Possible beneficial of application of TMPS on city buses

Cilj istraživanja je bio da se ustanovi da li bi ugradnja TPMS -a (uređaja za kontrolu pritiska i temperature u pneumaticima) na nove gradske autobuse imala tehničko i ekonomsko opravdanje. Za potrebe istraživanja sproveden je eksperiment u Gradskom saobraćajnom preduzeću u Beogradu. Na jedan gradski autobus bio je ugrađen TPMS sa šest davača koji je prethodno uspešno testiran na putničkom vozilu. Zadatak vozača autobusa bio je da popuni odgovarajući obrazac nakon dolaska i pre polaska sa zadnje stanice. U obrazac su unošeni sledeći podaci: vreme upisivanja, datum upisivanja, stanica i pritisci i temperature koju pokazuju davači. Pritisci vazduha u pneumaticima su podešeni na propisane pre početka ispitivanja. Tokom ispitivanja oni su se menjali u skladu sa promenom temperature vazduha u pneumaticima. Padovi pritisaka vazduha u pojedinim pneumaticima, nakon mesec dana rada, kretali su se između 3% (o,2 bar) i 4% (0,3 bar). Izuzetak je bio prednji levi pneumatik gde je zabeležen pad od 12% ili 0,9 bar. Obradom rezultata dobijene su i srednje temperature vazduha u pneumaticima. One su bile, zavisno od položaja točka na vozilu, između 27oC i 36oC. Maksimalna izmerena temperatura iznosila je 56oC. Sprovedena je i cost-benefit analiza i dobijeni rezultati ukazuju da bi se investicija u TPMS vratila u drugoj godini eksploatacije i da bi se njihovom ugradnjom unapredila bezbednost i komfor autobusa. .This research should provide the answer if there are technical and financial justifications the Tire Pressure Monitoring System to be included in tender for purchase of new buses for Belgrade Transport. For this purpose Tire Pressure Monitoring System (TPMS) was purchased and previously successfully tested on the passenger car for more than 1000 km. Six TPMS sensors are mounted on valves (instead of caps) of outer tires, and receiving control unit in the drivers cab. Equipped bus was operating for one month. Drivers of the buses had the task to fill in the appropriate form with the data about tire pressure and temperatures, during the breaks on the end of the each route. Tires pressure declined till the end of experiment differently from tire to tire; the differences are between 3% (0.2 bar) and 4% (0.3 bars). Front left tire is exception and the pressure drop on this tire is 12% or 0.9 bars. Average bus tire air temperatures during experiment were between 27 oC and 34 oC. Maximum recorded temperature was 56 oC, and it was attained in evening not in rush time. Research and Cost Benefit Analysis indicated that the investment would pay back in second year and existence of TPMS on the buses would increase the safety and quality of transport.

Possible beneficial of application of TMPS on city buses

Cilj istraživanja je bio da se ustanovi da li bi ugradnja TPMS -a (uređaja za kontrolu pritiska i temperature u pneumaticima) na nove gradske autobuse imala tehničko i ekonomsko opravdanje. Za potrebe istraživanja sproveden je eksperiment u Gradskom saobraćajnom preduzeću u Beogradu. Na jedan gradski autobus bio je ugrađen TPMS sa šest davača koji je prethodno uspešno testiran na putničkom vozilu. Zadatak vozača autobusa bio je da popuni odgovarajući obrazac nakon dolaska i pre polaska sa zadnje stanice. U obrazac su unošeni sledeći podaci: vreme upisivanja, datum upisivanja, stanica i pritisci i temperature koju pokazuju davači. Pritisci vazduha u pneumaticima su podešeni na propisane pre početka ispitivanja. Tokom ispitivanja oni su se menjali u skladu sa promenom temperature vazduha u pneumaticima. Padovi pritisaka vazduha u pojedinim pneumaticima, nakon mesec dana rada, kretali su se između 3% (o,2 bar) i 4% (0,3 bar). Izuzetak je bio prednji levi pneumatik gde je zabeležen pad od 12% ili 0,9 bar. Obradom rezultata dobijene su i srednje temperature vazduha u pneumaticima. One su bile, zavisno od položaja točka na vozilu, između 27oC i 36oC. Maksimalna izmerena temperatura iznosila je 56oC. Sprovedena je i cost-benefit analiza i dobijeni rezultati ukazuju da bi se investicija u TPMS vratila u drugoj godini eksploatacije i da bi se njihovom ugradnjom unapredila bezbednost i komfor autobusa. .This research should provide the answer if there are technical and financial justifications the Tire Pressure Monitoring System to be included in tender for purchase of new buses for Belgrade Transport. For this purpose Tire Pressure Monitoring System (TPMS) was purchased and previously successfully tested on the passenger car for more than 1000 km. Six TPMS sensors are mounted on valves (instead of caps) of outer tires, and receiving control unit in the drivers cab. Equipped bus was operating for one month. Drivers of the buses had the task to fill in the appropriate form with the data about tire pressure and temperatures, during the breaks on the end of the each route. Tires pressure declined till the end of experiment differently from tire to tire; the differences are between 3% (0.2 bar) and 4% (0.3 bars). Front left tire is exception and the pressure drop on this tire is 12% or 0.9 bars. Average bus tire air temperatures during experiment were between 27 oC and 34 oC. Maximum recorded temperature was 56 oC, and it was attained in evening not in rush time. Research and Cost Benefit Analysis indicated that the investment would pay back in second year and existence of TPMS on the buses would increase the safety and quality of transport.

