We know that there are many landing gear products on the market to choose from, and it can be overwhelming to find the one that fits the specs of your trailer. One important deciding factor is how much weight your semi-trailer landing gear can hold. We’re here to break it down for you.
What Is the Purpose of Semi-Trailer Landing Gear?
Trailer landing gear is the retractable support equipment that keeps a trailer level when removed from the semi-tractor. It’s located at the front of the trailer and will keep you and your truck safe. The landing gear consists of two legs that can support the heavy weight of the trailer.
What Are the Different Types of Semi-Trailer Landing Gear?
Here at JOST International, we’re an industry-leading manufacturer of trailer landing gear and component parts. We offer an expansive product line, and our signature internal gearbox is the key feature and integral part of our landing gears’ durability and . Our internal gearboxes protect the gears from damage and significantly reduce moisture intrusion, which extends the product’s life and provides our customers with a stronger, more reliable product.
While there are several types of semi-trailers landing gear, most can be divided into either drop legs or standard landing gear legs. Here’s what you need to know about both.
Drop leg landing gear products utilize a spring-loaded lower tube. The drop handle must be turned 90 degrees to disengage. The internal spring keeps the drop leg retracted until the force is applied. A smaller spring on the drop handle forces it inward, allowing the drop handle to align with the following hole location as the internal spring retracts the lower tube.
Drop legs are ideal for various commercial trucking applications looking to save operator time and overhead costs. They’re lightweight, easy to use, and perfect for smaller loads and drivers looking for an efficient way to speed up the coupling and uncoupling process.
Landing Gear Legs
Our landing gear maintains all the mechanical advantages of JOST’s drop legs, but trades the spring drop function for a more durable,single speed and two speed crank mechanic only. JOST internal gearboxes are completely filled with premium all-weather lubricant, an elevating screw that can be fully encased in a grease tube, completely sealed landing gear legs, and austempered ductile iron gears.
JOST landing gear is ideal for heavy-duty applications. They’re the best option for protecting against water and chemicals on roads.
How Much Weight Can Semi-Trailer Landing Gear Hold?
At JOST International, each of our high-quality landing gears has its own standout features, including weight capacity. If you need to find the perfect semi-trailer landing gear for you, ask yourself these questions:
What’s your application?
How much weight do you need to support?
A JOST landing gear product can support:
Static Load Capacity: 160,000-200,000 lbs
Lifting Capacity: 55,000-70,000 lbs
Note: Varying models are available to support both heavier and lighter applications.
A JOST drop leg product can support:
Static Load Capacity: 12,000–35,000 lbs
Lifting Capacity: 12,000-35,000 lbs
Note: Varying models are available to support both heavier and lighter applications.
If you’re looking for superior landing gear from an industry-leading manufacturer, JOST International is here for you. Our landing gear meets or exceeds international standards for OEMs and fleet use in North America and internationally. Plus, we use top-of-the-line technology, so you can always trust that you and your equipment will stay safe.
Whether you’re new to coupling trailers or you’re just trying to get a handle on all of the technical part names, the JOST team is here to provide all the information you need around fifth wheels and industrial transportation.
In this article, we’re discussing the basics of kingpins for semi trucks. Here’s everything you need to know about what a kingpin is and what it does.
What is a Kingpin?
Frequently referred to as the “pivot point between the tractor and semi-trailer,” the kingpin is the part used to connect a semi-tractor and a semi-trailer. A kingpin may resemble any of the above images but always shares a few key features:
A welded side. One side of the kingpin is always welded to the semi-trailer. This is why kingpins are often considered a “trailer solution” rather than a “truck solution.” They are always fixed to the trailer and then coupled with the tractor using a fifth wheel coupling device.
A tapered section. Every kingpin has a tapered section that is narrower in width than the sections above and below it. This is where the fifth wheel locks around the kingpin to provide a secure coupling. By making the areas above and below the tapered area wider, manufacturers ensure another layer of protection, minimizing the potential that a kingpin could slip out of a fifth wheel’s coupling mechanism.
What Does a Kingpin Do?
This small but mighty part comes in a variety of shapes and sizes, but works to do one thing: connect the semi-truck and trailer.
