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  1. 5th Wheel Pin Box
  2. Curt
  3. Fabex 730
  4. RBW 7019
  5. Upgraded Pin Box
  6. Absorbs Road Shock and Reduces Chucking
Trailair Air Ride 5th Wheel King Pin - Fabex 730, RBW 7019 - 21,000 lbs
Curt

Trailair Air Ride 5th Wheel King Pin - Fabex 730, RBW 7019 - 21,000 lbs

Part Number: UF35-946215
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$1,823.79
5th Wheel Pin Box
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Experience smooth, stable towing with your fifth-wheel trailer by replacing your ordinary pin box with an air-ride-equipped model. The scissoring action of the coupler allows the interior air bag to absorb road shock so that you won't feel it. 1-800-940-8924 to order Curt 5th wheel pin box part number UF35-946215 or order online at etrailer.com. Free expert support on all Curt products. Great prices and Fastest Shipping for Trailair Air Ride 5th Wheel King Pin - Fabex 730, RBW 7019 - 21,000 lbs. 5th Wheel Pin Box reviews from real customers.
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Curt 5th Wheel Pin Box - UF35-946215

  • Fabex 730
  • RBW 7019
  • Upgraded Pin Box
  • Absorbs Road Shock and Reduces Chucking
  • Curt
  • 21000 lbs GTW
  • Fixed Turret

Experience smooth, stable towing with your fifth-wheel trailer by replacing your ordinary pin box with an air-ride-equipped model. The scissoring action of the coupler allows the interior air bag to absorb road shock so that you won't feel it.


Features:

  • Air ride pin box replaces standard pin box on your 5th-wheel trailer to enhance performance
    • Cushions and absorbs road shock
    • Improves handling and overall ride
    • Limits strain on truck and trailer frames
  • Scissor action allows pin box to compress, compensating for jarring and bounce
    • Internal air bag absorbs the road shock
    • Built-in spring ensures that pin box rebounds - keeps air bag from breaking down
  • Direct replacement for OEM pin box
  • King pin connects to any 5th-wheel trailer hitch
  • Sturdy steel construction


Specs:

  • Designed to replace the following pin boxes:
    • Fabex 730
    • RBW 7019
  • Weight capacity: 21,000 lbs
  • 1-Year warranty


Notes:

  • Not for use with any type of gooseneck adapter
  • Because of the size of this item, it ships via truck freight

Eliminate the bounce from your ride with the Trailair air ride coupler. The unique scissoring action of the pin box ensures that road shock is absorbed, preventing the harsh, rigid ride that you typically encounter while towing your fifth-wheel trailer. Not only does this improve your overall towing experience, but it also helps maintain a sound, well-functioning system. Less bounce and jarring means less stress on your truck, trailer and hitch.


Trailair Air Ride Coupler

How the Trailair Air Ride Works

When you encounter uneven terrain on your trip or hit a pothole on the highway, the Trailair pin box compresses, transferring the road shock to its internal air bag. A built-in air spring ensures that this compression occurs in a controlled fashion so that the air bag doesn't burst. It also causes the pin box to appropriately rebound, positioning it so that it's ready for the next bump in the road.



177696 Curt Trail Air Kingpin Box - M14

Replaces 35-946215 UltraFab Trail Air Kingpin Box - M14

Lippert Trail Air Kingpin Box - M14






Customer Reviews

Trailair Air Ride 5th Wheel King Pin - Fabex 730, RBW 7019 - 21,000 lbs - UF35-946215

Average Customer Rating:  5.0 out of 5 stars   (1 Customer Reviews)

Experience smooth, stable towing with your fifth-wheel trailer by replacing your ordinary pin box with an air-ride-equipped model. The scissoring action of the coupler allows the interior air bag to absorb road shock so that you won't feel it.

by:

The pin box worked out very well. You still feel the bumps but almost no chucking. My wife likes to sleep in the truck with her head against the head rest, but she could not do that with the old pin box. The only thing that I had to do with the new pin box was drill out the holes because the old pin box had bigger bolts.



by:

the fit was perfert. as you can see from the pictures is attached, i drilled a hole in the top to drain water that collects. i fabercated a cover to fit over the opening.



by: 05/08/2023

We're so anxious to try out our new Curt TrailAir.
Installation went smoothly, it looks great.
We can hardly wait to experience the ride!



by:

Swapped out the MorRyde cushioned pin box. This Air Ride is awesome



by:

