2 floor dummy waiter elevator design

Thread Starter

jtomich77

Joined Apr 27, 2020
10
Hello group! I am new to electronic design. By trade I am a mechanical engineer and have limited knowledge on circuit design. I have a small project I am trying to figure out and hoping some of you might assist me on a basic layout. I am trying to help out a friend with an elderly mom who has currently a make-shift dummy waiter/elevator at her 2 story house. She uses it for groceries and other things. Its a very simple system, basically a switch connected to a winch style motor. Problem is second floor or first floor its on/off and have to hold the button until you think where it should stop.
I would like to build a simple system using relays to call the car on the second floor or first, stop where it should using limit switches. The winch system is 120v@20A unit. I was thinking to put all of it in a small enclosure then run wires to the first and second floor with its limit switches installed. Can someone layout a diagram for me on what to do exactly? I just don't know where to begin. I've done research but cannot find something like this.
 

MaxHeadRoom

Joined Jul 18, 2013
21,630
You need a limit switch at each floor for a start, The call PB (whatever floor) will latch in a relay to pick up the motor and unlatch when the dumb waiter hits the limit.
Also you need a dual contactor relay, for up/dwn.
Also do you need safety built in, such as a door or shutter to be closed before the D.W. moves?

Max.
 
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Thread Starter

jtomich77

Joined Apr 27, 2020
10
You need a limit switch at each floor for a start, The call PB (whatever floor) will latch in a relay to pick up the motor and unlatch when the dumb waiter hits the limit.
Also you need a dual contactor relay, for up/dwn.
Also do you need safety built in, such as a door or shutter to be closed before the D.W. moves?

Max.
No doors or shutters. Simple little platform up/down.
 

Thread Starter

jtomich77

Joined Apr 27, 2020
10
This is a 2 floor elevator design that I played with a while back. Thought project, but not tested. Seemed like it would work.
Seems close to what I am needing. I wouldn't need doors or lights. This is a small platform. Would I simply delete those features and everything is the same?
 

Tonyr1084

Joined Sep 24, 2015
5,239
AC won't work for a simple reversible motor. DC will.

I only viewed this thread because I'm building a second floor on my garage for a wood shop workshop. I need a way to get materials up and projects down. I'm building a trolly and rail system to raise and lower stuff. I have an old garage door motor that is geared down. It's a 130 VDC motor. With further gear reduction it will be able to raise three 4' x 8' plywood 3/4 inch panels at a time. Finished projects will be lowered via the same trolly. Only, I don't need call buttons. Just two locations where I can run the trolly up or down. Yeah, holding the button is not a big deal, as I want to be able to stop mid way should something go wrong. Don't want the system destroying itself.
 

Thread Starter

jtomich77

Joined Apr 27, 2020
10
AC won't work for a simple reversible motor. DC will.

I only viewed this thread because I'm building a second floor on my garage for a wood shop workshop. I need a way to get materials up and projects down. I'm building a trolly and rail system to raise and lower stuff. I have an old garage door motor that is geared down. It's a 130 VDC motor. With further gear reduction it will be able to raise three 4' x 8' plywood 3/4 inch panels at a time. Finished projects will be lowered via the same trolly. Only, I don't need call buttons. Just two locations where I can run the trolly up or down. Yeah, holding the button is not a big deal, as I want to be able to stop mid way should something go wrong. Don't want the system destroying itself.
I use AC reversible solenoid relays all the time. DC can be more simplified of course.
 

Tonyr1084

Joined Sep 24, 2015
5,239
My maintenance team used these in the past. I am sure they're are plenty of other flavors out there. They also make solid-state units too besides mechanical.
https://www.sherburn.com/motor-reversing.html
Guess my comment was not as clear as I thought. I was referring to the motor. Those are reversing relays, probably meant for reversing motors of various types. Since I'm not highly experienced with motors I just assume AC motors (single phase) are uni-directional (CW or CCW depending on field orientation). Three phase AC motors ARE reversible by simply swapping two of the phases. If you're running a 3Ø motor then those relays may be useful (as far as I know).

Universal motors can run on AC or DC. But they always run in one direction. If you know how to reverse a single phase AC motor - please share. It's my opportunity to learn something.
 

MaxHeadRoom

Joined Jul 18, 2013
21,630
Universal motors can run on AC or DC. But they always run in one direction. If you know how to reverse a single phase AC motor - please share. It's my opportunity to learn something.
Universal motors can be simply reversed by swapping either the field or armature.
AC motor, depends on the technology, for e.g. for a shaded pole motor the rotor has to be swapped end for end!
In a capacitor start, there is the PSC, permanent start cap motor, where you simply swap the motor windings with a SPDT centre off switch.
For a cap start motor, you reverse the start or run winding connections.
Max.
 

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KMoffett

Joined Dec 19, 2007
2,909
From Post #1:
"Problem is second floor or first floor its on/off and have to hold the button until you think where it should stop."

Their motor must be reversible. Would be really helpful if we could get a wiring diagram of the current system.
 
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andrewmm

Joined Feb 25, 2011
658
suggestion.
get your self an Arduino, some leds and some switches, motors etc,
make a model of what you want to do, and control it from the Arduino.

Then, plan for the bigger system,

debuging the simple system is going to be a lot easier then the big one,
 

crutschow

Joined Mar 14, 2008
25,664
for a shaded pole motor the rotor has to be swapped end for end
I thought a shaded-pole motor rotation direction was determined by location of the shaded pole (shorted windings).
I don't see how swapping the rotor would affect that(?).
I believe you have to flip the stator.
 
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