- Location
- S.E. Wisconsin
Joe, was the lifting ratio of the GRCS you mentioned also from Mark?
easy to use GRCS
- Thread starter frans
- Start date
O.K. Mike: do you remember this link?
http://www.tpub.com/machines/3a.htm
There is a really simple concept that can be applied to the Hobbs. 2 pieces of information are needed. Radius of "Spool", and the length of the pry-bar when inserted into the device. Correctly knowing these 2 things will allow any1 to know the lifting ratio of the Hobbs. The ratio is ideal since friction is not accounted for, but it is correct. Mark knew length of the pry-bar, the radius of the spool, the simple formula, and where the force is applied. It is very simple and a truth that cannot be left unaccounted.
http://www.tpub.com/machines/6.htm
In this section, one can get an idea of how gears increase or reduce speed, change directions of a force, or even create a mechanical advantage. These show theoretical numbers because friction is not taken into account as a factor. When Greg Good, the creator (I'm assuming he engineered the GRCS) of the GRCS, 1st started selling his unit, he advertised a tremendous 44:1, and 22:1 gear ratio! I fell for it as well. The publication of the gear ratios did not properly reflect the actual force output in relation to the force input of the unit. From reading the "gear ratios" one can get the impression if one applied 100 lbs of force to the winch one could receive 4400 lbs of force output from the unit.
Greg Good, maybe hearing a few complaints along the way and being the smart man that he is reworks the advertised gear ratios in a way that he comes up with an input/output ratio for lifting. He could not have done this without applying a combination of ideas and concepts.
The written material you now have access to had to be applied in one way or another for him to come up with his input/output lifing ratio. That's unless he came up with this ratio strictly with empirical data. So, no Mike, I didn't get the lifting ratio of the GRCS from Mark Adams, it is published in the 2003 Sherrill catalog.
Joe
http://www.tpub.com/machines/3a.htm
There is a really simple concept that can be applied to the Hobbs. 2 pieces of information are needed. Radius of "Spool", and the length of the pry-bar when inserted into the device. Correctly knowing these 2 things will allow any1 to know the lifting ratio of the Hobbs. The ratio is ideal since friction is not accounted for, but it is correct. Mark knew length of the pry-bar, the radius of the spool, the simple formula, and where the force is applied. It is very simple and a truth that cannot be left unaccounted.
http://www.tpub.com/machines/6.htm
In this section, one can get an idea of how gears increase or reduce speed, change directions of a force, or even create a mechanical advantage. These show theoretical numbers because friction is not taken into account as a factor. When Greg Good, the creator (I'm assuming he engineered the GRCS) of the GRCS, 1st started selling his unit, he advertised a tremendous 44:1, and 22:1 gear ratio! I fell for it as well. The publication of the gear ratios did not properly reflect the actual force output in relation to the force input of the unit. From reading the "gear ratios" one can get the impression if one applied 100 lbs of force to the winch one could receive 4400 lbs of force output from the unit.
Greg Good, maybe hearing a few complaints along the way and being the smart man that he is reworks the advertised gear ratios in a way that he comes up with an input/output ratio for lifting. He could not have done this without applying a combination of ideas and concepts.
The written material you now have access to had to be applied in one way or another for him to come up with his input/output lifing ratio. That's unless he came up with this ratio strictly with empirical data. So, no Mike, I didn't get the lifting ratio of the GRCS from Mark Adams, it is published in the 2003 Sherrill catalog.
Joe
- Location
- Central US
I just purchased GRCS after debating for many years.
All one needs to do is research the capabilities of each product thoroughly. I once leaned towards the Hobbs mostly because of the lower price. But after further research and talking to many different people using them vs. the GRCS, the clear winner is the GRCS. The major drawback with the Hobbs was how it attached to the tree,i.e. no rubber feet.
I agree, Hobbs is outdated...GRCS is the ONLY way to go and you do not need fiddle blocks etc.
As I mentioned, I have only used mine a very few times but it is marvelous.
