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中文简体Trucks are equipped with drum brakes that use friction and rotation to slow and stop the vehicle. These brakes are prone to heat checking, which is cracking of the brake drum’s braking surface. Heat checking can occur in a number of ways.
This study aims to establish a prediction model for the brake-drum temperature by applying energy conservation law. It has a full theoretical foundation and allows users to customize its main parameters, such as initial brake-drum temperature, downgrade length and percentage, and truck weight and speed.
Brake Shoes
The brake shoes carry the friction material in drum brake systems. They're fastened to a curved piece of metal known as the brake drum. When a driver applies the brakes, hydraulic pressure from the wheel cylinder forces the brake shoes against the drum, slowing the vehicle down. Return springs return the shoes to their rest position when the brakes are released.
Brake drums are made of cast iron or aluminum, and they have a machined friction surface on the inside. The braking strength of the drum depends on how well the friction materials match up with the surface.
A poorly matched pair can cause brake fade, which reduces the effectiveness of the drum and disc brakes. When brake drums show signs of wear, they should be resurfaced or replaced. Check the drum for heat stress cracks, gouges and severe hot spots. Also, measure the interior diameter of the drum to ensure it's within specification before reuse.
Brake Pads
Brake pads are composed of a durable material that absorbs the force required to bring your truck to a stop. Originally, brake pads were made with asbestos, but since then they’ve been replaced with non-asbestos materials that are just as efficient at absorbing the friction necessary for braking.
When you step on the brake pedal, your truck’s master cylinder converts electrical power into hydraulic pressure, which is then delivered through tubing to the wheel cylinders that push the brake shoes against the brake drums. Some drum brake systems even compensate for load by adjusting the wheel cylinder pressure, a feature not found in disc brakes.
The type of brake pad that you choose depends on the size of your truck, how much weight you often haul and the terrain to which it will be exposed. Organic brake pads are a good choice for most drivers, as they tend to generate less dust than semi-metallic or metallic alternatives.
Brake Lines
Brake lines deliver the pressure that causes calipers to clamp and drum shoes to engage. They're made of a flexible steel piping. Stainless steel brake lines resist corrosion and don't swell up like rubber ones can, which decreases brake fluid pressure and reduces overall braking power.
Manufacturers found in recent decades that coating plain steel lines with polyvinyl fluoride greatly increases their resistance to rust and corrosion. PVF-coated metal brake lines last as much as 30 times longer than a standard uncoated steel line.
Performance brake lines are made of a variety of materials, including braided carbon fiber, Kevlar or Teflon. They can be expensive to install, but they improve pedal feel and performance with no compromises to driving safety. Braided lines are also a good choice, as they can't swell up and degrade braking performance like rubber ones. They require regular inspection for nicks and tears, though. When you install new brake lines, use a tube cutter to get an accurate cut that's clean with minimal fraying.
Brake Drums
Truck brake drums are typically made of a special form of cast iron. This is because they need to be strong enough to stand up to the intense friction and heat generated when a truck stops. They must also be able to dissipate this heat rather than gather it in one spot.
Brake drums are often lined with a steel or aluminum liner, which improves their durability and allows them to operate at lower temperatures than iron. Regardless of the material used to line the drum, it's important to inspect the surface for signs of wear or damage.
Sometimes a brake drum becomes warped or rough, which reduces its ability to disperse heat or create friction with the brake shoes. This can lead to brake drag, which causes the driver to push the pedal harder for adequate braking power. Brake fade can also cause a drum to overheat, which decreases the amount of energy it converts into kinetic energy.
