If your 5th wheel won't release, the most common cause is pressure on the locking jaws. When the tractor has pulled forward even slightly, or the rig is parked on a slope, the kingpin pushes against the jaws and the release handle won't budge. The usual fix: set the trailer brakes, back the tractor gently into the trailer to take the pressure off, set the tractor brakes, and pull the handle again. Below is the full step-by-step procedure, what to check when that doesn't work, and how to pull the release without hurting your back.
How to Release a 5th Wheel: Step by Step
Follow your company's procedure and your fifth wheel manufacturer's manual first. This is the standard sequence most drivers are trained on:
- Position the rig on firm, level ground, with the trailer lined up straight with the tractor. Check the ground under the landing gear for soft or uneven spots.
- Set the trailer brakes and ease the pressure on the jaws. With the trailer brakes set, back the tractor up slightly to relieve the pressure between the locking jaws and the kingpin. Schneider's uncoupling procedure calls for exactly this step.
- Set the tractor brakes, shut down the engine and take the key with you.
- Lower the landing gear until both pads are firmly on the ground. Some training manuals suggest a few extra turns on a loaded trailer to take weight off the fifth wheel (without lifting the trailer off it). Follow your company's rule on this.
- Disconnect and stow the air lines and electrical cable.
- Pull the 5th wheel release handle to open the jaws. Stand beside the tractor, clear of the tires, and pull steadily with your legs rather than your back. If the handle doesn't pull easily, don't fight it. Go back to step 2 and ease the pressure again.
- Pull the tractor forward slowly until the fifth wheel is just clear of the trailer apron, stop and check that the landing gear is holding the trailer, then pull clear.
Why a 5th Wheel Won't Release
If backing up doesn't free the handle, work through these common causes. Truck News' guide to fifth wheel problems covers most of them in detail.
1. Pressure on the jaws
By far the most common cause. On an incline, the kingpin puts longitudinal pressure on the jaw, and even a small forward roll of the tractor does the same. The fix is to slowly back the tractor into the trailer, with the trailer brakes set, to relieve the pressure. On a slope, have someone chock the wheels before you try again.
2. Air suspension pushing up on the jaws
Improperly inflated tractor air bags can put upward pressure on the jaws. Make sure the suspension is at normal ride height, and don't dump the air bags while you're trying to release unless your procedure calls for it.
3. Jaws adjusted too tight
If the lock is adjusted too tight for the kingpin, or a jaw pin has over-adjusted for kingpin slack, the release can bind. Adjustment should be checked by a mechanic with a new SAE kingpin or a test gauge. Don't adjust it repeatedly yourself: Fleet Equipment notes that frequent adjustments can cause premature wear of the locking mechanism.
4. Dirt, old grease, snow or ice
Packed snow, ice or dirt can restrict the lock. So can a buildup of old grease and grime. Clean the fifth wheel and keep it properly lubricated as part of routine maintenance.
5. Worn or misadjusted parts
A release rod that has slipped out of its track or wasn't adjusted properly, a jammed safety latch, or worn lock surfaces on the jaws can all stop the release from working. These are shop repairs. If the fifth wheel is worn, ask your dealer whether it can be rebuilt rather than replaced.
6. Air-release systems
Some fifth wheels have an air-operated release controlled from the cab. Some only work with the parking brake set. If an air release won't open, check your air pressure and brakes before suspecting the lock itself, and check your manual for the manual-release procedure.
Pull the Release Without Getting Hurt
The 5th wheel release handle sits low and close behind the tractor's drive tires. Pulling it by hand means bending, twisting and reaching, and a sticky handle invites a hard yank. That's how drivers end up with neck, shoulder and back injuries, and with grease and road grime all over their clothes. Sprains and strains account for about half of all trucking injuries.
- Never put any part of your body under the trailer or between the tractor and trailer while the rig can move. Brakes set, engine off, key with you.
- Stay clear of the tires when you pull the handle.
- Pull steadily, don't jerk. If it won't move, relieve the pressure on the jaws rather than pulling harder.
- Use a release tool so you can reach the handle from an upright position.
Using a Fifth Wheel Pin Puller or Release Hook
A 5th wheel release tool (often called a fifth wheel pin puller or pull hook) is a steel bar with a hook that grabs the release handle, so you can pull it from beside the tractor instead of reaching in by hand. To use one:
- Set the brakes and lower the landing gear as above.
- Stand beside the tractor, clear of the tires, and seat the hook on the 5th wheel release handle.
- Pull with a steady pull, using your legs rather than your back, until the handle locks in the open position.
OPNBar makes several release tools, all made in the USA from steel:
- 5th Wheel Release Hook & Pin Puller: a dedicated release hook that also works as a container door leverage bar and tire thumper. 24 in, 3 lb, fits behind the seat.
- OPNBar V4 5th Wheel Release Version: V4 leverage bar, pull hook and detachable extension bar for extra reach.
- OPNBar V5: a tight-clearance container leverage bar with a built-in 5th wheel hook.
- OPNBar V2 New Angle Bend: container leverage bar, 5th wheel hook and tire thumper in one.
Not sure which one fits your work? Compare them all in our shipping container leverage bars and trucker tools collection.
Official OPNBar instructions: How to release a 5th wheel hitch with the OPNBar | How to Use the OPNBar | OPNBar Instructions
FAQ
Why won't my 5th wheel release handle pull out?
Usually because the kingpin is pushing against the locking jaws. Set the trailer brakes, back the tractor up slightly to relieve the pressure, set the tractor brakes and try again.
Should I back up or pull forward to release a 5th wheel?
Back up, gently, with the trailer brakes set. Pulling forward increases the pressure on the jaws.
Does a stiff 5th wheel need adjusting?
Sometimes. If relieving pressure and cleaning don't help, have a mechanic check the lock adjustment with a kingpin gauge. Don't adjust it repeatedly, since that can wear the lock prematurely.
How often should a fifth wheel be lubricated?
Follow the manufacturer's maintenance schedule for your fifth wheel. Keeping it clean and lubricated helps prevent a sticky release.
What is a fifth wheel pin puller?
A hooked tool that lets you pull the fifth wheel release handle from a standing position beside the tractor, without reaching under the trailer by hand.
Can I use a 5th wheel release tool on tandem axle slider pins?
The OPNBar release hooks are designed for the fifth wheel release handle, not for tandem slider pins.
This article is general information, not professional or legal advice. Always follow your fifth wheel manufacturer's instructions, your company's procedures and applicable regulations. See our full Company and Products Disclaimer.