Flatbed vs Step-Deck vs Lowboy vs RGN: Choosing the Right Trailer for Heavy Equipment
One of the most common questions equipment shippers ask is: what trailer do I need? The answer depends on three things — your equipment's height, its weight, and whether it can be driven onto the trailer or must be crane-loaded. Get the trailer type wrong and you're either paying for more trailer than you need, or worse, arriving at the pickup site with a trailer that can't legally carry your machine. This guide breaks down the four main trailer types used in heavy equipment transport and tells you exactly when to use each one.
The Four Main Trailer Types for Heavy Equipment
Heavy equipment transport uses four primary trailer configurations, each designed for a different range of equipment dimensions and weights:
- Flatbed: Standard open trailer, deck height approximately 5 feet above ground.
- Step-Deck (Drop Deck): Two-level trailer with a lower rear deck, approximately 3.5 feet above ground.
- Lowboy (Double Drop): Very low deck, approximately 18–24 inches above ground, with raised sections at front and rear.
- RGN (Removable Gooseneck): Similar deck height to a lowboy, but the front gooseneck detaches to allow drive-on loading.
Flatbed Trailers: When to Use Them
Flatbeds are the workhorses of freight transport — versatile, widely available, and cost-effective. For heavy equipment, they're appropriate when:
- Equipment height is under 8.5 ft (the deck adds ~5 ft, so total load height stays under the 13.5 ft federal limit).
- Equipment width is under 8.5 ft (no oversize permit required).
- Equipment weight is under 48,000 lbs (standard flatbed payload capacity).
Common equipment on flatbeds: Small forklifts (under 8 ft tall), skid steers, small attachments, pipe racks, generators under 8 ft tall, and construction materials.
Flatbed limitations: The 5 ft deck height is the primary constraint. A machine that's 9 ft tall on a flatbed creates a 14 ft total load height — over the federal 13.5 ft limit and requiring an oversize permit. Even a machine that's 8.5 ft tall on a flatbed is right at the limit.
Step-Deck Trailers: The Middle Ground
Step-decks lower the rear deck by about 18 inches compared to a flatbed, bringing the effective deck height to approximately 3.5 ft. This creates about 18 inches of additional vertical clearance for the cargo. Use a step-deck when:
- Equipment height is 8.5–10 ft (on a step-deck, total load height stays under 13.5 ft).
- Equipment width is under 8.5 ft (or slightly over with a permit).
- Equipment weight is under 48,000 lbs.
- Equipment can be loaded with a forklift, crane, or ramps — step-decks don't have drive-on capability for most equipment.
Common equipment on step-decks: Mid-size forklifts, telehandlers, scissor lifts, boom lifts, small excavators (mini excavators under 8,000 lbs), and construction equipment 9–10 ft tall.
Lowboy Trailers: For Tall, Heavy Equipment
Lowboys drop the deck to 18–24 inches above the ground, providing maximum vertical clearance for tall equipment. The raised front and rear sections (the "wells") accommodate the trailer's axles and gooseneck. Use a lowboy when:
- Equipment height is 10–13 ft (on a lowboy, total load height stays under 13.5–14 ft).
- Equipment weight is 40,000–80,000 lbs (standard 2-axle lowboy capacity).
- Equipment cannot be driven onto the trailer (no self-propulsion, or drive-on is impractical).
Common equipment on lowboys: Large excavators, bulldozers, motor graders, compactors, large wheel loaders, and other tall construction equipment that must be crane-loaded or ramp-loaded.
Lowboy limitations: The fixed gooseneck means equipment must be loaded via ramps or crane — there's no drive-on option. For self-propelled equipment, this adds crane rental cost and loading time.
RGN Trailers: The Heavy Hauler's Choice
The RGN (Removable Gooseneck) is the most versatile trailer for heavy equipment transport. The front gooseneck detaches hydraulically, allowing the deck to drop to ground level for drive-on loading. Use an RGN when:
- Equipment is self-propelled and can drive onto the trailer (excavators, dozers, wheel loaders, ADTs).
- Equipment height is 10–13 ft (same deck height as a lowboy).
- Equipment weight exceeds 80,000 lbs (multi-axle RGNs can handle 150,000+ lbs).
- Equipment is very long (stretch RGNs extend to 53+ ft for long machines).
Common equipment on RGNs: Excavators, bulldozers, cranes, wheel loaders, articulated dump trucks, motor graders, and any large self-propelled machine.
RGN advantages over lowboy: Drive-on loading eliminates crane rental costs and loading time. Multi-axle configurations handle extreme weights. Stretch capability accommodates very long machines.
Quick Reference: Trailer Selection by Equipment Type
| Equipment | Typical Trailer | Why |
|---|---|---|
| Mini excavator (<8,000 lbs) | Step-deck or flatbed | Small enough for standard trailers |
| 20-ton excavator | RGN lowboy | Self-propelled; 10+ ft tall |
| 50-ton excavator | Multi-axle RGN | Heavy; self-propelled; 12+ ft tall |
| Skid steer | Flatbed or step-deck | Under 8 ft tall; under 8,000 lbs |
| Large forklift (15,000+ lbs) | Step-deck or lowboy | 9–11 ft tall; crane-loaded |
| Bulldozer (D6–D8) | RGN lowboy | Self-propelled; 10–12 ft wide |
| Articulated dump truck | Extendable RGN | Long; self-propelled; 9–11 ft wide |
| Motor grader | RGN lowboy | Self-propelled; 10+ ft wide |
| Generator (<8 ft tall) | Flatbed | Standard dimensions |
| Crawler crane | Multi-axle RGN + additional loads | Must be disassembled; very heavy |
Not sure which trailer your equipment needs? IronHaul Logistics will assess your machine's dimensions and weight and recommend the right trailer configuration. Call (208) 495-2260, email [email protected], or request a quote online — we'll handle the trailer selection and permit requirements so you don't have to.
Common questions
What is the difference between a lowboy and an RGN trailer?
Both have similar deck heights (18–24 inches), but an RGN has a detachable front gooseneck that allows the deck to drop to ground level for drive-on loading. A lowboy has a fixed gooseneck and requires ramps or a crane to load equipment. RGNs are preferred for self-propelled equipment; lowboys are used when crane loading is acceptable.
When should I use a step-deck instead of a flatbed?
Use a step-deck when your equipment is 8.5–10 ft tall. A flatbed's 5 ft deck height would push a 9 ft machine to 14 ft total height — over the 13.5 ft federal limit. A step-deck's 3.5 ft deck height keeps the same machine at 12.5 ft total height, within legal limits.
What is the maximum weight for a standard lowboy trailer?
A standard 2-axle lowboy handles up to 40,000–80,000 lbs. Multi-axle lowboy configurations can handle up to 150,000+ lbs. For loads over 80,000 lbs GVW, overweight permits are required regardless of trailer type.
Can a skid steer be shipped on a flatbed?
Yes. Most skid steers are under 8 ft wide and under 7 ft tall, making them suitable for a standard flatbed. The total load height (skid steer height + 5 ft deck) stays well under the 13.5 ft federal limit.
What trailer do I need for a 20-ton excavator?
A 20-ton excavator typically requires an RGN lowboy. These machines are 9–10 ft wide and 10–11 ft tall, requiring a low deck to stay within height limits. The RGN's drive-on capability is preferred since excavators can drive onto the trailer under their own power.
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