Browse Topic: Brake drums
The use of drum brakes in Battery Electric Vehicles (BEVs) offers numerous benefits, including energy efficiency, reduced brake dust emissions, and reliable performance under challenging weather conditions. The capability of regenerative braking reduces the friction brake application frequency in BEVs and therefore the brakes can be prone to corrosion and performance degradation especially considering conventional disc brake systems. The closed design of a drum brake prevents corrosion of the friction-components by sealing out water, dirt or snow. A common sealing concept is performed with a labyrinth between the gap of the rotating drum and the axle mounted backplate. A hermetical isolation of water and snow ingress into the drum cannot be achieved with this concept, so additional aerodynamic measures are necessary to deflect the air/water path and protect the inner brake components. Additionally, interfaces like wheel cylinders, electric park brake parts, brake shoe pins, and axle mountings can potentially lead to leaks on the backplate. This study highlights the impact of water/snow ingress on the example of a frozen parking brake during cold climate on-road testing. Through scientific investigation using the state-of-the-art fluorescence method, drum leakages were visualized, and the extent of water ingress was measured. Multiple multiphase CFD simulations supported the design phase of the aerodynamic measures. Subsequently, the vehicle was cooled down to -10 °C to simulate the cold climate test conditions. The frozen parking brake situation could be reproduced with this method, and beneficial aerodynamic and sealing measures were extrapolated to avoid the drum brake from freezing. The tests were conducted in the FKFS Thermal Wind Tunnel, a wind tunnel comprising a two-axle-dynamometer and water irrigation systems with UV illumination.
This SAE Recommended Practice is intended for qualification testing for brake drums used on highway commercial vehicles with air brakes using an inertia-dynamometer procedure. This document consists of two distinct tests: Part A, durability and speed maintenance test, and Part B, heat check drag sequence test. Each test can be considered to be an independent evaluation of the brake drum which tests different properties.
This SAE Recommended Practice is intended for measuring the static brake torque performance of a pnuematically actuated brake assembly, friction material, and drum/disc combination on an inertia brake dynamometer.
In Brazil, 20% of the accidents involve commercial vehicles, the high load capacity and the big dimension of commercial vehicles, such bus and trucks, become this situation even more dangerous. To prevent crashes, robust parts and product validation methodologies are essential for a safer and cheaper transport. The drum brake is widely used in commercial transport, due to the cheaper cost of production. The disadvantage of the drum brake system it’s his low thermal dissipation, to decrease the vehicle velocity, the brake converts kinetic energy in thermal energy, causing loss of efficiency, degradation of material mechanical properties and life reduction, these thermal effects can be even more dangerous under extreme conditions, as overload, speeding, over adjustment (dragging), and bad system maintenance. Due the fact that the temperature affects significantly the vehicle performance, especially in drum brakes system, the friction pair is tested under the worst road scenarios, manufacturers often use dynamometers to safely reproduce severe load conditions applied in brake systems. The challenge is to comprehend and reproduce the thermal and mechanical effects on brake drums using Computer Aided Engineering (CAE) to develop safer and cheaper solutions for the commercial vehicles industry. This paper aims to show a case study for a drum brake system, studying the most common failures in dynamometers and their representation in finite element models, allowing an effective prototype project design before the component production. The main target of this study is to search solution ideas for the most common brake drum failures and a better knowledge of combined thermal and mechanical loads acting in the brake structure.
When driving in mountainous areas, vehicles often encounter long downhill sections. Due to the large mass of bus and the drum brake with poor heat dissipation effect, it is easy for bus to produce braking thermal decay in long downhill section, which makes the vehicle out of control and causes safety accidents. The braking methods of parallel hybrid electric bus include drum braking, engine braking and regenerative braking, whose torque models are established in this paper. The coasting test in Trucksim is used to verify the correctness of the engine braking torque model. Based on coupling braking torque curve with vehicle speed in different gradient, the stable speed is determined and the shift strategy is proposed. The temperature rise model of brake drum is established to analyze the temperature change of brake drum during long downhill. Then, according to the ramp data of G22 freeway, the above models are simulated. The results show that shift strategy can make full use of engine braking torque and reduce the temperature rise by 136°C, which is equivalent to 38% of the temperature under drum braking only, effectively reducing the braking thermal decay and ensuring the driving safety. It is also found that regenerative braking also has a great meaning on reducing the temperature rise of brake drum, and the reasonable design of battery management system will make the battery SOC in the appropriate range, which can increase the regenerative braking time. So the viewpoint might provide a new idea to design the battery management system of electric commercial vehicle.
To maintain the vehicle speed in a proper range, the commercial vehicle needs to brake frequently on a downhill path. The drum brake system of the medium- and heavy-duty commercial vehicles often faces the danger of brake fade, which reduces brake efficiency or even causes braking failure. They are critical potential risks on the road. The kinetic energy is transferred into thermal energy during the braking process. The temperature rises dramatically during the braking process due to the massive thermal energy caused by the huge mass of the commercial vehicle. The brake efficiency and the life of the brake drum will decrease with the rising temperature. A malfunction of the brake system may occur if the drum brake is overheated. To improve the cooling efficiency of the drum brake, a forced-air cooling system driven by the air compressor in the diesel is designed for the drum brake system after the analysis of its thermal model. A computational fluid dynamics (CFD) model is established and modified after comparison with the test result. Based on this modified model, the parameters of this system are optimized through adaptive particle swarm optimization (APSO). This optimized forced-air cooling system decreases the maximum temperature of the brake system from 291.9°C to 200°C under the most critical work condition. It allows the commercial vehicle to operate in a safer situation with a lighter weight compared to the current water cooling system.
