What Are Retarders On A Truck – What You Should Know!

Are you trying to get a CDL driving license and you are interested in learning what are retarders on a truck? If so, you’re in luck because there’s a lot to cover on this subject where we’ll learn everything there is to know about these kinds of brakes.

Each week, a collection truck’s brake system is put through a tremendous amount of stress in some of the harshest conditions. In traffic situations ranging from the freeway to dense urban traffic to the constant stop-and-go of the collection route, the truck must maintain normal braking functions.

What Are Retarders on a Truck

Let’s get started now before we discuss more complicated subjects like the different kinds of retards that exist. Let’s first examine what retarders are in general. Knowing this will be very helpful, particularly for newcomers who are not interested in trucks and want to learn more about the brakes on a semi-truck. Therefore, without further ado, let’s introduce ourselves to the subject and discover what retarders on a truck are.

The word “retarder” refers to something that retards, as the name suggests. This indicates that the vehicle deliberately slows down so that it loses momentum and comes to a stop.

Consider a torque converter or another object that is spinning quickly. A good illustration of this process of retardation is the torque converter in automatic transmissions. There is a device inside the torque converter that, in order to function, slows the driveshaft’s speed, lessens the vehicle’s momentum, and aids in the vehicle’s ability to come to a stop. This device uses hydraulic fluid.

Therefore, if your vehicle has an automatic torque converter, you undoubtedly have one of these retarders. The car loses momentum and comes to a stop every time you take your foot off the gas. despite minimal braking.

Although there are a few different types of these retarders that are utilized, the process in trucks is somewhat different. which we’ll discuss later in the article. Knowing what truck retarders are right now is crucial for you.

A Primer on Braking Systems

The braking system on a refuse-collection truck is divided into two sub-systems: the service brake and the parking brake. The service brake is intended to be operated by the foot pedal and applied during normal vehicle operation. The parking brake is a mechanical system that is intended to hold the brakes whenever the vehicle is parked and the motor is turned off. A work-brake system, which combines the features of both the service brake and the parking brake, can be used in circumstances where the driver must repeatedly exit the car while positioning it in a parked position without significantly wearing out the spring-applied parking brake.

Air or hydraulic fluid are used to operate braking systems. Although both systems can be used effectively on a variety of vehicles, the primary braking system on refuse-collection vehicles is air-operated. As well as a storage tank to keep the compressed air, this requires a compressor to produce air at the right pressure. Moisture can decrease the efficiency of the braking systems, so the air is then treated to remove it. In order to give the system redundancy, the braking system is frequently divided into circuits. In the event of a circuit failure, this redundancy is designed to allow the vehicle to retain more than 50% of its braking function. A suitable valve system in each circuit distributes air to each wheel assembly’s foundation brakes.

The most popular platform is air-brake systems because of their dependability and affordable maintenance. “An air-brake system is a forgiving system,” states Ron Bailey, technical sales manager for the Elyria, Ohio-based Bendix Spicer Foundation Brake LLC. “You can use an air-brake system even if there is a small amount of system leakage without the brake system failing. In other words, even if one component of an air or hydraulic system fails, the other component will continue to function. Although you can’t really do that with a hydraulic system, an air system can still function even with a small leak in the system. A hydraulic system develops a leak, and you lose some of the system.”

Drum brakes or disc brakes can be used as foundation brakes. On most refuse-collection vehicles, the braking system is an S-cam drum brake, which uses a brake chamber and slack adjuster to turn an S-shaped cam that presses the shoes against the drum to generate braking force. Disc brakes use a caliper to exert pressure on a rotor through the use of pads. While disc brakes apply pressure to a disc rotating perpendicular to the road surface, drum brakes apply pressure to a drum surface that is moving outward against the drum surface that is moving parallel with the road surface.

Bailey claims that there are some obvious differences between the two systems. “Less than 2% of the heavy vehicles in the States are air disc brakes,” he says. “The economics, in my opinion, are the main cause of that. Although air disc brakes have a better opportunity because of longer lining life and simpler maintenance, disc brakes are typically more expensive in the short term than other types of brakes. However, we believe there are life-cycle payments that will lower this cost. Drum brakes, in contrast, have a few drawbacks that disc brakes get around. Stability comes first. Drum brakes can vary from right to left by as much as 30%. Disc brakes are much more stable by nature—there is probably less variation from brake to brake, at most 10%. Brake fade, or the reduction in brake effectiveness, is another advantage of disc brakes over drum brakes. Drum brakes will unquestionably lose efficiency as the temperature rises as the brakes heat up. In a drum brake, the fade from a cold to a hot condition can be as much as 30% to 40%. The temperature variation for disc brakes is probably under 10%. Refuse collection is thought of as a heavy-duty hotbrake operation. Up to 60 stops have been recorded for refuse every mile. As the temperature rises, the drum brakes become hot, fade, and lose some of their stopping power. They also experience increased lining wear. When you do need to replace the pads, disc brakes can offer better lining wear and a much faster service time because they are much less sensitive to those conditions.”