Comparative analysis of characteristics of passenger car tires in Serbia

U radu su predstavljeni rezultati istraživanja stanja i karakteristika pneumatika koji se voze u Srbiji. Prikupljeni su podaci o pohabanosti dezena, dimenzijama, starosti, marki, tipu više od 700 pneumatika kao i podaci o vozilima na kojima su montirani. Osnovni zaključak je da je stanje pneumatika dobro, odnosno znatno bolje nego što je sanje voznog parka u Srbiji. Prosečna izmerena dubina šare protektora bila je oko 5 mm, a prosečna starost kontrolisanih pneumatika oko 3 godine. Značajan deo pregledanih vozila bio je opremljen zimskim pneumaticima. Prva istraživanja (Beograd, novembar 2009) o korišćenju zimskih dala su dobre rezultate sa oko 25% automobila opremljenih sa takvim gumama. Tokom drugog istraživanja (Beograd, juli 2010) uočen je pad od oko 5%. U Užicu, gde su sprovedena istraživanja u novembru 2010 godine utvrđeno je da se taj procenat popeo na 50%. Struktura i starost voznog parka u Srbiji su ocenjeni kao nezadovoljavajući. Sa sadašnjim stepenom obnove voznog parka, takvo stanje će se veoma polako menjati na bolje što će uticati i na strukturu i karakteristike pneumatika koje će vozači u Srbiji kupovati u narednim godinama.The paper presents the results of the condition and characteristics of tires that are in use in Serbia. Data on wear patterns, sizes, ages, brand, type, more than 700 tire and vehicle information to which they are mounted. Data about tread depth, dimensions, tire age, brand and type of more then 700 tested tires were gathered, as well as information about vehicles to which they are mounted on. Primary conclusion on tire condition is positive, notably better then than the Serbian vehicle fleet condition. Average age of tires was around three years and measured tread depth about 5 mm. A significant part of the examined vehicles was equipped with winter tires. First survey (Belgrade, November 2009) for winter tire usage had good showings with around 25% cars equipped with such tires. During the second survey (Belgrade, July 2010) decline of about 5% was found. In Užice, where survey was conducted in November of 2010 it was found that the percentage of winter tires increased up to 50%. Structure and age of the passenger cars fleet in Serbia have been assessed as unsatisfactory. With the current level of fleet renewal such a situation will be very slowly changing for the better and that will affect both the structure and characteristics of tires that will be bought in Serbia in the coming years. With the current level of renewal of the fleet, such situation will be very slowly changed for the better that will affect the structure and characteristics of tires that that will be purchased in the coming years in Serbia

