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Technical Paper

“Triple-Safe” Air Brake System: Service, Emergency, Parking

1971-02-01
710211
The term triple safe is used to identify an air brake system with three separate circuits, two of which are service brake systems of virtually equal effectiveness; the third is a spring parking brake system. The paper reviews the spring parking brake chamber capability and describes a triple-safe air brake system and chambers that have similar service and emergency capacities, and parking capabilities, to meet future requirements of trucks and buses.
Journal Article

“Sticky” Lining – the Phenomena, Mechanism and Prevention

2008-04-14
2008-01-0819
An unique bonding mechanism was studied after several instances, where the linings stuck to the brake drums on transit buses, were reported. Evidences suggested that the linings were “glued” to the brake drums surface after wear debris (dust) was turned into “adhesive paste” through complicated thermal and chemical changes. Factors such as the friction materials, environment and service conditions, which could activate and deactivate the lining bonding, were observed and discussed. The prevention measures are proposed.
Technical Paper

“ROADRUNNER”-Real-time simulation in anti-lock brake system development

1995-02-01
950758
The simulation system “Roadrunner” has the ability to compute 3-dimensional vehicle behavior during simulated ABS-stops or Traction Control (TC) operation on a PC based test rig system. This can be done in real-time mode with fast DSP (digital signal processor) boards and an ABS/TC-ECU as a ‘Hardware-in-the-loop’ device (HIL) or off-line (non-real-time), on the PC only. In the off-line-mode, the PC additionally performs the ABS/TC control algorithms. The simulated system includes model equations for chassis and wheel movement, hydraulics and road to tire interactions. A driver model enables the reproduction of standard steering maneuvers.
Technical Paper

‘Wheel Slip-Based’ Evaluation of Road Friction Potential for Distributed Electric Vehicle

2016-04-05
2016-01-1667
As a typical parameter of the road-vehicle interface, the road friction potential acts an important factor that governs the vehicle motion states under certain maneuvering input, which makes the prior knowledge of maximum road friction capacity crucial to the vehicle stability control systems. Since the direct measure of the road friction potential is expensive for vehicle active safety system, the evaluation of this variable by cost effective method is becoming a hot issue all these years. A ‘wheel slip based’ maximum road friction coefficient estimation method based on a modified Dugoff tire model for distributed drive electric vehicles is proposed in this paper. It aims to evaluate the road friction potential with vehicle and wheel dynamics analyzing by using standard sensors equipped on production vehicle, and fully take the advantage of distributed EV that the wheel drive torque and rolling speed can be obtained accurately.
Technical Paper

iLokTM Nut - An Innovative Fastener that Solves a 30 Year Old Problem for Rear Axle Hub Assemblies

2019-04-02
2019-01-0339
Truck and bus manufacturers have been constantly facing an issue to disassemble the rear axle shaft from the hub when transporting the truck from the factory to the dealership. In addition to that, the dealerships have the very same problem every time they have to replace the brake pads in some truck models, which leads to excessive service time, extra costs and aftermarket complaints. The current problematic fastening system is composed by a lock nut, a flat washer and a coned slotted bushing. The concept of this 30 year old design involves the coned slotted bushing being pressed against a tapered hole on the shaft’s flange. After tightening the lock nut, the bushing clamps towards the stud and it gets stuck in between the shaft and the stud generating the problem described above. This paper shows the R&D process that Tekfor used to come up with the 1-piece fastener named iLokTM nut that replaces the problematic 3-piece fastening system.
Technical Paper

eBrake® - The Mechatronic Wedge Brake

2002-10-06
2002-01-2582
eBrake® (1, 2) - a new “brake-by-wire” technology, was developed at the German Aerospace Centre, DLR e.V.. It is based on an electric powered controlled friction brake with high self-reinforcement capability. To avoid jamming the brake a special control technology was developed. Thus, by intelligently controlling a brake wedge, the kinetic energy of a vehicle is transformed into braking power. Furthermore an advanced design was found to deal with a broad variation of the friction coefficient. The physical effects involved lead to a significant reduction of energy consumption of the brake actuator compared to “conventional” brake-by-wire systems.
Journal Article

