Limit switches

Thread Starter

Haropas

Joined Aug 16, 2019
10
I have a linear actuator with built in limit switches on each end. But the actuator has more stroke length that i need.( And i cant open the actuator in order to change the place of one limit switch).

Can someone please send me a diagram of the wiring connection of this system?( I can connect them into the possitive and negative pole of the motor)

I want a limit switch acting as a limit switch stoping the power after the stroke hits it, and an other limit switch acting like a switch that reverse the polarity and makes the actuator going backwards. When it reaches all the way back the built in limit switch will cut the power .and again as i push the limit switch acting like a polarity changer the actuator will go forward and then again the limit switch that i put it will cut the power again .

I dont know if this is even possible ( i think it is ) but i tried a lot. Hope you understand at least something
 

BobTPH

Joined Jun 5, 2013
2,192
1. How are you changing direction? A bridge, a relay, a switch?

2. Please try again to explain the behavior. I cannot follow your description. You say the limit switch cuts the power, and then you say it reverses the direction.

Bob
 

Thread Starter

Haropas

Joined Aug 16, 2019
10
1. How are you changing direction? A bridge, a relay, a switch?

2. Please try again to explain the behavior. I cannot follow your description. You say the limit switch cuts the power, and then you say it reverses the direction.

Bob
Actually i need a button when i push it, the stroke will going right and when reaches the limit switch stops. And when i let go the button the stroke goes left and when reaches to the built in switch stops. And so on
 

crutschow

Joined Mar 14, 2008
24,047
Here are two approaches using relays to control the direction.

This uses a single DPDT relay but the motor current goes through the limit switches.

1581796779454.png

This uses two SPDP relays but only the relay coil current goes through the limit switches.

1581796561714.png
 
Last edited:
For good reliability it is best to not run the motor current through the limit switches. It does not matter what the printed label claims that the limit switches are rated for, motor starting inrush is always a lot more with normal motors. That is why a relay or two make much better sense. In addition, at least one of those circuits will constantly cycle as the motor gets reversed when the limit switch is released.
 

MaxHeadRoom

Joined Jul 18, 2013
19,671
I recall at least two industrial back gauges for a sheet metal benders that used the rectifier across the LS approach on their products,
They only operate momentarily until the motor drives off the limit.
Max..
 
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