How fifth wheels have advanced over the last century

How fifth wheels have advanced over the last century

Making and keeping good connections means you need the right fifth wheel for the job.
Fontaine said its Ultra LT is the industry’s lightest-weight fifth wheel slider system, offering weight savings of up to 100 lbs. or more over other fifth wheel systems and making cost per pound very attractive to fleet operators.

They say, “If you bought it, a truck brought it.” And in addition to that being a dandy title for a country song, for fleet managers, the fact remains if a truck brought it, it likely did so in a trailer connected by a fifth wheel hitch.

Coupling devices using a king pin and receiver plate have been in operation for 100 years now. According to trucking lore, an innovative truck designer named Charles Martin built a gasoline-powered tractor to pull horse-drawn carriages and wagons. Impressive, certainly, especially back in 1911 when there were very few miles of paved roads, but there were a lot of people developing a lot of different vehicles back in the infancy of the trucking industry.

Perhaps even more impressive was Martin’s other invention. To connect the tractor and trailer, he developed a coupler consisting of a round plate with a hole in it, attached to the tractor’s frame. Wagons could be converted by adding lifting jacks and removing the front axle, then installing a king pin to the front of the trailer. Lowering the pin into the plate’s hole allowed the new vehicle to pivot and accommodate rough roads.

In a century that has seen so much technology advancement in every aspect of life and business, fifth wheels may seem decidedly low-tech. After all, if you look at them, they haven’t really changed all that much since their inception, have they? What could there possibly be to know about this product that you haven’t already heard?

“You would be amazed at how much difference there is between fifth wheels,” says Mark Molitor, vice president of product engineering, SAF-Holland, Inc. “Even within our own brand, there are many options that need to be considered with specifying a fifth wheel for your tractor.”

Rich Carroll, vice president of sales & marketing with Jost International, confirms that judging a book by its cover—or in this case a fifth wheel by appearance alone—is often a mistake. “I would say that fifth wheel systems are alike only that they all do the same job, which is to keep the tractor-trailer safely locked. The various locking systems are actually quite a bit different from supplier to supplier and in most cases a given supplier now offers several different locking mechanisms within their product portfolio.”

The simplicity of the Jost locking mechanism is that it has just four moving parts. All Jost fifth wheels use the same locking action.

Terry Mennen, vice president of sales and marketing at Fontaine Fifth Wheel, agrees on the need to give fifth wheels the respect they deserve. “It’s important to note that the fifth wheel is a critical safety item on the vehicle. Its function is to keep the trailer coupled to the tractor.”

In other words, if your fifth wheels aren’t properly maintained, your fleet’s looking for trouble.

Technology benefits
Luckily, technology is playing an ever-growing role and the benefits are tangible. From reduced weight to quicker, easier locking, today’s fifth wheels offer fleets safety and convenience that Charles Martin could just have dreamed about. What do fleets need to understand today?

“While some fifth wheels are simpler than others, what is important to understand from a driver’s perspective is how do they know the fifth wheel is safely locked?,” says Carroll. “From a technician’s perspective, they need to understand the principle of operation, how to check for proper adjustment, how to troubleshoot and repair the wheel when it will not open or close properly. At Jost, we pride ourselves in the simplicity of our locking mechanism with only four main moving parts.”

How have designs changed? This drawing of a round fifth wheel hitch is dated 1940 and comes from the SAE-Holland archives. It calls for weekly greasing of the wheel and its zerk fittings.

Fontaine’s Mennen agrees. “The biggest difference in fifth wheel systems is today’s lock technology. All Fontaine fifth wheels incorporate a patented lock design, which eliminates high-hitching. You will find differences in coupling force, handle pull force required, material (cast or stamped) of the top plate and differences in the type of top plate and lower assembly that are driven by application.

“Fontaine Fifth Wheel takes great pride in offering the only No-Slack lock in the industry,” Mennen continues. “This feature provides a snug fit around the kingpin, which reduces shock inputs into the frame when braking and accelerating. The result is improved driver comfort and extended service life of other frame components.”