Freight co delivery estimated for Friday, arrived today. (Tuesday). Borrowed a tractor, dropped the old and lifted this monster into place. 12- 15/16 bolts (originally) 18 hole mount. Not sure if the height is correct for the bed, but will adjust it down if after the rubber bumper is inflated, if it doesn’t sit level. The bolt pattern was correct. better get help! From dropping the MFG lippert, to getting the thing lifted an bolts snugged up, about 45min. Will take a bit longer to attach the deadman switch and electrical box. Well crafted, definitely heavy. This should save my truck n RV from porpoising damage as I’m going over Bridges and bad roads.



by:

I purchased this Lippert Air Ride hitch for my 40 foot Genesis Supreme trailer and wish I had bought it 2 years ago and installed it. What a difference is has made both in the trailer when towing as well as the difference in my truck while pulling it down the road. eTrailer had the best price and fast shipping. They as well helped me with verifying the right part number that works with my trailer. I purchase many parts and accessories from eTrailer and will continue to purchase from them in the future.



by:

Fit my 2018 Velano 39ft 5th wheel like a glove. Less than 1/2 hour by myself, with forks on my compact tractor for lifting, and it was installed. Ride is so much better than prior roto flex box



by:

Delivery was sooner than expected. We only drove the 5th wheel from the repair shop to home.
I’ll update after our west coast tour.



by:

Havent used it yet, but M19 pin box is well made. As usual, etrailer shipped it quick and it arrived with zero defects. Ill update after first use



by:

Our fifth wheel experienced pin box cross frame cracking while on a trip. After having it properly repaired I decided to invest in the Trail-air pin box to alleviate the shock and harsh pounding from our lousy roads. I purchased from etrailer.com and installed it myself. Being only a 29 foot 5th wheel the tounge weight is low so after experimenting with pressures I run 40 psi in it and it flexes when hitting bumps or dips taking the stress off the trailer. Tows like a dream. Knowing what I know now I would have bought and installed it when I bought the 5th wheel and saved a repair during a trip. It is expensive but well worth it.



by:

This is my second Trailair pinbox. They are a step above another. My first time dealing with etrailer and I think they are also a step above.



by:

I am well pleased with the ride improvement this king pin provides. It greatly reduces the chucking and makes for a much more enjoyable journey.



by:

Great product takes the hard up and down jerking of a rough road. Things in the the trailer are tossed around.



by:

Have put around 10K miles on the hitch so far and it has performed well. An extra step in the pre-departure checklist to check the airbag pressure/ride height, but it is worth it as it greatly reduces the jarring from pot holes and abrupt changes in road surface. Installation was easy; perfect fit.



by:

I just completed a 2800 mile trip after installing the Trail Air Air Ride pin box on my Solitude 5th wheel. I was able to install it myself from the bed of my pickup using a hydraulic bottle jack to lift it into position.

I previously made the same trip with the factory installed MORryde Cushioned Pin Box and the Trail Air provides a greatly improved ride. With the MORryde, I encountered several sections of concrete highway that set up a front-to-back oscillation which persisted across many miles. I didn't have that issue with the Trail Air.

I didn't order the Flex Air model that also included the flexible block because I was concerned the added height of that pin box would have been a problem. However, after installing the non-flex Trail Air I've found that the other one would have also worked out if I lowered my truck hitch an inch or two.

Also worth noting, this pin box is four inches shorter than the 1621 MORryde it replaced. However with a long bed truck I have no clearance issues and can still lower the tailgate when hitched up.



by:

I’ll start from the second I ordered this online. Confirmation email, then within days a shipping confirmation. When I ordered my shipping said 2 weeks out for delivery. I got the item in 9 days. The communication from the freight service was top notch. Unlike, some reviews the item was in great condition when it arrived. On a pallet in a box. No complaints. The driver even let me back up to his lift gate and help me slide the item into my truck for easier install. I had previously removed the factory hitch box prior to arrival so when the upgraded item arrived I was ready for install. Took about an hour to line everything up. Used a jack in the truck bed to help lift item where I needed it. I haven’t towed with it yet, that’ll be next week. But it looks beastly and like it’ll be a much more comfortable ride for me and my truck. Very happy so far, will leave an updated review after an out of state trip next weekend. etrailer was great. First item Ive ordered from you all but I’ll be back. Thank you!! Happy customer!!



