Modifying Hoist Remote: 120V Rocker Switches, Gate Interlock, Limit & Emergency Stop

Hi guys,

I am new to this forum and seeking your help. Interfacing with hoist remote wrings I like accomplish following changes to hoist remote:

Replace the up and down toggle switch that came with hoist following:
1 - Disable up and down functionality if the gate is not closed
2 - Control up and down functionality of the hoist by three separate 120V Rocker Lit switches ( one for location)
3 - Add an emergency stop switch for each location
4 - Adding limiting switches to stop up or down movement of the motor at predefined point
5 - Use the 120V for components requiredThanks in advance, please see attached the circuit diagram.

Jamal - you will note that the black (active) wire goes straight to the up/down switch.  So if you interrupt that wire, the hoist will not operate.  If you interpose 4 normally closed switches as in the diagram below in the black wire (3 emergency stops plus one gate switch) this will do what you want.  If there are long distances involved, you could have these switches operating a relay which connects the black wire to the up/down switch.  You could include the limiting switches in this loop.  However it would be better to go a bit more complicated and have indicators for each of the cutoff conditions  (Gate/ top limit / bottom limit / emergency stop).
To have up/down switches at three remote locations, I would use 2 relays operated by the remote switches in place of the existing up/down switch.  You can get 3- or 4-pole relays and use one contact of each relay to remove power from the other relay so that once one is operated, the other cannot be, even if two opposing switches are pressed.
You are dealing with mains power here which can be lethal.  You should have these modifications designed and installed by electrical switchgear technicians, unless you are qualified you should not try this yourself.This would be a nice project for a PLC (Programmable Logic Controller) - you would be much more versatile in what you could do and the indication of the status of the hoist.  A PLC would also let you run your user switching at a lower and safer voltage (usually 24V DC).  But it would involve a bit more expense which may not be warranted.Hope this helps / regards // David

Thanks DavidI am not too sure  how to connect the two relays  as you suggest. Could show it to me on  diagram?Also if I were to redesign the project with requirements below how would the schematic change1. One Up switch inside the lift to move the lift from main to 2nd floor2. Down switch inside the lift to move the lift from 2nd floor to main floor3. One down switch outside the lift  to send the vacant lift to main floor4. One recall switch outside the lift on the second floor to recall the lift from main floor to second floor
Thanks Jamal

Jamal...thanks for the reply.  OK, if this is for a lift the requirements change a bit.  On a lift you want to press a button and the lift moves up or down to its end position, even after the button is released.  This does add a bit of complexity.  I can do this but am really busy at the moment so you may have to wait a few days.
I will use contactors, which are really high power relays.  You'd need two because there are very few relays that have a centre off position like your switch, so you have to use one for each side of the switch and (a) make them latch on a button press and (b) make them release once the end stop is reached.Have a think about how you would do this in the meantime.Cheers // David

Thanks David, That is cool any help would be appreciated.BTW I live CANADA and I like to use 120v all the way.
Cheers!
Jamal

Jamal - sorry for the delay, been busy.  Here you go.  I have shown the original colours of the remote control cable but you will also need access to the Neutral (white) wire of the incoming 3-core mains cable for this.  You will need to get 120V AC relays or contactors for this.
As soon as the UP button is pressed, the UP relay will operate and the first contact above it will operate, keeping power to that relay.  The relay will stay operated until the lift reaches its top limit and the limit switch will then remove power from the relay.  Similarly for the DOWN button.  Each relay gets is power from a contact on the opposite relay so while it is going up, pressing the down button will have no effect.Each relay will need an additional 2 contacts (can be normally open only) to simulate the original control switch.  These will need to be fairly beefy as they are supplying the motor.  you can get contactors with this kind of arrangement - high current main contacts and a set of lower current contacts for latching and switching.  I have shown colours for all connections.If you want emergency stop and gate switches, implement those as per my post above.This is pretty quick and dirty and may need some refinements, if you construct it be very careful when testing and maybe test without the motor first and with push buttons in place of the limit switches.  Take appropriate care or (if you are not electrically qualified) get an electrician to build and test this for you.
this is a bit small - if you'd like me to send you a larger version, give me your email address (use (at) and (dot) in it to avoid spammers picking it up)