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Trailair Air Ride 5th Wheel King Pin - Fabex 750, 765 and 770, RBW 7028 - 21,000 lbs

Trailair Air Ride 5th Wheel King Pin - Fabex 750, 765 and 770, RBW 7028 - 21,000 lbs

Item # UF35-946212
Our Price: $1,711.62
Fifth Wheel King Pin
Shipping Weight: 184 lbs
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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 Lippert fifth wheel king pin part number UF35-946212 or order online at etrailer.com. Free expert support on all Lippert products. Great prices and Fastest Shipping for Trailair Air Ride 5th Wheel King Pin - Fabex 750, 765 and 770, RBW 7028 - 21,000 lbs. Fifth Wheel King Pin reviews from real customers.
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  • Reviews (144)
  • Q & A (0)
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Lippert Fifth Wheel King Pin - UF35-946212

  • Fabex 750
  • Fabex 765
  • Fabex 770
  • RBW 7028
  • 21000 lbs GTW
  • Upgraded Pin Box
  • Lippert
  • Absorbs Road Shock and Reduces Chucking
  • 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 750, 765 and 770
    • RBW 7028
  • 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.



155927 Lippert Components (LCI) Trail Air Kingpin Box - L04

Replaces 35-946212 UltraFab Trail Air Kingpin Box - L04






Customer Reviews

Trailair Air Ride 5th Wheel King Pin - Fabex 750, 765 and 770, RBW 7028 - 21,000 lbs - UF35-946212

Average Customer Rating:  4.7 out of 5 stars   (144 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:

Worked out great on my 2011 Cameo, wouldn't own another 5th wheel with one.



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:

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



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:

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:

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:

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



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:

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:

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:

Pinbox came 3 days earlier then expected. It was packaged well, no damage. I unbolted the original inbox and 2 friends lifted the Curt into place and I bolted it back into place. Took about 15 minutes. Now for the real test when we head back up to the north for the Summer in Montana.



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:

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:

Obviously a quality product made with quality materials. As you can see in the photo I placed the bottom bolts in the bottom hole. Problem is the bottom steel place is very close to the hardware so I had to have the bolt facing outward on the two bottom forward bolts. Don’t like torquing bolt heads but it worked. This is being very nit picky Torqued to 160 ft lbs.



by:

This is an outstanding pin box. It makes our trailer pull really nice. I know everyone says "I didn't even know I was towing anything" which is usually not the case, however with this, it really was like nothing was/is behind me. I highly recommend this product.



by:

I think that this is just what the doctor ordered. I have not installed it yet, but this looks very much like what I need for my trailer!



by:

Easy install. I dropped it down one hole Vs. the factory one and still has all 10 bolts without drilling any holes.



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:

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:

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:

With the help of my wife, I had the Flex Air pin box installed within 1.5 hours. Used a floor jack on top of my pickup tailgate.



by:

I love this AirRide by Trail-air. It provides an incredibly smooth ride on the road. You can adjust the amount of air for your ride, the Schrader valve is right on top of the unit and easy to access. My Trail air installed easily on my Forest River Sandpiper 372LOK mid bunk, especially with help from my Dad. This Trailair solved a big problem for me. I needed an extra couple of inches space between my 2018 Ford Super Duty DRW and the coach. My truck came with the Ford factory-installed Reese 27K hitch and I needed more clearance to allow the tailgate to drop without touching the coach. The kingpin on the Trailair sits at least 2” forward of the factory kingpin and provided that desperately needed space. It really makes for smooth and quiet ride !
etrailer folks were very helpful. The first unit was damaged by the freight company and when I notified them, etrailer sent another unit quickly. I will buy from etrailer whenever I can..



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.


