Near Intersection of I-35 & I-90 Southern Mn. | franks - 3/11/2019 09:06
It is a switch that changes direction in the terex loader. its not a momentary switch it is a constant ON-OFF-ON. it just powers two different solenoids and we think a standard spdt will work as we have energized the solenoids manually to make things work. i am also unsure what the 4th wire is for. it is not a lighted switch but there are directional lights in the dash. terex cant replace just the switch but will replace the whole joystick for $2800, so we are trying to avoid that. trying to find the exact switch is like trying to find a needle in a haystack. I would say 18ga wire.
Apparently you have gotten the machine to move by jumping the solenoids. I think you are saying that by jumping one solenoid, the machine moves forward. Jumping the other solenoid causes the machine to move backwards and otherwise the machine is stopped. If such is the case then I would agree that a Single Pole Double Throw switch with Center OFF should work.
I'm trying to visualize what the fourth wire might be used for. You say there are directional lights in the dash. When you jump the solenoid to make the machine move forward does the correct directional light come ON and then go OFF when you remove the jumper? I would think those lights should just be wired in parallel with the solenoid to inform you if one is active.
Now that I read the other post about a neutral safety starting switch that would make sense to me. Are you able to start the engine with the switch removed?
If starting the engine is part of the purpose of the switch then it may be what I would think of as a 3 position switch. Front Down => 12V to run one solenoid to move forward. Back Down => 12V to run the other solenoid to move backward, Switch in the Middle => 12V to fourth wire which is involved with the starting circuit. This would prevent the starter from engaging unless the switch is in the Neutral position.
If the switch is a 3 position type with the center used for neutral starting, it might be difficult to find an exact match. At that point I would think you would have the option of bypassing the neutral starting switch and just using a more common SPDT ON-OFF-ON for direction. This would defeat the neutral safety starting feature which may not be wise.
Not knowing the machine, I'm thinking that maybe a separate momentary switch could be installed in this safety circuit. This would require the operator to hold down this new switch while they engaged the starter. This wouldn't completely prevent "starting in gear" but might prevent some accidents.
Here's another more elaborate scheme that I think would work, but you might not feel it's worth the effort. It wouldn't really cost all that much and would only work if my other assumptions are correct.
This involves using two 12V SPDT relays. SPDT relays have 5 terminals. Two for the coil as well as a Common, a N.O. and a N.C. terminal for the output The common is connected to the N.C. terminal until the relay is activated, then the common is connected to the N.O. terminal.
Wire one coil terminal to the Forward solenoid. Wire one coil terminal of the other relay to the Reverse solenoid. Wire the remaining coil terminal on each relay to ground. This means that one relay will be active when the Forward solenoid is engaged. The other relay will be active when the Reverse solenoid is engaged. Neither relay will be activated in Neutral.
Wire the common and N.C. output terminals of the two relays in series with the neutral start circuit. There would be no connections to the N.O. terminals of the relays.
To do this, run the neutral safety starting circuit to the common terminal of one relay, connect the N.C terminal of that relay to the common terminal of the other relay. Connect the N.C. terminal of that relay to the starting circuit. This means the starting circuit passes through the outputs of both relays.
Let's analyze what happens. If the vehicle is in either Forward or Reverse, the corresponding solenoid AND relay become active. This would break the start circuit and prevent starting. If the vehicle direction switch is in Neutral, both relays would be relaxed which would allow the neutral start circuit to be complete. The starter circuit should engage when the key or normal start button is used.
Edited by tedbear 3/12/2019 08:30
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rocker switch
