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We have two at work with the thought process being to set these as the middle strut first to allow someone in the trench to set the rest of the acme thread struts. Basically eliminates having to spin the collars with a pike pole or extension pole/duct tape. Does anyone have any experience with these, pros or cons?
Yes, they are perfect for trench. Things to be careful, ensure that you clean the struts thoroughly around the bearings and no petroleum based lubricants.
We have all Acme Thread, never used the LockStrokes so let me ask; How do they unlock?
Nothing wrong with your system. Hell, it is how you have to set Airshore (put someone in the hole). I do see the safety aadvantage to rescuers of waiting till the trench is completely secured, but we also like to perform rescues, not recoveries. Are you just shooting the LockStrokes to 100psi, set the others and air all of them up to 200 at the same time?
Unlocking requires de-pressurizing, then sliding back a locking collar to collapse them. We've played around with a few things, it seems to work best exactly how you described it, otherwise you have to make sure every strut is tied off so you don't end up with everything in a pile at the bottom of the trench. Safety wise it's good, but I still think just setting top, middle, bottom is quicker and more efficient. I can't say I'm a true fan of them, but in a low manpower situation they can be beneficial.
Personally, the lock stroke is perfect for Trench. You lower each of your struts, shoot them, and secure them. THE BEST THING IS NO ONE ENTERS THE HOLE UNTIL SECURING COMES INTO PLACE. The pressure is set to 200 psi, if the 1/4" increment/notch does not secure your panel firmly, add a little to the reg. and that is it. To remove them you add a little pressure and push the head to release. DO NOT SEND PEOPLE IN THE TRENCH UNTIL IT SECURED TO SAVE A FEW MINUTES. YOU MAY BECOME THE "OTHER" PATIENT". TAKE CARE ALL
A technique that I learned at a class in Michigan is to place 1-1/2 inch wide female Velcro on the Acme Thread collars. You then place a couple of 18 in long pieces of male Velcro onto the handle of a pike pole or expandable painter pole.
Once the strut has been set and shot to the correct pressure, the Velcro on the pole is placed against the Velcro on the strut collar and pulled upwards in a rapid motion. The Velcro on Velcro causes the collar to close and lock quickly, often in one pull. Takes a little practice but works well and is a quick, safe way to lock all of the struts before entering the trench.
In trench he use all Lock Stroke initially and if called for we'll use a Acme Thread. We lower the middle strut in place next the top strut then a rescuer enters the trench via ladder to waist height of the middle strut. The bottom strut is lowered down and the rescuer eyes the position than calls to shoot the strut. We like them because their hands free if the situation dictated it they could be set without placing anyone in the trench. One of our members developed a tool to unlock the collar when removing the strut. It's a long pole and on the end of it is a "U" shaped piece of metal. Picture cutting a can in half, the piece fits over the strut, we have a member shoot the strut and at the same time the collar is pushed forward using this tool.
-Mike-
With the Acme threads a painter's pole with some pipe insulation duct taped around it is our locking tool... The Q-Tip.
No one around us uses the lock stroke struts. Most use the Acme thread. We have used some duct tape and a piece of webbing. Tape the end of the webbing to the collar. Roll the webbing up on the collar, in the direction of tightening the collar. Tape the rolled webbing lightly. Lower, and shoot the strut. Pull the webbing like your starting a lawn mower. As long as you neatly roll the webbing and secure it with the tape, we have never had problems with it.
The one negitive to the lock stroke strut is it is hard to get a accurate reading of preasure pushing agaist the wall. Like Canff said, putting velcro around the collar of the strut and the end of a painters stick will allow you to use the acme thread much easier. That way having no one enter the trench until its shored properly. Here in Michigan thats ALL we use.
Thers also another very good thread going regarding L trenches check it out