Hobbs switch alternative?

[Gary - K7GLD]

If a fella wanted to install something similar to a Hobbs switch - a switch that is used to trip a circuit at some pre-determined PSI, would a common oil pressure sensor as used in vehicle Idiot Light applications work? They are common, and relatively inexpensive...



I'm interested in such a switch to use in a fuel pressure alarm setup - but don't know at what PSI they are normally built to trip their circuit - I'd be looking for something that trips at 5 PSI or so - any suggestions?

 

[Philip]

Yes that type of switch will work. Go to a good parts store and they can set you up. The switchs can be had with different PSI points. Some of the one I have used have been 3,5,7,15 PSI models.



Most of those switches are a grounding type. Run power to your idiot light then run the ground to the switch.

 

[Gary - K7GLD]

Yes that type of switch will work. Go to a good parts store and they can set you up. The switchs can be had with different PSI points. Some of the one I have used have been 3,5,7,15 PSI models.



Most of those switches are a grounding type. Run power to your idiot light then run the ground to the switch.

Thanks Phillip - I see Ebay has a few offerings - I'll check at the local parts store - wonder if there's a specific engine brand/year to use for a specific PSI?



I sorta hate to walk in to the local NAPA store and ask for a "5 PSI idiot light oil sensor" - they're likely to make comments about the "Idiot" doing the asking... :-laf :-laf



BUT, I'll give it a try...

 

[rbattelle]

Oil pressure switch for any 3rd gen truck will work. They trip at 6psi. Runs $13 from the dealer, I believe.



On edit: on second thought, the threads are goofy on those switches. Something like M14x2 with an o-ring.



Ryan

 

[Philip]

Just go in and tell them you need a sending unit. 1/8" NPT thread that trips at 5 PSI and it needs to be a grounding type. They have books that list them by spec's instead of year models.

 

[Gary - K7GLD]

Just go in and tell them you need a sending unit. 1/8" NPT thread that trips at 5 PSI and it needs to be a grounding type. They have books that list them by spec's instead of year models.

GREAT! Thanks again.

 

[nickleinonen]

On edit: on second thought, the threads are goofy on those switches. Something like M14x2 with an o-ring.



Ryan

m14x1. 5...



an oil pressure switch should work ok. hobbs switches have some advantages, as you can get ones that are NO and NC on the same switch, and can be fine tuned pressure wise by removing the rubber cap and tightening/loostening the allen key set screw to get your ideal pressure trip [i have some 15 and 25 psi ones, and can easially adjust up/down 5 psi on the switches]

 

[Bob4x4]

Thanks Phillip - I see Ebay has a few offerings - I'll check at the local parts store - wonder if there's a specific engine brand/year to use for a specific PSI?



I sorta hate to walk in to the local NAPA store and ask for a "5 PSI idiot light oil sensor" - they're likely to make comments about the "Idiot" doing the asking... :-laf :-laf



BUT, I'll give it a try...

Napa does have them listed by psi... ... ... . no big deal



Bob

 

[Gary - K7GLD]

Lots of good info - and excellent alternatives - thanks!



Looks like I scored a new 3-7 PSI Hobbs from the internet for $20 - they DO have some advantages, but if this doesn't come off as planned, the oil pressure switch will be my next approach.

 

[PToombs]

Gary, try Surplus Center. They have all kinds of switches, Hobbs, pressure, vacuum, etc. Really cheap prices too! Not to mention mower transaxles, motors, gearboxes, engines, winches, contactors, gauges, the list goes on and on!

 

[Gary - K7GLD]

Gary, try Surplus Center. They have all kinds of switches, Hobbs, pressure, vacuum, etc. Really cheap prices too! Not to mention mower transaxles, motors, gearboxes, engines, winches, contactors, gauges, the list goes on and on!

Do they have a website Pete?

 

[Philip]

Here you go Gary



http://www.surpluscenter.com/

 

[PToombs]

Thanks Philip!

Sorry Gary, I should have linked it on the other post!

 

[Philip]

Yea we know Pete you had a senior moment. :-laf :-laf

 

[DieselTweaker]

McMaster Carr



the have a few pieces that would work.