All one needs to do is research the capabilities of each product thoroughly. I once leaned towards the Hobbs mostly because of the lower price. But after further research and talking to many different people using them vs. the GRCS, the clear winner is the GRCS. The major drawback with the Hobbs was how it attached to the tree,i.e. no rubber feet.
I agree, Hobbs is outdated...GRCS is the ONLY way to go and you do not need fiddle blocks etc.
As I mentioned, I have only used mine a very few times but it is marvelous.
- Location
- Retired in Minneapolis
Winch formulas
In Brion Toss' book, Chapman's Nautical Guides: Knots he gives this forumula:
"The amount of leverage offered by a winch is determined by the difference between the drum radius and the handle radius."
In The Complete Riggers Apprentice he writes:
"The winch handle is the lever arm, the barrel axis is the fulcrum, and the load is applied at the barrel face. Divide the distance between fulcrum and face into the length of the handle, and the result, in an ungeared winch, is the amount of your advantage."
His example shows a winch with a 3" radius and a handle that is 12" long, giving a 4:1 mechanical advantage.
The winch that's used in the GRCS has an internal gear box too so there is even more of a multiplier.
In Brion Toss' book, Chapman's Nautical Guides: Knots he gives this forumula:
"The amount of leverage offered by a winch is determined by the difference between the drum radius and the handle radius."
In The Complete Riggers Apprentice he writes:
"The winch handle is the lever arm, the barrel axis is the fulcrum, and the load is applied at the barrel face. Divide the distance between fulcrum and face into the length of the handle, and the result, in an ungeared winch, is the amount of your advantage."
His example shows a winch with a 3" radius and a handle that is 12" long, giving a 4:1 mechanical advantage.
The winch that's used in the GRCS has an internal gear box too so there is even more of a multiplier.
- Location
- S.E. Wisconsin
Re: Winch formulas
The GRCS is made out of a sailboat racing winch. They come in all different sizes, shapes, and gear ratios. So, you first take the gear ratio, how many turns of the handle to get one turn of the drum, then use the simple formula Mark used for calculating the lift of the hobbs, that gives you a power ratio.
Most winch manufacturers use the power ratio as the basis of choice: it is how much pulling power you get on the line (work) for every pound of pressure you exert on the handle (effort). The formula is: 2 x handle length x gear ratio ÷ drum diameter = power ratio.
Theoretically, a winch with a 10:1 power ratio gives 100 lbs. of pull on the line for every 10 lbs. you exert on the handle.
I assume Greg's original ratios where taken directly from the winch manufacturers advertising.
Harken's site with samples of winches and specs
That's my understanding, and I must be lost somewhere(no mystery, I suck at math), because the hobbs and the GRCS are about the same size(handle and drum) but the GRCS has the gear ratio working for it, shouldn't it have a higher power ratio?
Not having ever used a Hobbs, I wonder if the mechanical advantage is gained with a long handle.
The GRCS is made out of a sailboat racing winch. They come in all different sizes, shapes, and gear ratios. So, you first take the gear ratio, how many turns of the handle to get one turn of the drum, then use the simple formula Mark used for calculating the lift of the hobbs, that gives you a power ratio.
Most winch manufacturers use the power ratio as the basis of choice: it is how much pulling power you get on the line (work) for every pound of pressure you exert on the handle (effort). The formula is: 2 x handle length x gear ratio ÷ drum diameter = power ratio.
Theoretically, a winch with a 10:1 power ratio gives 100 lbs. of pull on the line for every 10 lbs. you exert on the handle.
I assume Greg's original ratios where taken directly from the winch manufacturers advertising.
Harken's site with samples of winches and specs
That's my understanding, and I must be lost somewhere(no mystery, I suck at math), because the hobbs and the GRCS are about the same size(handle and drum) but the GRCS has the gear ratio working for it, shouldn't it have a higher power ratio?
Not having ever used a Hobbs, I wonder if the mechanical advantage is gained with a long handle.