In addition to that primary function, a kingpin is also responsible (in partnership with the larger fifth wheel) for the steering and handling of the coupled rig. When properly coupled, the kingpin keeps the trailer and tractor together while allowing the tractor to turn and pivot around its fixed point, ensuring semi trucks are able to transport product with ease.
What Should I Look For in a Good Kingpin?
If you’re in the market for a new kingpin, you might be wondering how you decide from all the different kingpin types and manufacturers. Here are 3 key things to look for when purchasing a kingpin you can trust to keep you safe for years to come.
A kingpin is only as good as its lifespan. This is an integral component for any rig, and should the kingpin fail, your trailer cannot move. That’s why it’s important to look for a kingpin with proven durability. To assess this, evaluate:
Manufacturing materials. What is the kingpin made out of? A kingpin made from high-quality steel is likely to last significantly longer than a kingpin manufactured with poor-quality materials.
Manufacturing methods. We’ll talk more about manufacturing requirements and standards below, but how a product is manufactured can tell you a lot about how it will perform. Choose kingpins from manufacturers with safe, reliable manufacturing standards and safety requirements.
Manufacturer standards and warranties. Does the manufacturer stand behind its product with a warranty or stringent manufacturing standards? If not, you may have a problem finding a kingpin that can stand up to long hours of wear and tear on the road.
Perhaps the most important feature of any kingpin is its ability to keep the operator and the rig safe. Choose kingpins from reputable manufacturers with a long track record of safe manufacturing practices. Quality manufacturers will be happy to provide you with the information you need to verify the safety of their products.
03. Local Standard Compliance
Every trailer OEM has its own international standards. Your trailer must meet those standards to ensure safe, compliant hauling in your area. To ensure you’re in compliance, first find a manufacturer that produces kingpins according to your local standards, and then verify their compliance. A great manufacturer will prove with data how their kingpins meet established performance requirements.
If you’re not sure what standards to look to, the most popular standard compliance requirements in North America include:
SAE (Society of Automotive Engineers) specification for dimensions, materials, and installation).
AAR (Association of American Railroads) specification for SAE dimensions and greater installation, structure, and material strength/wear specifications.
TMC (American Trucking Association — Technology and Maintenance Council) RMP-750 – kingpin and upper coupler inspection for deformation and wear replacement standards.
Safe hauling starts with safe parts. And no one manufactures for safety better than JOST international. If you’re looking for a superior kingpin from an industry-leading manufacturer, JOST can help. Our kingpins meet or exceed international standards for OEMs and fleet use in North America and internationally.
A fifth wheel is a part that almost anyone in industrial trucking is familiar with. We know it works to connect the semi truck tractor and trailer, and if you’ve been in the business for a while, you might even be familiar with a few of the key features that are nice to have in top-of-the-line models.
But when there are so many options to choose from on the market today, it can be helpful to know what you truly need to have and what options are add-ons. Since all fifth wheels are manufactured a little differently, we’re going to dive into the 5 essential parts of a fifth wheel. This should give you the information you need to find the best fifth wheel for your unique application.
01. Top Plate
The top plate is the cast part of the fifth wheel. It usually looks like a large horseshoe shape. The top plate secures coupling components and vertical trailer or cargo load. It’s the largest component of a fifth wheel.
02. Release Handle
Not all fifth wheels have this type of handle — the release handle (shown blue in the image above) is a unique part specific to JOST fifth wheels. In a JOST fifth wheel, the release handle makes it easy for operators to couple and uncouple a fifth wheel while ensuring ultimate safety.
The release handle also provides operators with secondary locks and visually indicates that the coupling is secure. While not all fifth wheels feature a release handle, JOST has prioritized this part for the safety and security of all our customers. When operators can visually confirm that tractor-trailer coupling is successful, there’s no guesswork, and you know you’re hauling safely.
The lever is a relatively small component of a fifth wheel, but that does not make it unessential. The lever links the release handle to the locking bar. Together, all three components work to slide the locking bar across the opening of the cushion ring, supporting and securing the lock jaw and ensuring the tractor and trailer are appropriately coupled for transit.
04. Lock Jaw
The lock jaw is the coupling mechanism that locks around the kingpin to hold it in place. In the above image, you can identify the lock jaw by it’s “C” shape. This shape allows the jaw to fit snugly around the kingpin. It is connected to the lever and release handle, and is the primary securing mechanism holding the tractor and trailer together.
