Breakaway Cable or Secondary Coupling? 🧐

Light trailers up to 750kg maximum laden weight are classed as cat O1 vehicles.

There is no requirement for O1 trailers to have a braking system but, they must be fitted with a ‘secondary coupling’ so that in the event of a breakaway or a primary coupling failure, the trailer is prevented from running away.  The secondary coupling has to be strong enough to restrain the fully laden trailer, and short enough to prevent the drawbar striking the ground, thereby retaining some residual steering.

If a cat O1 trailer is fitted with brakes, they must be operational on all wheels and it will be treated as a Cat O2.

Above 750kgs up to 3,500kgs, maximum laden weight, a trailer is a cat O2 vehicle.  All cat O2 trailers are required to have an operational braking system on all wheels and, it needs to be auto-reversible.  In general, this is achieved via an over-run (inertia) primary coupling, allied with auto-reverse mechanisms in each brake assembly, which detects when the wheels are operating in reverse mode.  This self releases when the trailer moves forward.

All O2 trailers must be fitted with a breakaway cable that, in the event of a detachment or primary coupling failure, will activate emergency braking, bringing the trailer to a standstill.  ALTERNATIVELY, (but only up to 1500kgs maximum laden weight), an O2 trailer can be fitted with a secondary coupling as per O1 trailers.

A secondary coupling restrains  the trailer and needs to be securely attached to the towing vehicles tow frame.

A breakaway cable allows the trailer to separate from the towing vehicle, but with the brakes fully applied, at which point the cable snaps and will need replacing.

Road Vehicles Lighting Regulations 1989 (and amendments).

Probably the most abused rule regarding lights & reflectors on trailers (including a-frame towed cars) is that regarding “Retro-Reflective Rear Triangles”.

Size is everything!

Specifically, each triangle should be red, be equilateral, 160mm along each edge (making it 140mm tall), and it must meet the photometric and colorimetric requirements laid down in EC regs or UNECE regs. It must carry either EC approval marks or UNECE approval marks including IIIA (class). https://eur-lex.europa.eu/legal-content/EN/ALL/?uri=CELEX:32008L0089

With positioning, the triangles must be fixed vertically with apex to the top and the apex needs to be no more than 400mm from the outside edge of the trailer body. A matching pair is required, fitted between 350mm and 1500mm from the ground. They must not be fitted to a moveable panel (which includes on to, or inside, a boot lid of a towed car).

The above rules most likely render the majority of marker boards supplied by a-frame suppliers, effectively illegal.

OTHER LIGHTS.

Category O1 (unbraked) and O2 (braked) trailers must replicate the lights of the towing vehicle, including (if 1600mm wide or over) white front position lamps. They must also carry the registration mark of the towing vehicle.

From Oct 2012, all braked trailers are required to be fitted with (at least one) operational reversing light(s).

There is NO requirement for an a-frame towed car to carry any additional signage but, it’s not illegal.

Additional sidelights or reflectors are required on trailers over 5mt long. (Boat trailers are exempt from this and from the requirement for front position lamps).

Towing Behind A Motorhome. What you should know....

This article was first published in 1998. I may have updated it elsewhere!

Towing behind a motorhome. What you should know

If you are thinking of fitting a towbar to your motorhome, just check a couple of things before you start.

Firstly, do you actually have the spare capacity to do it? If your vehicle handbook does not list a towing limit, have a look at the VIN plate. This should give the Gross Train Weight (the largest figure) followed by the Maximum Gross Weight. Two other figures you would expect to see are Axle Weights. Deduct the MGW from the GTW and the difference would normally be your maximum towing limit.

Secondly, check the wheelbase of the vehicle (centre of front axle to centre of rear axle) and then measure the overhang (the distance from the centre of the rear axle to the extreme back). The overhang can go up to 60% of the wheelbase and the towbar needs to fit within this limit.

If your vehicle has an Al-Ko chassis, do not allow the fitter to drill extra holes for the towbar mounting. Your chassis warranty would be invalidated.

Braked versus unbraked

To tow without brakes on the trailer, the Maximum Gross Weight of that trailer must not exceed 750 kgs or half the Kerbside Weight of the towing vehicle, whichever is the least. Unbraked trailers must be clearly marked with the year of manufacture and their Maximum Gross Weight. If built after 1/1.97, they must have a secondary coupling fitted.

Braked trailers manufactured after 1968 must have brakes on all wheels. If built after October 1982, an hydraulically damped over-run coupling is required and, if built after April 1989, the trailer must have an auto-reverse brake mechanism which meets the efficiency laid down in EC directive 71/320. Additionally, braked trailers need to have a breakaway cable fitted which is capable of operating the handbrake mechanism if the trailer becomes detached from the towing vehicle, it is an offence not to use it and, it must be ‘securely attached’ to the towing vehicle. It is unlikely that merely looping round the towball would be considered a secure attachment!

'A' frames and Dollies

Q. What is a trailer?

A. A road vehicle, usually (but not necessarily) two wheeled, towed by a motor vehicle.Given the above dictionary definition, it is fairly clear that anything attached to the towball and having wheels in contact with the ground is a trailer. This includes cars on ‘A’ frames and dollies. Bearing in mind that the unbraked towing limit of 750 kgs refers to Maximum Gross Weight (i.e. the figure on the towed cars VIN plate) and not to actual weight, it severely restricts the options. The only cars I know of with a MGW of less than 750 kgs is the Aixam range. These are around 450 to 550 kgs.

There are strict regulations on braked trailers and, whilst a braked ‘A’ frame attached to a towed car constitutes a braked trailer, it is not legal for transportation as it cannot comply with EC71/320. With car dollies, the situation is somewhat different. Under regulation 83 of the Road Vehicles (construction & Use) Regulations 1986 (SI.1986/1078) Amending Regulations, a car dolly, with a car in place, will be considered as two trailers. This is legal for recovery but, under the Road Traffic Regulations Act 1984 (Schedule 6) the combination is limited to 40 mph on motorways and dual carriageways and 20 mph elsewhere.

Note that there is a very specific difference between recovery and transportation. Recovery is the removal of a broken down vehicle to a place of safety. It does not include removing a rotor arm (for instance) and travelling the length and breadth of the country. The police are well aware of the difference due to the regulations covering Tachographs and Operators Licences. Recovery vehicles are exempt.

It is well known that some countries in the EEC tend to overlook the regulations (the UK included) but some countries don’t. The situation regarding enforcement could change at any time and, as a result, the only safe way to transport another vehicle behind a motorhome is on a car transporter trailer. Play safe! Don’t take the risk!

The regulations which cover this aspect of towing are:- 91/438/EEC covers driving licences. 71/320/EEC covers auto reverse braking systems and couplings. S.I. 1971 No 450 Part III covers the obstruction of number plates. 94/20/EEC covers type approval of towing equipment and ‘S’ and ‘D’ values. 95/48/EEC covers Masses and Dimensions of M1 class vehicles. E.T.R.T.O. 1991 section 13 covers wheels and tyres. BSAU 113c covers 50mm ball and coupling dimensions. BSAU 24a (1989) covers eye couplings and pin/jaw arrangements. 98/12/EEC covers brake linings and will be implemented in the UK from 1/4/01.And not strictly towing but applicable to motorhomes is EN1648-1 covers extra low voltage installations in Leisure Vehicles and Caravans.

Disclaimer The information in this guide is as accurate as the writer is able to make it, however, no responsibility can be accepted for any inaccuracies which may be in the text. It is the responsibility of any person wishing to depend on the facts to check for themselves with original documentation or any updating regulations, instruments or changes in the law. Interpretation of the law is a matter for the courts.