- Location
- S.E. Wisconsin
Re: Winch formulas
Let's plug numbers into the formula, and use the Harken B74.2STR WINCH-AL ST R
2 x handle length(10") x gear ratio(22:1) ÷ drum diameter(5 7/8") = power ratio.
Anyone want to try(I won't embarass myself)?
Let's plug numbers into the formula, and use the Harken B74.2STR WINCH-AL ST R
2 x handle length(10") x gear ratio(22:1) ÷ drum diameter(5 7/8") = power ratio.
Anyone want to try(I won't embarass myself)?
Re: Winch formulas
After reading this article, I'm going to admit I'm not sure what the purpose of advertising the gear ratios and the lifting capacity means.
http://www.harken.com/winches/wnchpower.php
http://www.harken.com/winches/wnchpeop.php
I really enjoy these types of quests, but, I don't like to be left hanging. Thanks for correcting me Snarf and Mike. Mike: thanks for the Harken link.
Mike: The m.a. of the Hobbs does depend on the length of the pry-bar. I'm sure of this fact.
Joe
After reading this article, I'm going to admit I'm not sure what the purpose of advertising the gear ratios and the lifting capacity means.
http://www.harken.com/winches/wnchpower.php
http://www.harken.com/winches/wnchpeop.php
I really enjoy these types of quests, but, I don't like to be left hanging. Thanks for correcting me Snarf and Mike. Mike: thanks for the Harken link.
Mike: The m.a. of the Hobbs does depend on the length of the pry-bar. I'm sure of this fact.
Joe
HOORAY JOE!!!!
(Taking a bow) Thank you treejac.
Since I'm having such a good time with this thread, I want to comment more about the gear ratio of the GRCS
and it's m.a. In the 2003 Sherrill catalog, the 44:1 and 22:1 gear ratios are no longer published. They are now stating "gear reductions" of 4:1 in high gear and 12:1 in low gear. I believe these #'s reflect the m.a. of the device. They are stating a ground"man" can lift 2000 lbs. It doesn't seem realistic since this would depend on about 170 lbs of input from the groundman. I did witness Greg Good on his video get 1800 lbs out of his device. Greg's a big guy.
Joe
Since I'm having such a good time with this thread, I want to comment more about the gear ratio of the GRCS
and it's m.a. In the 2003 Sherrill catalog, the 44:1 and 22:1 gear ratios are no longer published. They are now stating "gear reductions" of 4:1 in high gear and 12:1 in low gear. I believe these #'s reflect the m.a. of the device. They are stating a ground"man" can lift 2000 lbs. It doesn't seem realistic since this would depend on about 170 lbs of input from the groundman. I did witness Greg Good on his video get 1800 lbs out of his device. Greg's a big guy.
Joe
Hey Joe,
Looks like you're coming around. I don't pay to close attention to the details, but I can tell you that with hands on experience you will be impressed with the GRCS. I encourage you to borrow one from a colleague if possible. Try it out. Forget about all you have read in brochures, all you've heard from salespersons at trade shows, and all of your prejudice. Just try it. You'll be glad you did. Best of luck to you.
Matt
Looks like you're coming around. I don't pay to close attention to the details, but I can tell you that with hands on experience you will be impressed with the GRCS. I encourage you to borrow one from a colleague if possible. Try it out. Forget about all you have read in brochures, all you've heard from salespersons at trade shows, and all of your prejudice. Just try it. You'll be glad you did. Best of luck to you.
Matt
Hi, Sergio;
It seems your questions are ment for the guys who use and promote the GRCS, but, I'm enjoying this conversation too much to keep my mouth shut.
The ideal m.a. of the lowering device is 15:1. This does not include losses due to friction. Otherwise, we don't know the lowering devices efficiency rating. An efficiency rating of 100% would mean the ideal m.a. of the lowering device is the actual m.a. one could obtain when using it, which again would be 15:1. I believe somebody knows the efficiency rating of the Hobbs lowering device.
The literature from both devices suggest the Hobbs is tougher than the GRCS. I think the Hobbs is a tougher piece of equipment.
