Round Bar vs Trunnion Bar Spring Bars

A round bar has a forged ball-shaped end that drops into a socket in the hitch head from above, so the bar hangs below the head. A trunnion bar has a squared end that slides into a slot in the head horizontally, so the bar sits at roughly head height. Everything else follows from that geometry.

• Steep driveway, ferry ramp, or a sharp dip at the end of your road. Trunnion. A round bar is the first thing to touch down and it will find that transition every single time.
• Crowded A-frame with propane bottles and a battery box close to the coupler. Round bars generally need less room ahead of the coupler. Measure before ordering either.
• Heavier trailer near the top of the range. Trunnion bars tend to be offered at the higher capacities, which is often what decides it without any thought about clearance.
• Budget is the constraint and the driveway is flat. Round bar. The transfer performance is not the thing you are giving up.

Quick picks

Tap any row to jump to the full write-up. How these are chosen - and what we do and do not claim to know - is published in full on our research methodology page.

#	Product	Best for	Our read	Price
1	CURT Round Bar Weight Distribution Hitch with Sway Control (14K) Round bar	Mid-size travel trailers	Lower cost, lower clearance, 14,000 lb gross	Check price on Amazon→ #ad Affiliate link - we publish no price; Amazon shows the current one
2	Blue Ox SwayPro Weight Distribution Hitch Underslung	Owners who hitch and unhitch often	Clears low A-frames and front boxes	Check price on Amazon→ #ad Affiliate link - we publish no price; Amazon shows the current one
3	CURT TruTrack 4P Weight Distribution Hitch (10-15K) Heavy duty	Heavy travel trailers near 15,000 lb	Four-point friction to 15,000 lb gross	Check price on Amazon→ #ad Affiliate link - we publish no price; Amazon shows the current one

1. Round bar

CURT Round Bar Weight Distribution Hitch with Sway Control (14K)

CURT · Best for mid-size travel trailers

A conventional round-bar system with integrated lubrication and sway control, rated to 14,000 lb gross and 1,400 lb tongue. The built-in lubrication matters more than it sounds: a dry weight distribution head is the usual source of the groaning people mistake for a failing hitch.

Published specifications

Gross trailer weight

14,000 lb source

Tongue weight

1,400 lb source

Shipping weight

102 lb source

What works

• +Integrated lubrication at the head, which is where the noise usually comes from
• +Round bars sit lower and clear more trailer tongues than trunnion bars
• +Limited lifetime warranty

What does not

• −Round bars hang lower than trunnion bars and are the first thing to catch on a steep driveway
• −Sway control here is a function of the head, not an adjustable four-point system

Skip it if

Skip it if you regularly cross steep transitions - a round bar is the lowest part of the whole rig and will find the pavement before anything else does.

Check price on Amazon→

#ad Affiliate link - we publish no price; Amazon shows the current one

Raw specifications: CURT’s own page. We earn nothing on that link.

2. Underslung

Blue Ox SwayPro Weight Distribution Hitch

Blue Ox · Best for owners who hitch and unhitch often

Underslung spring bars on clamp-on latches, which makes hitching faster than chain-and-snap-up systems and keeps the bars out of the way of a low A-frame. Blue Ox publishes the range in tongue-weight bands rather than one do-everything model, so the sizing decision is made before you buy.

Published specifications

Tongue weight bands offered

350, 550, 750, 1000, 1500 and 2000 lb source

Maximum gross towing weight

20,000 lb source

Shank sizes

2 in receiver, or 2-1/2 in on the BXW2000 source

What works

• +Latches clamp on rather than needing chains snapped up under tension
• +Sold in defined tongue-weight bands, which makes correct sizing the default
• +Underslung bars clear low A-frames and front storage boxes

What does not

• −Bar bands are narrow, so a big change in how you load the trailer can put you in the wrong band
• −Clamp-on brackets are another part to keep clean and lubricated

Skip it if

Not the one if your loaded tongue weight sits near the top of a band - buy up a band, because a bar run at its limit transfers less than a bar running in the middle of its range.

Check price on Amazon→

#ad Affiliate link - we publish no price; Amazon shows the current one

Raw specifications: Blue Ox’s own page. We earn nothing on that link.

3. Heavy duty

CURT TruTrack 4P Weight Distribution Hitch (10-15K)

CURT · Best for heavy travel trailers near 15,000 lb

Four-point sway control with adjustable friction, rated to a 15,000 lb trailer and 1,500 lb tongue. The adjustability is the point: you can dial resistance up for a long, tall trailer and back it off for a short one, instead of living with whatever the geometry gives you.

Published specifications

Gross trailer weight

10,000-15,000 lb source

Tongue weight

1,000-1,500 lb source

Rise

5.75 in source

Product weight

123.6 lb source

What works

• +Friction is adjustable rather than fixed by the geometry
• +Rated range covers the tongue weights that half-ton trucks genuinely struggle with
• +Limited lifetime warranty on the structure

What does not

• −At 123.6 lb assembled it is a heavy thing to lift on and off a shank
• −The 10,000 lb floor means it is over-specified for a small trailer

Skip it if

Wrong tool below about 10,000 lb gross trailer weight - under the rated floor the bars barely flex, so you get the weight penalty without the load transfer.

Check price on Amazon→

#ad Affiliate link - we publish no price; Amazon shows the current one

Raw specifications: CURT’s own page. We earn nothing on that link.