Hi i have recently been given a few items two of which are in the title does anybody have any experience using the rocker as a fall arrest/self belay and anyone use the pro allp tech as a decender? I currently us the petzl stop but reading up on the P.A.T it seems a more gucci option?

The Rocker has been around for some time now. When it was first introduced it was hoped (by Troll anyway) that it would become the alternative rope access back-up device to the Petzl Shunt. Extensive testing was carried out by IRATA and the UK's HSE but it was concluded that it offered nothing better, in terms of safety, than the Shunt, other than conformance to an industrial EN standard, EN12841A, as opposed to EN567 for the Shunt (EN567 being a mountaineering standard for ascender devices).

Getting equipment to pass an EN standard test is one thing, whether it will work or not in the real world is something completely different. I carried out extensive testing on the device with a number of different test weights and found the device to be ineffective with anything other than the 100kg test weight as used for the Standard. Very worrying. The main issue with the device, or indeed any device that is either required to be towed down the rope or is free travelling and simply requires you to overtake the device to make it engage, is that you won't necessarily overtake it or, more likely, in the event of a fall you will simply, by way of a natural reaction, grab the device or grab the rope above the device rendering it ineffective. There have been at least 2 fatalities and numerous other very serious accidents in the rope access industry due to people grabbing the device in a fall and usually not letting go until they hit something on the way down.

The UK HSE in October 2014 stated at an IRATA Health & Safety Committee meeting that they would recommend against anyone using towed type back-up devices or indeed any devices which could be rendered ineffective if grabbed. From an industrial point of view there are really only the 2 x Petzl ASAP's which will work in any eventuality.

It was at this same meeting that the HSE talked about the most recent work at height accident they were investigating which involved two fully equipped fire fighters. They were doing a snatch type rescue, lost control of the descender and the Rocker simply slithered down the rope until they both hit the deck, both suffering serious lower leg fractures. The device was rated for rescue loads of up to 250kg.

IRATA, in its infinite wisdom, decided not to publish the comments made by the HSE in the meetings minutes, possibly because the Chairman (and minute taker) of the committee still uses Shunts in his operations.

The Pro Allp Tec was designed by Dave Allport (formally of Troll). Its primary use was for mountain rescue, particularly allowing a controlled descent with a horizontal stretcher by the attending barrow boy. A slow, constant descent rate can be set with the wing nut and if you need to get past an obstruction, e.g., an overhang, the handle can be deployed to speed up the process, reverting back to a controlled descent. The wing nut can also be set to allow the handle to be operated as a standard auto lock descender. They are actually very good for what they were designed for. They are a bit big and heavy for caving though.

Both the Rocker and the Pro Allp Tech are made by International Safety Components (ISC) in the UK.

I'd stick with your Stop.   

Mark

I'd also stick with your stop. If you don't like the jerky action of a stop and the sore hand on long pitches, get a rack to occasionally use.

Mark thankyou so much for your very in depth description completely spot on and answers all questions!!! 

Thanks Mr Kernow i havent tried a rack yet id like to give one a go though they are.meant to be quite nice. To be fair for what i do the stop will be sufficient. I also have an australian 2 way stop which is big and bulky but very smooth

Cartwright26 said:

Thanks Mr Kernow i havent tried a rack yet id like to give one a go though they are.meant to be quite nice. To be fair for what i do the stop will be sufficient. I also have an australian 2 way stop which is big and bulky but very smooth

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You are more than welcome to try my micro rack next time we play with ropes at DCRO.

I still prefer a J rack. When you whack a bar out on a long pitch, you can spread the bars, thus getting rid of enough friction to proceed!

I still use a stop for fiddling, but the rack gets used for everything else. Plus, if you've used one, you will know that if you let go of it, you will not plummet (unless you're on 9mm)

Or, instead of a rack, try the Petzl Simple.

Above ground, I've used the Rocker for a few things including self belay on climbs and found a few things:

Rope diameter massively affects how quick you stop
Weighting the rope helps it feed through
Choice of attachment carabiner (weight), lanyard, position on harness all make a big difference
Overhangs are best avoided

After using one, I'd never consider it suitable to back up two people. Mark, do you happen to know what diameter rope they were using?

The thing I liked mine for was not for going up the rope but down; when doing a climbing abseil having it on a lanyard on the same rope (above the belay device) I thought was a slick way to protect either going too fast and losing control, or dropping the dead rope due to rock fall or face planting. Much better than a prusik knot at least, which are so distracting that they probably make many abs more dangerous.

Underground, it works well on fat handlines which would not otherwise be protected, such as when you'd not normally carry SRT gear or there is a person in the group with less confidence on climbs.

I'm not 100% sure but its likely the recent accident happened on 11mm rope, certainly not smaller than 10.5mm.

One of the issues with the Rocker, and a Shunt for that matter,  is its inability to lock onto an already loaded rope.  Whilst putting tension in the rope below the device will make it run up and down the rope better, it is also likely that, in the event of a fall, it won't actually lock at all as the tension will prevent the Rocker actually Rocking and sunbsequently locking onto the rope.

Mark

That's interesting that it failed that badly on an 11mm. I often felt that the use of a 10.5mm rope was slightly pushing it, it had that same not quite right feeling like using a Stop on an 8mm rope, but I would have thought it solid at 11mm.

With weighting the rope, my recommendation was to add a kilo or so at the bottom, which would be likely smaller than the weight of the rope on a climb. I can see the reason for concern though. (Obviously it was also backed up by a different device, either a shunt or a basic on a separate line.)

