How to Identify & Complete the Most Common Fifth Wheel Repair

How to Identify & Complete the Most Common Fifth Wheel Repair

Just like any other piece of trucking equipment, fifth wheels require regular inspection, maintenance, and repair. Often, problems found during inspection can be attributed to the same component. Below, we’ll discuss what the most common fifth wheel repair is and give you some quick and simple tips for how to fix it.

What Fifth Wheel Part Most Commonly Needs Fixing?

The fifth wheel part that most commonly requires repair is the top plate. The top plate is a horseshoe-shaped plate that’s attached to the main frame of the vehicle. It offers trailers and cargo a secure connecting point for heavy loads. 

Why is the top plate the most common fifth wheel repair? It’s under intense stress while in use. This high stress can damage the plate and normal wear can break down internal, smaller components like lock jaws and cushion ring inserts, bushings, release handles, and more to the point of replacement. You may also struggle with fifth wheel top plate troubles if your coupling attempts aren’t in compliance with JOST’s Operating Instructions or the industry standard TMC RMP-654.

All of these possibilities show why following standards and being proactive about inspections and maintenance is key.

Troubleshooting: How to Inspect & Repair a Fifth Wheel Top Plate

Should you have an issue with your fifth wheel top plate, here are the steps you can take to diagnose and fix the problem.

1. Review the Top Plate’s Surface

Pull the release handle out and hang it on the release notch; it must be flat and straight. Then ensure the adjusting screw shows ⅜” to 1 ½” of threads. If it shows less or more than that, there is an issue. 

If no issue is found, scrape any excess grease from the top plate surface’s recessed center. Check the cushion ring insert for any chipping or damage, and make sure the locking bar tip protrudes further into the throat than the coupling guide lugs.

2. Review the Lever with the Bushing Under the Top Plate

You can also inspect your top plate and diagnose any issues by looking underneath it. First, verify that the lever with the bushing is in appropriate condition and position. Then check the pivot bolts to ensure there’s one washer between the lever and castellated nut on each of them. Finally, check the release handle attachments to ensure proper attachment.

3. Use a Lock Tester to Check Operation

A third and final inspection is to use a lock tester to check operation. Start by engaging the lock test tool to lock the fifth wheel, then verify that the release handle is in the locked position (Document Link). 

Also, note the lock jaw and locking bar positioning. The lock jaw must accept the kingpin and fully rotate. The locking bar must fully cross the throat. If one of these positions is incorrect, replace the damaged Lock Jaw, Lever, or Release Handle. 

Once you’ve determined what is worn or damaged, you can either fix or replace it. 

Watch this video or download this troubleshooting guide for more information, visuals, and commonly stocked top plate repair parts at JOST. 

Repair vs. Replace: How to Know When It’s Time for a New Fifth Wheel

In many cases, a quick top plate repair can get your fifth wheel back and better than ever. However, there are some instances where a repair won’t do enough and it’s time to completely replace your fifth wheel. 

How do you know which is best? Follow these guidelines. 

Repair if: 

  • Your top plate is still mostly in good condition, and a quick or simple fix will get it back to normal. 
  • Your top plate shows some wear but still has good grease grooves and no unsalvageable damage.

Replace if: 

  • Your top plate surface is worn down to the grease groove at any point (see Page 1, Item 1, Figure 1 of this document).
  • Your top plate’s casting is cracked. 

Get World-Class Truck and Trailer Products From JOST International

Time for a fifth wheel replacement? Contact JOST International. We’ve been manufacturing fifth wheel coupling devices across the world since 1956 and have continued innovation ever since. From our unique locking mechanism to our new sensor fifth wheels, our products are the standard option at every OEM. 

Visit this page to order your replacement today.

Here’s Your Complete Guide to Fifth Wheel Coupling

Here’s Your Complete Guide to Fifth Wheel Coupling

There are several critical safety aspects to heavy vehicle combinations, one of which is couplings. Understanding fifth wheel couplings is vital to the safety and efficiency of any trucking fleet. We’ll dive into the world of fifth wheel coupling and what some of the best products on the market currently offer. 