According to John Hall, vice president of product engineering at Webb Wheel Products in Cullman, Alabama, a number of variables determine whether a disc or drum braking system is suitable for a given application. Duty cycle, driving preferences, cargo type, weight, and price are a few of these variables.

Air disc brakes are currently much more expensive than drum brakes. The main cause of this is that a drum brake’s component volume is significantly higher than that of an air disc brake. Component prices are highly volume dependent. The price difference between an air disc brake and a drum brake will get smaller as the volume of air disc brake components grows.

Why Retarders Are So Important to You

As a result, we gained knowledge about truck retarders and discovered that they serve as either an alternative to or aid in the use of the friction brakes that are installed on the wheels to bring the truck to a complete stop.

Have you thought about why these retarders are so crucial to you as a truck driver, though? What makes them such a necessity that no truck driver should be without and something that cannot be replaced? Now that we’ve established the significance of these brake retarders, let’s go into more detail.

Getting your driving test pass is necessary if you are a new truck driver. Additionally, there is a very high likelihood of failure if you don’t know what a retarder is.

Consider climbing a steep hill and then descending it while a truck is loaded with heavy cargo.

You decide to slam on the brakes as a result, but the trailer simply swerves to one side, leaving you seriously injured or even dead.

Or in another scenario, the truck’s brakes get too hot from use, it loses the ability to stop, and you rear-end someone or end up in a ditch. Both of these scenarios have the potential to be dangerous or even fatal.

For this reason, brake retarders were developed. when approaching a downhill road that is steep, to reduce the vehicle’s momentum.

Without your involvement at all, the brake retarder will handle this task and gradually but steadily slow down the truck.

Improving Brake Drum Life

The life of replacement brake drums may be increased by not following the common practice of “trueing up” a new brake drum before putting it into service. Nowadays, the majority of drum manufacturers produce the drum in a single chucking. As a result, the runout between the diameter of the braking surface and the pilot diameter can be reduced. By increasing the diameter of the braking surface, the practice of further milling brake drums shortens their lifespan. Additionally, by increasing the runout of the braking-surface diameter in relation to the pilot diameter, this practice can help to promote the development of heat checks on the braking surface. Finally, this might shorten the life of the drum.

The operating temperature of brake drums in demanding service may be lowered by using vented drums in conjunction with brake turbines. Increased drum life is correlated with lower operating temperatures.

Chuck Eberling, senior staff engineer at Bendix Commercial Vehicle Systems, claims that by including a work brake, the braking system can be used more effectively. “One of the biggest enemies of a braking system on a refuse vehicle is the application of the park brake on house-to-house routine stops,” he observes. “We have learned through studies with the industry that it is literally impossible for the charging systems that are typically used on these vehicles to maintain a route of 800 to 1,200 stops where the driver actually applies the park brakes at each stop. It’s crucial that he has the so-called work brake, which will use the service brake. As a result, the air consumption will be reduced by three times, giving the charging system the chance to keep up with demand. If the charging system is unable to keep up with demand, the system will become saturated and experience internal corrosion, freeze-ups, and other issues in the future.”

Types of Retarders on a Truck

We can now move on to learning more about the various types of truck retarders since we’ve already discussed what they are.

Retarders come in a variety of forms and are utilized worldwide. Some of them are ridiculously straightforward, while others require a lot of explanation. However, we’ll make certain to provide the best response possible to these queries.

We will briefly cover these types in the chapters that follow. But after that, we’ll go over them in greater detail and gain a much better understanding of how they operate. So let’s begin.

1. Exhaust Retarder

Therefore, we gained knowledge about truck retarders. Let’s now examine the first kind of retarder that is most frequently used on trucks.

The exhaust retarder is one example of this type of retarder. Likewise called the exhaust brake. So how does the exhaust cause your car to stop?

The flow of exhaust gases can be limited in some ways by diesel engines, but doing so slows down the engine’s operation. When the crankshaft rotates more slowly, the vehicle also moves more slowly.

