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Different approaches on how to improve braking performance in M3 vehicles to meet secondary brake requirements from ECE R13 regulation through low cost solutions

Industrial and Systems Engineering Graduate Program PUCPR-Roberto Zanetti Freire
Volvo Bus Corporation-Luciano Ferreira da Cruz
  • Technical Paper
  • 2019-36-0011
Published 2020-01-13 by SAE International in United States
The braking system of any road vehicle is subject to extensive legislative standards and requirements in many regions around the world. In buses, which belong to M3 category, one of the most critical demands is occupancy rate of passengers that leads to affect Gross Vehicle Weight (GVW). More and more, customers are pushing the manufactures to increase the GVW of buses to allow more passengers inside and consequently increase profitability of the operation. By increasing GVW braking system has to present better performance to fulfill requirements. ECE R13 regulation establishes 2.5m/s2 as minimum Mean Fully Developed Deceleration (MFDD) and 64,4meters as maximum Stopping Distance (SD) acceptable to secondary brake performance. In a 4x2 vehicle with GVW of 19.5 tons fitted with disc brakes these requirements are actually fulfilled, but by adding 600 kg it became out of requirements. Based on the parameters which might affect braking performance, three different approaches were studied, tested and disposed in a decision matrix to choose most feasible in terms of performance, costs, manufacturing and time to implementation: a new…
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Experimental analysis of engine cooling capacity at different altitudes: a case study for biarticulated gas engine bus at high altitude

Scania Latin America-Gabriel Prado de Oliveira, Bruno Afonso Garcia
  • Technical Paper
  • 2019-36-0272
Published 2020-01-13 by SAE International in United States
The demand for mass public transportation is growing on the major urban areas worldwide along with stricter demands on exhaust gas emission levels driven by society’s concern on the environment, leading to the development of sustainable transport solutions. Some of the solutions to reduce emission levels, such as electrified powertrains, may not be affordable for emergent markets due to the necessity of investments on infrastructure as well as high costs of some technologies. Bogotá city in Colombia is renewing its bus rapid transit (BRT) fleet and aims to reduce emission levels in its operation. Therefore, the development of a biarticulated bus driven by a compressed natural gas (CNG) Otto engine can be a sustainable solution for such application reducing both emission levels and fuel costs (compared to a Diesel model). However, the development of a cooling system for such bus becomes a challenge due to several factors that have a negative impact on cooling performance such as: high gross train weight (GTW); high altitude application; CNG Otto engine (compared to a Diesel model) and limited…
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Analysis of High Cycle Fatigue In Welded Joints Of Profiles With Thin Walls Used In Bus Structures Subjected To Combined Loads Through Comparative Analysis

Marcopolo SA-Eng. Felipe Biondo
Universidade Federal do Rio Grande do Sul (UFRGS)-Dr. Eng. Afonso Reguly, Dr. Eng. Marcelo Favaro Borges
  • Technical Paper
  • 2019-36-0074
Published 2020-01-13 by SAE International in United States
Projects of bus body structures must be developed taking into consideration the dynamic loads that this type of vehicle is subjected to. Experimental and numerical methods can be used to evaluate fatigue life in order to determine the durability of these vehicles. Bus structures are basically constructed using welded thin walled profiles that are often oversized due to the lack of knowledge of several product characteristics such as the conditions of the pavements, deficiency of characterization of welded joints and the quality of the materials used. Allied to this the Brazilian road system counts on several types of roads, presenting roads in good conditions of conservation until roads in precarious conditions with extremely high severity. In addition, vehicle safety standards have been intensifying their requirements. With that in mind, bus body manufacturers are investing in research to produce more durable, efficient and safe buses, expanding the search through engineering tools to develop better and more competitive products. The aim of this work was to analyze high cycle fatigue life of welded joints of thin-walled profiles…
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Rolling Resistance Measurement Procedure for Passenger Car, Light Truck, and Highway Truck and Bus Tires

Highway Tire Committee
  • Ground Vehicle Standard
  • J1269_201912
  • Current
Published 2019-12-10 by SAE International in United States
This SAE Recommended Practice applies to the laboratory measurement of rolling resistance of pneumatic passenger car, light truck, and highway truck and bus tires. The procedure applies only to the steady-state operation of free-rolling tires at zero slip and inclination angles; it includes the following three basic methods:
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Akasol packs industry-leading energy density into new battery design

SAE Truck & Off-Highway Engineering: December 2019

Bill Visnic
  • Magazine Article
  • 19TOFHP12_08
Published 2019-12-01 by SAE International in United States

Projecting the market for full-electric and hybrid-electric commercial vehicles will continue to expand, Germany-based lithium-ion battery specialist Akasol recently announced production-readiness of a newly-developed battery pack that sets an energy-density benchmark. The company's president also confirmed Akasol will build a manufacturing facility in the Detroit area targeted to begin production in mid-2020.