by:

Good looking product. Mounted it on a Montana 40ft 5th wheel. It arrived 2 weeks ahead of schedule. It was easy to install. I did have to grind the corners of the trailer frame bracket as the jaw hinge wouldn’t allow the bolt holes to line up. Once the corners were ground, everything lined up perfectly. It only took my son and I to pick up the pin box and once the first bolt was in, it was simple and easy to do the rest. There are 3 things to complain about. 1. The position of the air valve sucks. Really hard to get at. 2. The mark on the shock for proper inflation is not marked well. Had to get on hands and knees with a flashlight to actually see it. It was suppose to be bright yellow, it’s black, same as the shock. My 3rd complaint would be the fact that I had to drill 3 holes into the pin box to reattach the brake safety cable and the electrical wire box. The biggest positive thing is, is how much of a difference it has made in the ride quality for not only with the trailer but the truck as well. Soooo much smoother than the original pin box. Would I buy another one? You better believe I would. Wondering why I didn’t buy it sooner. Won’t have another 5th wheel without it.



by:

Smooths out the ride greatly, really pleased with so far. I removed the Air chuck and installed a tee with Gauge and air chuck makes it easy to monitor air pressure before traveling, one should note that these do bleed pressure down in few weeks that is pretty much normal for air bags of this type. I have a Dewalt cordless mini compressor and it works great to quickly & quietly pressurize before trip. I usually set my at 65 PSI



by:

Smooths out the porpoising when traveling over rough roads and at uneven bridge abuttments.



by:

Have not did a road test yet but it’s installed.
Way heavier than factory. I have talked to many that have this and like it.
Helps reduce chucking back and forth movement. Nothing will be solve all if you are on a rough road you will feel it.
No hitch will eliminate.
Was fairly easy to install you will need help to lift. I used the tailgate on the truck and backed under and used blocking to get in place. I installed pretty much myself. My wife help some with aligning the bolts.



by:

Best upgrade to the 5th wheel you can do. Our first cross country trip and I-40 beat the snot out of us on all the bridge transitions with the stock pin box. Immediately ordered this unit and now it’s like the trailer is floating behind us. I run 65 psi in the airbag. Solid unit and easy installation.



by:

Exact fit replacement for cheap Keystone OEM part. Fit was so exact, I installed it by myself. Arrived earlier than expected. I hope this will reduce the chucking and smooth out the pull of a 16K RV trailer. I did have to purchase additional bolt sets from my local Home Depot (OEM was 12 sets, this is 18 sets 5/8-11 x 2in Grade 8 with flat and lock washers all torqued to 180 ft lbs).



by:

The king pin has eliminated about 80% of the chucking. I pull 16k fiver. I am very happy with it. Related I always use etrailer for my parts purchase. One time I was stranded near Disneyland. I needed shackle. They had me triple check for correct part and rushed delivery. These guys are the real deal.



by:

This is my second trailair pin box and I just love them it takes all of the bouncing out of the truck in the camper and makes it a smooth ride. Shipping was great and product came packaged as good as possible.



by:

I have used this product for a year now, I really like it , would not take my money back. Sure made my fifth wheel more fun to pull
Crossing bridges don't bounce me around like it did with the old standard pin box


