APRL you tube video

[Darryl]

Jan 30, 2009

Hey all, there were a few members interested in understanding how the APRL works and is used. I made a video with a few details showing some of it's functions. I hope those who are interested get a better understanding of its functionality. You can find the video here:

http://www.youtube.com/watch?v=b3HNq1tCd4E

Just copy and paste.

Good luck,
Darryl

[Darryl]

Hey Bill,

Sorry for the confusion, I am referencing heavy loads carried straight down. With a VO hook, when I would carry loads down at my side, the cable would be pulled causing the hook to open. When doing this, If I would also be trying to grasp within the hook fingers, they would open losing that grasp. This would also cause all of the weight to be concetrated on the top straps only until the cable reached its max.

The point I was making with the three points of distribution, was this: With a VC hook like mine The cable is fitted to be at its max extension when it is closed. I keep mine closed at rest most of the time. I need to relax my extension to get it to open. So If I go to carry something heavy at my side, the cable will not lengthen because the hook is already closed and at its max extension. therefore I use the cable harness as one of the points of weight distribution when loads are straight down. So If I am trying to also grasp a heavy object as well as carry it, then the hook only gets tighter on the object. The same goes for items in front of me like a chisel or nail set. All I need to do is extend my arm or roll my back a bit to make the cable tighten and force the hook to become tighter on the object. I don't have to rely on rubberbands, and there is a type of feedback with what I call active force, versus inactive force relying on rubberbands.

When pulling on something, I also use the three points of distribution, and the tight cable and harness keep the pros from pulling off. The cable harness being below my arm increases the amount of pulling strength I have and therefore I am not only relying on the top strap on the tricept cuff. As for lifting in front with my arm, it is the same for me as it is for you, weight on the stump. I am also a LBE. I have about 6 or 7 inches from the tip of the elbow.
I hope that clears it up a bit.
Talk to you soon,
Darryl

[Bill Taylor]

Hi Darryl,
Well, I guess I'm fairly out of the loop when it comes to VC. I had just thought the pros was the same but shorter, with a different terminal device. When lifting with my VO, all the load is on the top side of my stump and the underside of my elbow, except when my arm is fully extended. Then, all the weight is supported through the cuff of my figure 8 harness, across my back, and under my right armpit [I'm lbe.] So this pulls up on my armpit. The only times when weight goes on the cable is when I'm lifting a really heavy load pretty straight down, so that the harness kinda slips down. I'm really interested in knowing how your harness is set up different to provide more points of support. That could be that extra margin of safety I'm looking for when tower climbing. (My present harness came apart in about 6 places without any significant load in the first few months, so I'm really not willing to trust my life to it.) It'd be especially interesting if it's a modification I can make myself.

Hey, now I'm getting hauled off to dinner...more later from this end as well.
Bill

[Darryl]

Bill,
I am not sure about the extra strain on my shoulder. No shoulder issues as of now on my pros side. I do find that because heavy objects pull down on the cable, it helps in distributing the force across my back, not just on the pros harness alone. I actually could not function without some of the load on the cable. Otherwise I can see how, with a VO, that all the weight would only be on the harness. So for me I have 3 points of weight distribution instead of only 2 with a VO. As to length, yes it would be hard to switch with something longer.
For pressure on the hook itself, maybe adding alot of force could help to wear it out, but I believe that it is just use related. I open and close it a hundred times a day. I really needs beefing up on the inside. And of course changing from VO to VC would be very hard.
I will send more later. Out of time right now.
Thank you for all the info,
Darryl

[Bill Taylor]

Hey Darryl,

Just wondering, wouldn't you have a lot more problems with cable wear and strain on your shoulder with a VC? It seems like if I had a VC, I'd always be clamping down on heavy stuff, and generally doing more with it. As it is, I've messed up my shoulder fairly much by lifting heavy stuff with both my hand and my hook together...so that the harness is pulling up on my armpit at the same time that arm is being pulled down by the weight of the load...It's like my shoulder's getting twice the load.

Also, do you find that the internal parts of the APRL are damaged by trying to lock on too tightly, or do they just wear out with use? It looks like the overall length of the APRL is probably greater than say my Hosmer no. 5. If so, in switching between the two styles, it might be awkward from a changing arm length aspect, as well as VO vs. VC operation.

Sorry if you've already addressed these issues...I have ultra slow dialup, so I can only check out videos and stuff in a library.

Bill

[Darryl]

Thank you Bill for all the info.

My VC hook has internal springs that open it. As for closing it, of course add force to the cable, but an internal cam locks the APRL closed in any location along its travel. So you can apply little force, as in holding an egg. Or lots of force as in holding a chisel. Either way it will lock. To release it, you need to add a bit more force to unlock the internal cam and the springs open the fingers. I would say the nice part is I never have to think about having enough force to hold something. I just add more if I need to.
I appreciate all the insight you have with you VO hook. If there is more info to share, that would be great.
Darryl

[Bill Taylor]

Hi Darryl,

I've never used or even seen a VC hook, so I probably have some misconceptions about how they work.

