Auto control of winch to lower a table down and then back up again in one continuous winch movement. Change of direction occurs when the cable is full

sghioto

Joined Dec 31, 2017
5,376
Can you provide a short explanation?
I'll try.
First, the schematic is shown in standby with the table at the top.
When S1 is closed C2 which is charged to the supply voltage discharges through the SET coil and activates K1.
Contact K1B closes and connects to RL1 which starts the table Down and closes upper limit switch 2 followed by opening upper limit switch 1.
Upper limit switch 1 is there to remove S1 from the circuit when the table starts Down.
Table continues Down until Lower limit switch is open. Pressing S2 reactivates RL1 and the motor continues to run in the same direction as K1B is still activated until it reaches upper limit switch 2 and 1.
The next press of S1 will allow C1 to discharge through the RESET coil of K1 and close the circuit for RL2 which reverses the motor direction.
C3, C4 and R5 provide a short delay to prevent both relays from trying to activate when S1 is closed.
S1 and S2 need to be held closed until the mechanism has closed the require limit switch.
RL1 and RL2 rated for 1/2 supply voltage.
Values shown in the K1 circuit based on 24 volt relay KRT424F-24.
There is a small constant current drain in the K1 circuit.
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