| Author |
Message |
Jack Conrad (Jackconrad)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, March 08, 2005 - 3:57 pm: | |
I need to install a solenoid in my pick up to control the air supply for the tow braking system I am building. I have a few 24 volt solenoids and I tried one on the 12 volt system, it works. Here is my question: What will be the long term effect , if any, be on the solenoid. I recall that when voltage is reduced, amps increase. Will this be detrimental to the coil in the sloenoid? Thanks in advance, Jack |
gillig-dan
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, March 08, 2005 - 4:04 pm: | |
Actually, the amps would decrease also. The problem I see, especially with a critical braking system, is that the solenoid would not hold as well. It could cause intermittent operation.... or, not?
Gillig-Dan |
TWODOGS (Twodogs)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, March 08, 2005 - 4:14 pm: | |
12 volt ford starter solenoid..junk yard..farm supply..cheap (???) |
Sean Welsh (Sean)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, March 08, 2005 - 4:51 pm: | |
Jack,
If we're talking about braking systems, I wouldn't take the risk...
The coil won't be hurt, but the magnetic field that causes the solenoid to work will be much weaker -- less than half as strong. The core that the field pulls against to open (or close) the solenoid may appear to work in dry tests, but due to the much weaker operating force, the valve may open(close) under pressure, or even when jostled going over a bump.
Most air solenoids have interchangeable coils -- you might see if a 12 volt coil is available for your unit, either from the manufacturer, or on eBay (where I have found quite a number of these type of items).
HTH
-Sean |
Jack Conrad (Jackconrad)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, March 08, 2005 - 5:37 pm: | |
Thanks guys. Actually, I did a driving test, energizing the solenoid when I let off the gas at about 40 MPH. I have the pressure regulated to 25 PSI and it brought me to a smooth full stop.
I will check ebay for a 12 volt model,or replacement coil. Jack |
jimmci9 #2
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, March 08, 2005 - 7:30 pm: | |
the ford type 2d mentions is $7. at o'reillys... lifetime warranty is $13.... i just bought 5 for a project... |
TWODOGS (Twodogs)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, March 08, 2005 - 7:31 pm: | |
yeah....wonder why he ignored my post....I must have B.O. |
Sean Welsh (Sean)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, March 08, 2005 - 7:41 pm: | |
2D/jim
He's talking, I think, about an air solenoid, not an electric one.
-Sean |
TWODOGS (Twodogs)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, March 08, 2005 - 7:42 pm: | |
OOOHHHHHH |
Jeff Pritchard (Jeffpritchard)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, March 08, 2005 - 9:36 pm: | |
" I recall that when voltage is reduced, amps increase. "
Finally something I know about!
Jack, your quote above is absolutely true, for a completely different situation.
In your situation, think of the tired old analogy of voltage as pressure. Your 24 volt solenoid is designed to let enough current flow to actuate it when there is 24 volts pushing the current through. When you hook it up to 12 volts, the solenoid is still putting up just as much of a fight (resistance) to letting current go through but there is half as much pressure, so half as much current. (and a lot less electromagnetism)
As the other posters said, your solenoid in it's present state of repair and with the air pressure you're using is working, but as it wears out, or if a higher air pressure requires more electromagnetism to actuate it, then it might not. In short, you got lucky but your luck could run out.
As for your quote, I think you got that from a discussion of Inverters. Two otherwise identical inverter setups powering the same sort of AC equipment, the one with the lower DC voltage would have to supply more DC current to the inverter to supply the same amout of power at the output. Its completely different simply because you've got active circuitry in the inverter that is going to suck as much current as it needs from the DC source in order to supply the needed output power.
Hope this made it less confusing rather than more so.
jp |
jimmci9 #2
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, March 08, 2005 - 9:43 pm: | |
ww grainger has electrically operated air (or gas) solenoids.... so does womack power hydraulics.... google search for either....also the little electric over air valve that controls most horton air clutch-type fans.... |
John Jewett (Jayjay)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, March 08, 2005 - 9:47 pm: | |
Jack, the only caveat I would put forth is to be certain that the solenoid you buy is rated for "continuous" duty. Some are rated for "intermittent" use only. Cheers...JJ |
CoryDaneRTS
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, March 08, 2005 - 11:30 pm: | |
JP
If you know as much as I think you do, you are simplifing the theory to a fault.
There is no easy answer when dealing in volts, AC or DC and resistance with the added encomberance of load.
Your explanation is very light, which would be adequate for this moment but highly lacking for any actual use.
As the resistance of the coil does not change, the current should increase, however, with the magnatism and core probably absorbing the flux and allowing less movement, it is feasable that the current will be higher than double, lessening only if the flux from the electro magnet gets smaller. That, of course, can only happen at full travel of the core.
It gets more absure the higher the voltage you are working with. We used to deal with transmission voltages where 345,000v were common. The effects on the transmission lines and at the transformers can make for an interesting formula....
cd |
CoryDaneRTS
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, March 08, 2005 - 11:33 pm: | |
JP
If you know as much as I think you do, you are simplifing the theory to a fault.
There is no easy answer when dealing in volts, AC or DC and resistance with the added encomberance of load.
Your explanation is very light, which would be adequate for this moment but highly lacking for any actual use.
As the resistance of the coil does not change, the current should increase, however, with the magnatism and core probably absorbing the flux and allowing less movement because the "force" of the flux is less, it is feasable that the current will be higher than double, lessening only if the flux from the electro magnet gets smaller. That, of course, can only happen at full travel of the core. You really can't tell without taking measurements, all else is a calculated guess.
