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Proceedings ArticleDOI

Heavy truck deceleration rates as a function of brake adjustment

01 Feb 1991-SAE transactions (Society of Automotive Engineers)-Vol. 100, Iss: 2, pp 22-38
About: This article is published in SAE transactions.The article was published on 1991-02-01. It has received 25 citations till now. The article focuses on the topics: Brake.
Citations
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Journal ArticleDOI
TL;DR: In this paper, a mathematical model of the mechanical subsystem of the trailer brake axle is described, which consists of a brake actuator, an application device and a drum brake, and the model is used for testing transient processes in the air braking systems of tractor and truck trailers.
Abstract: A mathematical model of the mechanical subsystem of the trailer brake axle is described, which consists of a brake actuator, an application device and a drum brake. In the differential equation of motion, the total force from the mechanical subsystem reduced to the piston is described with a two-range linear-exponential model. The parameters of this model were determined using numerical identification, based on experimental, quasi-static curves of pressure in the air brake chamber as a function of pushrod displacement. An example of use of the mechanical subsystem mathematical model to simulate the dynamics of a single-axle agricultural trailer’s dual-line braking system with the Matlab- Simulink software is provided. The obtained results confirmed that the developed model is useful for testing transient processes in the air braking systems of tractor and truck trailers. The proposed experimental force curve determination method can also be used in the diagnostics of brake adjustment.

11 citations


Cites background from "Heavy truck deceleration rates as a..."

  • ..., 2003; Mahanty and Subramanian, 2009) or pushrod displacement (Heusser, 1991) in the simulation of vehicle braking....

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Journal ArticleDOI
TL;DR: In this article, a mathematical model for the mechanical subsystem of the air brake system that can be used to monitor this clearance is presented, and the results are corroborated with experimental data.
Abstract: Most commercial vehicles such as buses and trucks use an air brake system, often equipped with an S-cam drum brake, to reduce their speed and/or to stop. With a drum brake system, the clearance between the brake shoe/pad and the brake drum may increase because of various reasons such as wearing of the brake shoe and/or brake drum and drum expansion caused by high heat generation during the braking process. Hence, to ensure proper functioning of the brake system, it is essential that the clearance between the brake shoe and the brake drum is monitored. In this paper, we present a mathematical model for the mechanical subsystem of the air brake system that can be used to monitor this clearance. This mathematical model correlates the push rod stroke transients and the brake chamber pressure transients. A kinematic analysis and a dynamic analysis of the mechanical subsystem of the air brake system were performed, and the results are corroborated with experimental data.

9 citations


Cites methods from "Heavy truck deceleration rates as a..."

  • ...The equations developed by Heusser (1991) through regression analysis relate the push rod stroke to the brake torque and the brake application time....

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  • ...The method developed by Kandt et al. (2000) combined the masses of the mechanical subsystem, and the governing equations of motion were given in terms of the push rod stroke....

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Journal ArticleDOI
TL;DR: In this article, the authors conducted a 2-year study of the effect of heavy-vehicle mechanical condition on road safety in the province of Quebec, Canada and found that heavy vehicles are responsible for 10 to 20 percent of accidents involving this type of vehicle in Quebec.
Abstract: A 2-year study was conducted of the effect of heavy-vehicle mechanical condition on road safety in the province of Quebec, Canada. The results in this summary include an evaluation of the effect of an existing annual heavy-vehicle mandatory mechanical inspection program (MMIP) on road safety and its effectiveness in improving heavy-vehicle mechanical condition. The effect of various mechanical components on road safety and the importance of their periodic inspection also are analyzed. Among the main findings were (a) heavy-vehicle mechanical condition is responsible for 10 to 20 percent of accidents involving this type of vehicle in Quebec; (b) if older vehicles (12 years or more) are not taken into account, the MMIP seems to prevent accidents caused by mechanical defects for a subsequent period of 2 to 3 months; (c) the MMIP is not fulfilling its mandate adequately, because the observed frequency of heavy vehicles with noncomplying mechanical components is high, independent of the elapsed period since the last MMIP; (d) heavy vehicles affected by major noncomplying components have a propensity to be involved in accidents that is five times higher than that of complying vehicles; (e) the braking system is the most affected by major noncomplying components; (f) the braking system comes in first when the dangerousness of mechanical components is considered, followed by tires, chassis, and steering system; (g) the inspection program is not equally effective in identifying defect locations; (h) heavy vehicles are responsible for 46 percent of the accidents in which they are involved; (i) pretrip inspections appear to be the ideal complement to the MMIP in preventing accidents caused by mechanical defects. Based on these findings, recommendations are made on the inspection program, the data, and braking system maintenance to improve the mechanical condition of heavy vehicles and to reduce accidents caused by mechanical defects.

7 citations

References
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01 Apr 1985
TL;DR: In this article, the authors provide detailed vehicle information and test data that support the technical report (Volume 1) and a detailed vehicle test data analysis (Appendices A through G).
Abstract: This volume consists of Appendices A through G which provide detailed vehicle information and test data that supports the technical report (Volume 1)

11 citations

01 Apr 1985
TL;DR: In this article, a number of different types of heavy duty air-braked vehicles including buses, trucks, truck tractors and trailers were tested to determine their stopping capability in straight line and turning maneuvers on various types of road surfaces including ice.
Abstract: A number of different types of heavy duty air braked vehicles including buses, trucks, truck tractors and trailers were tested to determine their stopping capability in straight line and turning maneuvers on various types of road surfaces including ice. In addition, the braking force distributions of the vehicles were experimentally determined, several different brake proportioning systems were evaluated and the effect of initial brake temperature on stopping capability was investigated. Results of the testing indicate that stable stopping capability is primarily determined by brake force distribution. If brake force distribution is close to the normal force distribution on the axles of a vehicle, its stopping capability will be optimum; however, if brake force distribution does not match normal force distribution, premature wheel lockup and loss of control will occur before the vehicle is able to achieve full utilization of the friction forces available at the tire/road interface. Brake force distribution on most heavy duty vehicles is fixed at a level that favors the loaded condition and therefore they do not perform as well in the empty condition. In addition, many heavy duty vehicles are "underbraked" on their front steering axles under all operating conditions and would benefit even in the loaded mode if front brake force level was increased. Devices that adjust braking distribution as a vehicle's load changes appear to provide very significant gains in braking performance not only in the straight line stopping situation but also in braking and turning maneuvers.

6 citations