Cost benefit analysis of Belgrade tram rolling stock

Tramvajski saobraćaj ima važno mesto i perspektivu u sistemu javnog gradskog prevoza u Beogradu. Sagledavajući sadašnje stanje i buduće potrebe, Grad Beograd planira revitalizaciju, rehabilitaciju i osavremenjivanje ovog vida prevoza. Zadatak "Cost-benefit analize tramvajskog voznog parka", prikazane u radu, bio je da predloži takav način obnove tramvajskog voznog parka koji bi, uzimajući u obzir sva tehnička, finansijska i vremenska ograničenja, građanima Beograda obezbedio bezbedan, komforan i ekonomičan prevoz u narednih 20-30 godina. Za analizu je korišćen specijalizovani računarski program za višekriterijumsku analizu Criterium Decision Plus.The tram traffic has important place and good perspective in Belgrade public transportation system. According to the current state and to the future needs, city of Belgrade plans revitalization, rehabilitation and modernization of this form of transportation. The mission of "Cost-benefit analysis of Belgrade tram rolling stock" was to recommend renewal of tram rolling stock in a manner that would, seeing the all technical, finance and time limits, provide safe, cozy and economical transport to the citizens of Belgrade in the next 20-30 years. For analysis was used special computer program for multimeasure analysis Criterium Decision Plus

Comparative analysis of characteristics of passenger car tires in Serbia

U radu su predstavljeni rezultati istraživanja stanja i karakteristika pneumatika koji se voze u Srbiji. Prikupljeni su podaci o pohabanosti dezena, dimenzijama, starosti, marki, tipu više od 700 pneumatika kao i podaci o vozilima na kojima su montirani. Osnovni zaključak je da je stanje pneumatika dobro, odnosno znatno bolje nego što je sanje voznog parka u Srbiji. Prosečna izmerena dubina šare protektora bila je oko 5 mm, a prosečna starost kontrolisanih pneumatika oko 3 godine. Značajan deo pregledanih vozila bio je opremljen zimskim pneumaticima. Prva istraživanja (Beograd, novembar 2009) o korišćenju zimskih dala su dobre rezultate sa oko 25% automobila opremljenih sa takvim gumama. Tokom drugog istraživanja (Beograd, juli 2010) uočen je pad od oko 5%. U Užicu, gde su sprovedena istraživanja u novembru 2010 godine utvrđeno je da se taj procenat popeo na 50%. Struktura i starost voznog parka u Srbiji su ocenjeni kao nezadovoljavajući. Sa sadašnjim stepenom obnove voznog parka, takvo stanje će se veoma polako menjati na bolje što će uticati i na strukturu i karakteristike pneumatika koje će vozači u Srbiji kupovati u narednim godinama.The paper presents the results of the condition and characteristics of tires that are in use in Serbia. Data on wear patterns, sizes, ages, brand, type, more than 700 tire and vehicle information to which they are mounted. Data about tread depth, dimensions, tire age, brand and type of more then 700 tested tires were gathered, as well as information about vehicles to which they are mounted on. Primary conclusion on tire condition is positive, notably better then than the Serbian vehicle fleet condition. Average age of tires was around three years and measured tread depth about 5 mm. A significant part of the examined vehicles was equipped with winter tires. First survey (Belgrade, November 2009) for winter tire usage had good showings with around 25% cars equipped with such tires. During the second survey (Belgrade, July 2010) decline of about 5% was found. In Užice, where survey was conducted in November of 2010 it was found that the percentage of winter tires increased up to 50%. Structure and age of the passenger cars fleet in Serbia have been assessed as unsatisfactory. With the current level of fleet renewal such a situation will be very slowly changing for the better and that will affect both the structure and characteristics of tires that will be bought in Serbia in the coming years. With the current level of renewal of the fleet, such situation will be very slowly changed for the better that will affect the structure and characteristics of tires that that will be purchased in the coming years in Serbia

