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Up Topic Welding Industry / General Welding Discussion / Murphy Switch?
- - By Cumminsguy71 (*****) Date 10-16-2010 12:11
Not sure what the Murphy switch is exactly but here's what I'm thinking. Is it kinda like an oil pressure switch or temp sender on a car that turns the light on in the dash to warn you with the exception being that the Murphy switch will shut down the engine on a welder? Just trying to learn more about these machines so I can better protect mine when I get her home. Thank you,

Shawn
Parent - - By nevadanick (**) Date 10-16-2010 13:59
Thats exactly right shawn,  the murphy switches "make or break" the ignition or run circuit depeding on whether or not the machines systems are within operating
parameters or not.  On a welder its usually "low engine oil pressure" or "excessive coolant temp"  that will shut it down.    Thats why when you start these
machines you have to push a bypass switch that temporaraly sends current to the ignition or fuel solenoid so that the engine can start and achieve oil pressure
and close the circuit to keep the engine running.  Obviously during a cold start up the coolant temp isnt an issue,  but if it gets too hot it will shut the engine off.
These "engine protection systems" are very common on machines like welders, air compressors, generators, because there is usually no operator close enough to
see an idiot light or buzzer.
Parent - - By Cumminsguy71 (*****) Date 10-16-2010 14:15
Thanks for the explanation Nick. 100 feet away kinda hard to pay attention to an idiot light or gauge, makes sense
Parent - - By hillbilly (**) Date 10-16-2010 14:41 Edited 10-16-2010 20:37
Let me know what you come up with. I`m running this SA naked for the moment. Haven't been terribly far from it in the field, so it hasn't been an issue yet.  I wasn't going to plunk the cash down for the Murphy stuff, just yet. I figured I would price out a homebrew setup first.
Parent - - By Cumminsguy71 (*****) Date 10-16-2010 15:21
yeah, they like those murphy gauge's from what I've seen!
Parent - By nevadanick (**) Date 10-16-2010 15:51
you can make your own setup very eaisly,  you need one of those small bosch relays, a panel mount momentary pushbutton switch, an oil pressure switch,
a coolant temp. switch and some wire.
The "murphy" switches are just a brand name that uses an actual gauge as the switch also.
Parent - By FixaLinc (****) Date 10-17-2010 00:19
For a engine with a mag all you need are the Murphy gauges, temp or oil, the switch is built into the gauge and connect it to a stop switch too and to the mag kill terminal.  Oil pressure gets too low or temp too high it grounds it out stopping it.  For a battery distributor setup you also need the Murphy relay switch setup plus the gauges.  Bill's and others sell those guage setups.  We been running Murphy products on farm irrigation engines for years and farm equipment, oil equipment, trucks.  On industrial engines unattended Murphy make all kinds of level gauges and other systems too.  Today FW Murphy makes all kind of new digital gauge setups too. 

http://www.fwmurphy.com/

Murphy mechanical gauges

http://www.fwmurphy.com/gages_mech_pressure/

http://www.fwmurphy.com/gages_mech_temperature/

http://www.fwmurphy.com/panel_mech/
- - By Sberry (***) Date 10-16-2010 14:38
This pic was on an old pumping unit and includes pump pressure. I even use them on tractors, had one save an engine a while back, just a freak deal where I had a greenhorn operator and engine failure. Have even built other alarms with them.
Attachment: Murphy.JPG (0B)
Parent - By 65 Pipeliner (**) Date 10-17-2010 23:31
Murphy switches have saved me several times. A couple from overheating and once from low oil pressure. I have a temperature switch listed on here for sale. They are easy to wire in and can save alot of money and headache.

Chris
Up Topic Welding Industry / General Welding Discussion / Murphy Switch?

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