On account of the traditional friction brake for heavy-duty truck (HDT), the massive quantity of heat accumulating constantly because of frequent using of friction brake system in the long and steep downhill road leads to brake temperature rising rapidly. Affected by structure frictional couple installed in the closed environment of the brake drum, it is difficult to dissipate the heat in time via heat conduction, heat radiation and heat convection, and the heat fade phenomenon of the brake emerges easily. The HDT would be in danger because of braking efficiency descending. This paper proposes an active water-cooled drum brake system (AWBS) to solve the problem. According to the principle of engineering thermodynamics, the structure and size of the back-stretching water jacket of brake shoe and the inner riveted the friction plate of brake drum are designed with restrained of GB 12676-2014 ‘Technical requirements and testing methods for commercial vehicle and trailer braking systems’. In order to meet the requirements of heat dissipation and structural strength for tractor and trailer, the composition and parameters of AWBS are proposed, including volume and type of coolant, radiator size, hydraulic pump parameters, tank capacity and connection type. To verify the performance of the system, the three-dimensional model and simulating model are established to simulate, the simulation results show that structure meet s strength requirements and the AWBS can significantly inhibit the rise of brake temperature, reduce the probability of brake thermal decay of heavy truck on long downhill, and improve the driving safety of the vehicle significantly.
Brake drum in commercial vehicles is very important aggregate contributing towards major weight in brake system module. The main function of brake drum is to dissipate kinetic energy of vehicle into thermal energy, as a results in braking operation major load comes on brake drum. Hence this is very critical component for vehicle safety and stability [1]. Objective of this paper is to increase the pay load, which is utmost important parameter for commercial vehicle end customers. To achieve the light weighing target, alternate materials such as Spheroidal graphite iron (SGI) has been evaluated for development of brake drum. Many critical parameters in terms of reliability, safety and durability, thickness of hub, wheel loading, heat generation on drum, manufacturing and assembly process are taken into consideration. The sensitivity of these parameters is studied for optimum design, could be chosen complying each other’s values. Digital thermal performance evaluated in house, fine-tuned and verified by correlating with test data available for existing cast iron design and then applied for new design with alternate materials. In two different designs around 10 Kgs weight saving per brake drum has been achieved as compared to conventional grey cast iron brake drum. Considering the most demanding 10x2 haulage platform in current commercial market approximately 100 Kgs payload increment for fleet owners was achieved, which will result in end customer profitability.
This SAE Recommended Practice is intended for qualification testing for brake drums used on highway commercial vehicles with air brakes using an inertia-dynamometer procedure. This Recommended Practice consists of two distinct tests: Part A - durability and speed maintenance test, and Part B - heat check drag sequence test. Each test can be considered to be an independent evaluation of the brake drum which tests different properties.
Brake system is the most important system in the vehicle considering the overall vehicle safety and speed control. Brake applications are repetitive during a city traffic and hilly terrain on downhill gradient. Frequent braking gives rise to an overheating of the brake drum and its components. Braking operations at high temperature gives rise to problems like reduced deceleration due to loss of brake pad friction characteristics, pad softening and sticking to drum, pad distortion and wear etc. All these factors collectively result in deterioration of the braking performance and reduction of brake pad durability with time. Till date most of the thermal analysis performed for brake drum heating are through physical testing using brake system prototypes and by means of CFD tools. These methods are time consuming and expensive. There is a need for an alternative method to reduce physical trials and prototype building and reduce dependency on CFD analysis. The present paper focuses on developing 1D mathematical model of drum brake system using Model Based Design (MBD) approach. By MBD methodology, the entire mathematical model is built by discretizing every component of brake system in finite metal masses connected with relevant heat transfer units. These units characterize the different modes of heat transfer viz conduction, convection and radiation. Convective heat transfer variation over drum and pad surfaces based on the change in vehicle speed is also accounted. The model simulates the temperature variations at different locations within the brake drum assembly. It is capable of simulating temperature change for various duty cycle profiles accounting change in brake energy due to vehicle speed. This model can be used in predicting temperature variation in the early stages of brake system design enabling the possibility of optimizing system for specific requirement.
Overheating in commercial vehicles, even though if it’s in LCV segment, is a problem of high significance. There could be various level of problems that may arise due to heat generation resulting from braking (oversized brake drums left the wheels with lesser packaging clearances for air flow and cooling) and some of them are: 1. Early tire wear /reduction in tire life, 2. Air valve heat damage /air leak issues, 3. Frequent puncture problems, 4. Failure of other mating components and other heat initiated failures. However optimum the vent hole shape in a wheel may be, the air flow in the vicinity of drum periphery and wheel rim ID wouldn’t be sufficient enough because of the lesser clearance and packaging space as mentioned earlier. The basic construction of a wheel with disc welded to rim base ID was apparently modified to integrate the disc and gutter and weld it to rim OD. This provides additional 8mm clearance with a normal brake drum and hence effective heat dissipation from the wheel - brake - tire assembly. Adding to the above, the Disc Gutter Wheel has better packaging clearance, having more than 300 cc of additional packaging, this paves way for it to be used with caliper brakes and not only with drum brakes and with clearance for better air flow and cooling. With this the Disc Gutter Wheel and its mating components does a cooler service than the regular versions. Zero Gutter crack/failure and freedom of flow forming options allowing for a robust design are additional benefits of the product.
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