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EDITORIAL: Hop on the hydrogen highway

SAE Truck & Off-Highway Engineering: December 2019

Editor-in-Chief-Ryan Gehm
  • Magazine Article
  • 19TOFHP12_06
Published 2019-12-01 by SAE International in United States

Two years ago at the inaugural North American Commercial Vehicle (NACV) Show in Atlanta, a recurring theme from nearly every truck manufacturer and supplier press conference was vehicle uptime, along with the various telematics and connectivity solutions that enable fleet managers to keep their trucks on the road. While these certainly were important topics at this year's NACV Show, the dominant takeaway from the Georgia World Congress Center was that alternative propulsion is top of mind for many industry players.

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Impact of Wheel-Housing on Aerodynamic Drag and Effect on Energy Consumption on an Electric Bus Body

ARAI Academy-Amitabh Das, Yash Jain
Automotive Research Association of India-Mohammad Rafiq Agrewale, Kamalkishore Vora
  • Technical Paper
  • 2019-28-2394
Published 2019-11-21 by SAE International in United States
Role of wheel and underbody aerodynamics of vehicle in the formation of drag forces is detrimental to the fuel (energy) consumption during the course of operation at high velocities. This paper deals with the CFD simulation of the flow around the wheels of a bus with different wheel housing arrangements. Based on benchmarking, a model of a bus is selected and analysis is performed. The aerodynamic drag coefficient is obtained and turbulence around wheels is observed using ANSYS Fluent CFD simulation for different combinations of wheel-housing- at the front wheels, at the rear wheels and both in the front and rear wheels. The drag force is recorded and corresponding influence on energy consumption of a bus is evaluated mathematically. A comparison is drawn between energy consumption of bus body without wheel housing and bus body with wheel housing. The result shows a significant reduction in drag coefficient and fuel consumption.
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Conceptualization and Modeling of a Flywheel-Based Regenerative Braking System for a Commercial Electric Bus

SAE International Journal of Commercial Vehicles

Delhi Technological University, India-Kunal Mathur, Lalit Kumar Choudhary, Aditya Manoj Natu, Krovvidi Srinivas, Vikas Rastogi
  • Journal Article
  • 02-12-04-0018
Published 2019-11-19 by SAE International in United States
The following article illustrates the detailed study of the development of a unique flywheel-based regenerative braking system (f-RBS) for achieving regenerative braking in a commercial electric bus. The f-RBS is designed for installation in the front wheels of the bus. The particular data values for modeling the bus are taken from multiple legitimate sources to illustrate the development strategy of the regenerative braking system. Mechanical components used in this system have either been carefully designed and analyzed for avoiding fatigue failure or their market selection strategies are are explained. The positioning of the entire system is decided using MSC Adams View®, hence determining a suitable component placement strategy such that the f-RBS components do not interfere with the bus components. The entire system is modeled on MATLAB Simulink® with sufficient accuracy to get various results that would infer the performance of the system as a whole. The overall efficiency of the developed system in terms of battery consumption is also computed in this study.
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Windshield Glare from Bus Interiors: Potential Impact on City Transit Drivers at Night

SAE International Journal of Transportation Safety

OSHTECH Incorporated, Canada-Peter Pityn, Sue Clouse-Jensen
  • Journal Article
  • 09-07-02-0008
Published 2019-11-15 by SAE International in United States
Windshield glare at night is a safety concern for all drivers. Public transit bus drivers also face another concern about glare caused by interior lighting sources originally designed for passenger safety. The extent to which interior light reflections contribute to glare is unknown. Unique methods for measuring discomfort and disability glare during bus driving were developed. An initial simulation study measured windshield luminance inside of a New Flyer D40LF diesel bus parked in a controlled, artificial, totally darkened test environment. Findings indicated significant disability glare (from elevated luminance) in the drivers’ primary field of view due to interior reflections. Any reduction in contrast would result in less prominent glare if actual driving conditions differ. To assess this, levels of windshield glare were also measured with the bus parked on the roadside under the “background glow” of the urban environment. Findings reveal that under road conditions the extent of disability glare from interior reflections is much less, but not negligible, when contrast is reduced. The information gathered in these studies may be useful to manufacturers and…
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Parking Brake Drawbar Pull Test Procedure - Truck and Bus

Truck and Bus Brake Systems Committee
  • Ground Vehicle Standard
  • J1729_201910
  • Current
Published 2019-10-17 by SAE International in United States
This SAE Recommended Practice provides a test method and instructions for measuring performance of parking brakes on air- or hydraulic-braked vehicles equipped with in-wheel or drive-line parking brakes. This procedure applies to truck-tractors, trailers, trucks, and buses.
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