- +Complete 12V system under one part number: horn, solenoid, compressor and 5.5 L tank
- +Built-in 80/110 PSI auto on/off switching, so no separate pressure switch is needed
- +Compact four-trumpet mini horn fits tighter spaces than full-size trumpets
- +Modest 12 A compressor current draw
- +Both parts (46123 horn, 46140 air kit) are sold separately as replacements
- −130 dB rating has a ±10 dB tolerance and no disclosed test distance
- −Only a 6-month warranty, with a dealer-noted exclusion for upside-down or under-truck mounting
- −$317–$392 street price is high next to comparable complete kits
- −No published compressor duty cycle, airflow or chord frequencies
- −Horn dimensions conflict between United Pacific's sheet and retailer listings
Methodology
This review aggregates publicly available information from manufacturer specifications, retailer listings, and verified user reviews. We do not perform hands-on testing. United Pacific’s truck-division site (truck.upauto.com) was behind bot protection at review time, so the core facts come from United Pacific’s own printed spec sheets for the 46173 bundle and the 46123 horn, as hosted by authorized dealer Vehicle Safety Supply. We cross-checked those sheets against five retailer listings (Big Rig Chrome Shop, Chrome and Parts, Chrome Country, Fleet Truck Parts and Classic Chevy). We found no published independent sound measurement for this kit. Last reviewed: October 1, 2026.
Quick verdict
The United Pacific 46173 Mini Train Horn Bundle is a simple pairing of two catalog parts: the 46123 chrome 4-trumpet mini horn and the 46140 heavy-duty compressor and 5.5-liter tank kit. It gives you a complete 12V system under a single part number. The pieces are sensible, but the bundle is hard to recommend at its typical $317–$392 street price. The 130 dB rating comes with a ±10 dB tolerance and no test distance, the warranty is only six months, and published specs are thin: no duty cycle, no chord frequencies and conflicting horn dimensions between listings. Our editorial rating: 3.2/5. It makes the most sense for a truck owner who already buys from United Pacific dealers and wants one SKU instead of piecing a system together.
What it is
The 46173 is United Pacific’s mini train horn kit. The manufacturer’s spec sheet describes it as a “Chrome Deluxe 4 Trumpet Mini Train Horn (UP Item # 46123) w/ Heavy Duty Air Compressor and 5.5 Liter Air Tank (UP Item # 46140).” The kit includes “1 Train Horn” and “1 Turbo Air Compressor and 5.5 Liter Tank System.”
United Pacific Industries makes products for heavy-duty trucks and classic cars, so the bundle targets the semi-truck and pickup crowd. The spec sheet’s fitment table lists “Universal” and the description opens with a pitch about trucking safety. The “mini” in the name matters: the 46123 is a compact four-trumpet cluster built on a single base. It is not a set of long, separately mounted trumpets like United Pacific’s 46130 or the Competition Series horns.
Because the bundle has its own compressor and tank, it also suits vehicles without onboard air. That is the main difference from the brand’s horn-only models, such as the 46129 and 46130, which assume you already have an air supply. For the rest of the lineup, see our United Pacific hub.
Specifications
| Spec | Value |
|---|---|
| Part number | 46173 (bundle); horn 46123; air system 46140 |
| Sound output | 130 dB ±10 dB (test distance not disclosed) |
| Trumpets | 4 (mini, single-base cluster) |
| Horn finish / material | Chrome-plated zinc alloy |
| Horn max air pressure | 150 PSI |
| Compressor auto-on / auto-off | 80 PSI / 110 PSI |
| Compressor voltage / current draw | 12V / 12 A |
| Compressor size | 6” L × 3.5” W × 5” H |
| Air tank capacity | 5.5 liters |
| Air tank size | 18” L × 5” W × 5-3/4” H |
| Air fitting | 1/4” air hose |
| Solenoid valve | 12V heavy-duty electric, included with horn |
| Horn dimensions | 12” L × 6-1/2” W × 6” H per retailers; “approximately 15” L × 9-3/4” W × 12-1/2” H” per the 46123 spec sheet |
| Chord frequencies | Not disclosed |
| Compressor duty cycle | Not disclosed |
| Package dimensions / weight | 29.5” L × 6.5” W × 8” H / 13.6 lb |
| Warranty | 6 months |
| Price | $369.85 at Vehicle Safety Supply; $317–$392 across dealers |
- Rated output
- 130 dB ±10 dB
- Working pressure
- 80–110 PSI (compressor cycle)
- Tank
- 5.5 L
- Power
- 12V, 12 A
A few notes on the numbers. The 130 dB rating appears on both United Pacific’s 46123 spec sheet and the dealer copy, always with a ±10 dB tolerance and never with a test distance. In practice that means “somewhere between 120 and 140 dB, conditions unknown.” Our advertised vs. real dB guide explains why that gap matters.
