Footswitch Hi/LoBeam Notes   
May 2021 R. Kwas   [Comments Added]

This Tech article is in Progress and not yet Complete! 

German made Footswitch of the 122s
Lucas supplied Footswitch of the (early) 1800s
Comparing 122 and 1800 Lucas Footswitches

Reference Information
    Galvanic chart
    Owner Findings


German made Footswitch of the 122s (and likely 544, to be confirmed)

These notes document a disassembly and design review of an original Amazon Hi/Lo Beam control Footswitch, once again sourced by Chris Horn, from his stock of vintage Volvo components.  He actually sent two...on one of which, the actuating button was completely locked (it also looked very much like the real thing, but which was a no-name, I can only guess from where!), and the subject switch here, whose actuating button felt fine, and where there is no doubt from whence it came!


A used Footswitch, as received.  Not too-too much oxidation for a part that spent its service life on the floor and literally under-foot!


Bottom View:  The OE switch is "Made in Western Germany", not by Lucas as is often suggested.  Lucas supplied the Footswitches for the 1800s and one of these switches was also procured and subjected to a tear-down, inspection and refurbishment, see below!


After just a little clean-up, terminal identifiers consistent with the Wiring Diagram are evident in the cast housing (Class Act!).   Wires removed are tinned (copper strands have been filled with Solder) to make the conductor essentially a solid conductor so it can interface well with the compression screw type terminal and without damaging individual strands.  The observant reader will see a depression in each of the wire-ends, where the securing screws have compressed the tinned wire.  This makes for generally a very secure and electrically adequate connection, but one can also see surface oxidation in the depressions...combined with any looseness occurring over time, this can lead to a poor current carrying an apparent failure of the Footswitch can often be cured by no more than simply removing the wires, one at a time, applying a dab of ACZP, and reinstalling them, snugging the securing screw!  Of course if it was me, I'd fully remove the set-screw and treat its threads also...!  


Disassembly in preparation for design evaluation: 

There are no rivets to be drilled out on this design...the pass-through spacers, part of the base-casting where simply swaged open a bit to lock in-place, and done...clever design really, these switches were never intended to be serviced, but that has never stopped the curious and resourceful Swedish-Embassy Hardware Disassembly and Evaluation Team SW-EM HDaET from getting inside a component!  The swaging is gently machined away (with in this case, a counter-sink), until the insert can gently be pried from the housing. 

Notice once again, the repeated use of the words gentle and gently...this is not by coincidence!  




Once  the securing swaging is out of the way, a gentle tapping on a wooden drift (use number 1007 of a give-away chop-stick!), the insert is slowly persuaded out of the cast housing.  Since removal force can only be applied one-sided (guaranteeing it will cock, or "rack" to one side as it moves) this must be done gently to prevent damage...I also expect the black plastic to be brittle Bakelite (more gentleness required!).



With the Housing now chucked into a soft-faced vice and held horizontally, more tappy-tappy is applied to the wooden drift, until a mini prybar (actually a small screwdriver bent into shape) can be stuck between the internal assembly and Housing to develop an opening.  More gentle prying minimizes the cocking...



The internal assembly is slowly making its way out of the housing...a little Tri-Flow light lube helps!  Once some more movement occurs, it becomes clear that the area around the screw terminals is a separate piece from the Bottom Cover.  A small flat screwdriver now serves as a wedge and mini prybar to separate the two further...the anticipation mounts...


...a bit more gentle persuasion, and the bottom cover finally releases its's almost like Christmas! 

First look at the internals...but not yet actual contact surfaces.  A phenolic contact plate, with beefy brass riveted contacts.  [ guess as to what will be done at the riveted connections...]


The Contact Plate is gently levered from the pass-through spacers with the mini prybar.


When the Contact Plate is finally liberated, it can be lifted from the Turning Contact 

Bottom and actual contact side become open to sunlight for the first time since about 1965.  Very beefy design is once again in evidence. 

The Bakelite screw-terminal separator can simply be lifted from the Contact Plate.


A closer look at the working contact surfaces.  Remarkably little wear is evident, but the two non-brass contacts do exhibit some corrosion, possibly due to a bit of dissimilar metal action.  A quick check of the Galvanic chart shows a 0.2V voltage potential (minor, and not too terrible, nonetheless present!) between brass and steel. 

Of course, it might not have been "galvanic corrosion" at all, but just "simple corrosion" (there is a difference...not in the final appearance, but in the mechanism which causes it!).  This matters only to those knitpickers among us studying the details, less so for the casual rebuilder...  


The Turning Contact Plate of brass, exhibits only modest wear at the actual contact circle, and a wavy contact surface, the reason for which might be something to do with the contact preload, and cleaning action, but many become clearer upon further disassembly of the actuating mechanism.  The sliding contact area is a massive, self-cleaning, first class, highly reliable design.  The overall impression of this component is very positive! 



The two (unused) contacts furthest away from the screw-connections are of a ferrous material other than the brass of the working contacts, so a bit of corrosion is evident only on these. 


A leadscrew mechanism contained mostly within the pushputton, converts the step-on-button-push into a turning motion at the Contact Plate.  The mechanism is stout with all parts exhibiting very minor signs of wear, because the original lube is still present and quite effective...but it is cleaned away in preparation for renewal. 