While user-friendliness is the goal of all companies, acknowledges Molitor, safety is equally paramount. “While our fifth wheels are designed to be user friendly, they have the very important function of making sure the tractor and trailer stay coupled. Because all coupling situations are not ideal, with variations in trailer age/condition, variation in the lots, and also variation in driver techniques and speed, we have spent a lot of time developing our locks to give a secure connection in less-than-ideal situations.”

But while technology is fantastic, the human element is still critical. “I cannot put enough emphasis that the drivers have the very important job of making sure that the fifth wheel has properly coupled to the trailer’s kingpin before it leaves the yard. This involves not only doing a tug test, but getting out of the cab and visually confirming that there is no gap between the trailer’s upper coupler and fifth wheel and ensuring that there is a secure couple,” Molitor says. “While rare, there have been incidents where a driver has left the lot with the kingpin either sitting on top of the fifth wheel or in front of it.”

To say that an understanding of your fifth wheels should be important may seem obvious, but perhaps because of its apparent simplicity, some review might be in order. Molitor suggests that because of the different types of lock mechanism in use today, fleet managers should carefully read their fifth wheel’s operations manual to know what indicators to look for. “They not only have to visually confirm that the lock mechanism has closed around the king pin, but also have to confirm that other visual indicators such as handle position, shaft position, etc., indicate the lock mechanism has fully closed,” Molitor says.

The top plates of Fontaine 7000CC Series Clean Connect fifth wheels don’t require grease since they contain high-strength plastic insert pads that reduce friction between the top plate surface and the trailer coupling plate.

“I would return to understanding completely on how to know that a fifth wheel is safely locked—once safely locked, fifth wheels do not suddenly open,” says Carroll. “The problem is that with new locking systems entering the market—in many cases as a result of the drive for lighter weight components—we believe the industry may be distracted somewhat from keeping in mind the safety of the locking mechanism. At Jost, we now offer lighter, complete assemblies without changing or sacrificing safety and durability. Remember the top plate is only half of the equation in a fifth wheel assembly; the mounting system, either fixed or sliders, also is important.”

Mennen agrees that safety features should never be taken for granted. “There are a number of features that enhance safety or reduce maintenance costs. With in-cab air release, the driver is no longer required to use the pull handle to open the fifth wheel. The fifth wheel will not open unless the parking brake is set. Fontaine’s Clean Connect top plate eliminates the need for lubrication on the plate surface, which improves steering, increases tire life and helps protect the environment. The Techlock sensor feature lets the driver know with an in-cab light that the fifth wheel is properly closed.”

New fifth wheels
Today’s fifth wheel has three separate parts, say our experts, and differences may be found in the mount, top plate and lock mechanism.

Mounting styles: You can either have a stationary mount where the FW position is fixed relative to the chassis, or a sliding mount where the FW position can be altered for different trailer or load distribution. Both types of mounts have different options to attach to the frame rails—outboard, inboard, or direct mount. In addition, you may find no tilts, semi and fully oscillating, and manufacturer-specific mounts for special applications.

Top plates: Top plates are manufactured by a few different methods and materials such as cast steel, cast ductile, fabricated and even forged aluminum.

Lock types: As stated earlier, several different lock mechanisms are used by the various manufacturers. New designs for automated coupling and electronic monitoring systems are being promoted to the market.

A technician checks the lock mechanism on an SAE-Holland fifth wheel. Because of the different types of lock mechanisms in use today, fleet managers should carefully read their fifth wheel’s operations manual to know what indicators to look for.

The relationship between a fleet and its preferred truck manufacturer can’t be ignored, because the relationship between the OEs and fifth wheel manufacturers is just as strong. The type of fifth wheel you are most familiar with may be directly related to the brand you drive.

“A very high percentage of fifth wheels are OEM factory-installed today; some are installed at the dealer level or through modification centers. On new truck specifications the fleet owner has choices and considerations,” says Carroll. “For example, if the fleet keeps its equipment for more than a few years before trading in, then it should absolutely be considering lifetime cost of ownership beyond the initial acquisition cost. If you know you are keeping the equipment long enough to where rebuilds are likely, then it is wise to choose a fifth wheel that can be rebuilt in 30 minutes without removing the wheel from the tractor, which is the case with Jost.”

Carroll says the aftermarket typically comes into play after the first user, as the fifth wheel either wears to the point of rebuild or is damaged.

