Momentary switches to reverse polarity?

[Jliddle]

This is a follow up thread to my latching circuit earlier this year. Which work s great.

The goal here is to take two momentary switches and reverse the motor direction of a center stand on a motorcycle.

Press one momentary switch and the stand folds down, press another and it folds up.

These switches are factory supplied auxiliary switches which I have located the signal wires within the harness. They use a molex connector on the back so I cannot alter how they are wired within the bikes harness. Everything will need to be seperate and just use the signal from the two momentary switches.

 

[ard]

Sure. Just build a motor control circuit that will work with the two momentary inputs....

What causes the motor to stop? Is there already some control circuit you are feeding? Or just a 12VDC (?) motor??

 

[nine4gmc]

Latching relays. You would probably need a timer or micro switch to disconnect them at full up/down though.

 

[matt_i]

Here's something to throw darts at.

You need relays with a couple different contacts. The basic "seal" circuits are there, the "up" is inhibited by the "down" and vice-versa, as mentioned above, you need a limit switch to signal the end of travel in both directions. A timer would not be my first recommendation as its "open loop" and the dynamics can yield an unfavorable result...

 

[Jliddle]

Guess I should've mentioned that the momentary switches are being held down for operation.

 

[matt_i]

Try again, we will...

 

[Jliddle]

Ok I got the jist of the circuit. Please forgive me but I'm not quite sure what the 40 and 50 labeled symbols mean.

 

[Z2V]

Relay coils.

 

[matt_i]

Yes, sorry, the round circle ---( )---- is the coil of a relay.

The --] [-- is a normally open contact which pulls closed when the coil is energized.

The --]/[-- is a normally closed contact which goes open when the coil is energized.

 

[ard]

OP-

what happens to the motor when it reaches the end of the travel? lets say someone hold the button down constantly.... any ill effects?

 

[AntonLargiader]

What you are describing is exactly the way electric windshields work (BMW, Yamaha, others). There are typically limit switches and two relays. Without the limit switch wiring you won't get a complete picture of the circuit.

BMW does a powered centerstand but it is done differently... and a bit better I think. Only powered in the 'lift' direction, with some safety interlocks. But it's heavy and more complicated.

 

[Milton Shaw]

Home trash compactors have switches that do reverse the motor. The way they work is the forward switch is active when the ram is all the way up. When you start the motor that switch sends the ram down and once the ram clears the switch it sets the motor to run in reverse. The reverse direction is not reached until the motor stalls out compressing the garbage, then the motor restarts in the reverse direction, going back up to the start position. It will also reverse any time the motor is switched off in the middle of the cycle as the reverse start winding is already connected waiting for the start switch to activate.

 

[Jliddle]

Yes, sorry, the round circle ---( )---- is the coil of a relay.

The --] [-- is a normally open contact which pulls closed when the coil is energized.

The --]/[-- is a normally closed contact which goes open when the coil is energized.

Ok I gotcha. I'm not familiar with a diagram like that is why I was asking. I'm still a little confused haha. I'm trying to interpret that drawing into a little more visual type.

OP-

what happens to the motor when it reaches the end of the travel? lets say someone hold the button down constantly.... any ill effects?

I believe the motor has a limit switch

 

[Jliddle]

I drew this up from a similar circuit online. Would it work?

 

[matt_i]

If my relay is numbered like those, I don't think it will work. The Bosch 30A relay in my hand has coil of 85...86 and the Normally open is 30...87. The Normally Closed is 30..87a.

The way I read that diagram, 86 is connected to the B+ and 85 is ground. So both of the relays coils are energized in 100% of the time....so in that state, 30 and 87 are always connected. Both of the motor terminals are being fed with +12vdc. I don't think the motor at right will run at 0vdc potential....

So to answer your question, I wouldn't wire it like that

 

[MikeF2316]

Scroll down to the power lock circuit. There are 2 3-way switches in parallel, your 2 switches will act like one of them. There are multiple motors, all in parallel, your circuit will just have one.

http://www.ohio.edu/people/ridgely/volvo_docs/documents/volvo_240__1987.pdf