What Is Fifth Wheel Coupling?

The technology of fifth-wheel coupling provides the connection between a semi-trailer and the towing truck, tractor unit, leading trailer, or dolly. A fifth wheel connects the two components, allowing them 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 so you can hit the road and navigate your equipment. 

What Does a Fifth Wheel Coupling System Consist Of?

As a whole, the fifth wheel coupling system consists of the fifth wheel and the kingpin.

  • Fifth wheel – This equipment is a flat, non-rotating horseshoe-shaped coupling device installed on the semi-truck tractor.
  • Kingpin – A metal component that protrudes from the trailer that’s frequently referred to as the “pivot point between the tractor and semi-trailer.” 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. 

Invest in High-Quality Coupling Systems With Advanced Technology

When you need to invest in high-quality coupling systems with top-of-the-line technology, look no further than JOST International. Our JSK37UBK Series wheel is revolutionary – it allows the driver to know when the fifth wheel is properly and safely coupled from inside the cab. The sensor technology in the wheel sends a signal to a display in the cab that lets the driver know when the wheel is properly coupled.


  • Throat Illumination (sold separately) – An LED Light shines into the throat to allow clear inspection of the coupled fifth wheel. 
  • Go Light – A green light indicates the fifth wheel is properly coupled, with both kingpin and handle in the locked position.
  • No-Go Light – A flashing red light with an audible alert indicates that the kingpin and/or handle are not properly coupled. 

Capacities & Ratings:

  • Maximum Vertical Rating: 55,000 lbs
  • Maximum Horizontal Rating: 150,000 lbs

How It Works:

  • The Loc-Light system enhances your JOST fifth wheel with the addition of our two-sensor monitoring system as well as a LED throat illumination. 
  • The dual-sensor system is connected to the Go/No-Go indicator light located next to the handle. A proper coupling with the handle and kingpin in the locked position will be lit up as green or “Go light”. If the system does not detect the handle and/or kingpin in the proper locked position, the light will flash red or “No-Go light” 
  • The throat illumination light option (sold separately) automatically turns on when the system is engaged. The light shines directly into the throat of the wheel to provide a better view of the lockbar for pre-trip inspections.

If you need to know how to couple and uncouple JOST fifth wheels, take a look at our instructional video.

Looking For More Coupling System Information?

If you’re looking for more information about JOST International’s coupling systems and top-notch technologies, contact us today. Our experienced team members would happily listen to your needs and share how we can help. We offer an expansive range of fifth wheels, kingpins, turntables, landing gear, coupling systems, and more. 

Follow This Fifth Wheel Inspection Checklist Before Hitting the Road

Follow This Fifth Wheel Inspection Checklist Before Hitting the Road

When you want to set yourself up for a safe, successful trip, performing a thorough fifth wheel inspection is key. It can be a little daunting but necessary for any semi-trailer driver. We’re here to help walk you through the complete fifth wheel inspection checklist. 

What Is a Fifth Wheel Inspection Checklist?

A fifth wheel inspection is a process of carefully examining your vehicle and its components and systems. This checklist usually takes about 15 minutes to complete and is required by the Federal government. 

Why Are Fifth Wheel Inspections Important?

If you’re a semi-trailer driver, you know that the job comes with a lot of responsibility, which isn’t as easy as it looks. Performing fifth wheel inspections before trips is essential for many reasons, including:

  • Safety – Driving a semi-trailer can be dangerous. According to the Bureau of Labor Statistics, drivers of heavy trucks and tractor-trailer trucks suffer fatal accidents more than any other occupation. Making sure all your equipment is in proper working order can be the difference between a safe trip and getting into an accident.
  • Maintenance – Performing the checklist allows you to find minor issues before they become serious. This can save you money on maintenance by solving problems before your trucks get on the road.
  • Compliance – Pre-trip inspections keep you in compliance with the Department of Transportation regulations. In the case of an audit, the DOT may review your pre-trip inspection checklist to ensure they have been filled out correctly. 

