Has anyone tested out the viability of using hooks to lift totes?

We were thinking about using some sort of belt/hook system to manage totes- the totes would be lifted via small hooks which would hook onto the lips of the totes (each set of hooks would only support one tote).

We’re currently debating this vs another idea, and I was wondering if anyone here had already conceived of / prototyped this idea. I myself really dont like having to rely on hooks to lift these things (especially if they only hook into one edge of the tote), but I’d really like to see if you guys have any evidence to indicate that my fears are misplaced

Several of the Robot in 3 Days teams have posted prototypes of this method of lifting totes and containers.

I think if you explore team 842’s web page, you might find a short video. I’m not going to the effort to find the link again, that’s up to you…but they have so many neat things on the web, that it’s worth spending some time searching for it. The wrong turns can be rewarding, too.

Our team has been prototyping a system using hooks on a chain system. We have been able to hold onto the totes despite violent shaking of the mechanism. It works better when you hook onto the long side of the tote.

How many totes can you guys stack/hold? Our mentor has said that we could at maximum stack four totes with this mechanism (something about needing a space in between each tote), but I’m not sure that this is a constraint that other teams haven’t overcome

We’re thinking about this and figure atleast 5 totes, maybe 6 with this system. If your mentor is thinking 4, it’s probably because he figures the crates will hang down thanks to the handle location and sloped sides. Then you have to lift each crate higher to fit the next one underneath. There’s no good reason you have to let the crates hang down, though. If you’re putting a bunch of hooks on a chain, add a (wide) bumper below each hook to level out each crate. Or a bigger bumper to tilt them up, even.

I agree with your mentor. You need to leave enough space between the totes so you can align the hooks with the next one underneath. This occurs because the totes tip slightly forward and are angled so they take up sightly more space vertically. We haven’t thought of a way around this yet. In theory, we should be able to cary 3-4 totes and a recycling container on top. Without a recycling container, we might be able to carry 5 totes.

How does one get a hook onto a chain without welding it? Dumb question 1000 for the day:D

If your hook is never going to go over a sprocket, you can bolt through the chain.

Otherwise, you might investigate something like http://www.mcmaster.com/#roller-chain-attachments/=vd6xnc

I’d consider using belts instead. We’very found some 1.5 inch thick industrial belts which would be plenty strong, I can send you the link if you want

#8 bolts will go through #35 chain and #4 bolts will go through #25 chain.

I would say there is no limit to ho many totes you can lift with hooks within reason.

That is if you are concerned about the strength of the hooks or lips of the totes.
The GreenHorns Hook Mechanism

Is there a way to mount a hook on a timing belt so that it would be able to pass through a timing belt pulley?

A wide-spread reliance on hooks to lift the totes worries me. I wonder about the ability of the box lips to stand up to match after match without damage.

During Ri3D with our hook mechanism we intentionally beat up the totes by adding a bunch of weight to them and driving around. No this isn’t the same as a regional event, but I would say there shouldn’t be a great concern over the durability of the totes. Ours were just fine.

my team has been toying with the idea, today we made a prototype and it worked pretty well

Conceivably, you could pocket the pulley (or sprocket, if using chain, for that matter) where the hardware that’s attaching your hooks would interfere.

That is – provided that all of your pulleys were an even tooth count – the link or section of belt with the hook attached will always mate with the same tooth when it arrives at the pulley. So, you could remove that tooth and create clearance for the hardware.

If you were to take the chain or belt off, you’d have to be very carefully when reassembling things to make sure the timing lines up the same way as it did initially.

Sure… it works great. We plan to use rollers (bearings) rolling along either side of a 1" square tube to do the guiding of the hooks. We prototyped this today and there’s no problems that we could see.

We laser cut our hooks from 1/4" baltic birch plywood, using a narrow 7/32" wide hook, and no breakage even when bouncing it in different directions.

Another option is to use a wide belt. You could then use two narrow pulleys with a spacer between them, teeth aligned of course, or use a wide pulley and cut a groove with a lathe down the center.

You could use double strand chain and drive 1 strand and mount hardware on the other.