These retarders are among the most effective and straightforward types available. We will go into greater detail about the operation of this type and why it is so beneficial later on. Therefore, we gained knowledge about truck retarders. Let’s now discuss the second variety of retarder.

2. Jake Brake

We now understand what a truck’s retarders are for, so let’s look at the second kind of retarders that are available. And these are the Jake brake retarders. So what exactly is a Jake brake retarder?

A Jake brake retarder is comparable to the earlier variety that we discussed. Engine retarders are what they both are. which implies that they lower the engine’s RPM. However, each of these types is going about it in a different way. The earlier did this by preventing gases from escaping from the exhaust, whereas the Jake brake takes a different approach.

In particular, this system is tinkering with the exhaust valves. It does this by opening the valves just as the compression stroke is about to end, releasing the trapped compressed gas in the cylinders, slowing the car in the process. If you ask me, it’s a pretty clever design. The specifics of this design’s operation will be covered later when we go into more detail. Let’s proceed to the following system now.

3. Hydraulic

We are familiar with the function of truck retarders, so let’s look at the hydraulic retarder as the following type.

As we mentioned, a torque converter and a hydraulic retarder are somewhat comparable. This part is typically mounted on the vehicle’s driveshaft and transmission.

Therefore, when stopping power is required, hydraulic fluid is pumped into this component, and this fluid then adds some resistance to the spinning motion of the gear. The hydraulic fluid creates a drag that is viscous in order to lessen the spinning motion. This kind of retarder is frequently used on buses because it is effective.

This retarder’s quiet operation is a plus; you frequently can’t hear it. It is therefore much more practical than the first two types that we previously discussed.

4. Electric

Now that we are aware of what retarders are on trucks, let’s look at the final type of retarder that is available. This particular retarder is an electric model.

When it comes to where they are mounted, electric retarders and hydraulic retarders are very similar. Between the driveshaft and transmission, it is similarly mounted.

The use of electromagnetic induction by this retarder to produce a retarding force is the only distinction. Although they are less frequent, there are still many trucks out there that can use these retarders. But why is it important to understand what truck retarders are and the different kinds of these retarders? On this, let’s expand a little bit.

Retarders Aid Braking

The recognizable whine of an engine-retarder system can be heard by anyone who has stood alongside a downhill freeway off-ramp as a heavy truck slows. They are made to help the current braking system by converting the energy produced by the vehicle’s drive train into a braking system when used in conjunction with driveline and transmission retarders.

When the throttle of a collection truck is depressed, fuel is forced through the cylinders and ignited, producing work, which causes the engine to accelerate. The engine coasts after releasing the throttle. An engine retarder collects the engine’s exhaust and compresses it, making the engine work harder to push the gas out of the cylinders. As a result, the engine is retarded and slowed through resistance. By slowing down as a result, the vehicle can be stopped with less force applied to the service brakes.

Similar to brake retarders, transmission retarders work by increasing friction within the transmission to reduce the rotational forces of the driveline. Steve Spurlin, chief engineer for Allison Transmissions in Indianapolis, IN, describes how the system operates: “The retarder consists of a rotating vaned component known as a rotor. Stators are vaned components that are positioned on either side of the rotor but do not rotate. Oil is pressurized into the space between the rotor and stators. The output shaft of the transmission and the rotor are splined together. When the operator requests a retardation, the pressurized oil that is in contact with the rotor and stator slows the vehicle down. The retarder uses the regular transmission oil supply to pump up to 60 gallons of oil per minute.”

Driveline retarders use electromagnetic energy to balance the energy in the rotating driveline, much like an electric motor, and are installed between the transmission and the truck’s rear end. “In the refuse market, it is primarily purchased for brake-life extension,” says Regional sales manager for Telma Inc. Joe Gawlik of The Valeo Group subsidiary in Elk Grove Village, Illinois. “Given how frequently brake repairs are made in the refuse market, this will reduce tire life as well as brake life and the costs associated with maintaining them. [Two rotors that are connected to the driveline and rotate at the same rate as the driveline make up the system. The frame rail is stationary and the stator is fastened to it with bolts. You can slow down the truck without using your brakes by activating the retarder, which generates an electromagnetic field using eddy currents that slows down the rotation of those rotors.” According to John Gillespie, general manager for Telma, “Electromagnetic auxiliary braking is the best auxiliary braking technology for the refuse industry. Using this technology, we’ve seen tire failures caused by heat decrease and brake life increase by up to five times.”

