strength demo of the GRCS 6/5/04

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Frans, do you live in Humboldt county? Maybe head east of the mountains get a little closer to the sunrise in the morning, burn some fog off.
 
Carl,
I want to use the ratcheting capstan not the bollard.
the capstan is the one that really gets used day in and day out so we want to keep things as real world as possible.
I can assure all that any weak links in the system will be beefed up until all is tight and secure.
Toby Sherrill has generously offered to check all our figures using his new software program. We will work the figures old school using a pencil and paper and then submit them to him for final confirmation.
Pretty nice of him I think as well as adding an element of legitimacy to this whole insane idea. He volunteered to do this at no charge.
We will weigh the car and show the weighmasters certificate as well.
I will ask Gerry Baranek to see if he can post any short video clips on A.S.
thanks again for all your advice everbody. I have changed the set-up already due to advice from A.S. members

Frans
 
I think this is a great idea, and if it can catch that car and hold it once or twice it sure will get people to stop an look. With the crew you mentioned working on this I'm sure it will be top notch. I think it is important to film the guys walking up to the tree an putting the device on the tree, 3 guys on the pry bar tightening the strap as tight as it can get will take care. If you bolt it to the tree or do anyting out of the normal every day usage of the device it would be like cheating.
I think using a crane to drop the car would be the safest way to go, not more dangerous. A 70ton crane would have no problem picking up a 6000lb car with the stick out 60 feet away from the crane. Droping the load would not cause shock loads, they just let the winch go.
Gotta post that video!!
Greg
 
Greg, you wont find many hoisters who would suddenly cut loose a load. The backlash would flip the boom up and shock load the crane. If the cable accidently re-engaged the fallling load, that would potentiallly damage or destroy the crane.

Frank
 
I don't think the GCRS will lift a Caddy, even with someone tensioning the tail, I've had mine slip on 1500# using the self tailer.
 
Assuming the metal construction of each unit is similar in strength, the Hobbs will handle much more weight, due to its larger diameter capstan and much longer length, allowing room for more wraps.

Slippage at only 1500 lb doesn't sound very good. So far, with the two trees we lifted off houses with our GRCS, we had no problems, one with the 3/4 inch line, and one the 9/16th. Havent used it to slam dunk logs yet, would still prefer to use the Hobbs for that, due to the above reasons, and the fact that it is a cheaper, much simpler design, with no internal working parts....the spring loaded cams are in plain sight.

Anyhow, frans is only testing the ability of these units to withstand shock loads, which to me is not very realistic, as our goal in all rigging scenarios, is to limit shock loads as much as possible.
 
Originally posted by Lumberjack
Spent 850 on a Remmy 870 this Sat, and i want a AR-15 to go with it.

$850 for an 870? Are they that expensive these days? I got mine for $207 (course that was several years back, probably 6 or 7 years).
 
With the liberals pushing lawsuits against firearms makers every time some retard gets ticked and whacks his ball and chain, I'm surprisde they're still that cheap.
 
One final word on all this and then I'm done until I have the finished product on DVD.
Ken Johnson will be there (the manufacturer of the Hobbs) He has generously decided to come and oversee/ help.
Look for news regarding Ken's business soon! Check your local tree tool supply resources
Thanks
Frans
 
Update on Strength test: GRCS & New Hobbs

Spent all day today setting up and doing the tests.
We began with using an approx 3,000 lb. euc. log. It was about 8' long and 3' thick so the weight is just a guess but we will have it weighed and be able to supply an exact figure.
We used 5/8" & 9/16" inch lines to begin with because we wanted to show how the rope failes under real world conditions. For both devices the rope failed first at the capstan because of thermal heat breakdown. When we put approx. 10' (feet) of slack and let the log fall into the 5/8" line the rope failed at the marl- a clean snapping break.
Both devices seemed to experiance no problems with the pawls, baseplates etc.
On the first test of the day we had the GRCS mounted on the tree. The euc. is 90" Dia. so we had to cut "pads" for both devices to rest on, the tree just did'nt have any curve to it.
We mounted the GRCS incorrectly and it slid up the trunk digging a deep 4" deep groove in the trunk as it went up the trunk. When this happened the hinged portion that holds the strap bent slightly.
After that we positioned it correctly and experianced no problems with either device.
The New Hobbs worked just fine, no problems at all.
The chunk we were dropping was raised to maybe 40', and dropping 35' so it would "hit" the rope and stop.
I am real impressed with both devices and think they are everything both manufactures say they are.
Tomorrow we will begin the car drop test using heavier line. Ran out of time today what with setting up and running the lighter line testing.
We did extensive filming. I'll try to post at least a picture of the car drop.
Folks who helped today:
Sam Noonan
Robert Phillips
Ken Johnson
Me
Greg Liu
Gerry Baranek
and others not known in the tree world
Many thanks to all for making this first day a success and working so hard on this project


I'll post more when we are through tomorrow.
Thanks
Frans
 
i would think that you would want the line strength after knotting/lacing to be less than the GRC$, so that the line would be the first system 'fuse' to blow; rather than the lowering device or it's mount.