05. Lock Bar
A fifth wheel’s lock bar secures the lock jaw. When engaged, the lock bar slides across the opening of the cushion ring, under the lock jaw, and ensures the trailer kingpin is held firmly in the fifth wheel and is secure for transit. The lock bar provides superior structure to support trailer drawbar load.
Are these the only components of a fifth wheel?
While these five components are essential to the safe functionality of any fifth wheel, they are not the only components. For example, JOST fifth wheels also offer a range of features to ease operation and extend product life cycle, including:
Adjusting Screw. This allows the locking bar to maintain a snug coupling even as the lock jaw and cushion ring wear.
Grease Fitting. This delivers grease directly to the kingpin and lock jaw contact point to ensure that all parts are properly lubricated to extend the life of both products.
Cushion Ring Insert. This works to protect the kingpin and top plate casting from wear and damage.
There are a number of additional components featured on JOST fifth wheels, but the five mentioned above are essential to the functionality of every fifth wheel. At its core, a fifth wheel must have:
A top plate for the trailer to rest on
A securing mechanism to hold and secure the kingpin
An operational mechanism that allows the driver to couple and uncouple tractor and trailer
With a better understanding of each of these components and their importance to the safety of your daily operations, you’ll be able to select the ideal fifth wheel product for your specific application’s requirements.
JOST International has been manufacturing fifth wheel coupling devices since 1956. In fact, we submitted the patent for the first-ever steel cast fifth wheel coupling. As a leading manufacturer of fifth wheels, we want to make sure that anyone in the industry, new or experienced, has access to helpful, informative content about all of our components. With that goal in mind, we’re tackling a popular question from those new to the semi-truck and industrial transportation industry: “how does a fifth wheel work on a semi?”.
We’ll cover everything you need to know, from what a fifth wheel is, to how it works and what kind of fifth wheel might be best for your application. Let’s start with the basics.
What is a Fifth Wheel?
Not to be confused with an RV trailer, a fifth wheel is an important component of a semi truck’s tractor. A fifth wheel is the plate above the tractor’s back wheels where a semi trailer’s kingpin hooks to the tractor. The fifth wheel is what allows the tractor to turn with the trailer still attached. A fifth wheel is also designed to spread the trailer’s freight load evenly across the tractor and trailer so that the operator can safely haul, no matter where they’re headed.
How Does a Fifth Wheel Work on a Semi?
As mentioned, a fifth wheel is a key connection point between a semi-truck tractor and trailer.
To understand how this works, it’s important to understand the key components.
First, you have a kingpin, which is a metal component that protrudes from the trailer.
Then, you have a fifth wheel, where the kingpin engages. A fifth wheel is a flat, non-rotating horseshoe-shaped coupling device that is installed on the semi-truck tractor.
The kingpin on the trailer installs into the fifth wheel on the tractor. The semi trailer’s surface, with the kingpin at the center, rotates against the upward-facing fifth wheel. Grease is applied to reduce the friction of these two components rubbing together and works to extend the life of both the kingpin and the fifth wheel.
What is the Purpose of a Fifth Wheel?
A fifth wheel has two key purposes:
A fifth wheel connects the semi-truck tractor and trailer, while allowing both to articulate, move around, and steer comfortably. Without a fifth wheel, it would be almost impossible for a semi-truck to make a turn.
A fifth wheel evenly distributes weight between a semi-tractor and trailer.
While the first purpose is fairly self-explanatory, the second can be a bit more complicated. Since every load is a little different, fifth wheels must accommodate to ensure that semi-truck weight is balanced appropriately. To do so, there are two key types of fifth wheels, fixed and sliding.
Fixed and Sliding Fifth Wheels: What’s the Difference?
Fixed and sliding fifth wheels perform the same function, but they do it a little differently.
A fixed fifth wheel stays in exactly the same place on a semi-truck tractor. It is “fixed” on the vehicle and is typically used for rigs that are hauling about the same size load, no matter what. Because the load is the same for every trip, there’s no need to adjust where the fifth wheel sits to accommodate different types of loads.
A sliding fifth wheel is designed to support a variety of load weights. They can slide backward and forward to facilitate safer hauling. As the operator slides the fifth wheel forward or backward, they can better distribute the weight of lighter or heavier loads.
