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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
In Stock
$1,851.15
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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  • Reviews (1)
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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.

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So far very happy! Thanks for all the great help Adam.



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The product bolted right up.



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Workin good.



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Works great, no problems



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It works great on my triple tow



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Works Great! Takes the bounce off your tow vehicle.



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Working out great. Thanks for the follow up



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Love it. I have plate collection and hauls great.



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Really smoothed out the ride. Should have had one years ago.



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Product does cushion the bumps on the road. I’m pleased with product.



by:

Shipping was great and my camper pulls so much better. Great product!



by:

Works great helped ride 110% will always use one from now on. And as usual great people that do a excellent service job an polite thank you a business is hard to find with customer service y’all have 5 stars.



by:

Works really well. Installed it myself. Definitely smooth out the ride between the pick up and the RV.



by:

Does help lessen impact of chucking on most roads. Unfortunately even this unit is no match for the s**t roads in central CA from Bakersfield to Modesto.



by:

Works great but doesn't hold air for more then a couple days.



by:

Service was good as usual! Hope it works as well as expected. Haven’t used yet. Will re-rate later.



by:

Every thing went Like you said it would .It was in very good shape with no damage .Going to put it on my RV and see how it works. Thank you


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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.
    view full answer...
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  • Can a Reese Revolution Pin Box be Replaced with Trailair Pin Box
    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.
    view full answer...
  • 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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  • Can a Welded-On Capture Plate be Cut Off of a TrailAir M14 Pin Box
    If you were to take a torch or grinder to the pin box you run the risk of damaging or weakening the skid plate. If you wanted to do that I would have it done by a professional welder to ensure that the skid plate is not damaged. Ideally though you would replace the TrailAir pin box with a new one, # UF35-946215.
    view full answer...
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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.
    view full answer...
  • 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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  • 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...
    view full answer...
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  • Replacement Trail Air Pin Box for a Fabex PB730H 5th Wheel
    Yes, the Trailair air ride fifth wheel king pin # UF35-946215 will replace your current Fabex PB730H pin box. The Trailair will improve your handling and the maximum weight capacity is 21,000 pounds.
    view full answer...
  • 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...
    view full answer...
  • 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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  • 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...
    view full answer...
  • 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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  • 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...
    view full answer...
  • 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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  • How Much Air Pressure Should Trailair Cushioned Pin Box Have
    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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    Image 1 for
  • Should an Air Ride/Air Bag Pin Box Be Used when Towing 5th Wheel with Peterbilt Rig
    Typically, 5th wheel pin boxes with airbags are used when someone wants to improve the ride quality of the tow vehicle while pulling the trailer. You can certainly use a pin box with an air bag to help reduce the stress on your trailer while towing with your rig, but the stress reduction will likely be minimal. An air ride pin box will not provide a noticeable difference in ride quality with your rig. If you decide to replace your existing pin box with an air ride pin box, you will want...
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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.
    view full answer...
    Image 1 for
  • Comparing Longevity of Reese and TrailAir Cushioned 5th Wheel Pin Boxes
    The cushioned 5th wheel replacement pin boxes we offer, including Reese and TrailAir items, are all shown on the linked page. Like you, I take note of the major difference in the warranty coverage between these brands and if it were me that difference would matter. I can also suggest that for your assessment of these products you check out the reviews posted by our customers that have purchased these products from us. On each item's page you can click on the review link next to each photo....
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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...
    view full answer...
  • Availability of TrailAir Cushioned Pin Box to Replace Lippert Unit on 2007 Keystone Cougar 310SRX
    Compatible replacement 5th wheel pin boxes are determined based on the original item's part number. Lippert's most popular pin boxes are their 1621, 1621HD and 1716 models and these part numbers usually appear on the sticker located on the driver's side of the pin box. Once you know your pin box part number you can check for available replacement units like the TrailAir Flex Air # LC328492, for example, which bolts right up in place of a Lippert 1621. The linked page displays all such...
    view full answer...
  • 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...
    view full answer...
  • King Pin To Front Bolt Hole Measurement For The Trailair Air Ride 5th Wheel King Pin # UF35-946215
    From the center of the first set of bolt holes to center of the king pin on the Trailair Air Ride 5th Wheel King Pin # UF35-946215 is approximately 14". I do want to note that the # UF35-946215 only fits the Fabex 730 and RBW 7019 bolt patterns. If you don't have one of these two patterns then you would need to find the appropriate match. If you don't know what your bolt pattern is and have a serial number on the front or side of your pin box then I can run the numbers to determine the...
    view full answer...


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Info for this part was:

Employee Mike L
Expert Research:
Mike L
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Michael H
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Jameson C
Employee Adam R
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Employee Jeffrey L
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Employee Lindsey S
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Employee Jeff D
Installed by:
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Employee Kathleen M
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