Semi-Trailers The Major Types to Know About

Feb 25, 2021

When the layperson sees a truck they just see “a truck”, but if you know what you’re looking at then you know the variety of types and combinations is nearly endless. And each one is intentionally matched to where it’s going, the job it’s got to do and the freight it’s carrying.

In this article, we’re going to leave the prime mover to the side and just talk about trailers. Flat top to tautliner, this is a quick review of the Southern Cross Truck Rentals range.

Before we get into things, we are going to refer to the general guidelines from the National Heavy Vehicle Regulator (NHVR) of:

  • Maximum width of 2.5 metres
  • Maximum height of 4.3 metres
  • Maximum overall vehicle length of 19 metres (including the length of the prime mover).

Flatbed Trailers

You see flatbeds – or flat tops – everywhere. Why? Because they can haul almost anything. As the most versatile trailers around, the flatbed is ideal for carrying bulky or oversized loads. Pretty much, if you need to shift something that is easy to tie down, okay to be exposed to the weather and presents a low theft risk, a flatbed is the easiest trailer to use. An ideal example is, say, 20 tonnes of steel plate.

What’s more, because there’s no structure above the load deck, the only loading and unloading issues with a flatbed are depot/dock access and how good you are with materials handling equipment.

Extendable Trailers

Where a flatbed is all well and good, sometimes you need even more space. That’s when you call on an extendable trailer. Simply, slip the pin and let the trailer out to the length you need. Then, when you’re done, slide it back in and enjoy the ease of driving a shorter combination.

Skel Trailers

Skel trailers – short for “skeleton” – really live up to their name. They’re basically just a frame of “ribs” with wheels attached to a “spine”. The loads slot into the top. In most cases, this load will be shipping containers.

Because the container itself already holds the load, the trailer carrying them doesn’t need to be much more than a frame to hold it. This means a skel trailer can be quite light (sometimes as little as 4 tonnes), and less weight means less wear and tear on components and less fuel use. All up: less operating cost.

Drop Deck Trailers

A lot of people get flatbeds and drop-decks confused at first. The main difference, of course, is where a flatbed is flat end to end, a drop-deck starts flat and then “drops” approx. 60cm to a lower level. This step-down takes place at the point on the trailer where there’s pivot clearance past the prime mover’s rear axle (or axle group).

Why do this? Overall vehicle height. As mentioned above, the usual max combination height allowed on Aussie roads is 4.3 metres. If you’re carrying a piece of equipment or stacked load that’s fairly tall and you don’t want to chase up a special overheight permit (and plot a special route), then those 60 cms can make all the difference.

Low Loader Trailers

Vehicle height comes in here again. When the common drop deck just can’t give you enough clearance to squeeze under the usual regulations … or your load is simply oversize regardless, you might need a low loader.

In their quest for the lowest load floor possible, low loader trailers even use special extra-small wheels. These are sometimes even smaller than the wheels found on a passenger car, but are, of course, designed to carry much more weight. So, where a flatbed trailer might have a deck height of 1600mm, a low loader’s deck height can be less than half that.

Taut Liners

Taut liners, also called curtain-siders, are the go-to trailer for many jobs. They’re ideal for palletised cargo. Simply roll up the side curtains and your forklifts can get in there and shift the cargo in, out and around. Then, when you’re loaded, bring the curtains down, ratchet them taut, and hit the road – knowing whatever’s in the back is out of the elements and kept under fair security.

Renting The Right Trailer

So, that’s your rundown of basic info about the basic trailer types. If you want to hire one or know more, why not get on the line with Southern Cross Truck Rentals? Let’s talk about what you’re hauling and the best gear to get it from A to B.

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