defined as a merchandise of force act at perpendicular distance from fulcrum to the line of push rod ( Bonnick, 2008 ) . Pedal ratio ( fig. 1.8 ) , which is tantamount to mechanical advantage, is the distance ratio from pivot of attempt to lade.

Pedal ratio = Velocity ratio = Mechanical advantage

Figure 1.8

The force transmitted to input rod of brake supporter is force applied to the pedal ( Fped ) multiplied with the transmittal ratio of pedal ( iped ) .

Therefore ; Force on brake supporter

F = Fped. iped

Example 1.2: The force applied to the brake pedal is 450N. The motion of footbrake tablet is 80mm. The pedal mechanical advantage is 3.15. If the machine efficiency is 90 % , find the push rod travel and force applied on it.

Solution:

MA = Pedal Travel

Rod Travel

3.15 ( 90 % ) = 0.08 m

ten

ten = 0.0282 m

Force on push rod ;

F = Fped. iped

F = 450N X 3.15 ( 0.9 )

F = 1275.75 N

Vacuum Booster

In the vacuity supporter, the push rod operates the valve of the supporter to let depressions force per unit area flow into working chamber of the supporter. The stop force ( Fdia ) is created by diaphragm force per unit area ( pdia ) on the affectional stop country ( Adia ) ,

Therefore ;

Fdia = Adia. pdia

where ;

Adia = Total diaphragm country – Power Piston country,

pdia = Ambient force per unit area – Manifold force per unit area

The encouragement ratio of vacuity supporter is the consequence from relationship of detector Piston to reaction phonograph record. Therefore, in the computation of the end product force ( FoutB ) of the supporter, the force of return spring ( Fsp ) of the supporter must be taken into consideration ( Breuer and Bill, 2008 ) . The end product force of the brake supporter appears as below:

FoutB = Fdia – Fsp

Where ;

Fsp = ( jumping pre-tension + motion of spring ( m ) X spring rate )

Example 1.3: The stop in the supporter has a diameter of 300mm and the power Piston diameter is 65mm. The diaphragm spring pre-tension is 180N. Spring rate is 30 N/mm and the ambient force per unit area is 110 Kpa. Engine manifold absolute force per unit area is 30 Kpa. Find the maximal aid from vacuity supporter if the power Piston moves 5mm.

Solution:

Fdia = Adia. pdia

Adia = 0.25p ( 0.3 ) o – 0.25p ( 0.065 ) o

= 70.68 Ten 10 A o – 3.31 X 10 A o

Adia = 67.36 X 10 A o

Pdia = 110 Kpa – 30 Kpa

= 80 Kpa

Fdia = ( 67.36 X 10 A o m o ) X ( 80 X 10 o N/mo )

= 5388.8 N

Hence, supporter end product force ;

FoutB = Fdia – Fsp

FoutB = 5388.8 N – ( 180N + 6mm Ten 30 N/mm )

= 5028.8 N

Maestro Cylinder

Master cylinder is component that transmits force created by brake supporter on the maestro cylinder push rod to hydraulic force per unit area in the brake system. The hydraulic force per unit area ( Phyd ) is calculated from the maestro cylinder Piston force ( FoutMC ) and the affectional country of maestro cylinder ( AMC ) as,

Phyd = FoutMC / AMC

= FoutD – FSp.MC

AMC

Where, FSp.MC = ( Piston spring pre-tension + motion of Piston x spring rate )

Figure.9 Cross subdivision position of tandem maestro cylinder

Example1.4: A maestro cylinder being pushed 7mm by 850N force from supporter. Master cylinder diameter is 10mm and spring pre-tension is 12 N. If return spring rate is 3 N/mm, find the force per unit area crated in brake pipe.

Solution:

Phyd = FoutMC / AMC

= FoutD – FSp.MC

AMC

Phyd = 850N – ( 12N + 7mm Ten 3 N/mm )

0.25p ( 0.01 ) o

= 10.40 Mpa

Disc Brake

The computation of force transmitted to the brake unit is different, depending on brake building and characteristic ( e.g. disc brake, drum brake etc. ) . As for phonograph record brake, irrespective any agreement of the brake caliper cylinders, the force ( FoutC ) developed on caliper Piston fundamentally is the hydraulic force per unit area ( phyd ) generated in the system acts on the entire caliper Piston country ( ACP ) ( Breuer and Bill, 2008 ) . The end product force on calipers defines as below:

FoutC = P hyd. ACP

Example 1.5: The maestro cylinder develops a force per unit area of 10.40 Mpa to the brake line, which deliver force per unit area to caliper cylinder. It the calliper Piston diameter is 50mm, find the force developed by calliper Piston.

