Hi, all! First off, I'm asking this because I'm not a professional logger, nor at all familiar with forestry operations. But I am trying to build a model of a Madill 071 Tower Yarder, and I am trying to understand the functions of it's winches to better understand how to approach replicating the machine. It has five operations winches, according to the brochure: Skyline, Main, Haulback, Straw, and Tag. The Skyline seems obvious; it runs over the top of the spar and is secured downrange. The carriage with chokers hangs from this. The Main and Haulback lines are attached to the carriage, and move it back and forth on the Skyline. Correct? But what do the Straw and Tag lines do? And how should they be routed and stowed when the spar is down for transport? Likewise, the three guyline winches obviously handle lines that are used to provide stability to the spar when in operation. Do they attach to the structure of the yarder after routing through the sheaves atop the spar, or are they routed away to some other location? And where would they be stowed? Any insight into how the rig works would be immensely helpful to me in planning and executing the project. Thanks!
A link to the Worksafe BC Cable Yarding Systems Handbook http://www.worksafebc.com/publications/health_and_safety/by_topic/assets/pdf/cable_yarding.pdf
Thank you, sir! Looks like I've got a lot of reading to do on that site, but it should tell me just about everything I need to know.
The strawline was used for taking the haulback out in the initial rig up and for changing roads. The heavy skyline was taken out and moved by the haulback. Strawline was light enough to be pulled by hand and came apart in 200-250' sections or "extensions". (dumb name, I know) The tag line was usually slightly larger than the strawline and its original purpose was in operating older style dropline carriages, such as the Berger. Most modern carriages don't require a tagline and it is often used now as an auxilary strawline drum. The 071 had three guylines that were anchored to tailhold stumps on the opposite side of the yarder from the yarding lines. I can't quite recall exactly where on the machine the drums were anchored. There should be some good pics on Google that might help you.
To avoid confusion, the Americans call strawline, haywire. Talk to an American rigging slinger about strawline and he looks at you with an even blanker look than usual.
I've seen several 071's with an optional 4th guyline added. No clue if they were factory added or logger added.
What's the diference betwene the Northbend and Southbend systems?I understand the northbend system but have no idea how the southbend functions.
North Bend System: Developed by Phil Grabiski (sp?) superintendant of North Bend Timber North Bend Washington. This involves a fixed skyline where the mainline (or inhaul line) is tailholted on a carriage riding on the fixed skyline, from there it passes through a drop block which has the chokers attached along with the haul back. From there, it is straight to the bull block and down to the drum. The only difference on a South Bend System is the mainline passes through a sheave on the carriage and back down to the fall block. On some occasions, there is a two sheave drop block and then the mainline passes back up to the carriage where it is tailholted. Basically, they are the same system with the exception of parting the main line on the drop block. A side note, the skyline at the tail tree and sometimes at the head tree ran through a “skyline jack” it was prohibited by state laws to have a block supporting the skyline at the tail tree because the metal of the blocks in those days with a fixed line on the sheave and the stresses involved would cause the sheave to crystallize and shatter thus a major safety hazard. A jack was just a formed casting with wood lining to allow the skyline to bend easily from the tail tree down to the tailholt. A great reference is A Loggers Lexicon, which is now out of print. You can purchase a used one anywhere’s from $100 to $750… Crazy…
Hi Jumbo In BC the tree jack was referred to as a "Dutchman". I asked one old timer how it got that name. "Cuz it had wooden shoes inside it for the skyline to rest on, dummy." was the reply. I looked inside and sure enough there were blocks made from what looked like oak. We used a modern Dutchman later on and by then he'd traded his wooden shoes for ones made out of high tech polyurethane.
BDFT LOL at least they're called rigging slingers both sides of the border.
Actually; they are called many things, on both sides of the border. Unfortunately most are not repeatable in this fine forum. (And rightly so.)
Down here we also have a few different names. We call strawline strawline but we call a length of it a coil as it is broken down and rolled into coils for lugging around the bush. We also call the tagline a tagline though its most common use down here would be to hold the carrage on a northbend system. Useful for bridling and land logs. The haulback for the most part is called the tailrope though some call it a haulback. The difference seams to be tower haulers have tailropes and swing yarders have a haulback. Down here a dutchman is something a little different. Aside from a man who forgets his wallet when it is his shout a dutchman is a system of rigging that pulls a skyline sideways. This is usually done with a block and a skyline extension hung off a machine. Back the machine away from the tailhold stump and you move the skyline. It is used when there are no tailhold stumps available and a machine can not get in the right position to hold the skyline directly. We do not use tail spars much down here.