In general, if you or your operators are hauling about the same size load for every run, a fixed fifth wheel is sufficient. But, if you’re an owner/operator, or if your team often deals with varied load types, then a sliding fifth wheel is likely the better option.
Looking for a New Fifth Wheel or a Fifth Wheel Replacement?
The kingpin of a trailer is a small but essential component. It’s responsible for coupling a trailer to a tractor, which means its one of the few things keeping a rig together on the road. Operators know that the kingpin is the last thing you want to go bad while you’re on the road, but how can you identify a bad kingpin before it becomes a problem? Here are 5 symptoms of a worn or bad kingpin to look out for every time you’re coupling or uncoupling a trailer:
1. Hard to Couple
If you’re having problems coupling a trailer on the tractor, it could be a sign that you have a bent kingpin or upper coupler.
A kingpin that is in great shape should make it easy to couple your tractor and trailer. So, if you’re noticing problems with a specific trailer, the kingpin could be to blame.
What’s the cause? In the case that you’re having trouble coupling your trailer, the issue could be a result of a worn or failing upper coupler structure.
Why fix it? If your kingpin or upper coupler are bent, not only are they making coupling more difficult, but they’re no longer supporting your trailer and cargo safely. This is an unsafe way to haul, and it’s also a leading cause of accelerated top plate surface wear.
In any case, the best solution is to have the upper coupler structure and kingpin inspected and replaced if possible. You’ll spend less in the long run by addressing the problem now rather than waiting for it to affect other parts of your rig.
2. Hard to Uncouple
Maybe your tractor and trailer coupled just fine, but now you’re having problems uncoupling them. This is a key sign of a bad kingpin. The symptoms here are similar to those that occur when it’s difficult to couple a trailer, and it’s also usually a sign of a bent kingpin or coupler.
This is another fix to make as soon as possible. If you’re unable to have the problem addressed, a bad kingpin can add significant wear to your tractor and fifth wheel. What’s more, it’s an unsafe way to haul. It’s always best to get a bent kingpin fixed as soon as possible.
3. Fifth Wheel Adjustment Will Not Tighten — Worn Down Shoulder
If you’re experiencing problems with your fifth wheel adjustment, it’s usually a sign of a bad kingpin. There are two issues that could be causing this, the first of which is a worn-down shoulder.
When the shoulder of the kingpin wears down, it becomes impossible for your fifth wheel adjustment to tighten securely. There’s not enough material for the fifth wheel to tighten against, and if you cannot tighten your fifth wheel adjustment, you cannot safely haul.
This is a sure sign of a worn kingpin in need of replacement. The best solution is to address this as soon as possible by installing a new kingpin.
4. Fifth Wheel Adjustment Will Not Tighten — Worn Down Throat
As mentioned, there are two key problems that will prevent a fifth wheel adjustment from tightening. The first was the worn-down shoulder, and the second is a worn-down kingpin throat. When this happens, the throat has become so worn down that there is nothing for the fifth wheel adjustment to tighten against.
This presents a similar problem to a worn-down kingpin shoulder, which is that the coupling cannot be safely secured. Here too, it’s essential that you replace the kingpin before using the trailer. It is unsafe to haul if the coupling cannot be secured properly.
5. Lack of Lubrication
The fifth and final symptom of a bad kingpin is a lack of lubrication. If a kingpin has been poorly lubricated, excessive wear can happen quickly — and excessive wear is a surefire sign of a bad kingpin.
The kingpin and fifth wheel should always be well lubricated to reduce grinding between the tractor and the tractor’s fifth wheel. If the kingpin is not properly lubricated, it will wear unevenly and prematurely, which can create unsafe hauling conditions.
Signs of poor kingpin lubrication include the galling of kingpin contact surfaces and premature wear. If you know that a kingpin is not at the end of its life but is showing significant wear, a lack of lubrication is likely the problem. Unfortunately, once worn down, and especially when worn down unevenly, and kingpin must be replaced to ensure the safety of the operator and the rig.
Invest in a Better Kingpin
Forget the symptoms of a bad kingpin when you invest in a better kingpin developed by experts in the commercial transportation industry. JOST kingpins have proven themselves mile after mile over the world’s most challenging roads. They’re built for quality, safety, and durability. If you’re ready to upgrade, we have the solutions you need. Find a dealer near you.