I will not ignore what these other guys are saying about the GRCS. I'd love to get my hands on one for at least a few days just to see how well I'd perform with it.
Joe
It seems your questions are ment for the guys who use and promote the GRCS, but, I'm enjoying this conversation too much to keep my mouth shut.
The ideal m.a. of the lowering device is 15:1. This does not include losses due to friction. Otherwise, we don't know the lowering devices efficiency rating. An efficiency rating of 100% would mean the ideal m.a. of the lowering device is the actual m.a. one could obtain when using it, which again would be 15:1. I believe somebody knows the efficiency rating of the Hobbs lowering device.
The literature from both devices suggest the Hobbs is tougher than the GRCS. I think the Hobbs is a tougher piece of equipment.
I will not ignore what these other guys are saying about the GRCS. I'd love to get my hands on one for at least a few days just to see how well I'd perform with it.
Joe
- Location
- Home of the New Jersey Devils
Wow, I am impressed. I've been following this discussion and am pleased to see that it has not only stayed on track, but has been a beneficial one to follow. Great job to all.
As many of you might know, my experience has mainly been with the GRCS. I have used a Hobbs only at the TCI Expo. I have had my GRCS for over three or four years and still love it each and every day that we do removals (including today). I do believe that I would say the same for the Hobbs if it were on the truck. And as for it being outdated, well I would have to disagree with everyone who feels this way. As Joe says, it has its' place.
I am wondering if anyone knows of the tensile strength of the Hobbs? Ken Johnson must, afterall he is not really one that you would refer to as anything less than a master mind. He knows tree work and he knows a bunch more on manufacturing his device. I trust that it will keep evolving as he sees fit.
I don't really see how the Hobbs would be any stronger or tougher though? Why would you say this? I know that each of the devices have been tested and broke. Does anyone have info on this?
As far as which one is better, well which chipper is better, which bucket truck does the best job, and so on... Why must we even try to decide. I am all for debating things like this so that we might learn more about our gear. I just don't see how we might agree on a "winner". I enjoy the fact that there are such choices to be made. It enhances our profession and we all know that competetion on such things breeds excellence.
I too feel good about advising fellow arborists to purchase the GRCS but can't say that I wouldn't do the same with the Hobbs if it were the device we had.
As many of you might know, my experience has mainly been with the GRCS. I have used a Hobbs only at the TCI Expo. I have had my GRCS for over three or four years and still love it each and every day that we do removals (including today). I do believe that I would say the same for the Hobbs if it were on the truck. And as for it being outdated, well I would have to disagree with everyone who feels this way. As Joe says, it has its' place.
I am wondering if anyone knows of the tensile strength of the Hobbs? Ken Johnson must, afterall he is not really one that you would refer to as anything less than a master mind. He knows tree work and he knows a bunch more on manufacturing his device. I trust that it will keep evolving as he sees fit.
I don't really see how the Hobbs would be any stronger or tougher though? Why would you say this? I know that each of the devices have been tested and broke. Does anyone have info on this?
As far as which one is better, well which chipper is better, which bucket truck does the best job, and so on... Why must we even try to decide. I am all for debating things like this so that we might learn more about our gear. I just don't see how we might agree on a "winner". I enjoy the fact that there are such choices to be made. It enhances our profession and we all know that competetion on such things breeds excellence.
I too feel good about advising fellow arborists to purchase the GRCS but can't say that I wouldn't do the same with the Hobbs if it were the device we had.
- Location
- Austin, Texas
TREEJAC AND OTHERS, IT IS EASY TO LOOK DOWN (WHAT A PUN) ONN THE GROUND CREW BUT TRY TO BE PATIENT WITH THEM BECAUSE THEY LOOK TO THE CLIMBERS AND CREW LEADER FOR LEADERSHIP. I think if one had morons on any difficult tree removal the JOB SHOULD BE POSTPONED UNTIL A BETTER GROUND CREW IS AVAILABLE. REMEMBER ATTITUDE IS LIKE !@#$ AND !@#$ FLOWS DOWN HILL.