It gets more absure the higher the voltage you are working with. We used to deal with transmission voltages where 345,000v were common. The effects on the transmission lines and at the transformers can make for an interesting formula....
cd |
gillig-dan
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, March 09, 2005 - 9:11 am: | |
I have to respectfully disagree Cory. We are talking about DC here. Yes, there will be a rise time for the current to reach maximum but, the DC resistance of the coil will determine the final current value. The coil will go to full current in a blink of an eye, depending on the inductance value (number of turns) and the circuit resistance (very low in this case).
I would like to see your final set-up posted here Jack. Sound like something I might want to cobble together also.
Gillig-Dan |
Richard Bowyer (Drivingmisslazy)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, March 09, 2005 - 11:02 am: | |
Cory, I also have to respectfully disagree. This is a DC circuit and the current is directly proportional to the applied voltage. The lower the voltage, the lower the current and vice-versa. At least that is my opinion. LOL
Richard |
Sojourner (Jjimage)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, March 09, 2005 - 12:34 pm: | |
To my friend Jack;
Check good old “Lou’s Paint Spot” in Arcadia where they modify school bus into orange picker’s truck.
Some air brake bus have 12v solenoid valve. Usually for free if they have any.
About "I recall that when voltage is reduced, amps increase”.
12v coil use twice the wire size of circle (dia.) surface area wire then 24v for equal watts.
Or 24v coil is twice the resistant than 12v to for same wattage.
Volt x Amp = Watt
Ohm’s law calculator http://www.csgnetwork.com/ohmslaw2.html
Or http://www.the12volt.com/ohm/ohmslaw.asp
Like others post said, it won’t hurt coil but weak magnetic field. However if armature doesn’t fully engage into coil or magnetic field, it will heat up quicker or otherwise be cool warm.
Replace with a continuous duty (almost all are 100%) 12v dc coil for your solenoid.
All air or water solenoid units have replacement coil available in any volts either AC & DC.
Need model & brand information or take your unit to most any industrial supply such as Grainger.
Or buy the whole solenoid to meet your need.
FWIW
Sojourn for Christ, Jerry |
Jack Conrad (Jackconrad)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, March 09, 2005 - 4:33 pm: | |
Ok,here's the plan.
I installed an air tank I had laying around in my shop (10" diameterX18" long). I mounted it to the frame under the truck. I fabricated a bracket that I installed under the drivers seat. I made an air cylinder mount out of square tubing that slides into the bracker under the seat. I installed an air cylinder (7/8" boreX 12" stroke) on this mount. The other end of the air cylinder attaches to a bracket on the brake pedal.
The air line from the tank goes to a pressure regulator and then to a 24 volt solenoid (skinner valve). From the skinner valve, the air line is connected to the cylinder via a standard air quick connect fitting.
Power to the solenoid comes from the brake light circuit. Power also will come from truck battery through a breakaway switch to the solenoid.
Air pressure will be supplied be a 12 volt compresor (yet to be installed). In addition to providing air for the brake system, this will allow a set of air horns as well as an air supply for airing up tires, etc.
System was tested by charging air tank from my shop air and going for a test drive,activating the solenoid to test brake function. (Brake booster vacumn line was disconnected and plugged to compensate for no power assist when towing)
I plan to connect truck batteries to house batteries when driving to keep truck battery charged (compressor will run off truck battery).
System will be monitored in bus by installing a pressure sender in the line from the solenoid to the air cylinder. This will activate a light when air cylinder is activated.
This system will allow breakaway braking and in case of a air line failure, bus air is not comprised. One 7 conductor RV plug and breakaway cable are all that has to be connected.
All comments and questions welcomed. Jack |
CoryDaneRTS
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, March 10, 2005 - 2:05 am: | |
Not a problem guys
All that is important is that the end solution works satisfactorily and is safe for the intended work.
AC and DC are similar, only different.
Loads also are simiar and act similarly. BOTH AC and DC have distinct differences in operation. An explanation can be interesting of operation or theory.
Then again, what in this hobby Does'nt have its own interesting peculiarities.
cd |
Buswarrior (Buswarrior)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, March 10, 2005 - 10:42 pm: | |
Hello Jack.
I sure do like your plan!!!
I'm thinking you'd want a way of indicating low air in the truck air tank, and confirming a proper release of the brakes while underway so you don't burn the truck brakes out if something sticks.
Using one of those security system magnetic proximity switches on the air cylinder, set up to be together for the released position would let you know that the arm moved from rest, and returned... answering both questions in the moment, but you'd want to know about low air before you needed to stop....
How about: Use the same circuit, a low air pressure switch makes a dash light go on, and the proximity switch on the movement of the air cylinder makes the light go on. Depending on what you are doing, the light means trouble, or the light means proper operation? Low air, and the cylinder not at release would both be "light on" conditions while driving. Cylinder not at released position while braking is a "light on" condition and a good thing.
Going one step further, using the existing brake light pressure switch in the coach brake system, you could rig a relay to make a buzzer go off with "light on" without a coach brake application, stay silent when everything is working properly under braking, and another relay could get it to alarm if there was no cylinder movement under braking.
A bit of trickery required to have enough delay to prevent buzzer chirps in the transitions, but fun to goof with the ideas!
Hmmm, maybe we should patent this process?
happy coaching!
buswarrior |
gary b. turner (Garbs2)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, April 06, 2005 - 7:48 am: | |
Contact our customer service at the number below, with the valve part
number and inquire.
Parker Hannifin Corporation
Fluid Control Division (Skinner Valve)
95 Edgewood Ave
New Britain, CT 06051
Tel: (860) 827-2300
Fax: (860) 827-2384
ask they will give you dealer where to buy one |
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