Light Curtain for forklift pick up

OkiePC said:

I agree with this, except I think a light curtain is the correct device to use. I don't know of any fork-truck resistant mats, and a photo cell would need to be aligned carefully to ensure it always detected the leading edge of the truck (the forks which are likely to be in motion vertically).

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Yes, I guess I missed the part about the fork truck specifically.

I my mind, I was picturing the 'pusher' continuing to push bricks with a photo-eye on the last couple 'stations'. When the bricks get to the end that stops the pusher so the fork-truck can come in and grab it. After X seconds of the last station being clear, push the bricks over one station.

Now that I read, it does sound like the pusher just continues to push non-stop, so the process probably doesn't work the way I'm thinking.

Rson said:

Yes, I guess I missed the part about the fork truck specifically.

I my mind, I was picturing the 'pusher' continuing to push bricks with a photo-eye on the last couple 'stations'. When the bricks get to the end that stops the pusher so the fork-truck can come in and grab it. After X seconds of the last station being clear, push the bricks over one station.

Now that I read, it does sound like the pusher just continues to push non-stop, so the process probably doesn't work the way I'm thinking.

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Yes the pusher just pushes non stop when there is a cube in its area, after some LS are made and what not. There is nothing outside to STOP the cubes (electrically) There is a metal stop plate that prevents them from running off in to the concrete

GaryS said:

I think you are over engineering this it is not a safety device a light curtain is over kill.
If I understand this correctly all you are looking to do in to prevent the pusher from advancing when the lift truck is present.
Why not use a simple photo beam that get blocked when the lift truck is at the pickup point.
Beam blocked pusher, advance stopped. No muting, no reset of the curtain.
The only issue I can see if a person walking in front blocking the beam will pause the pusher if it is moving. There should not be any personal in that area anyway.
if mount the photo eye at an angle it will catch the lift truck
Keep it simple

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If it's not safety I will be notified. As the assessment has to be made before moving further.
I prefer a light curtain more points of contact with what ever is entering a zone.
Also there should not be any personnel there. But you have to make things dummy proof.

Just a few thoughts to through out there
If I understand it the term “Cube” to mean a pallet of bricks aprox 40” on each side containing many bricks. Each pallet would weight over 2,000 lb the pallet would be picked up from the end of the conveyor using a lift truck.
The pallets are pushed down the conveyor to the pickup point. There would be many full pallets on the conveyor at any given time so you could be pushing in excess of 10,000 lb. that’s a lot to push, are you sure you are using a pneumatic pusher. I would think you would use a hydraulic system for that much pressure.
A safety assessment should have been done on this conveyor a long time ago. The conveyor should at the very least be enclosed in a gated cage to prevent personnel from entering when the conveyor I in motion. If you were to get caught between the pallets when pusher moves it would cut your leg off. Guarding in this case is necessary on this type of conveyor a light curtain should be in place at the point where the lift truck enters to allow the lift truck to enter and pick up the pallet but prevent plant personal from entering without shutting down the pusher.
These guards and light curtains need to be manually reset only after it has been verified that the conveyor is clear.
You will still need to sense when a lift truck enters to pick up the pallet and mute the light curtain while the lift truck makes the pickup. This can be easily done with a single photo eye or a series of a few photo eyes placed to sense the presence of the lift truck. Or if you wanted to restrict the muting of the curtain to just a single flit truck then place a reflector on the truck and have a photo eye set up to look for the reflector and mute the curtain for just that truck.
No matter what you do, do a full safety assessment before you make any changes. Once you touch it you own it.