Though it was a couple of years ago, I believe I recall the Rocker locking more consistently onto rope loaded with a few kilos. I think when there was little weight on the rope the rope could come into the device almost horizontally and feed through quite happily in a gentle curve without troubling the device (though not without troubling the user!). A bit like depicted in
http://blog.climbtools.eu/index.php?rex_img_type=leftright&rex_img_file=12_rocker_belastet.jpg
but with greater radii of curvature of the rope. Perhaps the stiffness of the rope could be a variable.

If there was a lot of loading on the rope, such as someone standing on the end, it would lock but then the elasticity of the rope would 'bounce' the device back to unlocked and you'd drop another couple of metres before the process repeated.

As for abseiling with a Rocker or Shunt on the rope (on a cowstail and above the abseil device), I never had any problem (on used 10.5mm) rope getting either to lock. An ab that was too rapid would simply cause the Rocker to move up the rope faster than it slipped down, load the cowstail and lock. With the shunt, letting go of the tow cord always caused an immediate stop.

Its quite possible that these observations mislead me as they weren't rigorously scientific. It's interesting and concerning though that people can have very different experiences of the same piece of kit.

10.5mm or 11mm, drop 250kg onto it and it'll be about 6mm for a short period. A short enough period though to stop the Rocker locking and starting the long slip down the rope. The testing we did on Shunts showed similar problems though with a smaller 200kg load. Dropping 200kg onto a Shunt attached 1m below the anchor with a 1m cow's tail at FF1 (excluding the 1m of rope to the anchor) will slip just over 8m before eventually coming to a halt.

All the testing done for the purposes of EN standards is with new rope so there could always be issues when using different rope diameters and taking account of the rope's condition, e.g. worn or wet. Some rope manufacturers go to some lengths to ensure their rope performs in a wide range of conditions, others don't. The stuff that has been widely field tested will generally be the most expensive. You get what you pay for.

After extensive field testing of the new DMM 'Catch' back-up device they recommend using a minimum 11mm rope due to its inconsistent performance on 10.5mm rope.

The main reason for tensioning the rope is to make upward progression safer as it stops loops being created above the device as you ascend. The Rocker is designed around many of the mobile fall arrestor devices on the market. The idea is to have the device attached via a very short link to a sternal harness attachment. Leaning backwards slightly as you descend, typically down a vertical ladder,  usually ensures it doesn't lock accidentally. 

There have been quite a few accidents involving Rockers being attached to the end of a cow's tail. On one occasion a technician was stood on the edge of a 20m high glass roof that sloped off to the vertical. He was about 2m from the edge with his Rocker on the end of a long cow's tail and actually dangling over the edge. Long story short, he slipped, the Rocker went whistling down the rope and he simply followed it down. Because he naturally reacted to the fall by grabbing the rope above the device it slowed his fall down sufficient that he never overtook the device and they both hit the floor. He was very lucky to survive though never with the 100% mobility he had before the accident.

The very fact there is a human action in the equation, e.g. will you or won't you grab the device or rope in a  fall, it will always be difficult to carry out realistic and above all scientific testing.

Mark 

The manufacturers seem to give the impression that sure, you might get a little bit of slipping when using a Shunt or a Rocker if you load it hard, but it'll lock soon afterwards and all will be fine. Guess that's not the case!

I've always resisted the saying of 'you get what you pay for' with safety gear, feeling that you get whatever the specs of the gear is. I think its time to change my attitude.

That example is both sad and particularly relevant for the idea of using a Rocker as extra (not replacement) protection on a handline. If you fall off a handline climb you could well still be holding the line and not accelerate (particularly with gloves on) fast enough to lock the Rocker. Hmm.

Thanks for the information.

You might find this report interesting. Its quite an old one and done before Petzl first introduced their ASAP device, which, when tested for every eventuality, passes all the tests with flying colours.

http://www.irata.org/pdf%20downloads/Back-up%20system%20Testing%20J%20Holan%20S%20Beason.pdf

Mark

tamarmole said:

You are more than welcome to try my micro rack next time we play with ropes at DCRO.

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Thanks Mr S

Having 'abseiled' recently on nothing more than a Petzl pulley, on a counterweight hauling system, I was compelled to take my ASAP underground for the first time, specifically as we needed a no-hands operation - and a reasonable chance of survival should one of the many potential hazards actually occur - falling off the rigid but muddy climbing ladders, and pulley or bucket failure being the main ones. I'm pleased to say it performed flawlessly even in a grotty environment, as I did jump off the ladder (near the bottom!) early on and later to test it. That was attached via a short lanyard of 11mm dynamic with some humungous barrel knots at each end, which was stiff enough to work but with plenty of bounce. I wasn't putting the Absorbica through that kind of punishment.

I carried out some Rocker tests a few years go at work for a customer.
The results were carried out in a proper testing environment and were interesting to say the least.
we used a 10.2mm rope and on some tests added a little tension as our customer wanted to work near power lines, so this would stop the loose end blowing around.
The result was the rocker worked fine till we added the tension, then it failed to work.
The reason is the action of the device - it has to put a slight bend in the rope to start the locking process and if the rope is tensioned enough the device is unable to kink the rope, so cannot start the locking process and so simply slides down with no noticeable slowing effect.
We then looked to see how little tension was required to achieve this effect, then measured the tension force and worked out how much weight of rope would create the same tension force.
In the case of the rope we were using it was approximately 60metres which could be achieved by having a long length below, or excess rope bagged up and hanging from the end to help the device run - which it certainly seemed to in every sense. 
The conclusion we came to was that this style of device is not ideal on tensioned ropes or where there is a long length below.
Don't forget CE marks and test standards are the minimum requirements for sale. They are not a quality stamp and do not necessarily prove fitness for purpose.
I suggest people use items for their main purpose and if innovating then invest some time to ensure they understand the potential consequences.