The 150 PSI maximum is the horn’s limit. The included compressor shuts off at 110 PSI, so as delivered the horn runs at 80–110 PSI. That is below its rated maximum but typical for a compact 12V kit. See train horn PSI explained for what that means for tone.
The two horn-size figures disagree. Big Rig Chrome Shop and Chrome and Parts list 12” × 6-1/2” × 6”, which matches the 46123’s 12.4” × 6.7” × 6.7” package size. United Pacific’s own 46123 sheet says “approximately 15” L × 9-3/4” W × 12-1/2” H.” Measure your mounting space before you buy.
What’s in the box
Per United Pacific’s 46173 and 46123 spec sheets and dealer listings:
- 1 × 46123 Chrome Deluxe 4-trumpet mini train horn
- 12V heavy-duty electric solenoid air valve (comes with the horn)
- Horn mounting pad and hardware, plus a wiring diagram
- 1 × 46140 heavy-duty “turbo” 12V air compressor with auto on/off switch
- 1 × 5.5-liter air tank with 1/4” air-hose fittings
None of the listings we checked mention an air line, horn button, relay, fuse or pressure gauge. Plan to buy those separately (see install notes below).
Pros
- Complete 12V system under one part number: horn, solenoid, compressor and 5.5 L tank ship together
- Built-in auto on/off pressure switching (80/110 PSI), so no separate pressure switch is needed
- Compact four-trumpet horn that fits where long-trumpet United Pacific horns won’t
- Modest 12 A compressor draw for a 12V kit
- Widely stocked by truck-parts dealers, and both parts are sold separately as replacements (46123 and 46140)
- Chrome-plated finish suits chrome-heavy semi and pickup builds
Cons
- 130 dB rating carries a ±10 dB tolerance and no disclosed test distance
- Only a 6-month warranty, and one dealer notes it excludes horns mounted upside down or under the truck
- Bundle price ($317–$392) is far above what the parts look like on paper; budget 4-trumpet kits list near $126
- No published compressor duty cycle, airflow or chord frequencies
- Conflicting horn dimensions between United Pacific’s sheet and retailer listings
- Zinc-alloy trumpets, not brass or stainless like premium horns
Alternatives
- HornBlasters Mini Outlaw: about the same money ($369.99–$399.99) gets a complete three-bell kit with a 2-year warranty and a published fill-rate table. This is our pick if you are spending over $350 on a compact kit.
- Vevor 4-Trumpet 6 L Kit: a 4-trumpet horn, a 6 L tank and a 150 PSI compressor for about $126. Its specs are marketing-grade too, but it costs roughly a third as much.
- United Pacific 46130: if your truck already has onboard air, United Pacific’s full-size chrome 4-trumpet horn-only model runs $163–$210 and skips the compressor entirely.
For a wider view, see our best train horn for semi trucks and best train horn under $500 guides.
Install / compatibility notes
- Electrical: the compressor and solenoid are 12V. On a 24V truck you need a step-down converter or 24V-rated parts. See 12V vs. 24V train horns.
- Wiring: at a 12 A draw, run the compressor through a relay and an inline fuse rather than an existing accessory circuit. Our relay wiring guide and amp draw and wire gauge guide cover sizing.
- Air line: the tank uses 1/4” air-hose fittings. Line length and routing are up to you. See air line sizing.
- Mounting: one dealer says the United Pacific warranty excludes horns mounted upside down or underneath the truck. Mount the trumpets upright and protected from road spray.
- Compressor placement: no duty cycle is published, so give the compressor a cool, ventilated spot and avoid long refill sessions. See compressor duty cycle explained and where to mount the compressor.
- Maintenance: a 5.5 L tank collects condensation. Drain it periodically. See how to drain a train horn tank.
Before final mounting, bench-test the system with the compressor filling the tank to 110 PSI and the solenoid firing. Our first-fill bench test guide walks through it. Also check local rules: our are train horns legal on cars guide covers the basics.
A note on the “black 3-trumpet” listing
One dealer page, Big Rig Chrome Shop’s “Deluxe Mini Train Horn Bundle,” labels its included horn as a black 3-trumpet unit under part UP46173. United Pacific’s own 46173 spec sheet specifies the chrome 4-trumpet 46123, and Chrome and Parts, Chrome Country and Vehicle Safety Supply agree. United Pacific does sell the mini horn in black as 46144 and a separate black train horn bundle as 46172. Confirm with the seller which horn ships before you order.
