Electrical question for ya'll

NCWayne

Well-known Member
The Detroit that drives the bale buster I built last year has a heavy solenoid that's used to shut it down. The way it's designed the duty cycle on it is only something like 30 seconds before it over heats. The way I had to design it, the operator moves a lever, that hits a switch, to shut it down, and then moves the lever back to the start point. Basically it works the same way one of the mechanical shutdowns would but the lkever action hits a switch instead of moving a lever on the injection pump. That part works great, and hasn't been a problem. Instead the problem comes in with the safety shutdown part of the setup. What happens is the guys running it will hit one of the shutdown buttons, either intentionally (like when one lost a pitch fork and ran it through the baler), or they'll bump agaist one and shut it down accidentally. In either case they don't think to reset the button immediately after the engine shuts down. As a result they have already burned up two solenoids since the thing was put into operation. Both times could have been easily prevented, given a little thought, but you know how that goes with 'general labor' nowdays.

Ok, my dillema now is to get it rewired so no more solenoids get burned up. My thinking is to put it on a timer so the 'signal' from either the operator shutdown, or the emergency shutdown trips the timer and sends a timed 'signal' to the solenoid long enough to shut things down, but not long enough to burn it up. Basically the timer will need to close the contacts to the solenoid upon reciept of a signal and keep them closed for x amount of time. Once x amount of time elapses the timer will open the contacts to the solenoid and reset internally, regardless of wether the origional 'signal' goes away or not.

I've been looking at the various types of timers available, On delay, off delay, one shot, etc, etc, and I guess I'm missing something because as I read out the operation of each, none of them seem to operate the way I need it to. I know there are a few of ya'll on here that have done some electrical engineering work and I'm hoping one of ya'll might be able to enlighten me as to which one would work in this application. Too, it's a 12V DC setup. Grainger has some 12V timers but they are the only ones I've really been able to find that has them in the DC voltages. Any ideas of anywhere else that might have some rated at 12V DC as most others I have looked at are all AC rated?


Any help or ideas on another way to do this would be greatly appreciated.
 
You can buy CONTINUOUS DUTY 12 volt fairly high amperage solenoids like used in my RV. They look almost like the 12 VDC Ford type short duty starter solenoids but can take full time operation if needed.

You can also buy switching solenoids that only draw heavy current momentarily long enough to switch/latch between open or closed.

Sure some sort of timer will work, but Id look into continuous duty or switching solenoids as mentioned above.. theres also "delay relays"

John T
 
Safety systems are not to be activated by "power". A safety system is energized, pressurized, poised, springs tensioned etc . While the machine is in operation.
When power or pressure fails, then the shutdown system is supposed to operate via spring pressure or gravity.
Shut down should also be wired through a coolant temperature and oil pressure Murphy switch system.
 
Stole the words out of my mouth ... or is that fingers...

either way - I agree - the solenoid's over heating because it's not the right one for the job.

Get one with a higher current rating and that'll fix the problem.

Either that or the circuit itself is drawing more current than it should be for some reason - but that'd require much more info and diagnostics.

Assuming all is well in the circuit, I'd put in a bigger relay.
 
If you only use that circuit to shut down the engine, how about an oil pressure switch and a normally-open relay? When the oil pressure goes to zero, the circuit would be broken and the solenoid de-energized.
 
If the relay resets its self will the machine restart with no other input? You would not want that.
 
Those were my thoughts exactly.

Or there may be a #2 terminal on the alternator you could use the same way thru a relay. When it's running that terminal would be energiezed on the alternator but not energized when the engine is not running.
 
some good ideas here. if i'm following this right. you have the same set-up as early cummins 5.9 that had a solenoid with a pull link to move the arm on inj. pump. that one shuts down, & a few seconds later, you see the arm relax. however cummins is computer controlled.
 
Hey Wayne.

A latching relay takes the trigger voltage and stays closed until another input opens it.

You could easily wire a display light to signify that the relay is closed.

Available at grainger or other electronix outfits.

Brad
 
Is it possible to add a spring to the shutdown buttons that would make them reset itself? I have a shutdown button on my log splitter you have to keep pressed in until the engine stops. When you release it pops back out.
 
A glow plug relay may work. How long is needed to be absolutely sure that it will shut down? The biggest problem with this is that the engine could restart with the switch still in the off position, so it would have to be brought back to the on position and then back to the off position to shut it off. Not a big deal but given that people tend to not pay attention to the switch as it is, they won't have the safety shutoff. A Kubota part # for a 13 second relay is 36919-75212. Over $113.00 though, so it may not be worth it depending on the price of the solenoid.
 
Must have missed your post the first time around as this is actually a pretty good idea given the situation I'm working with. Thanks.
 
is there a ls tractor dealer near you ? most of the ls tractors (Mitsubishi engines)are shut down with a solenoid and use a timer , you will be off the tractor and walking away when you here it reset. just a thought.
 
Instead of push and latch emergency shut down buttons could you use momentary buttons (normally closed push to open?
If not, a latching relay that is normally closed and latches open would do the trick. Jim
 

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