The thing with pulling down heavy on load lifters is the force is counteracted by placing more inward pressure on the front of the waist belt. I have never been a big fan of waist belts. All manufacturers advertise these days that 'their' waistbelt transfers all the weight off the shoulders, all well and good, if this is more comfortable for the wearer. Like myself though, having the weight up top isn't such a 'huge' issue that these manufacturers seem to make out, but that is individual choice though, others prefer to carry the weight on the hips, certainly does not mean that one wearer is right and the other is wrong. Lumbar pads are the same, I am not a huge fan of big, thick lumbar pads. I bought a Kuiu Icon 5000 earlier in the year and while being an awesome concept, the lumbar pad just wasn't for me, nor was the waist belt when the lifters, or should I say stabilisers were pulled right down.
Imho I feel 'load lifters' is a bit of a catch phrase, that people can look way too deep into. Remember though, this is my personnel opinion and what works for me. I am vertically challenged lol with a short torso length with a stocky build, the point is, I wouldn't simply buy a pack because it has the world's best 'load lifters'.
Apologies for the hijack, but I did find trapperjay's question interesting.
Karl your packs look to be a great concept, is there anywhere I can view some more in depth images?
I think the major benefit of functioning load lifters vs. non-lifting load lifters is the ability to secure the load to your chest and back while still giving you options on how to vertically distribute the weight. By providing a more vertical angle you can change the amount of weight on your shoulders or hips. Or just redistribute as one area becomes more fatigued. What makes this possible is the angle of the lifter and the stiffness of the stays. As an engineer it's pretty easy to look at the straps as respective vector forces, with working load lifters you can increase the lateral force on the chest straps and counteract the negative vertical component of the pack by transferring it to the top of the stays. Stabilizers can increase the lateral force but cannot decrease the load. If its not something you care about then more power to you. If it is, well it's nice to be able to adjust the load to what's most comfortable.
Load lifters are not overrated IMHO. In order to carry heavy loads as comfortably as possible they are a crucial piece to the puzzle. Load lifters "lift" your shoulder straps off your shoulders and put the weight your shoulders would bare on the frame which is thus transferred to the waist belt which is wrapped around your hips. So for heavy loads in order to maximize the comfort and to get the most out of load lifters you need a comfortable waist belt. If you are going to put 80% of an 100+ load on you hope this is crucial. Then you need a rigid stay. I have had packs with 100+ lbs in them and when I tighten the load lifters the stays basically bend and I keep the weight on my shoulders. If you do this correctly you will have a good amount of pressure on the front of your shoulders, around the collar bone. But very little on the top of your shoulder. I don't know about how the rest of you are built but my legs and hips are the strongest part of my body and my shoulders fatigue too fast to bare half of a 100lb load for long. So no they are not overrated but some manufactures will say they have load lifters but are not as affective as a pack that has all the important pieces like I mentioned. Again this is my opinion.
Cam,
I DO think the stablizers are important, like when I'm in blow-down, steep country, and of course with heavy meat hauls. The way I see it, I can tighten and loosen my shoulder strap tension and loosen it slightly, and the pack "settles" onto my waist. I then get a little fatigued of that, and move the weight back onto my shoulders again. I DO use the L.L's, just not ever "cranked-down" to the max, I guess.
I've lived in an Airpack for almost 33 years--no L.L's--so I do know what they "CAN" do, because my shouldrs are getting killed for four hours on house fires from 32# (that's all) hanging off my back.
One more item I neglected to answer earlier. The "twist" in the 1 1/2" waist belt pass-through, was a previous manufacturer--dated, Circa, 2010-2012. We have "tightened" the tolerances at the end to eliminate any twist. It can be sloved by makeing sure the 1 1/2" pass-through is tight against the end of the bar-tack--not optimal, but you should have a better result by pulling the ends forward EVENLY, attempting to keep the buckle centered into your abdomen--near your umbilicus (Belly Button!).Thanks, kjf
This isn't a comment on the OPW kit, just an observation to clarify the discussion. There are two functions/types of straps that are often found on the tops of packs, load stabilizing straps and load lifters.
Like cmeier noted, load lifters "lift" the shoulder straps off of your shoulders slightly so that they are no longer weighing down onto your shoulders but are rather pushing into your shoulders from the front to keep the pack from flipping backwards off of your body. Load lifters are designed to work with a waist belt that is designed to pick up the load when the shoulder straps are "lifted" off of the shoulders. Without a functioning waist belt all load lifters become stabilizing straps.
The purpose of stabilizing straps is to pull the pack bag closer to the frame or more importantly closer to your body so that the center of gravity of you and the pack is closer to what the center of gravity would be without the pack. This helps with walking in rough terrain as Karl noted and makes for an overall nicer walk as you are not leaning over as you don't have to adapt as much to the weight on your back to keep it from pulling you over backwards.
Many stabilizer straps look like what people refer to as non-functional load lifters because they are attached to the frame/stay at a position that is not high enough above the persons shoulders, and as a result all they can do is pull the pack bag or frame closer to the persons shoulders.
Some designs allow both functions to work using one set of straps, others need two sets of straps that attach at different points on the stays or frame. The challenge is realizing what function the straps are performing since they basically will look the same.