Things you may wish to consider when deciding on a TowAFrame towing solution. Particularly with regard to which type of braking system you wish to use as there are many models available all of variable efficiency.
TOW A-FRAME
1. Weight – check that the A Frame is light enough to lift easily and will store in the boot
2. Manufacture – Made in the United Kingdom using EU Coded Materials
3. Human Designed & DPA Tested in the UK
4. Pozi-Lock – the only UK twist lock tow pin that actually locks and is not reliant on the A-Frame
DUO BRAKES
3. Brakes operating CORRECTLY – no intermittent cut outs!
4. Dual Sensing capability – no dragging brakes
5. Class Leading Warranty period
WEIGHT – this is perhaps the easiest to decide, you either feel comfortable lifting and handling the A-Frame or not. Will it store easily in the boot of your car? Consider such things as sliding bearings, if they are plastic/nylon will they swell when wet & cause the arms to seize? TOWtough = 6.9kg, TOWglide = 7.9kg – 30% less than the competition!
BRAKES – this is not so simple, especially operating correctly! According to the Police Accident Investigation Branch “the brakes and all component parts of the braking system must function correctly as intended by the manufacturer”. This includes any power assistance provided by any brake servo and that they operate proportionally with the Motorhome brakes and not intermittently using single signal progressive braking with cut outs.
DUAL SENSING – You would not wish to consider a braking system that operates ONLY on a light signal from the Motorhome rakes. In this case the slightest touch of the Motorhome brakes will activate 100% of the towed vehicle brakes. Meaning that every time you brake, even in slow moving traffic, the brakes on the towed vehicle operate without any proportionality and drag the motorhome to an abrupt stop.
Only with Dual Sensing do you solve the problem. Under engine braking, although the G Sensor is sensing deceleration, the brakes will not be applied until you touch the brakes in the motorhome and provide the second signal to the system. Under light braking on the flat a 12v signal may be sent to the brake system but with little or no deceleration sensed the G Sensor will keep any braking safely proportional. Simple, No Fuss, No Hassle, Cool Brakes!
TESTING – What is the difference between FEA testing and DPA testing?
Finite Element Analysis testing is a computer modelled process in which software will predict that a product can perform its functions correctly and predict areas of high stress that may fail under load.
This process involves modelling the product in an artificial environment gathering a set of test data and providing stakeholders with theoretical pass/fail metrics at the end of the test. This is a controlled theoretical process which we know is relatively effective and provides a limited degree of confidence that the end product will be able to perform its desired task correctly.
So how do we know that this same product is Fit for Purpose and can handle incorrect use? We generally do not! This is where DPA destructive testing comes in. By practicing Destructive Physical Analysis you are already aware that sometimes the user will not use the product correctly.
Now by incorrect use I don’t mean ultimately logging a defect with a summary of “Braking failed due to stop light bulb/LED failure”. I mean by performing unpredictable behaviour within the physical operation, it is only then that we will know that the product can handle it correctly. Remember, there is a difference between Predict and Proof!
It sounds like simple stuff but you would be surprised how often something this trivial will go unnoticed and leave users perplexed with failures and the likes. That is why we feel it is important that a DPA testing strategy is included in conjunction with, and not independent of, other testing methods, since along with the application now being fit for purpose, it should behave as proven when presented with unpredictable behaviour.
TowAFrames POZI-LOCK – makes it very fast to attach with a simple 90 degree turn. Pozi-Lock is made in the United Kingdom from EN16T steel, a stronger EU Coded material. The addition of a spring loaded locking bolt on the Pozi-Lock means the tow pins lock entirely independently and cannot rotate, Pozi-Lock does not rely on the A-Frame for security and is therefore Strong and Stable.
TOWglide ANTI BINDING RELEASE LEVERS – make it easier to release the TOWglide mechanism if the tow vehicle is parked on uneven ground. New Improved D Pins – the new design offers a safe and very secure attachment, all parts are intrinsically built together as one unit to prevent losing any parts – acts as cable holding clips.
CHECK – that the company you are dealing with is a full member of a recognized trade body such as the National Caravan Council or the National Trailer & Towing Association – HMB Leisure/TowAFrame are!
COMPARISON – TowAFrame DUO vs. Roadmaster Invisi-Brake
The TowAFrame DUO offers its Dual Signal activation sequence while the Roadmaster Invisi-Brake only offers Single-Signal Progressive braking. This means the Invisi-Brake has NO ADJUSTMENT to braking sensitivity. As soon as the brake lights of the Motorhome come on the compressor runs – the longer the lights are on the longer the compressor runs, the harder the brakes are applied regardless of the circumstances.
With Invisi-Brake there is adjustment only for the maximum amount of pressure generated, which can help reduce over-braking in stop-and-go traffic but comes at the expense of diminished braking effort during heavy or emergency braking. This is the case while moving and stationary – the system cannot discriminate between stopping conditions. This is especially problematic in diesel Motorhomes fitted with an exhaust brake. The Invisi-Brake must have a 15 second shutoff to prevent damage while sitting at stoplights and downhill exhaust braking.
The Single-Signal profile of Invisi-Brake also drastically reduces effectiveness in emergency braking as several seconds are required to build panic-level braking (1 second at 60 mph = 88 ft). If larger air lines were used emergency braking could be more effective, but at the expense of over-braking and “chucking” in normal stopping since Roadmaster Invisi-Brake cannot detect stopping intensity.
Utilising its Dual-Signal Activation sequence, TowAFrame DUO will not activate unless the Motorhome’s brake lights are on AND inertia is present. Once activated it will create a much smoother and quicker transition between intermediate stopping and heavy/emergency stopping while filtering out situations that would result in over-braking.
TowAFrame DUO’s installation is much more simplified taking roughly half the time of the Invisi-Brake and using just 1 screw into the firewall to the Invisi-Brake’s 6. TowAFrame DUO requires no components under the seat, no routing under carpet and no pulleys.
TowAFrame DUO also has superior warranty coverage – 2 years to RoadMaster USA’s 1 year – and a longer track record of excellence: TowAFrame DUO revised in 2007, Invisi-Brake released 2009.