How would one learn about old-style (circa 75 year old) voltage regulators? I'm thinking for streetcar/electric traction M/G sets where they are recharging batteries, and you want them to charge the battery properly.

I people less historically inclined say "Replace with silicon". And I hear that. But it's kinda cool, people asking "Why does an electric car make that noise?" Now how to make the darn things work?

The relatively simple streetcars would likely seldom or never have have had MG sets, or none with battery systems either, around the midwest here. Anything with K controllers used full voltage on the drum, and likely no low voltage systems needed in those cars. But rapid transit cars in Chicago had battery lighting which would flicker on when the cars crossed gaps in the third rail at grade crossings, or in crossing specialwork and switches.

A 'streetcar' with PC-5 electro-pneumatic control is in the collection at IRM and I am thinking that had dropping resistors for the low voltage side - no MG set, and no batteries.

Some of the newer interurbans did have MG sets. Seems the Indiana hi-speeds have that. I think most PCC cars have MG sets, especially the 'all-electrics' with low voltage controllers, door motors, etc.

The North Shore cars (and anything with low voltage master controllers and HL group switches) had batteries and I seem to recall a few of our shop guys sweating and cussing over an electrical panel that served as the regulator (and switching function should overhead power be lost). Lots of gadgets, wires, dropping resistors, and I think a relay or two. I do not know if they developed a schematic, or were working from one.

But I bet there were a lot of different designs depending on age and the system or property they ran on. Do you have something specific in mind, more details?

There are well developed and quite knowledgable trolley museum staffs that likely could go into detail, scattered around the country. What is your location?

Bob Kutella

Hi; If this Regulator is the Tirrill which contain about 25 EA of 2 1/4 round 1/8 carbon. I have a Cyclopedia of Applied Electricity pub American Technical Society 1917. Cover 4 page about DC Tirrill including drawing of the how to.

My E-mail is <o.paulsen@sbcglobal.net> If the Tirrill is correct I can E-mail the 4 page the you.

Stan
The Tirrill was use on Ship and sawn carbon at the place in San Pedro.CA
About 9 year ago.
Coles Battery & Ignition Service
555 W 5th San Pedro.CA
90731

It's funny, I started at Michigan Transit Museum, where just about everything had 32V electrical systems - the North Shore, 4000 Chicago Els, and the PCC. Now I'm active with WRM, and virtually nothing has it, except for the Key System bridge units and PCCs. (and the Vertol LRV, but that's another story.)

It's the bridge units I'm most interested in, as they seem to be causing an undue amount of trouble, and I suspect the voltage regulator is running amok and destroying batteries.

I've never bothered to understand how mechanical voltage regulators work, it's easier to replace with silicon. Not on an historic streetcar though!

Interesting! I didn't realize the bridge units even had batteries, having Type M control. What are they used for? I'm assuming lighting; some CA&E steel cars had batteries that were used solely for lighting. According to WRM's outstanding online roster database the bridge units have MG sets (type GMG-131) but I have no idea how exactly the system works. Another cause of problems might be shorts in the wiring, which was part of the reason IRM volunteers decided to preemptively rebuild the entire battery box under Indiana Railroad 65 last year.

On the 65 it turned out that the actual wooden battery box was so saturated with battery acid, that the wood had become conducting, allowing the battery charge to leak out through the conducting wood to ground, causing it to discharge quickly. Who'da thunk it? Which is why it was difficult to trouble shoot. That is why the box needed to be replaced.

On the Key Units there are a few lights and door control which operates on battery voltage, but the primary need for battery voltage was for the GRS coded cab signals and speed control.