Need help regarding a Simple Goods Lift.

Discussion in 'The Projects Forum' started by nsc2, Oct 4, 2007.

  1. nsc2

    Thread Starter New Member

    Oct 4, 2007
    1
    0
    I want to install a "goods lift" in my premises with the following specs.

    Levels: G + 2: 1st @ 10 ft., 2nd @ 18 ft.
    I have a 1.5 HP 900 rpm motor and a matching gearbox which will be mounted at top and a platform suspended by wire rope will be used to shift goods up and down.

    My requirement is:
    >a electronic or a electromechanical control system design for the elevator wherein we can press a button to send the goods at the desired level.

    >an emergency stop button.

    >limit switches at the top and bottom

    Any help in this regard will highly appreciated..

    Thanks,
     
  2. cumesoftware

    Senior Member

    Apr 27, 2007
    1,330
    10
    Well, I had a project for a dumbwaiter that used relay logic, but only had two floor stops.
     
  3. thingmaker3

    Retired Moderator

    May 16, 2005
    5,072
    6
    You'll need some kind of sensor suite to determine where the dumbwaiter is at. A microproccessor of some kind would be in order.
     
  4. cumesoftware

    Senior Member

    Apr 27, 2007
    1,330
    10
    You can use limit swicthes at the top and bottom to sense the presence of the lift in those floors. That is common to most lifts, dumbwaiters and so, and it is also mandatory. For the rest of the floors, a reed switch as counter is often used. If you have a three phase motor you have to take into account phase (and movement) reversal. So you need two extra limit switches that will stop inconditionally the lift case it exceeds its trajectory (which can be caused not just by a phase reversal, but also by a locked relay). For the middle floors a reed swich attached to the car will count magnets, each magnet in its floor.

    So you will have:
    Upper limit switch (once contacted, the lift wont go up or down/cuts power to the motor);
    Top floor limit switch (once contacted, the lift won't go up, but can go down/in case of movement reversal the lift will go up but not down, hence the upper limit switch);
    Contactor and magnets to count floors in between - or in your case, since you have only one middle floor you can use another limit switch that will stop the lift if it is called to that floor;
    Bottom floor limit switch (once contacted, the lift won't go down, but can go up/in case of movement reversal the lift will go down but not up, hence the lower limit switch);
    Lower limit switch (once contacted, the lift wont go up or down/also cuts power to the motor).

    Limit switches are more reliable than other kind of sensors, and they can provide the necessary safety interlocks.
     
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