Tow Bar FAQ

You can have either single, double, 13 pin or WeSt connectors fitted to your vehicle, which type will depend on several circumstances.

You may also need vehicle recoding.

7 pin is cheaper and widely available but bulky and can be unreliable. 13 pin is more costly and can be difficult to source but is reliable, secure and future proof. WeSt 13-pin is rare but very convenient and cost effective.

All caravans manufactured in the UK after 2008 and all trailers and accessories manufactured after 2010 have ISO 13-pin connector as standard.

There are three main types of thirteen pin kits:

Vehicle Specific 13-pin 12N function only:

• Essentially a standard vehicle specific kit with a 13 pin socket attached

• The kit provides Normal power supplied to the caravan/trailer for all legal light functions required for towing

• Indicators / turn signals, brake lights, fog lights and side lights

• The kit has no caravan supply feed

• The socket only contains pins 1 to 7

• Sometimes pin 8 for reverse is included

• This type of kit will soon be the standard and most popular vehicle specific kit

Vehicle Specific 13-pin with 12S preparation:

• Essentially a standard vehicle specific kit with a 13-pin socket attached

• The kit performs all light functions required by law but also has the facility for 12S function to be added easily

• The socket usually contains all 13 pins and wires

• Pins 1-8 are fully operational as standard

• The kit requires a 12S extension kit to become a full function 13 pin kit, this is an additional cost

• The extension kit consists of a power supply wire, that requires routing to the battery, the relevant fuses and connectors and also a split charge relay that connects to a pre-prepared socket

Vehicle Specific 13-pin with full function 12N/12S:

• As the title suggests this type of kit has complete 12N and 12S functions

• The kit performs all Normal light functions required by law

• The kit provides a Supplementary power supply to the caravan for all the additional functions

• No additional kits are required

• Full connection details are provided

• This kit has full compatibility with the latest UK and European built caravans

The EC Directive states that this should be 385 to 455mm with the trailer in the 'laden' condition.

'Laden condition' in this instance is when the trailer is loaded to its maximum specified mass, with this evenly distributed over the loading area.

The towball height is measured as the vertical distance between the ground and the centre of the towball.

This must be measured on flat and level ground – most surfaces are far from level!

Also, the laden condition of the vehicle must be known. (Note; In the case of "coupling height", this is the position of the centre of the towball location when within the coupling head).

Not necessarily! Many think (incorrectly) that it is essential to have the trailer chassis perfectly level and go to great lengths to try and achieve this. However, from the previous two questions it can be seen that there is inherently a wide height range for both the towballs and the trailer couplings.

Also, the specifications are written to promote a tendency towards a slightly 'nose down' attitude of the trailer, with the medium of the range for the trailer being 35mm higher than the medium of the height range of the towball on the towing vehicle.

Furthermore from the permissible ranges and laden definitions it can be seen that the difference can be extreme e.g.

- Towball at 350mm (fully laden vehicle) and trailer coupling at 520mm (not untypical of an unladen trailer)……a difference of 170mm!

- Towball at 510mm (unladen long suspension travel vehicle) and 385mm trailer coupling height (for fully laden trailer)…..a difference of 125mm!

The situation is further complicated by the fact that the towbar/towball is controlled by an EC directive, whilst it is currently not mandatory for the trailer to be EC approved – and very few are.

The 'nose load'is the commonly used term for the load, weight or mass applied by the coupling head of the trailer or caravan onto the towball/towbar fitted to the towing vehicle.

A towing stabiliser is a sway control device that restricts or alters the lateral and vertical articulation between the towing vehicle and caravan or trailer. It does not increase the inherent stability of an outfit.

There is an argument that, if correctly matched and loaded, an outfit will not require a stabiliser. However, unforeseen circumstances and outside forces can drastically reduce the stability of an outfit in an instant.

A stabiliser provides the driver with peace of mind and confidence that any instability will be subdued.

Trailer 'snaking' is an instability situation that occurs when the trailer acts as a swinging mass behind the vehicle (similar to a pendulum), whereby relatively little energy is required to initiate and maintain the pendulum movement.

Once the oscillations reach the natural resonance of the outfit the amount of movement increases uncontrollably prior to an inevitable crash.

This is a matter of personal choice and circumstance. There are three types of electrical kits and four types of connectors commonly available in the UK.

You would usually have the connector fitted that matches that of the connector on the caravan, trailer or light board. The type of electric kit will depend on your budget.

We can help with advise for the correct kit for your vehicle and situation.

You may also need vehicle recoding.

It is possible that there will be a universal, after-market dedicated, or original equipment dedicated unit that will be available to fit to your vehicle.

Which kit you decide to have fitted will depend on several circumstances which we can help assist to ensure you get the right one.

Connection adapters are used to interchange between UK 7 pin systems and ISO 13 pin systems:

• Some twin adapters do not contain full 12S function conversion

• Adapters will become a key component as caravan manufacturers change to the ISO 13 pin system from 2008/2009 season

• Trailers and accessories will change around 2010

• There are four types of adapter:
- 13 pin to 12N/12S
- 13 pin to 12N
- 12N/12S to 13pin
- 12N to 13 pin

You may also need vehicle recoding.

Directive Reg 55 was introduced as part of European Whole Vehicle Type Approval to provide a common standard throughout the European Community, thus creating an open market.

Irrespective of where a towbar has been manufactured, providing it has been Type Approved, a customer will know that it has been manufactured to a known technical and quality standard.

If your car is first registered on or after the 1st August 1998, you could be prosecuted for an infringement of Construction & Use Regulations or your Insurers may decline to pay out in the event of an accident claim.