Install Instructions for Trailair Air Ride 5th Wheel King Pin Fabex 730, RBW 7019 21K UF35-946215  

Question:

Helpful Expert Reply:

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 taken not to drop old pin box; this could cause injury. The pin box mounting wings will remain on the coach.

Step 2) Position the top of the upper bracket to match the measurement you took in Step 1 and hold securely in place with clamps. Adjust to make sure the top of new pin box is level with trailer by putting a level on top of and to the front of the new pin box. Match the top bolt on the Trailair bracket to same hole used on the pin box removed and position at that spot in the mounting wings. Care should be taken not to drop new pin box; this could cause injury. We recommend using the nuts, bolts and washers that came with the coach unless they are in bad condition. Make sure replacement fasteners are corresponding the same grade and diameter as those removed. For torque specifications on pin box bolts refer to manufacture’s specifications. If no torque requirements exist, torque 1/2” bolts a minimum of 110 ft/lbs and torque 5/8” bolts a minimum of 160 ft/lbs and torque 3/4” bolts a minimum of 210 ft/lbs.

Step 3) Insert brass bearings into the sleeve on each side of the inner cross tube. Make sure that both the sleeve and the brass bearing are clean and without obstructions. Brass bearings are relatively soft, so care should be taken not to allow the bearings to be damaged prior to insertion. Slide the lower pin box assembly into position with the upper assembly. Slide the 1” square stop pins located on each side of the lower jaw into the retainer section of the side plates of the upper body. These square pins will keep the pin box from overextending or collapsing. This will also help you locate the position of the hole in the jaw side plate with the tube in the main body so you can install the pivot pin. Carefully insert the large pivot shaft through both upper and lower assemblies (if difficult to slide in we recommend lubricating with WD-40). Secure the large shaft in place, on passenger side with serrated washer and bolt, driver side large black washer drops into slot then serrated washer and bolt. Torque bolts on each side to 100 ft/lbs. Use a back-up wrench to hold the bolt on each opposing end. IMPORTANT: Make sure both ends are tightened. ALWAYS CHECK THSE BOLTS BEFORE TRAVELING.

Step 4) Install the air bag: The bag is fastened at the bottom first by inserting the carriage bolt in the key hole shape opening on the lower plate allowing the bolt head to slide in and be pulled forward securing the bag in place. Secure air bag with the air fill fitting in the up position with 2 locking nuts, not exceeding 20 ft/lbs  - torque on the top plate of the air bag. Install air fitting using Teflon tape or pipe sealing compound. Install the shock absorber using the longer bolts with locking nut. Tighten nuts to 60 ft/lbs.

Step 5) Insure that the fifth wheel coupler located in your truck is properly mounted according to the instructions of the fifth wheel manufacturer. In addition, make sure that it is in good working condition as this could affect the performance of the Trailair air ride pin box and could result in unsafe towing. As a reminder, your fifth wheel connection should never be located behind the center of the drive axle.

Step 6) After all nuts and bolts are tightened, attach trailer to tow vehicle, before applying air to nozzle fitting at top of pin box make sure alignment pin is in the hole on the bottom of the air spring. Inflate the air bag with only enough air to raise pin box to the ride height mark on the front of the shock absorber with the truck and trailer at rest. WARNING: DO NOT inflate air spring unless fully secured by the pin box structure, otherwise bodily injury could result. Finish by installing the supplied air cap. The air spring is like a tire in that it can lose air pressure over time. Before starting on any trip you should check ride height mark on front of shock absorber with the truck and trailer at rest.

expert reply by: Michael H

1