Your truck's 2-inch receiver is already a bolted-on, rated mounting point that no one has to drill. Can it hold a battery train horn gun? Yes, and it's one of the easiest mounts to undo, as long as you plan for the four problems that come with mounting at the back bumper: rattle, theft, road spray, and getting it out of the way when you tow.
The short answer: yes, and the horn is the easy part
A traditional train horn kit doesn't belong in a receiver. It has a compressor, a tank, air line, and a 12V circuit that all have to be plumbed somewhere. Horn kit makers do sell mounts that bolt to the hitch area, but those use the factory hitch bolts or the spare-tire space under the bed. The receiver opening isn't involved, and you aren't pulling those back out on a Saturday.
A horn gun is a different job. The compressor, trumpets, and trigger are one unit, and the power is a cordless tool pack. The 5-Trumpet Horn Gun for Milwaukee® 18V Battery runs on any Milwaukee® M18™ pack, is rated up to 150 dB, and has a listed shipping weight of about 4.5 lb with a battery. A Class 3 receiver is commonly rated for 800 lb of tongue weight. Weight isn't the issue here. What decides whether a receiver mount lasts is how the horn is held, how it's locked, and what the back of a moving truck throws at it.
If you'd rather keep the horn up front or in the cab, our guide on how to mount a portable train horn gun on a truck with no wiring covers those spots. Everything below is specific to the receiver.
Know your receiver before you buy anything
Receiver accessories are sized to the opening, so measure the inside of the tube instead of trusting a sticker. Industry sizing guides group them like this:
| Hitch class | Receiver opening | Typical hitch pin | Where you'll see it |
|---|---|---|---|
| Class 1 and 2 | 1-1/4" | 1/2" | Cars, small crossovers, some motorcycles |
| Class 3 and 4 | 2" | 5/8" | Most half-ton trucks and full-size SUVs |
| Class 5 | 2" or 2-1/2" (some 3") | Sized to the receiver | Heavy-duty trucks |
Most readers will have a 2-inch receiver, and it also has the widest choice of accessory brackets. If your receiver is 2-1/2", buy a bracket made for that size or a reducer sleeve that's rated for it.
Three bracket styles that work for a horn gun
No one sells a receiver bracket made specifically for a train horn gun, so you'll be adapting a general-purpose receiver accessory. Three types work well:
- Receiver accessory plate. This is a short 2"x2" shank welded to a flat steel plate. Most are sold as winch or shackle mounts, and the ones built for winches use a 10" x 4-1/2" bolt pattern. That's far more plate than a 4.5 lb horn needs, but it gives you a flat, rigid surface. Bolt a cradle or a pair of padded clamps to it and strap the horn body down with the trumpets clear of the edge.
- Multi-hole accessory bar. These are steel brackets sold for whip lights and flags. They have several pin holes along the bar, so you can set the horn height and how far it sticks out. Lifting the horn above the bumper line keeps it farther from tire spray and easier to reach.
- Hitch cargo tray. If you already own a basket-style cargo carrier, a horn cradle bolted inside one corner is the lowest-effort option. It also puts the horn high enough to clear most mud. The drawback is that the tray, not the horn, now sets your rear clearance.
Whichever you choose, make the horn-to-bracket connection quick-release. If the horn can come off in a few seconds, the same bracket works for pulling the horn before a car wash or moving it to your boat. We go deeper into latch-and-base systems in quick-release train horn mounts for swapping vehicles.
Rattle and theft: the pin is doing two jobs
A plain pin-and-clip leaves a little play between the shank and the receiver wall. With a trailer on, the trailer's weight holds things in place. A light horn bracket has nothing holding it, so it buzzes over every expansion joint. Over time that vibration loosens bolts and wears the clamp pads on the horn.
- Use an anti-rattle pin or a clamp. Threaded anti-rattle pins pull the shank tight against the receiver wall when you tighten them with a wrench. Bolt-on hitch tighteners clamp the shank to the tube from outside. Note that threaded pins generally need a hollow-shank accessory. A solid-bar bracket needs the clamp style.
- Make the pin a lock. Locking hitch pins come in the standard 1/2" and 5/8" diameters, usually with a barrel lock and a dust cap. A standard pin and clip come out by hand. A locking pin means a thief has to bring tools and spend some time on it.