Fontaine’s Mennen says rebuild options are varied. “Top plate rebuild kits allow fleet operators to replace worn parts with a new jaw and wedge, along with springs and bushings. Other aftermarket parts include items such as pull handles, air cylinders and clean connect pads. Fleets and second-generation vehicle owners change top plates and/or lower assemblies for vehicles that are used in applications that are different than the original.”

Although the specifics may vary, the importance of maintenance is high no matter which brand of fifth wheel you have. “Each manufacturer, of course, has recommendations regarding service that are fairly similar. Like any mechanical device, proper maintenance has a great deal to do with product performance and lifetime,” says Jost’s Carroll.

“The two most important items in eliminating fifth wheel operating difficulties are proper fifth wheel preventative maintenance procedures and proper coupling procedures,” concurs Molitor.

“All fifth wheels need to be serviced and maintained and the fleets should consult their owner’s manual for proper service intervals and procedures.” Molitor explains. “Preventative maintenance includes cleaning, adjusting, lubricating and inspection. Keep in mind that the majority of fifth wheels on the road use grease to keep friction low between the trailer’s upper coupler and the top plate, and also within the lock mechanism. While new grease is very slippery, it is also a dirt/debris magnet. When you consider that the fifth wheel is mounted directly above the drive axle that is kicking up dirt and debris, you come to realize that it doesn’t take long for your new, clean grease to become contaminated with debris and become abrasive. This debris can cause wear and damage to the trailer’s upper couple, the fifth wheel top plate, and can cause your lock mechanism to not function as intended or to wear out prematurely.”

Research into reducing the amount of grease needed to lubricate the fifth wheel top plate and locking mechanism has resulted in low-lube and even “no-lube” options. In addition to lower grease costs and extended maintenance intervals, less grease allows technicians to work cleaner, safer and faster. On the road, these options can help eliminate excess grease on the drive axle and frame, and eliminate the need for drivers to regrease during a trip.

“These options can eliminate 35 lbs. of grease a year and the time it takes to clean and reapply the grease through a fifth wheel’s life. For example, if a fleet’s mileage dictates performing 12 PMs per year, they can reduce it to two with our no-lube option. This is about 2.5 hours of time plus the expense of the grease. The impact to our environment should also be considered. Consider that every tractor can shed up to 35 lbs. of grease onto our roadways and into our waterways it adds up to tens of millions of pounds of grease a year,” says SAF-Holland’s Molitor.

“Some fifth wheels are recommended for on-highway use only, while others can operate in off-road applications. Fleet operators and truck dealers should consult a fifth wheel application guide to choose the right fifth wheel,” explains Mennen.

Service and Maintenance
Fleets need to follow proper pre-service procedures, which include inspection and lubrication, explains Mennen. “For maintenance, we recommend a simple four-step procedure: visual inspection, function, adjustment and lubrication.”

Some specific maintenance steps:
• Clean, degrease, inspect and lubricate your fifth wheel every 90 days or 30,000 miles.
• Check for cracks in the fifth wheel assembly, mounting brackets and mounting parts.
• Check the mounting for any loose or missing hardware.
• Make sure the bracket pins on both sides are in place and secured by retainer pins and cotter pins.
• Check the operation of the locking mechanism using a lock tester. It must operate as described in the operating instructions.
• Free front to rear fifth wheel rock on brackets with greaseless liners.

“I cannot stress enough the need for fleets to train drivers to follow proper coupling procedures, stressing that the driver always do a visual verification of a secure coupling,” says Molitor. “Fleets need to understand that the driver is the last safety check before the tractor/trailer makes its way to our public roads. Almost as important for safety, and also profit, is proper preventative maintenance. As mentioned above, preventative maintenance and proper coupling procedures will increase the life of the fifth wheel and greatly increase the time before the fifth wheel needs to be rebuilt.”

Luckily, today’s fleets have something else that Charles Martin couldn’t have dreamed of: electronic training resources that will help them keep up with the latest procedures. Technicians and drivers can take advantage of videos, DVDs, PDFs and laminated instruction sheets. In addition, each of these suppliers offers additional product identification and training materials at its respective website.

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