What Does a Fifth Wheel Inspection Checklist Include?

You must thoroughly check each major system when performing your fifth wheel inspection. This process includes:

Engine Compartment

  • Check for leaks in the engine compartment.
  • Ensure every component is properly mounted and secured, including the water pump, power steering pump, alternator, front suspension system, and front brake system. 
  • Look for leaks in hoses.
  • Make sure all the tires, rims, and axles are in good shape and working correctly.

Fuel Tank And Battery Area

  • Inspect fuel tanks, caps, batteries, and exhaust systems and ensure they’re working properly.
  • Ensure mirrors, door hinges, and door handles are not damaged.
  • Look at the exhaust system, driveshaft, catwalk, frame, cross members, and gaskets for any malfunctions.
  • Check that the suspension system, brake linings, changers, slack adjusters, and pushrods are properly working.

Coupling System

  • Ensure that electrical lines and airlines are good to go.
  • The fifth wheel should be greased appropriately and have no gap between the fifth wheel and the trailer apron.
  • Make sure the skid plate of the fifth wheel and apron of the trailer are working properly.
  • Inspect the kingpin, mounting bolts, and locking pin. 


  • Check that landing gear, frames, cross members, mudflaps, and the rear door are ready for travel. 


  • Inspect turn signals, four-way flashers, brake lights, high beams, low beams, and brake lights.
  • Ensure that reflectors, reflective tape, and the color chamber are in good condition.

Fifth Wheel Inspection Checklist Resources

If you want more resources regarding fifth wheel inspection checklists, we’ve provided some below.

Check out our helpful JOST International instructional videos to make sure your fifth wheel, landing gear, and coupling systems are in proper working order. 

Take a look at this helpful Semi-Trailer Pre-Trip Inspection Checklist. In addition to ensuring your fifth wheel, landing gear, and major systems are in good working order, you should also inspect these elements of your semi-trailer before embarking on a trip. 

fifth wheel inspection checklist sheet

JOST International Is Here for All Your Semi-Trailer Needs

Once your pre-trip inspection is complete, you’re ready to hit the road! If you need any replacement parts for your semi-trailer, look to JOST International. We have a long history of developing efficient, safe, and innovative systems for trucks and trailers, including fifth wheels, landing gear, coupling technologies, kingpins, and more. 

A Complete Guide to the Most Common Types of Fifth Wheels

A Complete Guide to the Most Common Types of Fifth Wheels

If you work in the semi-trailer industry, you’re familiar with fifth wheels. But do you know what types of fifth wheels are on the market? From stationery to sliding, we’ve got them all. Plus, besides JOST International, other brands make their own models as well. Here are the types of wheels explained. 

Types of Fifth Wheels Explained: JOST International

At JOST International, we’re proud to be a world market leader and international supplier for the commercial trucking industry. We provide top-of-the-fifth wheels that accommodate various applications – sliding fifth wheels and stationary fifth wheels.

Sliding Fifth Wheels

A sliding fifth wheel is a coupler that connects the tractor unit and semi-trailer together. It features a mechanism that slides the coupler forward and backward. Sliding fifth wheels are mounted to the semi-tractor’s frame. Unlike a stationary fifth wheel, it can move along the frame rails.

Advantage: Sliding fifth wheels help transfer weight to or from the steer (front) axle when customers change trailer types or have variable loads. The number of options for customers and revenue opportunities are increased.

JOST sliding fifth wheel

Stationary Fifth Wheels

Stationary mount fifth wheels, also known as fixed fifth wheels, are the original fifth wheel. These fifth wheels are ideal for applications where the semi-trailer’s kingpin setting, axle loading, and vehicle length are all constant throughout the fleet. As a rule of thumb, stationary fifth wheels are lighter than sliding mount fifth wheels.

Advantage: Stationary fifth wheels offer greater weight savings and maintenance simplicity. Customers increase revenue through greater payload and reduce operating costs with greater simplicity.