There are two reasons, in Spurlin’s opinion, for any type of retarder system on a collection vehicle. “One of those is speed control on grades, which isn’t really what a refuse-collection vehicle would want it for,” he says. “The second goal is to give the car more stopping power so that the regular service brakes can last longer. The benefit is most common in jobs with a lot of starts and stops, like refuse trucks. Any type of retarder won’t help much when doing low-speed work in typical residential refuse collection because you’re moving at low speeds, whether it’s a sideloader, rearloader, or even a frontloader. The low speed results in very little braking energy being applied to the service brakes. All of those trucks, however, leave the area. They travel in regular traffic and, in the majority of cases, they travel at high speeds on a highway several times per day to landfills or transfer stations. Because they are traveling at higher speeds now and more braking energy is being used by the service brakes, they would benefit from the retarder in terms of brake savings. You can extend brake life if the retarder can absorb that energy instead of the service brakes.”

Retarder systems can be configured to activate based on the requirements of the operating system. “The drivers and the companies have a choice with how they want the system set up,” says Gawlik. “The majority of the vehicles used in the refuse market have foot controls, which activate the retarder in four stages at a 25% rate as soon as the driver applies the brakes. It is activated at 3, 5, 7, and 10 pounds of air pressure in the braking lines and is controlled by an air-pressure switch. The refuse market’s most preferred choice is that. Off-throttle control is one alternative, though. Approximately 25% to 50% of the power is activated as soon as the accelerator is released, with the additional stages being activated off the brake pedal, according to the option chosen by a few refuse companies. When you let off the accelerator, 50% of the retarder starts to function right away.”

Future Systems

To bring a Class 8 vehicle to a stop from 60 miles per hour in 355 feet, all braking systems must currently meet or exceed National Highway Traffic Safety Administration (NHTSA) standards. The NHTSA currently has a nine-step program to reduce fatalities involving heavy-duty vehicles by 50% by the year 2010. “In one of the major efforts, they are planning a reduction in that stopping-distance requirement from that current 355 down to 248 feet,” Bailey says. “Drum brakes might be able to achieve that level, but once you start installing much larger drum brakes on the front axles, that’s when this effectiveness factor really starts to matter. It can be handled by disc brakes. With disc brakes all around, we have data that shows the stopping distance for a typical tractor down to 185- to 215-foot stopping distances.”

Future systems will include features like stability controls and more sophisticated automated braking systems because activating the braking systems could affect stability and handling, especially in bad weather or emergency situations. “The advanced systems that we’re talking about are actually those which you would find more prevalent in a full electronic braking system, which is fairly commonplace in Europe,” says Eberling. “What we’ve actually done is incorporate the advanced features of an all-electronic brake system into the current anti-lock brake system platform because shorter stopping distance [requirements] don’t exist and it would be expensive to have one with the required pneumatic redundancy. With these cutting-edge ideas for roll stability and improved electronic stability, we believe our system has reached the point where a fully electronic brake system is of no real use.”

Why You Should Know All These Types of Truck Retarders

As we have learned about the various types of truck retarders and what they are, we now know what they are. We can now discuss the importance of this knowledge for you. Why is this crucial? Let’s go into more detail in the paragraphs that follow and see why this is important.

The CDL driver’s license is the primary reason why you need to be aware of the types, uses, and definitions of retarders on trucks.

All you need to do is be aware of this information if you decide to obtain a CDL driver’s license. Since how are you going to drive a semi-truck if you don’t know what an exhaust brake or a Jake brake is?

You really need to know this information in order to operate a commercial vehicle with this kind of equipment installed on it.

If you don’t know how to use these features, you risk overheating your standard brakes and crashing if you don’t know how to descend a steep hill.

The fact that everyone is familiar with these types of brakes is another reason. It didn’t hurt anyone to have a little extra information. You might eventually decide to sign up for a CDL. Therefore, being aware of this beforehand will help you spend less time learning how to prepare for and pass these exams. But enough on that.

Let’s learn how these brakes function and get some frequently asked questions about them in the chapters that follow. The exhaust brake and the Jake brakes will be our main area of attention as we learn more about their characteristics and mode of operation.

Engine Braking Systems

As we previously mentioned, since we now understand the function of a truck’s retarders, we can continue to learn more about engine braking systems. The hydraulic and electrical systems are not covered. but only the ones that the engine uses. which include the Jake brakes and the exhaust brakes. We will discover their primary functions and characteristics. So keep reading if you’re interested in learning more.

What Are Retarders on a Truck: What is Exhaust Brake

Now that we are aware of what truck retarders are, we can move on and discuss the first kind of brake retarder in detail. to be specific, the exhaust brake.

