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View Full Version : Rebuilding a failed pressure switch... ( Barksdale Series 9048)



Liger Zero
06-21-2010, 05:39 PM
http://www.barksdale.com/products/pressure/9048.htm

I'm working along today installing the Smell Blaster Advanced Stench Sucker at my friend's shop when the press came to a halt.

Bit of diagnostic work and he traced the problem to the switch mentioned above. He has (had) a spare, that is running the press now.

Apparently this switch turns pressure into an electrical impulse which the Allen Bradley interprets, without the switch the clamp can't cycle properly.


Being "that sort" of fellow I fished the "dead" one out of the bin and took it apart. Inside I found the following guts:

http://img.photobucket.com/albums/v469/Lizoid/BarksdaleSwitchRebuildTask.jpg

1 is where the oil pressure goes. There is a pin in here that moves with the oil pressure and pushes that lever inside the box. 2 is the adjuster, turning this puts more or less pressure on the other side of the lever 3 is the part that talks to the machine this sends the signal from that switch to the Allen Bradley. (I may have dumbed this down quite a bit, I don't know what the hell I'm talking about! :D)

When I opened it up it was FULL of oil... which is all over the newspapers on the kitchen table. Yes I am in trouble. ;)

Now first of all how does this thing work, and second can it be rebuilt. Email from friend tells me that it failed "no signal." That seems to indicate the switch is broken or oil-logged or something. :confused: Yes? No?

I am also thinking that it shouldn't have been full of oil like that... seems to indicate that part 1 may be the root cause of the failure.

DougA
06-21-2010, 06:50 PM
looks like a seal failure on part 1. What we professionals call a PSO (pressure squirting out). No pressure in the actuator so no push on the lever and no closing of the switch = no signal. Also why the box in full of oil. Maybe its actually a PSI (pressure squirting in).

MaxHeadRoom
06-21-2010, 06:57 PM
No1 it should not be full of oil!.
Switches in these type of sensors are usually Honeywell MicroSwitch, remove the two mounting screws and you can finger operate the switch and test with a meter if it operates, see if there is an identifying part # or make on it.
Should be easily replaceable if neccessary.
max.

TGTool
06-21-2010, 06:59 PM
http://img.photobucket.com/albums/v469/Lizoid/BarksdaleSwitchRebuildTask.jpg

<snip>

Now first of all how does this thing work, and second can it be rebuilt. Email from friend tells me that it failed "no signal." That seems to indicate the switch is broken or oil-logged or something. :confused: Yes? No?

I am also thinking that it shouldn't have been full of oil like that... seems to indicate that part 1 may be the root cause of the failure.

It looks pretty straightforward. There will be a small piston at the oil port. It pushes on one end of the crossbar against the adjustable spring held in the pocket at the other end of the bar. If the pressure is sufficient to compress the spring it moves the lever actuating the (probably standard) microswitch.

You can actuate the microswitch manually and check whether it's switching electrically. If kaput it can probably be replaced. Then check the seal on the piston as pointed out by others. It might well be a common O-ring and fix the oil leak. So you'll likely have a rebuilt switch at a fraction of the cost of a replacement.

Liger Zero
06-21-2010, 07:06 PM
. So you'll likely have a rebuilt switch at a fraction of the cost of a replacement.

That's the goal. I'll fix it for $40 then sell it back to him $800 plus "rush" processing fees.

Oh I should prob'ly strip the paint off and spray-paint it John Deer Green (extra glossy) so it looks new. :D


Kidding. I'll take it apart further after dinner... which for some reason tastes like Castrol. :o

darryl
06-22-2010, 01:35 AM
That looks like one of those microswitches that will go on and off with very little movement of the 'actuator pin'. That may or may not be important in that application, but other than that it's probably a fairly standard mcroswitch in the small size. The oil probably contaminated the switch.