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Show More Reviews

See what our Experts say about this Lippert Fifth Wheel King Pin

  • How Do Trailair Air Ride 5th Wheel Pin Boxes Work
    The Trailair Air Ride 5th Wheel Pin Boxes, such as # LC155943, are a series of air ride pin boxes designed to replace standard pin boxes on your 5th-wheel trailer. This design is to provide a cushioned, air ride. This improves handling and limits the strain on your tow vehicle. The internal air bag absorbs road shock and has a scissor-like motion that allows the pin box to compress; the built-in shock ensures that the pin box rebounds. The internal air bag should be inflated after the...
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  • Hole Spacing & Width of Trailair Air Ride 5th Wheel King Pin for Fabex 750, 765 Pin Box
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  • Compatible Upgraded Pin Box Replacement For A MORryde RPB72-770-06 Pin Box
    The MORryde RPB72-770-06 Pin Box you have is a Fabex 770 bolt pattern so the Trailair Air Ride 5th Wheel King Pin # UF35-946212 that you linked to will be a compatible fit. This air ride pin box will offer you 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. When you encounter uneven terrain on your trip...
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  • How to Determine Fifth Wheel Pin Box Model
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  • Trailair Cushioned Pin Box Recommendation for 2002 Forest River 27 with RBW 7028
    We have a Trailair cushioned pin box that works as a replacement for a RBW 7028, part # UF35-946212 but we do not have a Roto Flex at this time that fits your pin box. This is a great cushioned pin box though that will improve the overall ride quality quite a bit.
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  • Replacement Air Ride Pin Box For A Fabex 765 Bolt Pattern
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  • Cushioned Pin Box Recommendation for 2007 Keystone Cougar with 1621 Lippert Pin Box
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  • Availability of Replacement Sidewinder Pin Box for Fabex Pin Box
    Reese Sidewinder pin box # RP61412 is a correct replacement for several Fabex OEM pin boxes but not for their 770 model. We do not offer a Sidewinder replacement 5th wheel pin box for a Fabex 770 pin box. I confirmed with my contact at Reese that they do not offer a Sidewinder to replace the 770. We do offer two air-cushioned fixed pin boxes to replace the Fabex 770 and these can be seen on the linked page. Reese offers their 5th Airborne # 5AB-E510-710 and Lippert offers their Trail Air...
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  • Dimensions of Trailair Air Ride Pin Box for Fabex 750, 765 and 770, & RBW 7028
    I reached out to the manufacturer, Lippert, who was able to give me some of the dimensions you were looking for regarding the Trailair Air Ride 5th Wheel King Pin - Fabex 750, 765 and 770, RBW 7028 # UF35-946212. They didn't have the dimensions from the bolt holes, but were able to provide me with the spec sheet they did have, which shows the length, width, and height, which should be useful for you. As you can see by the accompanying cut out of the sheet, the Trailair Air Ride # UF35-946212...
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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 for RBW 7028 Pin Box to Reduce Chucking and Improve Ride Quality
    The perfect solution to replace your RBW 7028 pin box is the Air Ride # UF35-946212. It greatly reduces vertical shock that is caused by traditional rigid pin boxes and protects your trailer by reducing the amount of vibration to the the frame, which is more than just an added bonus, it's a way to protect your investment.
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  • Recommended Gooseneck to 5th Wheel Hitch Adapter for a 2014 Chevy Silverado 2500 with B&W Gooseneck
    We actually have quite a few products that you can use as a 5th Wheel to Gooseneck adapter, I am linking the product selection page so you can view the different options to see what you might like. Unfortunately we do not offer any replacement pin boxes that are compatible with your RBW 7028 pin box. Although we have many options, there are a few choices that are much better than other options. Since you have a short bed, the recommended 5th Wheel Hitch for you would be a sliding 5th...
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  • Replacement Pin Box for 2008 Cameo 5th Wheel with 21K Fabex 765 Pin Box
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  • 2011 Carriage Cameo Replacement Cushioned Pin Box Fit
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  • Will Trailair Pin Box Collect Water on Top of It When Parked
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  • Available Replacement Pin Box for RBW 7028 Pin Box
    The only available option we currently have to replace an RBW 7028 pin box is the Trailair Air Ride 5th Wheel King Pin - Fabex 750, 765 and 770, RBW 7028 - 21,000 lbs # UF35-946212. This is an upgraded air ride style pin box that will help provide some added cushion against road shock and help reduce chucking, so it's a nice choice to replace your old RBW 7028.
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  • Replacement Pin Box for RBW 7028 on Trailer
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    Since you have a Mor/Ryde RPB72-770 on your 2012 Carriage Cameo, this indicates that your trailer was originally set up for a Fabex 770 pin box. To replace a pin box on a trailer that originally came with the Fabex 770, Ultra-Fab offers the Trailair Air Ride 5th Wheel King Pin, # UF35-946212. Ultra-Fab does not make the Tri-Glide option for your trailer set-up.
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Do you have a question about this Fifth Wheel King Pin?


Info for this part was:

Employee Lindsey S
Written by:
Lindsey S
Employee Jeff D
Installed by:
Jeff D
Employee Jameson C
Expert Research:
Jameson C
Employee Kathleen M
Updated by:
Kathleen M
Employee Laura H
Updated by:
Laura H
Employee Chelsea B
Updated by:
Chelsea B
Employee Wilson B
Updated by:
Wilson B
Employee Mike S
Updated by:
Mike S

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