Low Water Button on Locomotive...

The 'low water button' on a locomotive. Is this a safety device or a protective device for the locomotive?

protection device for engine block, as is low oil button and crankcase over pressure.

Edited by a Moderator (typo) 8-2-09 558PM CDT

SO it would be legal to tape the button in if it keeps popping to keep the loco in service?

Legal ?? Yes, more like stupid, as the taping could cause a massive locomotive engine failure.
It could cause the locomotive to be out of service for a long time, so a CMO will frown on taping such a device.

Edited by a moderator 8-3-09 704AM CDT

Sometimes the buttons fail and pop out even though the engine has enough water,same can happen with the low lube oil pressure buttons. something to think about

A fusee used to work better, especially on older EMD's such as GP40-2s & SD40-2s, lol.

Over the years, I have worked on a many of locomotives that it was hard to get the low water button reset. I have seen it take sometimes maybe up to ten minutes or so plus or minus some. Both Water Pumps are in good operating condition and the engine protector is piped up correctly also. You can snap a couple of gauges on the output side of both water pumps and you wont hardley see any pressure. What you have to do is when you start the engine, pay attention to the water sight glass. Keep one hand on the low water button reset on the engine protector and put the other hand on the Layshaft and raise your engine speeds. When you do this you can see the water start to drop out of the sight glass and you will start seeing pressure on your gauges that you applied once the system has balanced out. I have seen countless number of water pumps changed out and that was not even the problem. From my experience, we have corrected the problem by applying new banks of radiators.

Don't assume that because it does not fall under the definition of "Safety Device" that there is no rule being broken by tampering with an engine protective device. I can assure you, that willfully destroying an engine worth well over $100,000 will get you fired.

If a low water button keeps popping, there is a problem. Normally, it's low water. But if the level is ok, then it's generally one of two problems. The actual Low Water detection device has failed, or, the air filters are plugged. The diaphram behind the button is balanced by air box pressure. If that pressure gets too low, you will end up with a very sensitive low water button. I have also seen sight glasses that give false readings thanks to sludge. I have drained loco's and the sight glasses stay full. The only way to be sure it's working is to open the petcock under the sight glass. Don't assume that if the water level seems to be ok but it keeps popping that it can't be a low water issue. And another VERY IMPORTANT issue to keep in mind.... On the EMD engine protective device, there are TWO buttons, one is the Low Water Button, the other is the COPD (Crankcase Over pressure Device) button. While usually, the Low Water Button is on the top and the COPD is on the bottom, it is NOT always the case. Sometimes they are reversed!. The only way to tell is to read the writing that is around the button. Reseting the COPD and then restarting the engine could cause an explosion!. And it can and DOES happen. I have seen the results. It's not a joke. Be absolutley certain you are reseting the correct button.

Bottom line, your not a machinist, don't pretend to be one. If the engine keeps dying, sit down in the seat and call the dispatcher and inform them of your issue and await the rescue engine or mechanical forces. Don't be a hero. Because if you start messing with engines with the hopes of keeping a train from being delayed and end up destroying the engine, you are in far more trouble then you can imagine. And to add, Mechanical forces i assure you will not be happy if you start taking work away from them. I know Engineers who have been threatend by Mechanical forces for trying to make repairs themselves and in turn, took money away from machinists. Things are bad enough with employees being furloughed and laid off, stick to your own craft and do not start being Mr. Goodwrench. Stick to the duties that are required of you and nothing more.

Legal ?? Yes, more like stupid,

Nope - wrong.

The FRA takes the position that if something is THERE, is must work as intended. Such as class lights. Most new locos don't have them, and while they may still be found on older units I know of no railroad which still requires them. Nevertheless, if there are class lights on an engine and a bulb is burned out, the FRA man can write it up.

Likewise, interfering with the low water button is not acceptable to the FRA. It may not be a safety sensitive item, and they certainly are not required to be present. But overriding one is a no-no. The guy may or may not actually write it up depending on his mood, but he sure can!

When looking at an Engine Protector, you have a couple of types. On a Engine Protector for a Turbo Engine, the Low Water Button is on top and the Crankcase Overpressure Button is on the Bottom. On a Roots Blower engine protector, the crankcase button is on the top and the low water button is on the bottom.

WVU wrote:When looking at an Engine Protector, you have a couple of types. On a Engine Protector for a Turbo Engine, the Low Water Button is on top and the Crankcase Overpressure Button is on the Bottom. On a Roots Blower engine protector, the crankcase button is on the top and the low water button is on the bottom.

While two models of EPD's exist (Three if you count the dual Low Water button versions common on Amtrak) It's not standard for Roots Blown vs Turbo. I have seen both types on SD40-2's and GP40-2's. You cannot rely alone on the type of locomotive to know where the button will be.

At one time CSX use to apply the dual low water button style engine protector to some of there locomotives. They were removed a few years later and they applied a Delta "P" engine protector device that works with the standardTurbo Differential Engine Protector. You can still tell by looking at the locomotives that use to have the dual low water buttons on there engine protectors by noticing that the Layshaft was cut in half.

Moderator's Note:

Folks, we have all sorts who come to railroad.net. Some are industry professionals and craftsmen/women. Some are true foamers, in the perjorative sense of the word. I know a couple of regulator types.

Please think before you post. Think about some over-enthusiastic guy who doesn't know diddly about a control stand trying to start a museum RS-3 or Geep somewhere. Let's not help him do something that will cost that museum big bucks, because they ruined an engine.

EDIT: For those who were responsible here, thank you for what you said. This is one of those notes where if the shoe fits, please wear it. For most, this shoe does not fit! I apologize for not making that clear when I first wrote this.

I've talked with Otto offlist about this. Thanks for your patience and forbearance.

John_Perkowski wrote:Moderator's Note:

Folks, we have all sorts who come to railroad.net. Some are industry professionals and craftsmen/women. Some are true foamers, in the perjorative sense of the word. I know a couple of regulator types.

Please think before you post. Think about some over-enthusiastic guy who doesn't know diddly about a control stand trying to start a museum RS-3 or Geep somewhere. Let's not help him do something that will cost that museum big bucks, because they ruined an engine.

I've talked with Otto offlist about this. Thanks for your patience and forbearance.

Speaking for myself and most of the others on here, i think we all made it clear to NOT touch it. The thread starter was not asking how to do anything, he was simply asking if it was allowed.

The only people who should EVER be touching any control and/or safety device on a locomotive is a trained and qualifed professional mechanic or Engineer. NOT a railfan or "foamer".

Its important to repeat, as it was mentioned above, that its quite common for the low water button to pop out when starting a cold loco. If it trips soon after starting, its okay to push it back in, or else the prime mover will shut down - It might take a few minutes of holding it in, or continual resetting on a cranky loco for it to stop popping out. Of course, the water level should be checked, but if the level is okay, its just "cavitation", basically air bubbles in the cooling system that are tripping the low water button.

On the other hand, someone who might not know this, in a museum, which was mentioned above with touching stuff and not knowing what you are doing, might do the opposite and NOT hold the low water button in or reset it when it pops. Then the engine shuts down. Then it gets cranked again and shuts down again - and this cycle keeps repeating itself until 1) the starters overheat or 2) the batteries die, or something else thats worse. Both of these could cause damage as well and cost money.