JOST stationary fixed wheel

For more information about our products, download our Fifth Wheel Product Line handout. 

Identifying Types of Fifth Wheels

JOST fifth wheels are standard products for many trucking companies. There are also other brands on the market that produce quality fifth wheels, including Holland and Fontaine. If you need to identify a type of fifth wheel, here’s how to do so:

JOST International Fifth Wheels

Every JOST fifth wheel has a unique red identification tab with the item’s model and assembly numbers. It will also have the JOST logo cast in the top surface or prominent on the ID tag.

Every JOST International genuine-made component meets the strictest OEM first-fit requirements for specifications. We make an array of compatible replacement parts for other brands of fifth wheels.

JOST logo fifth wheel

Invest in Industry-Leading Fifth Wheels

When it comes to types of fifth wheels for semi-trailers, JOST International is the industry leader. We’ve been manufacturing fifth wheel coupling devices globally since 1956, and we even submitted the patent for the very first steel-cast fifth wheel coupling. 

If you’re looking for more information about JOST fifth wheels, we’re here to help. Take a look at our inventory of fifth wheel products or contact our team today.

Download the jost fifth wheel catalog

A comprehensive look into each of the JOST fifth wheel products.

How to Winterize Your Fifth Wheel

How to Winterize Your Fifth Wheel

Freezing temperatures can take their toll on your rig, but don’t fret – winterizing your semi truck’s fifth wheel will help prevent damage and save you time and money throughout the season. Read on to discover our tips for semi fifth wheel winterization so you can face the elements with peace of mind. 

Your Go-To Guide for Fifth Wheel Winterization

States in cold climates use aggressive road salts for snow removal. These salts contain magnesium and calcium chlorides that can quickly develop corrosion on tractor and trailer components. The corrosion will adversely affect a semi truck’s fifth wheel’s performance if left unchecked. 

Don’t let your fifth wheel get damaged during the winter season. Winterize your semi fifth wheel and follow the following recommended inspections and preventive maintenance guidelines:

  • Thoroughly degrease and clean the top plate surface and underside using a steam-cleaning device and other suitable degreasing products. Be sure to remove any grease buildup within and around the lockjaw, throat, and pivot points.
  • Use an aerosol cleaner to clean the retractable release handle where the plate extends along the pins.
  • Inspect all areas and parts of the fifth wheel for damaged or missing parts, and if necessary, replace them with genuine JOST parts. 
  • Spray a penetrating oil, such as PB Blaster or Kroil, and lubricate both pivot points underneath the top plate, both slide plungers inside the plunger housings, the slide track, and the center pivot post where the pivot arm rotates. 
  • Verify that the lock closes completely and is operating correctly.
  • Apply lithium-based grease with an EP (extreme pressure) additive to the trailer contact surface of the fifth wheel.
  • Thoroughly degrease and clean the slide track and engagement rack, as well as the plungers and plunger housings using a shop steam cleaning device and suitable degreasing products. Be sure to remove any grease buildup in the slide release mechanism that would inhibit the free rotation of the pivot arm.

How to Service Your Air Supply System

Before the winter season kicks in, it’s also vital that you inspect your air supply system and perform any necessary repairs and maintenance. Follow these steps below to set yourself up for success: 

  • Drain out all of the water from the air tanks.
  • Confirm that all air tank lanyards are attached. 
  • Confirm that the air drier cartridge is less than three years old. 
  • Confirm that the air drier heat element is working correctly. 
  • Remove all the water from the air lines supplying the top plate and slider air release cylinders. 

Other Ways to Winterize Your Semi-Truck

In addition to fifth-wheel winterization, you should prepare other parts of your truck for the harsh winter elements. These are our best tips for preparing for the season:

  • Check your battery and electrical systems and perform any maintenance if necessary.
  • Look over the fuel filter and water separator to ensure everything works properly. 
  • Start using fuel additives.
  • Inspect the cooling system for any necessary repairs.
  • Prepare your windshield and install new wipers or wiper fluid if necessary.
  • Check your tires’ condition and pressure level.
  • Pack an emergency tool kit. 