Solution:

FoutC = P hyd. ACP

FoutC = ( 10.40 x 106 ) N/m2 X ( 0.25 P ( 0.050 ) 2 ) M2

= 20.420 KN

Transmitted force

Braking on the wheels occur when the clash surface ( tablets or run alonging ) Acts of the Apostless on phonograph record or membranophone. The familial force ( Ftrans ) from calliper Piston to the wheel is calculated based on perpendicular end product forced from calliper Piston ( FoutC ) acts on tablets with a deliberate coefficient of clash ( m ) . The coefficient of clash ( m ) is determined with a ratio of frictional force over applied force ( Breuer and Bill, 2008 ) .

Coefficient of clash ; m = Frictional force

Applied force

Hence,

Ftrans = FoutC. m. no. of tablets

Example 1.6: The caliper Piston applies a force of 20.42 KN on the two brake tablets. The coefficient of clash of pars is 0.48. Find the familial force.

Solution:

Ftrans = FoutC. m. no. of tablets

Ftrans = 2042N X 0.48 X 2

= 1.96 KN

Braking Torsion

The braking torsion is the force generate for vehicle to come to halt. The familial force from the brake exerts the frictional force on the wheels, which creates a torsion on axles. The torsion created, acts opposite way of the vehicle motion. Therefore, the vehicle will halt. The braking torsion for the phonograph record brake system is calculated as:

Braking torsion ( TB ) = Ftrans. Effective radius ( R )

Example 1.7: If the distance between the tablet ‘s centre of force per unit area and the centre of disc rotary motion is 0.12m and coefficient of clash between the friction faces is 0.35, find the braking torsion produced by clamping force of 1000N.

Braking torsion ( TB ) = Ftrans. Effective radius ( R )

TB = Ftrans. Roentgen

TB = ( 1000N X 0.35 X 2 ) X 0.12

= 84 Nm

d/2

Effective radius

D/2

Figure 1.10

Drum Brake

For a membranophone brake system, the sample analysis examine the building of simplex membranophone brake is shown in fig 1.11. Other types of brake membranophone ( e.g. dual anchor/double cylinder in fig 1.12, couple servo ) are normally used as a parking brake due to higher brake characteristic value ( Breuer and Bill, 2008 ) . Due to clamping force Acts of the Apostless in the way of rotary motion, self-energizing consequence is achieved with drum brake but non in phonograph records brake system.

Figure 1.11 Double ground tackle, dual cylinder building

The analysis as shown in figure 1-3 is made with premises:

The pivot is fixed.

The places are stiff.

vitamin E = perpendicular distance from pivot to propulsion force.

NA = Force acts on run alonging A and Drum.

n = Horizontal distance from run alonging clash point to the pivot.

m = Vertical distance from NA to the pivot.

m = Coefficient of clash

The braking force can be calculated with the derived equation as follows ;

For taking shoe For draging shoe

FA = me and FB = me

PA ( m-mn ) PA ( m+mn )

Entire Braking Force = FA + FB

Therefore ;

Braking Torque = F. R

Entire Braking Torque = Total braking force Ten Radius

= ( FA + FB ) . R

Niobium

Dad

A

Sodium

m

vitamin E

ten

Y

m

N

R

vitamin E

Figure 1.12 illustrated the forces acts on brake membranophone building and dimensions for computation.

Example 1.8: A brake membranophone has an internal diameter of 0.3m. The distance between the shoe pivot and the points of application of the forces triping the shoe is 0.18m. Assuming the places are centrally positioned in the membranophone and the coefficient of clash between the liners and membranophone is 0.38. Find the braking torsion on each places and entire braking torsion developed by both places, if the triping force if 680N.

