Automatic hook clamps

[Rowan]

I was just reading a topic in the stage and rigging forum about the need to safety a chain bag. On the post, the discussion came up about lanterns needing secondary suspensions because a lot of the failures are due to loose hook clamps. Somebody else mentioned something about chain bags having snap hooks to lock them in, and this whole discussion got me thinking.

 

Has anybody seen or heard of an automatic hookclamp? I'm thinking something similar to the spring loaded scaffold hooks that riggers use, that automatically clips to the bar as it is pushed onto it, although not necessarily holding it tightly. I know that you can get the trigger clamps, but they still require you to do them up in order to stop the lamp falling.

Noise boys use some clamps that use the weight of the item to hold the clamp locked as well as a screw, but if somebody were to forget the screw, and the clamp became unloaded (eg by some scenery catching) the clamp would fail.

 

sorry it's quite a random post, but I'm on the look out for the thing that will make me rich, just wondering if this is it!!

[Nicktaylor]

Nice idea. But if you are planning to get rich, dont put your idea on a public forum!

 

Now where is that patents office address! :)

[Rowan]

was aware of that, but I'm actually far too lazy to ever do anything about making it. just thinking from a safety point of view!

[eviljohn2]

Isn't it a bit like putting a carabiner on the end of the safety chain to choke it onto something? <_<

[Ike]

Noise boys use some clamps that use the weight of the item to hold the clamp locked as well as a screw, but if somebody were to forget the screw, and the clamp became unloaded (eg by some scenery catching) the clamp would fail.

So do lighting...we call them hook clamps!

 

It seems to me like it would be a case of reinventing the wheel. Hook clamps work, and work well at that. If you can't remember to tighten a clamp up a second or two after you hook it over the bar then are you really competent to rig the lantern in the first place?

 

In my personal experience the majority of accidents when the secondary suspension has come into play have been due to flown items colliding, if the hook clamps hadn't twisted off the bars there would have been a greater chance of bits coming off the lanterns and hitting the deck/performers.

 

Even if you did do away with the need for secondary suspension via a new "super clamp" what would happen if the new clamps spring failed, it seized up or part of the mechanism was lost or damaged and it wasn't noticed at the time of rigging. Wouldn't this be a lot more prone to failure than a hook clamp that wasn't done up?

 

Sorry it wasn't ment to be as much of a rant as it turned out to be :huh:

[greenalien]

Now that they are available at a reasonable price - around a fiver each if you bulk-buy - give me half-couplers over hook clamps any day. They are much more secure, smoother to adjust, have a HSE friendly '500kg max load' label and don't put marks on the truss. There are also 2-part versions available that lock together automatically if you don't mind paying the extra cost.

[robloxley]

Give me trigger clamps over half-couplers most days though!

[Chris_R]

Has anybody seen or heard of an automatic hookclamp?

 

Do you mean something like this?

[Rowan]

Has anybody seen or heard of an automatic hookclamp?

 

Do you mean something like this?

 

Not really, you still have to physically do something over putting the light on the bar to make it safe.

 

Granted, yes a hook clamp does use the weight of the item to keep it on the bar, but the ones the noise boys use actually tighten themselves round the bar.

 

I don't think it's an unreasonable, how many times have you been focusing a rig only for the proddy LX to shout down "hold on whilst I tighten this hook clamp." In flying houses it's common to rig all of the lights loosely on a bar, get the spacing and then tighten them all down once they are in the correct place. It only takes one of them to be missed.

 

Rob, I agree yes, trigger clamps are great in certain circumstances, but they still require a second action after the lantern has been placed on the bar before they become safe

[TomLyall]

I don't think it's an unreasonable, how many times have you been focusing a rig only for the proddy LX to shout down "hold on whilst I tighten this hook clamp." In flying houses it's common to rig all of the lights loosely on a bar, get the spacing and then tighten them all down once they are in the correct place. It only takes one of them to be missed.

 

...but they still require a second action after the lantern has been placed on the bar before they become safe

Being able to move a lantern once it's on the bar is an advantage of a non-automatic clamp! Yes, they can be missed, but you should have really put the safety on as soon as you've hung it on the bar, whether you've focused and tightened it or not.

 

Tom