Sources
- United Pacific — Mini Train Horn Bundle 46173 spec sheet (PDF, via Vehicle Safety Supply) — official kit composition (46123 horn + 46140 compressor/5.5 L tank), 6-month warranty, package dimensions and weight, universal fitment
- United Pacific — Deluxe 4 Trumpets Mini Chrome Train Horn 46123 spec sheet (PDF, via Vehicle Safety Supply) — 130 dB ±10 dB, 12V heavy-duty solenoid, mounting hardware and wiring diagram, “approximately 15 × 9-3/4 × 12-1/2 in” size, 12.4 × 6.7 × 6.7 in package
- United Pacific Industries (truck division) — 4 Trumpet Mini Train Horn, Chrome 46123 — official horn listing (behind bot protection at review time)
- United Pacific Industries (truck division) — Heavy Duty Air Compressor & Tank Kit 46140 — official air-system listing (behind bot protection at review time)
- Vehicle Safety Supply — United Pacific Mini Train Horn Bundle 46173 — $369.85 price, kit contents, 5.5 L tank, 13.6 lb package, 6-month warranty
- Vehicle Safety Supply — United Pacific 46123 — horn-only dealer listing, 4 lb package weight, 6-month warranty
- Big Rig Chrome Shop — Deluxe Mini Train Horn Bundle — $391.99 price, compressor 12V / 12 A / 80 PSI on / 110 PSI off, compressor and tank dimensions, 1/4” fittings, warranty mounting exclusion, “black 3-trumpet” labeling discrepancy
- Big Rig Chrome Shop — United Pacific 4 Trumpet Mini Train Horn — 150 PSI maximum, zinc-alloy construction, 4 trumpets, 12-1/5 × 6-7/10 × 6-7/10 in, black variant 46144
- Chrome and Parts — Mini Train Horn Bundle 46173 — $323.99 price, 130 dB ±10 dB, horn 12 × 6-1/2 × 6 in, auto on/off switch, 46123 + 46140 composition
- Chrome Country — Chrome Deluxe 4 Trumpet Mini Train Horn w/ Compressor & 5.5 L Tank — $349.88 price, kit contents, 6-month warranty
- Vehicle Safety Supply — United Pacific Black Train Horn Bundle 46172 — existence of the separate black train horn bundle, part 46172
- Fleet Truck Parts — Deluxe Mini Air Train Horn Bundle by United Pacific — $317.32 price (low end of range), 13.55 lb shipping weight
- Classic Chevy — United Pacific Heavy Duty Air Compressor & Tank Kit 46140 — 46140 description: high-volume turbo compressor, 5.5 L tank, 12V, auto on/off, 6-month warranty; United Pacific’s focus on heavy-duty truck and classic-car products
Train Horn Hub aggregates publicly available data. We do not test products in-house. All trademarks belong to their respective owners.
A tidy one-SKU 12V train horn system for truck owners who already buy from United Pacific dealers, but the thin specs and 6-month warranty make it hard to recommend over similarly priced kits with stronger documentation and support.
Frequently asked questions
Quick answers to the questions people ask most about this topic.
- How loud is the United Pacific 46173 Mini Train Horn Bundle?
- United Pacific rates the included 46123 horn at 130 dB with a ±10 dB tolerance and does not disclose a test distance. So the manufacturer claim covers anything from 120 to 140 dB under unknown conditions. No independent measurement of this kit has been published.
- What exactly comes in the 46173 bundle?
- According to United Pacific's spec sheet, the bundle includes the 46123 Chrome Deluxe 4-trumpet mini train horn (with a 12V heavy-duty solenoid, mounting hardware and wiring diagram) and the 46140 heavy-duty compressor with a 5.5-liter air tank. Air line, relay, fuse and horn button are not listed, so plan to buy them separately.
- What air pressure does the 46173 run at?
- The included compressor switches on at 80 PSI and off at 110 PSI, so the horn runs at 80–110 PSI. The 46123 horn itself is rated for a 150 PSI maximum.
- Will the 46173 work on a 24V semi truck?
- Not directly. Both the compressor and the horn's solenoid are 12V parts, so a 24V truck needs a step-down converter or 24V-rated replacements. Trucks with onboard air may be better served by a horn-only model such as the United Pacific 46130.
- What warranty does the United Pacific 46173 have?
- United Pacific lists a 6-month warranty. One dealer notes that it does not cover horns mounted upside down or underneath the truck.