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Show More Reviews

See what our Experts say about this Curt 5th Wheel Pin Box

  • Replacement Pin Box For A 2010 Carriage Carri-Lite 5th Wheel Trailer
    Based on the part number listed on your pin box (RPB72-730) you would have a Fabex 730 bolt pattern. At this time the only replacement option that we have available is the Trailair Air Ride 5th Wheel King Pin - Fabex 730 - 21,000lbs # UF35-946215. This upgraded pin box includes a shock and internal air spring in order to fine tune the ride quality of your trailer.
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    Can you get the pin box number off of the Revolution? You should see something like LIPP 1621 or Lippert 1621 or 1716. With that info we can determine which Trail Air you would need. Or if you see Fabex 730 or RBW 7019 the part # UF35-946215 you referenced would be a fit. It's interesting that you want to go from the Revolution to the Trailair. Typically the Revolution/Sidewinders are the most preferred pin box style and are what people switch to and not from.
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  • Measurements Of Trail Air Ride 5th Wheel King Pin # UF35-946215
    I went out to our warehouse and took some measurements for you of the Trailair Air Ride 5th Wheel King Pin - Fabex 730, RBW 7019 - 21,000 lbs # UF35-946215. Probably the most helpful measurements are: From the bottom of the king pin to the top of the air spring the measurement is 13 inches. From the bottom of the king pin to the top of the shock on the front is roughly 14-1/2 inches From the base where the hitch plate connects to the center of the first bolt hole is 9-1/2 inches. I've...
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  • How to Determine Fifth Wheel Pin Box Model
    If you are unable to contact your trailer's manufacturer with your VIN to find the factory pin box model number there are some steps you can take which will allow you to determine what pin box model you have so you can purchase a new FlexAir. To do this you will need to follow the steps in the linked help article, which I will go over with you. Start by selecting your pin box style like in the accompanying photo (which you will also find in the help article). You will then need to use...
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  • Can a Gooseneck Adapter be Used on a Trailair Air Ride Pin Box
    You can use the Convert-A-Ball Cushioned 5th-Wheel-to-Gooseneck Adapter # CAB-C5G if you change out your pin box, but unfortunately the Trailair Air Ride # UF35-946215 that you have cannot be used with a gooseneck hitch adapter. We do have some options for you to use a 5th wheel hitch like the B&W Companion # BWRVK3500 in a B&W gooseneck hitch but I would need to know what brand gooseneck hitch you have to verify a fit.
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  • Availability of Trailair Tri-glide to Replace RBW 7019 Pin Box
    The Trail Air air ride pin box that would replace your RBW 7019 pin box on your fifth wheel would be part # UF35-946215. You can see current pricing on the product description page I've linked for you. Having a good 5th wheel hitch that utilizes a wrap around jaw to firmly hold the king pin would go a long way to reduce chucking. The standard Air Ride pin box will offer a noticeable improvement in ride quality over an OEM pin box. If you would like to upgrade your fifth wheel hitch, I...
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  • Using 21,000 lb Rated Fifth Airborne Air Ride Pin Box on 6,400 GVWR 5th Wheel
    All of the 5th Airborne and TrailAir air ride pin boxes we offer as replacements for the RBW 7019 pin box are rated for 21,000 lbs. Although the capacity of the pin box is much higher than gross weight of your fifth wheel, it will not cause any problems. The bolt pattern used to connect your existing RBW 7019 pin box is specific to that model, so unfortunately using a different lower rated replacement pin box will not work for you. The Ultra-Fab TrailAir Air Ride 5th Wheel Pin Box, part...
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  • How Much PSI Should be Put in the Trailair Air Ride 5th Wheel King Pin
    Hey Debbie, thanks for reaching out about the Trailair Air Ride 5th Wheel King Pin # UF35-946215! According to the instructions you'll want to inflate the air bag enough to match the mark on the shock absorber. This should be 80-90 psi and then you can fill it up to 120 psi if you feel like this warrants it. The minimum pressure shouldn't go below 45 psi.
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  • Recommended Air Pressure in Air Bag of Trailair Air-Ride Pin Box
    The pressure in the airbag of the # UF35-946215 Trailair Pin Box can range from 20 to 120 psi depending on your situation. Once the pin box is installed, hitch the trailer to the tow vehicle on level ground. There is a sticker on the front of the shock absorber on the pin box. You should inflate the air bags until the bottom lip of the top shroud on the shock absorber is even with the arrows on the decal. TrailAir states keeping the ride level maintained at a certain level is the most...
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  • Troubleshooting Air Pressure Loss in my Trailair Pin Box
    The air bag in the Trailair Air Ride 5th Wheel King Pin part # UF35-946215 will seem to feel different when the camper is attached to the truck and can feel slightly softer after it is disconnected. It shouldn't loose any pressure. If you unhook the trailer and measure it at 30 psi it should be at 30 psi the next day as well +/- a lb. or so for temperature difference. If this is what is happening fill the bag to about 50 psi and spray with a soapy water solution to see where the leak...
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  • Trailair Air Ride 5th Wheel King Pin Pressure When Storing