Invest in High-Quality Fifth Wheels From JOST International

Set yourself up for success this winter and invest in a JOST International fifth wheel. JOST has been manufacturing fifth wheel coupling devices globally since 1956, and we were the first to patent steel-cast fifth wheel coupling. We’ve continued our dedication to innovation ever since with new technologies and exceptional safety features that respond to the needs of our customers. From our unique locking mechanism to our new sensor fifth wheels, our fifth wheels are a standard option at every OEM.

Download our Fifth Wheel Product Line handout to learn more about each product, or give our team a call today!

Manual vs. Air Release Fifth Wheels: Discover the Best Option for You

Manual vs. Air Release Fifth Wheels: Discover the Best Option for You

For years, manual lever-style fifth wheels were the go-to product in the semi-trailer business. Today, air-release fifth wheels have been introduced, providing convenience. So, what’s the difference between manual and air-release fifth wheels, and which option is best for you based on your application? We’re here to tell you all about it. 

Comparing Manual vs. Air-Release Fifth Wheels

The world of semi-tractor equipment has significantly evolved in efforts to improve efficiency and driver safety. One of the new pieces of technology is the air-release fifth wheel. Let’s compare manual and air-release fifth wheels. 

What Are Manual Release Fifth Wheels?

The main difference between manual fifth wheels and air-release fifth wheels is the coupling technology. With manual-release fifth wheels, you may verify that it’s coupled properly by doing a tug test. You should also visually inspect the fifth wheel to be sure. You’ll ensure the locking bar fully crosses the throat, all visual lock indicators are engaged (JOST 5th Wheel Lock Security Link), and check that there’s no air gap between the bottom of the trailer and the top of the fifth wheel. 

To uncouple this fifth wheel, the lock is released manually by pulling a handle on the fifth wheel. 

The Cons of Manual Release Fifth Wheels:

  • There are so many different products on the market, each with its own unique locking operation. Knowing what to check for can be confusing for drivers, thus resulting in safety risks. 
  • The manual lever style is more difficult for the operator to use – it involves more physical work, and it’s challenging to couple and uncouple.

What Are Air-Release Fifth Wheels?

JOST International air-release fifth wheels are favored for their state-of-the-art sensor technology. The sensors are paired with a coupling system that helps the driver confirm that the fifth wheel is properly attached and safely from inside the cab. No more tug tests or visual inspections under the trailer are needed! 

The Sensorkuppling and Lok-Lite systems contain dual sensors. The first sensor indicates that the kingpin is securely in the lock position. The second sensor shows that the fifth wheel is locked and the release handle is secured (JOST 5th Wheel Lock Security Link). The status of the lock is indicated by a JOST-supplied dash display, communicated through the vehicle’s CAN bus or via lighting at the top plate. 

To uncouple the device, air pressure is applied through a valve inside the cab. The driver can safely uncouple without even having to exit the vehicle! 

The Pros of Air-Release Fifth Wheels:

  • A safety system interlock requires the truck to be stopped and the trailer brakes applied before cab controls can be activated.
  • An automatically engaging secondary lock ensures security.
  • A visual lock indicator will confirm proper locking, so you can always be sure you’re good to go.
  • The fifth wheel can be rebuilt in under an hour without taking it off the truck – this significantly improves productivity. 
  • The throat cushion ring reduces wear on the kingpin and absorbs impact.
  • The full-size release handle allows for quick, easy, and convenient manual release.
  • JOST air-release fifth wheels are available for specification at all major OEMs.
  • Insurance costs and claims are reduced.

Air-Release Fifth Wheels From JOST International

As you can see, there are many advantages when you use air-release fifth wheels. From large national fleets to owner-operators, more and more semi-trailers are opting for JOST International air-release fifth wheels. Are you interested in learning more about JOST International air-release fifth wheels? Take a look at our brochure or contact our team today!