Synthlube is applied to all leadscrew mechanism and all sliding surfaces, making the mechanism function as smooth as butter! 




Riveted contacts on a phenolic baseplate is a typical '60s electrical construction technique.  Thankfully the riveted connections are all brass to brass, so no dissimilar metals corrosion will take the only resistance which might develop will be due to mechanical loosening...none is observed, but because I don't ever want to revisit the inside of this component, I will solder these connections, making them "forever"! 


The seven riveted connections are cleaned and prepped once again with my groovy little Micro-Wirebrush


60/40 electronic solder is applied, bridging the mechanical joints.  Visible residue of the (non-corrosive) rosin is cleaned away with isopropyl alcohol.


Cleaned, inspected, soldered, lubed, and ready for reassembly!  Screw-terminals (including the threads) get an ACZP treatment of course! 




Reassembly is as simple as reuniting the stack of prepped and lubed parts, and after a few satisfactory test operations, giving the remaining housing ferrules a slight peen to prevent the stack from separating while in storage and awaiting installation...when installed in-situ, the mounting screws will also hold the assembly together absolutely positively.  A resistance test was not performed on this very simple switch...I just didn't find it necessary... 


Lucas supplied Footswitch of the 1800s:  

A Lucas supplied Footswitch was also procured with the intent of performing a similar inspection and refurb, and maybe comparing the two designs. 






Comparing 122 and 1800 Lucas Footswitches: 

Lucas Footswitch on the left...connections are not visible, or labeled from the top...hmmmm


Bottom view of both...the Lucas version has push-on connectors (basically nothing wrong with that!), and no bottom cover, putting the connectors and their mates quite close to the mounting surface (there's a lot wrong with that!...but can this be?...I don't want to believe it!).  This certainly explains this occurrence of "Smoke in the Cockpit"! 



Summary of Design:  PLACEHOLDER



Links to other SW-EM Articles on Lighting:


Reference Information:

Galvanic Chart: 

Finding two different metals on this chart, and reading off how many volts of potential would exist between them if they were in contact, one can see how much potential there is driving the galvanic reduction of the least noble one (the one more to the left!).  The more voltage, or time in contact means more reduction...  As one can, Magnesium doesn't play well with any other metal...friendly tip:  Inspect used Mag components closely, and employ galvanic insulators to keep them electrically separate from other metals! 


Owner Findings: 

This is how some Footswitches, look at the beginning of restoration efforts. 

Ben Ernst picture posted with his kind permission. 

An example of a 122 original Footswitch which has had a hard life, literally under-foot...including some custom "wiring improvements"!  Notice also the wire-nut is positioned open side in a cup! it will hold any moisture which gets caught to keep the connection it is supposed to make, SUBMERGED...OH goody!  


Here is what this 1800 owner found at his Lucas Footswitch, and what he did in the way of adding an insulator between terminals and mounting surface. 

John Cork pictures used with his kind permission.

Again, no insulator!...I can't believe it!


John had some insulator putty "cork tape" from AC work on hand and used that after he saw this article...I guess it's OK, but it reminds me of what I scraped of the toaster-oven bottom after a pizza reheat went a bit long...and after removing the battery from the smoke detector...


What this owner found when he demounted the Hi/Lo Beam Sw of his '66 1800 (so unquestionably a Lucas unit), in response to my request on .  I am still trying to confirm if this is an OE insulator, or a (nicely made!) add-on by a PO who also thought without it looked too risky!

Gary Fallowfield pictures used with his kind permission.


If you would like to participate in this survey, simply inspect the Hi /Lo Beam Footswitch of your 1800, to see if it has that flat insulator, as highlighted here in Yellow.  If an Insulator is not apparent under the wiring, you might want to demount your switch and check more closely...but if you indeed find none, I strongly recommend adding one, as a preventative to "Smoke in the Cockpit!"...either of your own manufacture [not the smoke, but the insulator!], or contact me and I will make up one for you at a modest cost!  Please let me know in an e-mail of your findings...

Tip:  DON'T leave home without it (and maybe become the next Lucas equipped car visible in the IR spectrum from orbit)!

This is what it looks like when there is an insulator present.  It is located between terminals and wires, and mounting surface and prevent inadvertent short circuits to chassis!  


External material sources are attributed.  Otherwise, this article is Copyright © 2012-2022.  Ronald Kwas.   The terms Volvo and Lucas, and other manufacturers or suppliers, are used for reference only.  I have no affiliation with any of these companies other than to try to keep their automotive electrical products working for me, help other enthusiasts do the same, and also present my highly opinionated results of the use of their products here (like giving Lucas all the grief they so richly deserve!).  The information presented comes from my own experience and carefully considered opinion, and can be used (or not!), or ridiculed and laughed at, or worshipped, at the readers discretion.  As with any recipe, your results may vary, and you are, and will always be, in charge of your own knuckles! 

You are welcome to use the information here in good health, and for your own non-commercial purposes, but if you reprint or otherwise republish this article, you must give credit to the author or link back to the SwEm site as the source.  If you donít, youíre just a lazy, scum sucking plagiarist, and the Boston Globe wants you!  As always, if you can supply corrections, or additional objective information or experience, I will always consider it, and consider working it into the next revision of this article...along with likely the odd metaphor and probably wise-a** comment. 

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