- Don't leave the horn on a parked truck. A locked bracket protects the bracket, but the horn itself is still clamped on the outside of the bumper. At a trailhead or in a mall lot, unclip the horn and put it in the cab, or at least take the battery. A horn gun with no pack is far less useful to a thief.
If you'd prefer a spot thieves never see, our list of hidden no-drill train horn mounting spots is the better place to start.
Road spray, salt, and the low-pressure pocket
The back of a truck is dirtier than it looks. A vehicle with a squared-off rear leaves a low-pressure wake behind it, and the tires throw spray, dust, and slush straight into it. That's the same reason an SUV's rear glass gets coated in winter. A horn sitting in the receiver lives in that wake, so plan for it:
- Pitch the trumpets slightly down so water drains out instead of pooling. Our guide to trumpet orientation and moisture explains why this matters.
- Cap or cover the bells on gravel and salted roads, and take the covers off when you want to use it.
- Keep the battery out of the wake when you aren't using the horn. Charge the pack indoors and clip it on when you head out.
- Look after the receiver too. U-Haul's hitch-maintenance guidance says to remove receiver accessories when they aren't in use and to coat the inside of the receiver with a non-solvent protectant. A bracket left in for months can rust in place. One forum owner reported that a hitch left in the receiver about a year bent and broke before it would come out.
Pull it before you tow, and watch the plate and sensors
A receiver can only hold one thing at a time. When the trailer goes on, the horn bracket comes off. That's the main tradeoff of this mount, and also the reason a no-wiring horn gun suits it so well: there are no connectors to unplug. You pull the pin, slide the bracket out, and toss the horn on the seat.
Before you leave a bracket in full time, check two more things:
- License plate visibility. State rules differ. In Michigan, MCL 257.225 requires a plate to be clearly visible but specifically exempts a tow ball, bicycle rack, removable hitch, or other carrying device on the rear of the vehicle. In Georgia, an appellate court upheld a traffic stop where a hitch partly blocked one character on a plate. Keep the horn and bracket below or to the side of the plate. If you aren't sure about your state, take the bracket off when you aren't using it.
- Backup sensors and camera. On towing forums, truck owners report false parking-sensor alerts, and in some cases a "sensors blocked" fault, from large hitch hardware left in the receiver. A horn sitting out on a plate can do the same. Test it in your driveway, and check that the backup camera view is still usable.
Aiming matters too. A receiver mount puts the trumpets behind the truck, so pointing them straight back sends most of the sound away from whatever is in front of you. Turn the bell ends to the side, or forward under the bumper if you have room. Our article on which way train horn trumpets should face covers the tradeoffs.
Triggering a horn that's behind you
You can't reach a trigger on the back bumper from the driver's seat, so a receiver mount depends on a remote. The 5-Trumpet Horn Gun ships with a wireless remote rated up to 160 ft, which is plenty for a cab-to-hitch distance. If you also want to sound it from a campsite or across a field, the Long-range Remote (2000ft) is the upgrade.
If your packs are another brand, the same hitch setup works with any of our train horns with remote control. Pick the one that fits the batteries already in your garage.
FAQ
Will a hitch-mounted horn gun be as loud as one up front?
The horn makes the same sound wherever you mount it. What changes is where that sound goes. Trumpets pointed straight back under a tailgate will seem quieter to the driver of a car ahead of you, so angle them out to the side or forward.
Do I need a 2-inch receiver, or will 1-1/4 inch work?
Either works. A 4.5 lb horn is a tiny load for a 1-1/4" receiver. The 2" size just gives you more bracket choices. Buy the bracket for the receiver you have, and use the matching pin, 1/2" for 1-1/4" or 5/8" for 2".
Can I leave the bracket in all year?
You can, but you'll pay for it in rust, rattle, and possible plate or sensor problems. Treat the bracket like a ball mount: put it in when you'll use it, and pull it and grease the receiver when you won't.
Does mounting a horn gun in the receiver void my warranty?
It's a bolt-free accessory in a factory receiver with no wiring, so nothing on the truck gets modified. For the longer answer, see our article on whether a train horn voids your truck warranty.