So what does the exhaust brake do? The hot side of the engine’s turbo is where this unique brake is located. It is thus directly between the car’s turbo and exhaust, as the name implies.

You can see that this system is primarily installed on turbo diesel applications. Right next to the turbo’s hot side, the exhaust brake will be visible as a large hump.

It is even cleaner and simpler in some applications. When it comes to the engineering of this type of brake, more contemporary applications are more compact and simplified. But how does this exhaust brake function on an engine?

How Do Exhaust Brakes Work?

Backpressure is used to operate exhaust brakes. What then is backpressure? Backpressure occurs when the gases in the exhaust are unable to escape.

The engine will shut off if you place something inside the exhaust. The gas passage is partially closed by the exhaust brake, though. Therefore, there is enough gas passage for the engine to continue running while slowing down. But why does the engine sputter?

As we previously stated, the engine slows down as a result of the buildup of backpressure. Gases from the intake and exhaust systems should be distributed equally. Consequently, if you partially block the exhaust. You will then only require 50% less air than usual.

Therefore, as the engine burns less air in the cylinders, less power is generated. Additionally, the engine starts to lose speed.

The exhaust brake is nothing more than an adjustable butterfly flap. This brake has a variety of actuators that can be used to open and close it, including pedal-operated ones, two-stage pressure controls, and pneumatic or hydraulic actuator valves. The answer largely depends on the application.

It’s helpful to know that these brakes make more noise than the commonly used standard brakes. So, you need to keep this in mind. Let’s move on to the following type of brakes now that we are aware of what retarders on a truck are.

What Are Retarders on a Truck: Jake Brake Meaning

As we now know what truck retarders are, let’s discuss the second type of brake retarder that is most frequently used. The Jake brake is that.

Jake brakes are nothing new. Clessie Cummins was the inventor, and Jacobs Vehicle Systems launched their first production of them in 1965. They became known as Jake brakes as a result.

Due to the fact that they essentially alter the engine’s compression, these brakes are also referred to as compression brakes. On trucks, these brakes are typical. However, the drawback of these brakes is that they have some restrictions, which we will cover later in the article.

But how does this kind of brake actually operate? What causes your truck to stop when you need it most and all the magic? In the chapters that follow, we’ll go into more detail about this and examine the brakes’ mode of operation.

How Does the Jake Brake System Works?

The Jake brakes are compression brakes, as we’ve already mentioned. This implies that they adjust the engine’s compression to stop it. Let’s explain how they operate.

The car continues to move forward when the driver takes their foot off the gas pedal. Compression brakes, also referred to as Jake brakes, are now in use.

When this system is turned on, the cylinders’ exhaust valves are opened. however, just after a certain point. The compression stroke ends at that point.

In the cylinders, compressed gas had been trapped until this action. The piston is pushed downward by the compressed air that is produced during the compression stroke, which functions somewhat like a spring. Furthermore, by decelerating the crankshaft’s motion, this action aids in the engine losing momentum. the process of making the vehicle stop.

Furthermore, stopping power is excellent thanks to these Jake brakes. However, given what we now know about truck retarders, they do have some limitations that we will discuss in the following chapters.

Jake Brake Sound

Let’s discuss another intriguing topic, namely the legality of these types of brakes, now that we have learned how the Jake brakes function and what retarders on a truck are.

If you didn’t know, there are signs prohibiting engine braking in many locations across the nation. Why then is it actually the case that engine braking is prohibited in populated areas?

Of course, the sound is primarily to blame. Jake brakes as well as exhaust brakes produce sound.

Everyone really despises the brakes, particularly the Jake brakes. primarily because the sound these brakes make when you step on them sounds like a heavy machine gun is being fired. And your ears won’t find this to be a simple matter. No, sir; a Jake brake is so bad that it makes you feel as though the sky is falling on your head and the air force is bombing your home, especially if you live near a busy road.

So, there are numerous signs posted all over the country warning people not to use their brakes inside of cities. You must only use them in an emergency if you use them in the city otherwise you risk receiving a hefty fine.

Conclusion to What Are Retarders on a Truck

When it comes to what truck retarders are, we’ve covered a lot in this article. First, we gained knowledge of retarders and their purpose. After that, we discussed the different kinds of retarders that exist.

The reason you should be familiar with these distinct types is that you need to in order to obtain a CDL driver’s license, which is what we then went over. Later, we discovered the disadvantages of engine retarders and how they function.

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