I am installing a Redarc "Tow-Pro", for the simple reason that the unit can be mounted anywhere remote from the control dial. The control dial is small and can be fitted on the console or instrument panel taking very little room. Easy to install.

Quote " So, when we buy our towing vehicle, probably a Grand Cherokee and our van (dunno about that one yet, but the missus is leaning towards a Bailey of some description)"

My two pence worth is that I believe that the Bailey's van are single axle and very light in weight. My preference would be for a dual axle van.
Can not assist re brakes. We had a European van and sold same due to lightness and sway, when being passed by 32 wheelers or larger.
Jay&Dee

IMHO, pendulum based brake controllers, such as the Tekonsha units in the Hardings Swift tech note, are toys. About 20 (?) years ago I had to repair a Tekonsha brake controller that used a pendulum. I was amazed that a safety device could be so poorly constructed. It looked like something that a hobbyist might slap together. This pendulum only swung in one axis and the electronics were purely analogue. The braking effort was varied by pulsing the 12V supply to the brake solenoids (Pulse Width Modulation, PWM).

I expect that modern pendulum based controllers would be more sophisticated, but I would still prefer a proportional design that uses tri-axis accelerometers. In fact accelerometers have been around since the 1970s, so IMO there has never been any excuse for using pendulums. I would hope that modern units would have a microcontroller that could sense G-forces in all three axes and make appropriate decisions. Braking effort would still be controlled via PWM.

wasn_me wrote:

---

 I'm an old bolt & nut guy. I like to see how things work. I can understand inertia & a mechanical pendulum. How does a solid state pendulum work, how does a solid state switch work??? 

---

I'm glad you asked that question because I didn't know myself until just now when I examined some datasheets. I found several ICs that use capacitive sensing (MEMS), and one that uses thermal sensing.

It's not "nuts and bolts" language, but here is how they work:

http://kionixfs.kionix.com/en/document/AN003%20Multiplexing%20Rev%20A.pdf

Kionix MEMS linear tri-axis accelerometers function on the principle of differential capacitance. Acceleration causes displacement of a silicon structure resulting in a change in capacitance. A signal-conditioning CMOS technology ASIC detects and transforms changes in capacitance into an analog output voltage which is proportional to acceleration. These outputs can then be sent to a micro-controller for integration into various applications. Kionix technology provides for X, Y and Z-axis sensing on a single, silicon chip.

http://www.memsic.com/userfiles/files/Datasheets/Accelerometer-Datasheets/MXR9500GM__RevD.pdf

The MEMSIC device is a complete tri-axis acceleration measurement system in a single package fabricated on CMOS IC process. The device operation is based on heat transfer by natural convection and operates like other accelerometers having a proof mass except it is a gas in MEMSIC sensor.

Heat source, centered in the silicon chip is suspended across a cavity. Equally spaced aluminum/polysilicon thermopiles (groups of thermocouples) are located equidistantly on all four sides of the heat source. Under zero acceleration, a temperature gradient is symmetrical about the heat source, so that the temperature is the same at all four thermopiles, causing them to output the same voltage. 

Acceleration in any direction will disturb the temperature profile, due to free convection heat transfer, causing it to be asymmetrical. The temperature, and hence voltage output
of the four thermopiles will then be different. The differential voltage at the thermopile outputs is directly proportional to the acceleration. Please visit the MEMSIC website at www.memsic.com for a picture/graphic description of the free convection heat transfer principle.

https://www.sparkfun.com/datasheets/Accelerometers/MMA7260Q-Rev1.pdf
http://www.st.com/web/en/resource/technical/document/datasheet/CD00213470.pdf

The device consists of two surface micromachined capacitive sensing cells (g-cell) and a signal conditioning ASIC contained in a single integrated circuit package. The sensing elements are sealed hermetically at the wafer level using a bulk micromachined cap wafer.

The g-cell is a mechanical structure formed from semiconductor materials (polysilicon) using semiconductor processes (masking and etching). It can be modeled as a set of beams attached to a movable central mass that move between fixed beams. The movable beams can be deflected from their rest position by subjecting the system to an acceleration (Figure 3).

As the beams attached to the central mass move, the distance from them to the fixed beams on one side will increase by the same amount that the distance to the fixed beams on the other side decreases. The change in distance is a measure of acceleration.

The g-cell beams form two back-to-back capacitors (Figure 3). As the center beam moves with acceleration, the distance between the beams changes and each capacitor's value will change, (C = Ae/D). Where A is the area of the beam, e is the dielectric constant, and D is the distance
between the beams.

-- Edited by dorian on Monday 12th of October 2015 04:01:04 PM

dorian wrote:

http://kionixfs.kionix.com/en/document/AN003%20Multiplexing%20Rev%20A.pdf

Kionix MEMS linear tri-axis accelerometers function on the principle of differential capacitance. Acceleration causes displacement of a silicon structure resulting in a change in capacitance. A signal-conditioning CMOS technology ASIC detects and transforms changes in capacitance into an analog output voltage which is proportional to acceleration. These outputs can then be sent to a micro-controller for integration into various applications. Kionix technology provides for X, Y and Z-axis sensing on a single, silicon chip.

-- Edited by dorian on Monday 12th of October 2015 04:01:04 PM

---

 Thanks dorian, I think my aging brain can get a grip on the above.  The change in capacitance is the acceptable thing to me. It would be good to see a meter across a silicon structure & see the difference in capacitance take place under operation. I suppose this can be seen as the voltage rises under  braking, on a prodigy.

For a brain like mine, it comes back to just accepting that things happen with solid state electronics, 

Thanks for the reply, I'll forward this to a few mates who would also be interested. 

Cheers Pete