I don't think "just" means what you think it means...

I'm interested in what the rationale for this was. Were there already plans to include an inverter for other purposes or is the inverter being included solely to power the lights?

Pennsylvania Trolley Museum is currently working on a different adaptation of modern electronics technology in the interest of fire safety aboard old trolleys.

Several of our cars have 12V storage batteries that operate certain safety related lighting and other low voltage items. The batteries were formerly charged by being placed in the ground return of the air compressor's drive motors. It worked, sorta.... When it didn't work, the result was a battery boiled dry, or exploding, with the corresponding hazards of fire and acid exposure.

As restored, Pittsburgh Rys. 4398 and West Penn Rys 832 will have modern DC to DC converters that will charge the batteries from a 600VDC input. The electronics will be concealed under a seat, or some other invisible location, in a metal enclosure.

These cars have also had every inch of wiring replaced by modern low smoke rated wire and cable and all windows are now tempered glass. We are at present starting a project to replace all the 1938 wiring in PRCo PCC 1138. The present wire has rubber insulation covered with tar dipped cotton braid. It is life-expired.

Our justifications for deviating from original materials and methods are those of safety, reliability, and durability. To the extent possible, such adaptations are "not visually obvious" to all but the most discerning "inspectors."

Thanks Robert, but having done that job a couple times, and in the process making good repairs to all the other hidden problems that would have otherwise remained hidden until inconvenient or catastrophic failure, I'm convinced that old trolleys NEED to be stripped and rebuilt every few decades if they are to be in use. We can't keep raising the pole and smoke testing with our fingers crossed like it was 1970 again, and the cars were still fairly intact and even had wet lube from when they were retired.

Your mileage may vary, of course..........but it isn't that difficult and for our own protection, we need to be proactive.

dave

Could the electronics for the voltage converter used at Pa. Trolley Museum be hidden in the old battery compartment, even in an old (or new} battery case?
Grand Central Terminal had the same objection to curly tube compact florescent lights, so they bought commercially available CFLs that were made with an outer frosted globe. However, in a clear globe, a Light Emitting Diode might look like an old arc light.

Hiding modern electronics aboard vintage rolling stock can be a challenge, especially if it is desired to keep the "old" appearance in all instances. There is one advantage however in that modern stuff typically takes up a lot less space than an equivalent function in older technologies. Thus it would be possible to conceal the battery charger previously mentioned inside the gutted case of an old storage battery. In the case of the two cars being so equipped at PTM the DC/DC converter and associated protective devices are all contained in a steel box about a foot square and 6" deep. That fits nicely under one of the longitudinal seats in PRCo 4398, next to the battery. We're still considering where to put the device aboard West Penn 832.

Another adaptation we've made on 4398 and eventually on certain other cars is the use of the type of air dryer made for heavy trucks. These are quite efficient at keeping moisture out of the air system. They are essentially a pneumatic device, but they do require a thermostatically controlled heater for the discharge port to keep it from icing up in cold weather. That heater is one of the 12V devices powered by the battery. We found that the old form of charging circuit (battery in compressor motor ground) did not provide enough charging current when the dryer heater load was added. This was one of the motivations behind the use of the DC/DC converter for charging.

Your experience has sold me vis-a-vis in-car ceiling and wall lighting, which is usually not in conduit; especially if the ceiling and sidewalls are peeled off anyway. I'm not so sure whether to use modern or traditional materials. Modern materials are not necessarily better but are definitely unproven over 100 years. What really scares me is complex cars like...


A lot of these cars have a LOT of wire in their control systems, I'm talking PCCs, or MU equipped cars, say with HL, HB, AB, M, etc. And a lot of it runs in grounded conduit for this very reason. Is that kind of work really necessary? Are you really going to get the car back together right given decades of modifications?

And on this type of very complex work, is it REALLY the best way to spend volunteer hours? Or maybe should we be giving some of those canvas roof cars their 5-year oiling?


Was that an original design? Or was that improvised at the museum or near the end of the car's service life? I've rarely heard of 12V being used traditionally, and that suggests it was retrofitted for modern uses, i.e. to power the radio/PA. If so, go modern. I'd recommend a special-magic-expensive 600V-120VAC inverter, and then a common-cheap 120V-12V lead-acid battery charger. BART does things this way: exotic inverter to make common AC voltages, then every accessory is cheap, common AC gear, from the traction motor blowers to the fluorescent light ballasts. Allows you to replace a bad charger for $100 instead of $1000, and gives you 120VAC for future use on the car, again allowing cheaper accessories.