I do occasionally have trouble with dropping things because of not enough gripping pressure from the VO rubber bands on my hook. I guess once I got used to that, I just do that stuff with my hand. By keeping tension on the cable, i can hold an egg or piece of bread without squishing.

I don't have much problem with the hook inadvertently opening at the end of cable travel. I guess I'm just used to pointing my shoulder in the direction I'm reaching when I have a long reach. I have had problems when wiring in an attic by the eaves or in a crawl space not being able to operate my hook by any body motions available to me in cramped quarters...sometimes I reach over with my hand and pull the cable.

The main problem I've had with carrying things is with the cable or harness coming apart when I lift heavy stuff...when I get to the limit of travel of the cable, something hasta give. Sometimes the hook gets stuck shut by digging into the thing I'm carrying, so there's even less cable travel. But even with a VO, wouldn't there be the same problem once the hook is fully closed? I'm afraid I end up solving this problem by taking off my pros when I'm getting into potentially damaging situations. That sucks, but if it breaks I'll have to repair it one-handedly. I have an electrical insulator in my cable, whose aluminum ends wear through too easily too.

I'm concerned about the way the cable supports much of the pulling strain on my pros. Much to my prosthetist's objection, I insisted in having an old-fashioned pros with a lip over my elbow to help keep it on my stump when the pull isn't straight out...in a way it was lucky that it took him 3 months to finish my pros, since I had lots of time to get comments from amputees with experience. I do vertical tower climbing which puts much more strain on my arms than slanted ladders...it isn't too high off the ground before falling off gets uncomfortable. I just can't rely on my pros for doing things like this, so I just climb without my pros and work out ways to do the aerial work one-handedly, or carry my pros along and put it on aloft once I'm safely belted on. It seems like it should be possible to construct a super strong harness which can bear the whole force on the pros, and open or close the hook with a slightly different motion...I need to experiment with this. I realize this is opening up a whole other set of issues, but in a way it's relevant.

Somewhere, maybe on eBay, I think I saw a hook that was switchable between VC and VO...I'll post it here if I find it again.

Peace, Bill

[Darryl]

Bill,
Like you, I pay out of pocket. I am trying very hard to get the APRL updated and manufactured out of more durable materials. Daniel Paulsen has made great strides forward for the upgrades. As of right now I am testing the updated case which is made from milled aluminum instead of the cast aluminum. No problems, 2 months in. There are still cast parts susceptible to breaking: the arm where the cable attaches, and the movable finger assembly including the threads where the finger attaches. I feel that if this device were redesigned and made heavy duty, more people would be led to it. Right now prosthetists are steering active individuals away from it because Hosmer lists it as a light duty device.

On another note, Do you find it hard to use a VO device when working. I tried one a couple of times only to realize that everytime I would reach out to grab something the hook would open. I either needed to be closer or the item needed to be pulled closer to me. kind of defeats the purpose. The other issue is carrying heavy items. You cannot rely on the cable and the harness to help hold the item. The harder it pulls down, the more the hook would open. It seems counter intuitive.
With a VC you decide how much force to apply and when to apply it. Just like a hand. instead of opening first to grab, you close to grab. It just seems logical.

I have trouble believing that the APRL is the only device of its kind. I would like to see it redesigned and made heavy duty for those of us who can benefit from variable force input, and not a bunch of rubberbands.

Let me know what you think,
Darryl

[Bill Taylor]

Hi Darryl,

Thanks for making such a clear and thorough video on the APRL. I can certainly see the advantages of the APRL locking mechanism, and I guess voluntary closing would be about the only easy way to get a good tight grip.

For those of us who need to pay for prosthetic needs out of pocket and do heavy work, it would be essential to have a more durable design. Would it be impossibly heavy if the housing were made out of steel? Might it be that with the increased strength of steel, the whole spring/locking box might be made smaller and cast as one piece with the fingers, and thus shed some weight? At first I was aware of the about half-pound difference between my two hooks, but now I don't even notice, so I think I could tolerate even a pound heavier if the function were improved.

Would there be an advantage to using external rubber bands to open the hook to reduce the size of the box and maybe reduce the problem of debris clogging up the works? Or, at a minimum, putting some flexible gaskets around the gaps to keep stuff out.

As long as we're talking re-design, I would like to have some of the additional features added. I like the nailholder and chisel claws and the two grasping surfaces at right angles of the Hosmer No. 7. And, as long as I'm dreaming, how about easily replaceable rubber gripping pads (for the APRL or any rubber lined hook) that could be bought directly by the amputee without a prescription and replaced at home? With all kinds of super strong adhesives now available in hardware stores, I don't see why this has to be a factory repair. The hook even has a built-in spring or rubber bands for clamping the glue job overnight!

I really like the feel and usefulness in tight places of my solid steel Hosmer No. 5. I find those functions to be a nice complement to what I can do with my hand, so it would be hard to give that up, but I can also readily see that switching between voluntary opening and a voluntary closing could be a difficult mind warp. I wonder if the cable length is even the same for the two types? Anyway, thank you for all the good work.

Peace, Bill