How Are Brake Drums Made?

The materials, process, and exhibits all contribute to how brake drums are made. However, these techniques do not address the problem of thickness variations around the circumference of a drum, a problem that causes non-uniform wear and noise. Truck manufacturers have set a maximum thickness variation and weight limit for drums. Manufacturers also incur scrap costs when drums do not meet these specifications. To avoid these costs, the manufacturer should focus on ensuring that the drums are consistent and high-quality.

Exhibits

Brake drums are metal boxes that provide a non-pitched tone. Similar to an anvil, they can be heavier or lighter, depending on the manufacturer. Brake drums are hung from a nylon cord, mounted to a snare drum stand, and struck with varying weights. Here is a closer look at the manufacturing process. A computer-based controller 87 receives position-indicating output signals from sensors 78 and controls the position of a pneumatic drive mechanism 88. The lift and lowering motion of elevator 74 and platform 76 are controlled by mechanism 94. The platform 76 and ring 28 are held in place by tooling 82, which carries a set of welding torches 96.

A conventional brake drum is manufactured by forming the jacket of a ring with an annular band of sheet steel. Then, molten grey iron is centrifugally cast into the band and metallurgically bonded to the ring. The ring is then externally fixtured and machined to provide an internal cylindrical surface known as a rough bore. The inner surface of the drum flange 24 is then machined, and the entire assembly is conveyed to a subsequent station for a full weld.

One of the most important aspects of brake drum manufacturing is their durability. Unlike disc brakes, they can withstand significant heat, and they are more effective and efficient when braking. Disc brakes have similar features, but they are more expensive and require more maintenance. However, disc brakes offer advantages in terms of engineering and cost, and allow easy integration of a parking brake. However, the weight is an issue with drum brakes.

Process

The process of manufacturing brake drums includes fabricating the drum ring from steel stock. The ring comprises a pressed steel shell having radial flanges H on one edge and circumferentially spaced holes. The drum is then machined to the required dimensions, including the openings for mounting. These steps are performed at separate manufacturing stations. This improves the overall manufacturing process. Once the drum ring is machined, the drum is then assembled using the mounting axis.

After the machining of the ring and the flange, the back 16 is placed on the drum ring. It is then positioned such that the center axis of the openings is coaxial with the first harmonic of radial runout. After being positioned, the drum back assembly is tack-welded to the drum ring. The process of manufacturing brake drums is repeated until the desired diameter is achieved.

The brake drum sprue should be at least 40 mm from the brake drum. In small factories, this distance is lessened to minimize porosity. The molding sand should be at least 60-80 mm from the sprue. Smaller factories often hit the sand on a whole. After this, they insert a steel rod to tighten the mold. This method is best for minimizing porosity and ensuring quality and consistency.

A typical brake drum is manufactured in a conventional manner. In the case of truck brake drums, the applicants’ assignee forms the jacket as an annular band of sheet steel. Then, grey iron is centrifugally cast into this band to form a metallurgically-bonded composite ring. Then, the ring is externally fixtured and a cylindrical surface is machined on the inwardly facing surface.

Sensors

Electromechanical drum brakes have a high potential in electromobility and automated driving. These brakes are controlled by a controller, but variations in electromechanical actuator efficiency can cause variation in the brake torque and drum friction coefficient. Integrated brake torque sensors are one option to prevent such variations. However, integrated brake torque sensors have yet to be manufactured in series production. This paper explores the possibility of an integrated brake torque sensor. Regardless of the design of a new brake system, an integrated sensor may play an important role.

Despite the convenience of brake sensors, they are not the most exciting feature of your car. These are purely functional, however, and are designed to increase safety. In order to check brakes manually, you have to remove the wheels one by one and check the brake pads one at a time. The traditional method is also tedious and inconvenient. Moreover, not every car comes equipped with brake sensors. But if you have a vehicle that does, you can take advantage of brake sensors and inspect them yourself.

The basic wear sensor systems usually have one or more sensors installed in each corner of the brake rotor. These sensors are embedded in the brake pad’s inner layer. The number of sensors can vary depending on the model of your car. Some brake systems use a single sensor while others have up to four sensors. Regardless of the type of sensor, most of them work with two parallel resistor-involved circuits. The first circuit contacts the brake rotor face, ‘cocking’ a fault matrix. If this circuit breaks, the second circuit is tripped and the dashboard light is triggered.

When you replace a brake drum, make sure to check the sensors as well. They may be damaged due to heat and friction. Besides, it’s not a good idea to reuse old brake sensors with new brake pads. This will not work properly. As a general rule, brake drum sensors are only functional if they are replaced when the brake pad itself needs to be changed. In the worst case scenario, brake pad replacement is the best option.

Materials

Metals commonly used to manufacture brake drums include steel, cast iron, aluminum, and ceramics. While asbestos was the first choice for this component, it was linked to health hazards and was not used any longer. Nowadays, brake drums are typically made of composite materials, which contain various elements such as ceramic, cellulose, chopped glass, and rubber. These materials also retain friction properties. These brake components are critical for safety and performance, and are often subjected to high temperatures.

Metals used in brake drums may be either organic or inorganic. Organic drums are made from glass, carbon, Kevlar, and rubber, and they are typically more lightweight than inorganic drums. Some companies may even use a combination of materials. Some of these materials are listed below. These materials are widely used because they are lightweight and can be cast easily. They also have good dimensional stability.

Conventionally manufactured brake drums include a backplate with a plurality of openings. These openings are offset from the central axis of the drum. The mounting disc is then welded to the back plate with openings for mounting the drum. A backplate comprises a plurality of outwardly directed strengthening ribs. The drum back assembly is then tack welded to the drum ring.

The backplate of the brake drum absorbs the torque created by braking action. Because all braking operations place pressure on this part, it must be strong and wear-resistant. The drum itself is made from a special type of cast iron that is heat-conductive and resistant to wear. Brake drums must be durable enough to withstand the torque load generated when a brake shoe hits the frictional wear surface. In addition, they must also have robust bolt attachments to the hub. The McManus requirement requires that the brake drum be fatigue-resistant and have adequate strength over its life.

Location of manufacture

The present invention relates to a method of manufacturing brake drums, particularly truck-specific brake drums. The brake drum is constructed of an annular sheet-steel drum jacket and a central back with mounting openings positioned to produce zero first harmonic radial runout. The brake drum ring is then machined to a substantially uniform thickness by a centrifugal cast-iron process.

After finishing the fabrication, the brake drums are placed on a balancing machine. In order to achieve the proper weight-balance around the axis of rotation, one or more weights may be affixed to the periphery of the drum. After the drums are balanced, they are placed on a stand and then struck with a variety of weights to produce the desired sound.

The drums are comprised of six separate parts: the adjuster mechanism, the brake shoes, and the emergency braking mechanism. Each part must stay close to the drum to function properly. If the shoes are separated too far from the drum, the brake pedal will sink to the floor mat, requiring more effort to stop the car. To avoid this, the brake pedal must be pushed down. During this process, the shoes must remain close to the drum to maximize braking force.

Brake drums are a critical component of a car’s braking system. They reduce the vehicle’s speed by preventing a crash. In addition, brake drums help prevent the wheels from overheating, and the shoes will continue to wear if the brake shoes are not adjusted. Unlike brake pads, brake drums do not absorb water, making them highly susceptible to corrosion and wear. Hence, brake drums are important parts of any car.

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