    The air pressure on the Trailair Air Ride 5th Wheel King Pin - Fabex 730, RBW 7019 - 21,000lbs Item # UF35-946215 will gradually decrease over time, which is why the manufacturer states that you should check the pressure before each use. From what I've read from owners of this king pin the pressure typically holds for 2-3 weeks before needing to be filled up again. The environment you're in can affect this of course. So you can relieve the pressure if you want or leave it alone and it will...
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  • Cushioned Replacment Fabex 730 Pin Box
    If yours is broken it's time for a new one as there isn't a safe way to repair them. We have a replacement cushioned pin box to replace the Fabex 730 model you have on your trailer currently with the Trailair part # UF35-946215. This will bolt right up to what you have and give you a cushioned ride that will make towing much more enjoyable. This also has the same 21k capacity as your old pin box.
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    The Trailair Air Ride 5th Wheel Pin Box # UF35-946215 has an air pressure range between 20 and 120 psi and the amount of air you'll need to use will be determined after you hook your trailer up to your hitch. This will be indicated by a sticker located on the front shock and not by a specific psi. You will simply line up the lower part of the shock's outer tube with the top of the sticker. I've attached some photos to assist.
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  • 5th Airborne Premium Fifth Wheel Air Ride Coupler To Replace RBW 7026
    In my research I was unable to find 7026 as one of the RBW model pin boxes. It's possible the last number has worn off and what looks like a 6 is really an 8. You may want to check the number again to make sure it that isn't the case. If you find you have a 7028, which is a fairly common one, the replacement is part # UF35-946212. If you can't make out the last number for sure, you will need to measure the mounting holes to find the right replacement. I have attached a helpful article...
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  • Replacement Trail Air Pin Box for a Fabex PB730H 5th Wheel
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  • Recommended PSI For A Lippert Air Ride 5th Wheel Pin Box
    There isn't a set PSI for the Trailair Air Ride 5th Wheel King Pin - Fabex 730, RBW 7019 - 21,000lbs Item # UF35-946215. On the front of the pin box there is a shroud that wraps around the air shock absorber tube that will match right up to the tip of the arrows when the correct PSI is reached.
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  • Install Instructions for Trailair Air Ride 5th Wheel King Pin Fabex 730, RBW 7019 21K UF35-946215
    Yes, I can help you out. Below are the installation instructions for Trailair Air Ride 5th Wheel King Pin - Fabex 730, RBW 7019 - 21,000 lbs Item # UF35-946215. Step 1) The Trailair pin box is installed in two main sections, upper body and lower jaw. Level trailer front to back. Measure old box from bottom of the kingpin plate to the ground. Add 9.5” to this measurement and that will be the height of the top flat area of the upper body to the ground. Remove old pin box. Care should be...
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  • Fit of Trailair UF35-946215 Air Ride Replacement Pin Box on 415 Raptor 5th Wheel
    Air Ride pin boxes aren't RV specific, they're specific to the OEM pin box used by the manufacturer when your 5th wheel we manufactured. All the OEM pin boxes use a different bolt pattern, so it's crucial to identify which one you have. The air ride pin box you need will depend on the manufacturer and model number of the OEM pin box on your 5th wheel. The pin box will have a sticker or ID plate on it somewhere that lists the manufacturer and model number. The # UF35-946215 Trailair Air...
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  • Pin Box Replacement Recommendation for a Lippert 1116 to Reduce Chucking
    For a cushioned pin box to replace your Lippert 1116 pin box I would recommend the Trailair Glide part # LC155943 as it has been confirmed as replacement fit. Integrated steel rollers allow the bottom jaw to glide, reducing the push and pull that is typical in fifth-wheel towing. The internal air bag cuts down on bounce by absorbing road shock. The Trailair Tri-Glide works to defeat this troublesome occurrence by incorporating steel rods into the bottom of the pin box. These three rods...
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  • Recommended Air-Cushioned 5th Wheel Replacement Pin Box for Keystone Montana
    An aftermarket 5th wheel pin box that includes an air spring can improve your ride quality by taking some of the bumps out of your towing day. You can select a suitable cushioned pin box by noting the part number of your current pin box; usually this is found on the safety sticker on the left side of the box. Once you know your pin box number you can use the linked page to see the available models that will bolt up in its place. For example, if you have the popular Lippert 1621 then you'll...
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  • What is Minimum Clearance Between Fifth Wheel Overhang and Bed Rails of Truck
    The minimum distance you want to have between the overhang of a fifth wheel trailer and the bedrails of a truck is going to be 6 inches. Some argue it's only 4 inches but 6 inches is really the safest minimum number to go with. You can adjust the height of the fifth wheel hitch head and the pin box in the frame of the trailer typically to allow you to get this clearance. But you also have to keep in mind that the trailer needs to be kept as level as possible too.
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