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Compatibility of ABS disc/drum brakes on class VIII vehicles with multiple trailers and their effects on jackknife stability

Zagorski, Scott Bradley
http://rave.ohiolink.edu/etdc/view?acc_num=osu1069788894

Abstract Details

2004, Master of Science, Ohio State University, Mechanical Engineering.
A current priority of the National Highway Traffic Safety Administration (NHTSA) is to decrease stopping distances of commercial vehicles. It has been found that longer stopping distances during panic stops increase the chances of collision with other vehicles. By using ABS modulated air-disk brakes in conjunction with electronic actuation (Electronic Control Braking System, ECBS) on the prime mover (i.e. the tractor), the stopping distance can be decreased by as much as 30 %. However, due to fiscal reasons in the trucking industry and the nature of ECBS of adding a fourth line to the system, it has not been implemented on the trailer(s). Thus, there are compatibility issues between the tractor and trailer(s). Previous brake-in-turn studies have been done with single-trailer commercial vehicles. This study investigated the jackknife stability of double tractor-trailer combination vehicles in brake-in-turn maneuvers with varying loads and surface conditions, and brake configurations. TruckSimTM was used to model the vehicle dynamics of the vehicle and MATLAB®’s Simulink®, in parallel, ran NHTSA’s ABS model. A sanity check was performed on TruckSimTM’s doubles package with the aid of experimental data obtained by the University of Michigan Transportation Research Institute (UMTRI) at the Transportation Research Center Inc (TRC). In the Brake-In-Turn studies the tractor utilized a 4s/4m ABS configuration with pneumatic drum, pneumatic disc or ECBS disc brakes. The trailers and dolly utilized a 2s/1m select-high or low ABS control algorithm with pneumatic drum brakes. Conditions with ABS ON for the entire vehicle (and select-high control algorithm on the trailers and dolly) found that instabilities were exhibited under a surface friction coefficient of 0.3. Lane excursions occurred in the dolly and 2nd trailer or a jackknife occurred between the 1st and 2nd trailer. It was demonstrated that these instabilities could be avoided while utilizing a select-low control algorithm on the trailers and dolly. Conditions with ABS OFF for the tractor and on for the rest of the vehicle (with a select-high control algorithm on the trailers and dolly) found instabilities under every condition with the exception of one. The instabilities exhibited were either a lane excursion or jackknife. The difference between a jackknife and lane excursion situation was realized when investigating the discrepancy in time between steer and drive wheel lock-up. The greater difference in lock-up between the steer and drive wheels on a high friction coefficient resulted in a jackknife situation. On a low or medium friction coefficient, the smaller time difference in wheel lock-up increased the jackknife stability, but a lane excursion still occurred. A greater number of jackknife situations occurred on a tractor equipped with pneumatic drum brakes for this same reasoning. The tradeoff between the vehicle equipped with disc and drum brakes was discussed. Simulation results (with ABS OFF on the tractor) showed that a tractor equipped with disc brakes (ECBS or Pneumatic) had greater jackknife stability. However, the vehicle left the intended path at an earlier moment in the maneuver than a tractor equipped with pneumatic drum brakes under the same simulated conditions. A comparison showed that the dolly was the least stable unit in the vehicle with the ABS ON conditions; whereas, with the ABS OFF, the tractor was the least stable unit. A current priority of the National Highway Traffic Safety Administration (NHTSA) is to decrease stopping distances of commercial vehicles. It has been found that longer stopping distances during panic stops increase the chances of collision with other vehicles. By using ABS modulated air-disk brakes in conjunction with electronic actuation (Electronic Control Braking System, ECBS) on the prime mover (i.e. the tractor), the stopping distance can be decreased by as much as 30 %. However, due to fiscal reasons in the trucking industry and the nature of ECBS of adding a fourth line to the system, it has not been implemented on the trailer(s). Thus, there are compatibility issues between the tractor and trailer(s). Previous brake-in-turn studies have been done with single-trailer commercial vehicles. This study investigated the jackknife stability of double tractor-trailer combination vehicles in brake-in-turn maneuvers with varying loads and surface conditions, and brake configurations. TruckSimTM was used to model the vehicle dynamics of the vehicle and MATLAB®’s Simulink®, in parallel, ran NHTSA’s ABS model. A sanity check was performed on TruckSimTM’s doubles package with the aid of experimental data obtained by the University of Michigan Transportation Research Institute (UMTRI) at the Transportation Research Center Inc (TRC). In the Brake-In-Turn studies the tractor utilized a 4s/4m ABS configuration with pneumatic drum, pneumatic disc or ECBS disc brakes. The trailers and dolly utilized a 2s/1m select-high or low ABS control algorithm with pneumatic drum brakes. Conditions with ABS ON for the entire vehicle (and select-high control algorithm on the trailers and dolly) found that instabilities were exhibited under a surface friction coefficient of 0.3. Lane excursions occurred in the dolly and 2nd trailer or a jackknife occurred between the 1st and 2nd trailer. It was demonstrated that these instabilities could be avoided while utilizing a select-low control algorithm on the trailers and dolly. Conditions with ABS OFF for the tractor and on for the rest of the vehicle (with a select-high control algorithm on the trailers and dolly) found instabilities under every condition with the exception of one. The instabilities exhibited were either a lane excursion or jackknife. The difference between a jackknife and lane excursion situation was realized when investigating the discrepancy in time between steer and drive wheel lock-up. The greater difference in lock-up between the steer and drive wheels on a high friction coefficient resulted in a jackknife situation. On a low or medium friction coefficient, the smaller time difference in wheel lock-up increased the jackknife stability, but a lane excursion still occurred. A greater number of jackknife situations occurred on a tractor equipped with pneumatic drum brakes for this same reasoning. The tradeoff between the vehicle equipped with disc and drum brakes was discussed. Simulation results (with ABS OFF on the tractor) showed that a tractor equipped with disc brakes (ECBS or Pneumatic) had greater jackknife stability. However, the vehicle left the intended path at an earlier moment in the maneuver than a tractor equipped with pneumatic drum brakes under the same simulated conditions. A comparison showed that the dolly was the least stable unit in the vehicle with the ABS ON conditions; whereas, with the ABS OFF, the tractor was the least stable unit.
Dennis Guenther (Advisor)
227 p.
Axle; TruckSim; Tire; trailer; brakes; dolly; ABS

Recommended Citations

Citations

  • Zagorski, S. B. (2004). Compatibility of ABS disc/drum brakes on class VIII vehicles with multiple trailers and their effects on jackknife stability [Master's thesis, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1069788894

    APA Style (7th edition)

  • Zagorski, Scott. Compatibility of ABS disc/drum brakes on class VIII vehicles with multiple trailers and their effects on jackknife stability. 2004. Ohio State University, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1069788894.

    MLA Style (8th edition)

  • Zagorski, Scott. "Compatibility of ABS disc/drum brakes on class VIII vehicles with multiple trailers and their effects on jackknife stability." Master's thesis, Ohio State University, 2004. http://rave.ohiolink.edu/etdc/view?acc_num=osu1069788894

    Chicago Manual of Style (17th edition)

osu1069788894
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© 2004, all rights reserved.
This open access ETD is published by The Ohio State University and OhioLINK.