Hey, RB; i'll prolly end up buying one of those, actually between Nick's log weight calculator/spreadsheet and Spencer's Lean and DWT calculator's/sheets given here about all i see missing is calculator for acceleration of falling force(?).

But anyway, for all the old saw falling to bottom of strap and the force on hip etc. What would be the falling force of 100# falling 0',1',2', etc. to 5-10 or whatever. And if 7# were the falling load; would it's force be a even ratio of 7% of the 100# falling? i have seen it quoted where it would be different, not even ratio to weight for same height of drop? Pleaaaaaz!:blob2:
 
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Thanks for the update, frans. What a who's who of a team!

That's great that you started with some other tests. I'm wondering if you performed any of the tests as we normally would use the LD's, slam dunking heavy wood, trying to limit shock loads by letting it run. That would seem to be a logical test of both line and LD, assuming you use a 40,000 lb block and sling, as a good operator should be able to limit shock loading to 20,000 lb or less when lowering a 3000 lb log. But you'd have needed a 3/4 inch line for that test.
That said, for all I know with so many experienced riggers out there, maybe over 2000 lb and above loads have been slam dunked. Personally I don't think I've ever dropped over 1000-1200 lbs into the system. Lifted, yes, dropped, no.

My opinion still is that the Hobbs is stronger....you can notch the tree to easily keep it from sliding up. What did you do to solidify the GRCS mount? Wiley p has used wedges, I once tied a rope around the trunk below the GRCS, then attached it to the GRCS and it's sling in three places with short ropes. (That was the very first time we used "The Winch", lifting a 2000 lb failed cedar stem out of a house. You can see the setup in this pic..and the problem..a tapered cedar trunk where we had to mount the device higher up than normal, but it still had taper to contend with.

I eagerly await more news! And as much tech data as you record..
 
FINAL UPDATE ON HOBBS/GRCS TEST

Well after many hours and lots of laughs we finally got the tests done.
Yesterday and this morning we dropped tested a Euc log measuring approx. 8' long by approx 3' thick.
First we dropped the log using a 5/8" & a 3/4" line.
The log was dropped about 10'-15' into a 2" load line.
THe big line accepted the shock loads just fine and so did both devices. But the smaller lines failed either at the marl or at the drums (almost a friction/thermal break)
Interesting because we always hear about knots reducing the strength of a rope by +/-50% and now we saw this first hand. But by allowing the load to run a little the ropes failed at the drum.
We had a little trouble with mounting on such a big stem because the straps extended out from the devices without being able to cinch very well.

We dropped the car using the big line and let some slack in the system.
The Hobs took the load and bent within the channel iron on the base by about a 1/8" inch. The capstan still ratcheted fine.
The GRCS took the load but the bottom of the base plate lifted under the load away from the tree and the rope yanked off the outer part of the capstan in a sucking/pulling action not a shearing pull as we wanted.
The base plate on the GRCS was not harmed at all. The base pulled out easily with no pinching in the rails. The ratchet action of the core mechanism was not affected.
The Hobbs is one stout device that handled loads far in excess of any device or rope manufacture's guidlines.

The GRCS lifted the '79 Volvo station wagon (rated at 4300GVWR) by cranking up on the drum with the handle and the rope did not slip from the jaws.
Over all both devices seem to be the same strength, One will lift easily huge loads, self tail, lighter because of it's component assembly. The other is easy to operate, very strong, less expensive.

Overall I have come to the opinion that both devices have a place in the tree industry. One is not stronger or better than the other, just different devices.

I have changed my tune about the Hobbs and am here to say it is just as good as the GRCS.
I still think the GRCS is by far the more versatile of the two. For me I really need to be able to have one man operate the device not two like the Hobbs, and because of always working in tight areas I really need to be able to lift loads. So even tho I dont have any bad things to say about the Hobbs' construction, the GRCS still rules in my book.
The movie will be assembled by Gerry B. once we get all the different tapes to him. I'll let folks know who are interested and see about making copies.
Loads/weights, distances dropped and other details will have to wait until we get all the facts together.
This is just advance details
Thanks
Frans
 
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It would still be a nice load, but I'll be surprised if "the '79 Volvo station wagon (rated at 4300GVWR)" weighs in at more than 3000 pounds.&nbsp; 6 people at 200 pounds each, some fuel and some luggage would probably be a bit overloaded and maybe beyond the GVWR.&nbsp; But it <i>is</i> just a guess on my part.

I'll bet it was a pretty fun couple of days!

Glen
 
I wonder what the Volvo (supposedly the safest car in the world) people would say.

:laugh:
 


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