- Location
- Austin, Texas
YEAH, GREAT THREAD
Roughly, the GRCS manufacturer states when removing large wood, like when doing spar work, to use the bollard, not the winch.
Roughly, the manufacturer of the Hobbs states when doing tree work of any kind, to use this device.
Based on the information I have found through public sources which I believe is supplied by the manufacturers of each device, the conclusion I have made is the Hobbs is a tougher device.
I think the manufacturers are pleased with the information they have given. I'll let testimony prove the rest.
Joe
Roughly, the manufacturer of the Hobbs states when doing tree work of any kind, to use this device.
Based on the information I have found through public sources which I believe is supplied by the manufacturers of each device, the conclusion I have made is the Hobbs is a tougher device.
I think the manufacturers are pleased with the information they have given. I'll let testimony prove the rest.
Joe
- Location
- georgetown ontario canada
I always thought the bollard was there to reduce the wear on the winch. Ropes do cut into aluminum and it is cheaper to replace the bollard than the winch.
It could be to reduce the slam dunk forces on the gears but I know that sailing equipment has to be incredibly strong.
If I could afford a GRCS, I would keep it in my room when I sleep!
Dave
It could be to reduce the slam dunk forces on the gears but I know that sailing equipment has to be incredibly strong.
If I could afford a GRCS, I would keep it in my room when I sleep!
Dave
- Location
- Wales UK
I have a friend (yes, one anyway!) Who has been using the Hobbs for years, he still finds it an awesome tool. He has done some amazing stuff with it, on large rope diams 3/4" & 7/8" (and yes there is a call for these ropes, remember allways over estimate your load, and you will get no nasty surprises!) Sorry went off track a bit there, anyway, he recently bought a GRCS from me, and will definately be keeping his Hobbs as well, I will try to get him on here with his comparisons. Could be interesting?
OK. Let me see if I got this right...
The GRCS has internal gears that multiply the force applied in a 12:1 ratio. That WITHOUT taking into account the leverage of the handle. The Hobbs has no gears so it can't have a m.a. other than that provided by the lenght of the metal bar. Theoretically a GRCS could also be equipped with a longer handle...So the lifting capacities of the GRCS are definetely superior. It remains an open question if one is tougher than the other for lowering, but I doubt that a GRCS owner (which I'm not) would feel he needs something stronger.
I guess the choice between the two should concentrate on the economic aspect related to how many times one thinks he will need to lift wood during rigging operations.
Sergio
The GRCS has internal gears that multiply the force applied in a 12:1 ratio. That WITHOUT taking into account the leverage of the handle. The Hobbs has no gears so it can't have a m.a. other than that provided by the lenght of the metal bar. Theoretically a GRCS could also be equipped with a longer handle...So the lifting capacities of the GRCS are definetely superior. It remains an open question if one is tougher than the other for lowering, but I doubt that a GRCS owner (which I'm not) would feel he needs something stronger.
I guess the choice between the two should concentrate on the economic aspect related to how many times one thinks he will need to lift wood during rigging operations.
Sergio
- Location
- Wales UK
OK I'll put this another way, forget your maths for a minute, do you own more than one pair of boots? If the answer is yes, (and I'm sure it is), do you think you would prefer to have just one pair, and do you think your'e boots would last longer if you shared the wearing between the two pairs? Do you also think that maybe you would do your disco dancing (well those that still can!) in your climbing boots?? So we have two Boots both made for the same sort of job, both worn the same way, but each one has a place, so in plain terms, there is room for both these winches, if you are fortunate enough to be able to afford both, how many of you would say no to one? One other thing to point out here is there are no two people the same, we all have our likes and dislikes, if we all wanted the same thing, there would be none available! We ask for choice, let's be satisfied that we get it. Is anyone still with me? No didn't think so!
L.W
Some lead, other's follow!
L.W
Some lead, other's follow!