Solution:

n = R = 0.15m

m = 0.18/2 = 0.09m

For taking shoe ;

FA = me

PA ( m-mn )

FA = PA me

( m-mn )

= 680N Ten 0.38 X 0.18m

( 0.09m – 0.38 X 0.15 )

= 1409.45 N

Braking Torque ;

= F. R

= 1409.45 Tens 0.15m

= 211.4 Nm

For draging shoe ;

FB = me

PB ( m+mn )

FB = PB me

( m+mn )

= 680N Ten 0.38 X 0.18m

( 0.09m + 0.38 X 0.15 )

= 316.40N

Braking Torque ;

= F. R

= 316.40 Tens 0.15m

= 47.46 Nm

Therefore ;

Total braking Torque = ( FA + FB ) . R

= ( 1409.45 + 316.40 ) N X 0.15m

= 258.87 Nm

BRAKE OF THE FUTURE

There are many betterments has taken topographic point in brakes development, from older membranophone brakes to disc brakes so to multiple calipers. Now, a engineering developed by Siemens VDO called Electronic Wedge Brakes being introduced. The electronic cuneus brakes wholly replaced the conventional hydraulic system. The system is powered by an bing 12-volt power from the auto. In add-on the system has a faster reaction clip, about a 3rd quicker comparison to conventional system. It merely required 100 MSs to make full braking power comparison to hydraulic brake ‘s 170 MS ( Tan, 2007 ) .

The systems work by pressing the brake tablet that connected to the cuneus with cuneus shaped caliper. The calipers are moved by electric motors. With used of wedge rule of application, the braking power is multiplied with minimum energy outgo ( about one ten percent of conventional hydraulic brakes ) . Because of no mechanical connexion at all between brake pedal and calipers, the system can be defined as brake by wire system. Furthermore, because of the system controlled by ECU, other characteristics such as ABS, TCS and ESP can be integrated together with the system. Test consequence comparing Audi A6 fitted with EWB against another A6 with conventional brakes system shows the braking distance from 100 kilometers per hours to 0 kilometers per hour was reduced to half in A6 equipped with EWB ( Tan, 2007 ) .

For safety ground, the EWB is specified to be connected with two power supplies, the chief and the backup with secondary battery.

Figure 1.13 Illustrations of the Electronic Wedge Brakes ( EWB ) constituent

BRAKES SUSTAINABILTY

Brakes system sustainability could be achieved in several ways, either to fabricate the clash stuff with the non-hazardous stuffs, through the lightweight constituent design or through the rule of regenerative braking. Through the lightweight constituent design, it could lend towards cut downing CO2, as the lighter the vehicle the less fuel will be consumed. One agency of cut downing the constituent weight is to replace the constituent stuff with lighter stuffs. However, it could besides be achieved by developing the constituent with used of current stuff such as steel and Fe, but with a difference fabrication methods. For blink of an eye, Continental AG has developed a new procedure in industry the calliper Piston. Alternatively of dramatis personae or turning procedure, it used the imperativeness signifier procedure. It was formed from 3.5 millimeters thick round metal blank into a really thin, light and every bit stable Piston Subsequently, it resulted the Piston weight 25 % less than its dramatis personae predecessor ( Continental AG, 2008 ) .

The production of the brake tablets utilizing the asbestos stuff has stopped due to wellness and environmental issues, is has been replaced with other fibre stuff such as aramid fibers. Recently, they are brake tablets being develop utilizing natural fibers such as hemp and jute.

While, the sustainability attack in context of regenerative braking system could be achieved with energy recycling. Regenerative braking is really a procedure of recapturing and hive awaying the kinetic energy generated by braking for subsequently usage. The energy in signifier of heat that usually dissipated to the air can be stored automatically in signifier of tight air or flywheel, or electrically in capacitances or batteries.

Decision

The brake system has gone through many development epochs since people started utilizing it in traveling vehicle. It seems that, the earlier developments has contributed towards the braking efficiency and dependability. However, ulterior developments are traveling towards sustainability and environmental friendly. There is no uncertainty that the brake engineering has to maintain development as the vehicle engineerings developed.

Together with the brakes engineering, the brakes constituents besides went trough great stage of development, in term of stuff and production procedures. Component developments have produced lighter brakes constituents with the same capablenesss as conventional constituent stuffs. It is evident that, the automotive industries are really traveling towards the sustainability globally. Integrating design characteristics to ease end-of-life recycling and recovery is critical in component production. The tendency will be towards lightweight stuffs and lesser parts in vehicle design.

Through tonss of reading during fixing this paper, tonss of cognition has been gained and it appears that the brake system is a really huge subject to be discussed.

July 12, 2017