A little secret about so-called "maintenance-free" lead-acids is that it's not the battery. It's the charger. Modern lead-acid chargers have evolved to where they charge with extreme precision and do not overcharge the battery. If you overcharged ANY lead-acid battery there would be water loss or damage. The so-called "maintenance free" lead-acids rely on these modern chargers: if you stuck an obsolete charger on a sealed battery, you'd destroy it quick.

However, if by chance the 12V usage was traditional, it's quite likely they used Edison batteries, which are quite hardy against that type of misuse. They would not blow up (the internal resistance is too high) and they would simply boil off a lot of water, which is normal for them and not damaging.

Almost all old trolley cars show signs of fire damage around a few light sockets.
If a light bulb comes loose in the socket, an arc can develop between the bulb and socket. This arc can spread from the socket to the car wiring and then set fire to wood. That's why bulbs should be checked regularly to confirm that vibration or passengers have not loosened them in their sockets.

When a filament in a bulb opens, an arc can develop between the ends of the filament. This can spread to the filament supports and then migrate into car wiring. Street railway bulbs have a high vacuum to reduce this problem. However if the failure was caused by an air leak into the bulb, this protection does not exist. Occasionally well meaning volunteers will replace a burned out bulb with a regular bulb rather than a street railway bulb. You need to confirm that all bulbs are marked "street railway."

Bulbs in PCC cars have a different method of preventing arc damage but you can still get arcs in sockets if the bulb is loose or the internal shunt fails to work.

I think, Robert, that you use the best material in the best way you can but knowing that it will be replaced again by the next generation at the latest - and if you do test you can certainly find out if it becomes a problem sooner. It may well be practical to retrofit conduit such that wiring can be pulled to replace bad wire without removing sheathing. Everything is a tradeoff..........and we need to get comfortable with the trades we make for reliability and continued wear and tear.

In the second instance, if you have a problem getting things done properly with volunteers available, you have a management problem which is either too much ambition, too little rational planning, too much reliance on volunteers, to few volunteers - I'm getting tired already. In any case it is an imbalance between need and resources, which needs to be addressed somehow. If you can't even keep up with the shop work, which is the easy stuff, you will find it very difficult to handle the marketing and development, which is the lifeblood, not more paint jobs.

dave

Some responses to questions raised re activity at Pennsylvania Trolley Museum:

PRCo 4398 did not have a battery when originally constructed in 1917. Many PRCo cars had these low voltage circuits added later in their life to power a rear marker light, brake light, and/or emergency interior lights when there was no 600V supply, such as a dewirement. West Penn 832 did have a battery when built in 1929/30. Both cars are being restored to represent different time periods; 4398 as modified to "high speed" performance (and it REALLY does perform!) in the 1930s/40s and 832 to represent a mid-life period. In the case of 832 taking it back to 1930 was deemed impractical as WP had converted the 831-842 group to roller bearing journals in the mid-to-late 1930s and that's the way the car was when acquired in 1952.

As for rewiring PRCo 1138 to replace wiring put there by St. Louis Car Co. in 1938, the choice was driven by the insulation of the present wiring being very brittle, particularly where exposed to heat. The secret of such a project is proper preparation and documentation, and that's the current phase of the job.

A note about "Street Railway" lamps: Not only are they a vacuum type bulb, the leads inside the base are specially insulated to prevent an arc forming there when the filament fails. This feature is not present on garden variety bulbs, including Rough Service and related types. Thus a risk exists of an arc forming inside the base of the bulb. This will often propagate into total destruction of the bulb base and the socket, presenting a fire hazard. The Street Railway type bulbs are more expensive, but for good reason. Using any other kind of bulb on 600VDC series applications carries a definite risk.

As for the "cut-out" 30V lamps used 20 in series in PCCs, there is an alternate being considered as part of the PRCo 1138 rewiring. That would involve rewiring the interior lights to 5 in series (or perhaps 6 in series) so ordinary Street Railway lamps can be used. This would require modification of the existing sockets, which now short out upon removal of the lamp.