Trailers and our Kiwi lifestyle
Trailers are very much part of our Kiwi lifestyle, be it towing an excavator between jobsites, getting rid of some garden refuse on the weekend or moving the jetski to the bach for a long weekend. As we head into spring let’s take a few minutes to look at how we can keep ourselves, our families and other road users safe when it comes to towing.
When I first started working in the hire industry, I expected it to be heavy machinery like excavators and booms to be involved in most incidents but that has certainly has not been the case. Trailers and anything else that requires towing (think cherrypickers, log splitters, concrete mixers etc.) are rife with risks and have the potential to cause minor inconvenience through to fatal harm.
Injuries and incidents with trailers are related to just about every aspect of their use.
Interestingly Waka Kotahi NZTA don’t require tow bars to be rated on light vehicles or that tow ratings are strictly adhered to, however it is always recommended that you stick to the manufacturer’s recommendation and follow the specifications of both the fitted tow bar and the towing capacity recommended by your vehicle manufacturer.
Regardless of these ratings there is a however a legal requirement that a light vehicle towing a trailer is able to stop within a distance of seven metres from a speed of 30km/h.
As with all vehicles on the road, trailers should be regularly checked and maintained. Waka Kotahi NZTA recommend the following checks:
- Check tyre pressures, and look for signs of wear or damage.
- Clean all lights and reflectors and check all lights are working.
- Check with your local garage to ensure the tow coupling and brake mechanisms are well lubricated.
- Jack the trailer up and spin the wheels, listening for rumbling noises which indicate worn wheel bearings.
- Check all tie-down points are tight.
Remember, trailers also require both a Warrant of Fitness (WOF) and current registration.
Hooking them up
It’s not uncommon to see people manhandling a trailer to get it to a vehicle. This alone presents potential sprains and strain risks. When you’re moving a trailer around, be sure to consider the ground conditions, surface slope and the weight of the trailer.
One of the biggest risks with trailers is making sure they are securely fitted to the towing vehicle. Not all tow balls are created equally with two sizes prevalent in New Zealand. The first, and by far the most common is the 1 7/8 inch diameter which is slightly smaller than the 50mm diameter which has gained popularity with the increase in European vehicles on our roads.
Typically a well maintained 1 7/8” coupling won’t fit on a 50mm towball but a 50mm coupling will easily sit on a 1”7/8 towball – it just won’t be secure. It’s becoming more common to see dual couplers that can fit on both size tow balls or even interchangeable tow ball systems. Old school dual couplers gave the operator the option of selecting the correct size manually which also meant you could inadvertently select the wrong size. Over the last few years, new self-adjusting dual couplers have become more prevalent and they are excellent for removing the human error that can result in the wrong size being selected.
When hooking up the trailer it must also be secured to the towing vehicle with an appropriately rated safety chain unless the trailer is fitted with breakaway brakes. For any towing over 2000kg a second safety chain is required and trailers also require service brakes from this weight onwards.
Some trailers are fitted with a hand brake that needs to be disengaged before you tow. It’s not uncommon to see people forgetting to release this before towing which can result in in overheating potentially damaging the trailer brakes, bearings, hubs and more.
Just because it can fit on or in the trailer doesn’t necessarily mean it should. You’ll need to know the trailers empty weight (tare mass) as well as the gross vehicle mass (GVM) to know exactly how much weight a trailer can handle.
The risk we run is not being aware of the weight of the items we’re trying to move. As an example a full 3m3 trailer could weigh around 720kg if you were carrying bark, but more than 4t for a similar volume of sand. This is well above the legal towing limit, outside the parameters of most vehicle manufacturers recommendations and outside the GVM of most trailers this size. A quick Google search will help you find some calculators to help give you an idea of the weight vs volume of various products. I found this one here
to be quite useful.
Another important factor is how you spread the load on a trailer as this has a major impact when driving. Too much weight on the back of the trailer may reduce traction on the rear wheels of your towing vehicle and make it harder to control. There is a great video here that will help visualise this issue.
Loads should always be adequately secured to the trailer to prevent them from shifting around as this can affect your driving experience, and even worse see you lose the load in the middle of the road.
The max speed limit for towing trailers on NZ roads is 90k/h regardless if the posted speed is higher. But as with all driving the road and weather conditions may require you to reduce this.
Not all trailers are suitable for towing at high speeds and in some instances you may need to slow right down. Trailers that have unsprung axles or a narrow wheelbase (e.g. concrete mixers) may have a much lower speed recommended by manufactures which could be as slow as 50km/h.
Unloading and disconnecting
You would think getting the trailer to its final destination would be the end of the risk bit, but this is definitely not the case. Unloading and disconnecting trailers are not without their own hazards.
Parking on slopes is never ideal, particularly when you are loading or unloading heavy items like machinery. On slopes you should always consider chocking the wheels. When loading an item like an excavator or scissor lift onto a trailer on a slope, it’s possible that when the weight is on the rear of the trailer the upward force pulling on the drawbar may cause the rear wheels of the towing vehicle to lift resulting in the trailer and vehicle rolling down a hill.
It’s also important to assess the load distribution on a laden trailer when you are disconnecting it from a towing vehicle. If the load is predominately behind the trailer axle and therefor no downward weight on the tow ball, the drawbar may catapult up when disconnecting and could trap the operator’s hand or even worse hit them in the face or head causing concussion or worse.
Trailers are a tool many of us use daily, and some of us less frequently, both for work and pleasure. We own them, we borrow them and we hire them. They are so commonplace that it’s sometimes easy to forget the many risks they pose. Working in an industry that has thousands of trailers and towable items gives you a good window into the things that can go wrong. It’s worth ending this article with some of the top areas where people come into strife using trailers and other towable items:
- Sprain and strain injuries – typically caused by manually shifting trailers – particularly loaded ones or those with tandem axles. Also consider the ground conditions and slope. If you can, get your vehicle as close to the trailer as possible
- Failing to check that the trailer is adequately secured to the vehicle and that the safety chain(s) are attached – In a workplace and at home it’s not uncommon for more than one person to be involved in hooking up a trailer. Ultimately though, making sure it’s secure is the driver’s responsibility – always give the trailer a visual check and “tug test” to make sure it’s securely fitted and also ensure that the chain(s) are connected to the towing vehicle.
- Weight and security of load – a load that’s moving around on a trailer can be as dangerous as an overloaded trailer. Just because it can fit in the trailer doesn’t mean the trailer can handle the load. A 1000kg of sand takes has a much smaller volume than 1000kg of bark
- Understanding the weight distribution of the load and knowing the pinch points when disconnecting trailers from vehicles – a catapulting drawbar can cause serious injury
- Making sure the jockey wheel is securely locked in place when disconnecting or moving a trailer around by hand – if it’s not it could move and the drawbar could potentially come crashing down on your foot.
- Towing with the trailer park brake engaged – make sure you disengage this if fitted. Towing with these brakes engaged can cause serious overheating which could cause bearings to seize and shearing of the axle. Also, some trailers are fitted with a reversing latch that needs to be in the open position when driving. Not doing so will render the service brakes ineffective.
I’ll end with a disclaimer: this article doesn’t cover everything or every rule you need to know about towing but Waka Kotahi NZTA have some really good resources that can be found here:
As with any task, taking a few minutes to plan will help keep you and others out of harm’s way.