eABS: Regenerative Anti-Lock Braking for Electric Motorcycles

2013-09-30
2013-01-2064
Linked front and rear braking systems are difficult to implement properly on motorcycles due to the large changes in wheel loading under braking. At the braking limit, there is little to no load on the rear wheel and any brake torque could lock it, making the vehicle laterally unstable. Therefore, most motorcycles have independent controls for the front and rear brakes, requiring the rider to balance the brake force distribution. Electric motorcycles have the ability to utilize the drive motor to apply braking torque at the rear wheel. In this paper a control technique has been developed to link rear wheel braking torque to the front brake lever without risking rear tire lock. Thereby, it is also possible to recapture the energy from rear wheel braking. The control strategy has been tested on a transient pitch model, with rotating wheels and tire model data.
Journal Article

Yawing Angular Misalignment Provides Positive Damping to Suppress Frictional Vibration: Basic Applicability to Disc Brake Systems

2013-09-30
2013-01-2069
A novel method for suppressing frictional vibration in sliding systems without using additional devices (e.g., dampers or actuators) is theoretically proposed. This method is based on the principle that yawing angular misalignment provides positive damping to sliding systems. Even if frictional vibration occurs due to a negative slope of the friction versus velocity characteristic, it can be suppressed by applying a misalignment angle φ that is larger than the critical misalignment angle φcr. To examine the basic applicability of this method to disc brake systems, a braking test at a constant normal load was simulated numerically. It was found that yawing angular misalignment can not only suppress frictional vibration but also shorten the braking time as a secondary effect of suppressing frictional vibration.
Technical Paper

Yaw/Roll Stability Modeling and Control of HeavyTractor-SemiTrailer

2007-08-05
2007-01-3574
This paper sets up a simplified dynamic model for simulating the yaw/roll stability of heavy tractor-semitrailer using Matlab/Simulink. A linear quadratic regulator (LQR) based on partial-state feedback controller is used to optimize the roll stability of the vehicle. The control objective for optimizing roll stability is to be reducing the lateral load transfer rate while keeping the suspension angle less than the maximum allowable angle. The simulation result shows that the LQR controller is effective in the active roll stability control of the heavy tractor-semitrailer.
Journal Article

Yaw Stability Enhancement of Articulated Commercial Vehicles via Gain-Scheduling Optimal Control Approach

2017-03-28
2017-01-0437
In this paper, a gain-scheduling optimal control approach is proposed to enhance yaw stability of articulated commercial vehicles through active braking of the proper wheel(s). For this purpose, an optimal feedback control is used to design a family of yaw moment controllers considering a broad range of vehicle velocities. The yaw moment controller is designed such that the instantaneous tractor yaw rate and articulation angle responses are forced to track the target values at each specific vehicle velocity. A gain scheduling mechanism is subsequently constructed via interpolations among the controllers. Furthermore, yaw moments derived from the proposed controller are realized by braking torque distribution among the appropriate wheels. The effectiveness of the proposed yaw stability control scheme is evaluated through software-in-the-loop (SIL) co-simulations involving Matlab/Simulink and TruckSim under lane change maneuvers.
Technical Paper

Yaw Stability Control of Tractor Semi-Trailers

2008-10-07
2008-01-2595
Tractor semi-trailer stability during emergency braking and steering maneuvers has been an issue that was improved through implementation of Anti-lock Braking Systems (ABS). Although some improvements have been achieved, the need for new control methodologies is evident from the number of accidents reported by NHTSA involving tractor semi-trailers. In this paper, a new control algorithm has been developed for improving the tractor semi-trailer stability through utilization of yaw moment, i.e., tire differential braking strategy. This new, multifaceted, adaptive control algorithm which allows the estimation of the unknown vehicle parameters through use of the adaptation laws is based on the Lyapunov Direct Method. A tractor semi-trailer model with four degrees of freedom was used to develop the control algorithm and the adaptation laws. The controller was implemented on a 2-axle tractor 1-axle van trailer in TruckSim 7©.
Technical Paper

