Types of Truck Brakes and How to Choose it?

Different truck brakes are available in the market, each with pros and cons. The provision of the correct type of brake is more critical in trucks, which are approximately 20 times heavier than ordinary vehicles. This emphasises the importance of different types of brake systems used in trucks.

This article explores different types of truck brakes, the working of each style, and the advantages and disadvantages of each kind in providing road safety.

Discussed below in detail are the 4 different types of truck brakes, their working, advantages and disadvantages.

1. Air Brakes

For large vehicles such as buses and trucks, the dominant type of brake is the air brake system. They are known for their reliability and are heavily used for commercial freights.

Working:

The operation of air brakes in the truck is a simple and efficient procedure. Here's a concise explanation-

• Air is pressurised by an engine-mounted compressor.
• The compressed air is then stored in the air storage tanks.
• Compressed air from the front end will pull on the service brakes and release the parking brake.
• Pressurised air moves across a piston, translating the force to create friction and stopping the vehicle.

Advantages:

• Unlimited Supply: Unlike hydraulic brakes, where one uses hydraulic fluid, air brakes never run out of their operating fluid as they get supplied with a total amount of air.
• Minor Leak Tolerance: Air brakes are fail-safe, and despite small leaks, they can still stop a vehicle safely.
• Ease of Coupling: Air line couplings are more easily fit and removed than hydraulic lines. It avoids air entering into hydraulic fluid with no brake service bleeding.
• Potential Energy Storage: Force can also be controlled by compressed air, and therefore, air-brake systems have air tanks capable of sustaining the application of brakes even when there is a failure on the compressor side.

Disadvantages:

• Higher Cost: Initially, installing air brakes is often more expensive than hydraulic brakes, which should be considered in purchasing.
• Moisture Issues: Air dryers must eliminate the moisture from air compression. Initially, the price is much more costly because it entails high purchase and maintenance.
• Maintenance Knowledge: A driver must know enough about air brake maintenance. Before getting on the road, they must check that each tank is working correctly and that the entire air pressurisation system is functioning properly.
• Specialised Skills: Running a vehicle fitted with an air brake system demands specialised knowledge and ability because its blunders may lead to significant accidents and financial implications.

2. Hydraulic Brakes

Hydraulic brakes are of central importance for reliable and practical braking systems. These brakes operate on the principle of  Pascal’s law of liquids under pressure.

Working:

Hydraulic brakes function according to a straightforward but efficient principle. Here's a concise explanation-

• The push rod applies the pressure on the piston(s) of the master cylinder when the brake pedal is pressed.
• This force initiates brake fluid from the reservoir through the compensating port to the pressure chamber.
• The pressure of braking fluid within the system rises.
• This pressure is transmitted to relatively big-area pistons that push against the brake shoes.
• When the brake shoes rub against the rotor, frictional force produces a braking torque that slows down the truck.

Advantages:

• Equal Braking: Uniform braking of all wheels gives better control and stability for hydraulic brakes.
• Simplicity: Hydraulic systems are more accessible to design, maintain and repair than mechanical systems.
• Extended Brake Pad Life: They are famous for their wear-resistant brake pads, hence cutting the repair costs.
• Adaptive Brake Linings: Precise control can be achieved through brake linings of hydraulic systems, which adapt themselves to diverse driving conditions.

Disadvantages:

• Fluid Leakage = System Failure: Failure to pump inert fluids, which would lead to complete system shutdown due to leaking of brake lining fluid, would make it vulnerable to total system failure.
• Air Impacts Performance: The system needs meticulous air removal since any present air will reduce the efficiency of the brakes.
• Complex Maintenance: This is a regular activity, but it may also be expensive, considering proper cleaning of fluids and leakage.
• Intricate Construction: Repairs of hydraulics require advanced knowledge and specialist tools.

3. Transmission Brakes

The transmission brake is a unique and innovative brake system used in trucks. Contrary to the conventional braking system that functions directly on the wheel, transmission brakes act on the transmission system.

Working:

Here is a concise explanation of how transmission brakes work-

• Simultaneous activation of the forward and reverse clutch packs in the automatic transmission at the stall speed of a torque converter constitutes transmission or service brakes.
• This allows the engine to make full power before being passed to the driveline to hold the vehicle in place.
• The transmission brakes use either a dog clutch or a pawl, whereby there remains a secure grip on the vehicle while it is stationary.
• Engaging or using these brakes whilst moving can be dangerous and may even cause damage; therefore, it should never be done.
• Transmission brakes use the vehicles’ transmission and work by putting indirect pressure on the wheels instead of direct force.
• The truck operators may steer the vehicle and regulate the engine throttles for more control, in addition to using the transmission brake.

Advantages:

• Drivetrain Lock: The transmission brake, a common brake type which locks up an entire drivetrain of the vehicle, ensures that a four-wheel drive vehicle provides safe braking action.
• Uniform Pressure: With transmission brakes, constant and consistent pressure over the pads ensures effective braking.

Disadvantages:

• Cost: The cost associated with installing and maintaining a set of transmission brakes is also high.
• Specialised Repairs: Transmission brake maintenance is something that only some auto repair shops can work on.
• Performance Variation: Performance may depend on diverse types of vehicles under various conditions.
• Limited Control: Under some circumstances, such as an off-track condition or extreme lateral cornering, differential action within the drivetrain might permit some vehicle motion.

4. Disc Brake

Disc brakes are a common and effective brake system in trucks. They are very competent in braking power, which comes in handy for heavy vehicles, such as trucks and trailers.

Working:

• Discs provide friction to slow down or stop a vehicle. They squeeze the brake pad onto a rotor or disc to accomplish this.
• These disc brakes convert kinetic energy into heat energy and thus bring the rotational speed of a shaft (for example, motorised axle shaft) to a halt.
• The calliper applies pressure on the brake pads, which pushes them against the spinning disc, leading to frictional force.
• The combination of brake discs, callipers, and pads enables the trucks to stop efficiently when the driver applies pressure on the brake pedal for safe movements.

Advantages:

• Superior Stopping Performance: Thanks to good heat dissipation when it comes into contact with air, disc brakes are highly efficient in stopping, even in the most challenging circumstances.
• Firm Grip: They offer good traction, especially in moist conditions, which does not allow much water accumulation that could hinder overall performance.
• Rim-Friendly: This implies that disc brakes avoid wearing out wheel rims, hence reducing maintenance costs and increasing the wheel’s  l life.
• Enhanced Pedal Feel: Rear disc brakes may provide better pedalling control, resulting in precise and controlled braking.

Disadvantages:

• Higher Cost: Regarding cost for vehicle owners, these disc brakes are more expensive than others and thus impact initial costs significantly.
• Increased Weight: These brakes affect the vehicle’s fuel economy, adding weight and reducing manoeuvrability.
• Complex Maintenance: Maintenance may be challenging since it requires specialist tools and knowledge.
• Difficulty in Pad Replacement: Changing brake pads for disc brakes involves precision and is often done with specialised tools.

Some of the critical factors to consider when choosing the right type of truck brakes are:

• Determining the existing truck braking system.
• Checking if a brake booster is present.
• Carefully analysing the callipers.
• Considering the driving needs.
• Identifying the manufacturer of the ideal part.

In this article, we have explored the broad domain of different types of truck brakes, ranging from transmission brakes to modern disc brakes, along with efficient air and hydraulic brakes and delved into the pros and cons of each type of truck brake. However, choosing the right type of truck brake is more than just a matter of convenience.