Cost benefit analysis of Belgrade tram rolling stock

Tramvajski saobraćaj ima važno mesto i perspektivu u sistemu javnog gradskog prevoza u Beogradu. Sagledavajući sadašnje stanje i buduće potrebe, Grad Beograd planira revitalizaciju, rehabilitaciju i osavremenjivanje ovog vida prevoza. Zadatak "Cost-benefit analize tramvajskog voznog parka", prikazane u radu, bio je da predloži takav način obnove tramvajskog voznog parka koji bi, uzimajući u obzir sva tehnička, finansijska i vremenska ograničenja, građanima Beograda obezbedio bezbedan, komforan i ekonomičan prevoz u narednih 20-30 godina. Za analizu je korišćen specijalizovani računarski program za višekriterijumsku analizu Criterium Decision Plus.The tram traffic has important place and good perspective in Belgrade public transportation system. According to the current state and to the future needs, city of Belgrade plans revitalization, rehabilitation and modernization of this form of transportation. The mission of "Cost-benefit analysis of Belgrade tram rolling stock" was to recommend renewal of tram rolling stock in a manner that would, seeing the all technical, finance and time limits, provide safe, cozy and economical transport to the citizens of Belgrade in the next 20-30 years. For analysis was used special computer program for multimeasure analysis Criterium Decision Plus

Impact of feed rate, milling depth and tool rake angle in peripheral milling of oak wood on the cutting force

The paper presents the results of investigations performed in the peripheral milling of oak wood (Quercus robur), where the impact of cutting regime elements and tool geometry on the cutting force is analyzed. A large-scale experiment was conducted to implement the obtained results in developing a reliable analytical and simulation model for analyzing and predicting the cutting forces, depending on the feed rate, the milling depth and the tool rake angle. The generated mathematical model is adequate and describes accurately enough the dependence of the cutting forces upon the selected impact factors in the adopted test conditions. The evaluation of the model parameters significance indicates a significant impact of feed rate and milling depth, whereas tool rake angle does not show any significant impact in this case. The developed mathematical model can be employed in manufacturing conditions as an indicator of wood and wood-based materials machinability

Tire operating costs

U radu je analiziran uticaj faktora koji direktno utiču na troškove eksploatacije pneumatika. Kao primer uzeti su podaci dobijeni praćenjem životnog ciklusa pneumatika montiranih na točkove gradskih autobusa. Napravljena su poređenja za šest pneumatika različitih proizvođača prema nabavnoj ceni, veku protektora, ukupnom veku i jediničnim troškovima eksploatacije pneumatika. Analiza je dopunjena i poređenjem efekata koje pneumatici imaju na životnu sredinu. .Factors directly affecting the costs of tire exploitation are discussed. Data obtained by following the lifetime of tires of the city buses are shown. The purchase price, retread life, tire life and unit tire cost are compared for six tires produced in different companies. In addition a comparative analysis of the ecological effects of the tire exploitation is pursued.

Research of the effect of saw blade set dullness on the dimensions of longitudinally cut fir and spruce slats

This paper analyzes the problem of choosing the best way of operating and maintaining a set of circular saws intended for longitudinal processing. The study objective was the analysis of current procedures of tools usage and recommendations for their improvement, in order to achieve better quality and longer operating life of tools. The tested set (24+5 blades) was mounted on multisaw blade machine which produces slats from fir or spruce planks for three-layer parquet. Changes in thickness of sawed slats, operation time between two sharpenings and blade size changes after removing saw blades from machine and aftesharpening, were monitored. Control x-charts were used for stability evaluation. Work quality of saw blade set for longitudinal cut of fir and spruce planks was presented by cost-effectiveness ratio, ratio of total costs (for purchase of set and its servicing) and volume of sawed timber. The saw blade set did not reach the targeted coefficient based on the previous tests. After each sharpening, the set had a different persistence presented in time, and we could not determine the work dynamics. The persistence of saw blade set was affected by wood resin that accumulates on the saw blade surface, the method and angles of sharpening, work dynamics and the continuity of cutting

Tire operating costs

U radu je analiziran uticaj faktora koji direktno utiču na troškove eksploatacije pneumatika. Kao primer uzeti su podaci dobijeni praćenjem životnog ciklusa pneumatika montiranih na točkove gradskih autobusa. Napravljena su poređenja za šest pneumatika različitih proizvođača prema nabavnoj ceni, veku protektora, ukupnom veku i jediničnim troškovima eksploatacije pneumatika. Analiza je dopunjena i poređenjem efekata koje pneumatici imaju na životnu sredinu. .Factors directly affecting the costs of tire exploitation are discussed. Data obtained by following the lifetime of tires of the city buses are shown. The purchase price, retread life, tire life and unit tire cost are compared for six tires produced in different companies. In addition a comparative analysis of the ecological effects of the tire exploitation is pursued.