• Cab Heaters

  • General discussion about locomotives, rolling stock, and equipment
General discussion about locomotives, rolling stock, and equipment

Moderator: John_Perkowski

  by Bigt
A couple of questions. Back in the 1970's when I use to ride with some of the crews, all of the locomotives had cab heaters / defrosters that operated off hot water from the radiator (or so I was told). Many of the crews would complain of being too hot or too cold depending on the locomotive. I was also told that sometimes leaks in the plumbing to these cab heaters / defrosters were an issue. My question is this: with today's new generation of locomotives, and all the resulting technology, how is the heating and defroster needs addressed now? What is used now?

Finally, I have read some about air brakes. I see different number and letter combinations given to the various air brake systems in locomotives, the latest seems to be a 26L designation. What does this mean, and, why have these numbers changed over the years?

Thanks in advance.
  by FarmallBob
The last locomotive cab I visited - the slug end of a GP40-2 + RDSLUG (mother + slug) set had electric resistance cab heating. The engineer shared it heated the cab quite nicely - especially considering the unit lacks a prime mover and thus has no hot water to provide heat.

Also a few years ago when I was aboard an ES44DC I noticed the cab had electric resistance strip heaters (sort of like baseboard heaters) along both interior idewalls. I suspect it also had electric forced air heat also as the cab was toasty warm while the outside temp was in single digits.

Can't help on your air brake question.

  by Desertdweller

Locomotives have to have forced air heaters to act as defrosters. Hot air is blown onto the inside surface of the windshields through ducts in the window frame.
Some of the newer models have defroster heating strips in the glass like auto rear windows.

Electric heaters seem to work better than hot water heaters. They get hot faster, and do not need to be drained if the loco is left shut down in cold weather.
Sidewall heaters work well to defrost the side windows.

Some locos are equipped with electric strip heaters below the side windows at floor level. They can also be installed in the front wall of the cab.

The hot water heaters in the old Geeps and SD's were not very good, especially as built. There were two heater fans on the back cab wall, one on each side. They were powered by open-frame motors that gave a lot of trouble.

Like heater cores in old cars, the heater cores in old locos were prone to leaking. Once, after pulling a long grade up a mountain in a GP30, the rear cab wall heater on the fireman's side ruptured. The cab filled with steam, and my conductor (who was sitting directly in front of it) got a full blast of it. I had to shut off the water flow to the heater and air out the cab before we could continue.

As to the brake question, the 26L (don't ask me what the numbers and letter means, I don't know) is a late, perhaps the last, manually-operated freight brake valve. It does not have the "lap" position to maintain pressure like the 24-series that preceded it. You can make a direct reduction to any point in the service portion of the handle's travel, actuate the independent, and have a reasonable chance of maintaining that set. Second-generation EMD power came fitted with these, and most first-generation EMD power was retrofitted with it. The early Geep 7's (and probably early F's) were equipped with the 6HBL brake used on steam locos. These things did not have a pressure-maintaining feature, and were a real pain in the butt on a long downgrade if you did not have dynamics.

I used the term "manually-operated" because the newer units with the desktop controls, or the even newer faux side-mounted controls are not operated directly by manual force, but are "fly-by-wire". These new control consoles (like on an ES-44) use what look like 26L brakes, but in fact are computer-controlled with familiar-looking controls. I like the desktop controls best, unless you have to run a unit in reverse. I noticed on the newer CSX units there is an auxiliary speedometer on the back wall, very useful with the side console.

At night, running long hood forward, you can read the speedometer backwards in its refection in the back door glass. In the daytime, not so much.

  by Bigt
Thanks for the info., guys!
  by Engineer Spike
The 26L is self lapping. The further the handle is moved in the service zone, the more the brake pipe is reduced. The older systems had just a service position. The engineer puts the handle in service. When he has taken the desired reduction, he moves the handle to lap. The 24RL had the option of pressure maintaining. When I was on BN, the ex GN SD9s had 24RL. Some had maintaining, while others didn't.

Pressure maintaining maintains the pressure after a reduction has been made. If there is no maintaining feature, then leakage in the brake pipe keeps drawing down the brake pipe pressure. This causes the train brakes to keep applying harder. Engineers have a few tricks to circumvent leakage on non maintaining lead units. One is bridge braking. The handle is placed between lap and running. this causes a small amount of air into the brake pipe, which counteracts the leakage. The other method is to use the feed valve. This valve regulates the pressure fed into the brake system. Today these methods are risky. Modern car control valves are more sensitive to causing a release when a rise of pressure is detected.

There is a brake schedule called 30CDW. The actual equipment is the same as 26L, but it is designed for desktop applications. CN's SD70Ms have a conventional control stand, but have a 30 system mounted sideways instead of 26.

The. new systems are fly by wire. There are less mechanical parts. This has resulted in increased maintenance and inspection intervals. Emergency is the only position which is directly mechanical/ pneumatic.
  by Bigt
Engineer Spike,

I am glad you mentioned the control stands / desktops. I had wondered if there were any "conventional" control stands still being installed in new units. I would assume they come with new features not seen in the old style stands? I have heard pros and cons from others on the desktops vs. conventionals. What is your preference?
  by Desertdweller

Feed valve braking: if you have an event recorder, it should show up on the tape. Better to stop and set some retainers.

30CDW. I ran some locos with that, too, mostly early desktop-equipped ones. If I recall correctly, the independent brake was actuated by tipping the independent brake handle to the right. Later models (not sure of the model designation) had the control for actuation on the automatic brake lever. You pulled up on a spring-loaded toggle below the head of the handle, like actuating the reverse lockout on an old Muncie 4-speed.

  by scharnhorst
I can remember having an electric heater on the Sperry car's we had a Caterpillar 3306 to power the test equipment in the back of the car and a Caterpillar 3304 to power and move the car which is where our electricity came from as well. At night we ran a Lambo L34 generator for electricity and heat + A/C
  by Engineer Spike
I never did the feed valve trick, as I only had 24RL in the yard. The old timers did it in the per event recorder days.

There are various controls to actuate on the electronic brake systems. Some push the independent handle sideways. Others have a ring on the independent handle, which is under the knob at the end. This gets pulled up. The last method I've seen is a button on the side of the automatic handle.

I am really glad that the industry has gone away from the desk. A conventional control stand, with the gauges in front, below the windshield are best.
  by Bigt
Engineer Spike,

I am glad you mentioned the desktop controls vs. the traditional control stand. I have been wondering if the "battle" was still on between the two, what type held preference among most crews. I have heard pros and cons for both. Personally, I cannot see how sitting behind the desktop type for a period of time would be all that comfortable, let alone trying to do any type of back-up moves. Thanks to all for your answers.