Yaw Stability Control and Emergency Roll Control for Vehicle Rollover Mitigation

2010-10-05
2010-01-1901
In this paper a yaw stability control algorithm along with an emergency roll control strategy have been developed. The yaw stability controller and emergency roll controller were both developed using linear two degree-of-freedom vehicle models. The yaw stability controller is based on Lyapunov stability criteria and uses vehicle lateral acceleration and yaw rate measurements to calculate the corrective yaw moment required to stabilize the vehicle yaw motion. The corrective yaw moment is then applied by means of a differential braking strategy in which one wheel is selected to be braked with appropriate brake torque applied. The emergency roll control strategy is based on a rollover coefficient related to vehicle static stability factor. The emergency roll control strategy utilizes vehicle lateral acceleration measurements to calculate the roll coefficient. If the roll coefficient exceeds some predetermined threshold value the emergency roll control strategy will deploy.
Technical Paper

Wrought Magnesium Components for Automotive Chassis Applications

2011-04-12
2011-01-0077
Automotive structural components are exposed to high loads, impact situations and corrosion. In addition, there may be temperature excursions that introduce creep as well as reduced modulus (stiffness). These issues have limited the use of light metals in automotive structural applications primarily to aluminum alloys, and primarily to cast wheels and knuckles (only a few of which are forged), cast brake calipers, and cast control arms. This paper reports on research performed at Chongqing University, Chongqing China, under the auspices of General Motors engineering and directed by the first author, to develop a protocol that uses wrought magnesium in control arms. The goal was to produce a chassis part that could provide the same engineering function as current cast aluminum applications; and since magnesium is 33% less dense than aluminum, would be lighter.
Technical Paper

Wire Bonding with Corrosion Resistant Wire for Under-the-Hood Automotive Applications

1997-02-24
971009
Wire bonding has become one of the primary methods of interconnection for automotive-electronic units. This includes: ignition modules, pressure sensors, voltage regulators, anti-lock braking modules, air-bag systems, distributoriess ignition modules, etc. As the technologies in the automotive field increases, both the wire bonders and the wire have to keep pace. One of the improvements over the past few years was the development of corrosion resistant wire used for automotive-electronic applications. Corrosion resistant wire is unique in that there are some essential dopants in the wire that prevent the wire from physical damage.
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Wiley SAE MOBILUS® eBook Package

2018-03-23
Committed to being the primary source for aerospace and ground vehicle engineering resources, SAE International has added the full compilation of our Wiley eBook collections to the SAE MOBILUS® technical resource platform. Purchasable as an annual subscription and containing the titles from the Wiley Aerospace Collection, the Wiley Automotive Collection, the Wiley Computer Systems Collection, and the Wiley Cyber Security Collection.
SAE MOBILUS Subscription

Wiley Automotive Collection

2018-03-23
Purchasable as an annual subscription, the Wiley Automotive Collection contains 20 eBook titles and focuses on a wide range of categories, including engines, transmission, chassis, body, electrical, safety, and manufacturing. Titles covering new and emerging topics such as battery technology and electric and hybrid vehicles are included as well, making the series an essential addition to any institution’s automotive resources.
Technical Paper

Why Disc Brakes

1965-02-01
650172
A family of disc brake systems, capable of braking vehicles with gvw's from 3000-6000 lb, has been developed and released on the 1965 Lincoln and Thunderbird with power brakes as standard equipment, and on the 1965 Mustang with manual brake as an option. These systems, while retaining the desirable characteristics of current drum brake systems, provide significant performance advantages in the areas of fade resistance, stability, and serviceability. The disc brake systems on the Ford products consist of a ventilated rotor, in conjunction with a fixed, multiple-piston caliper utilizing segmental brake linings. Duo-servo rear brakes are used with a hydraulic proportioning valve which compensates for the nonlinear rear brake output.
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