Skyline Logging Carriages

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Maki Motorized Carriage
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The carriage trade means differing things to different people, but to a logger it refers to the the heart of a cable logging operation. Weavers have shuttles, but loggers have carriages. Like mouse traps, a lot of people have looked for a lot of ways to build a better carriage. Carriages run the whole gambit from very simple ones to very complex ones--the former being one or more blocks which ride the skyline and some weight and the latter having a radio controlled engine.


Oregon State University White Paper on Carriages for Skylines

Shotgun or Gravity Carriage

On the simple end is the Shotgun carriage. I've seen home made ones consisting of simply a block hooked to some iron for weight. The mainline and the chokers are hooked to the iron, and the rider block hangs on the skyline. To operate you raise the skyline, and release the brake on the main line. The weight of the carriage falling down the skyline, pulls the mainline out. The chokers, usually about 20 feet long are hooked directly to the carriage. When the carriage rolls out to the proper place, the yarder engineer brakes the mainline to a stop and slacks the skyline lowering the carriage to the ground. The choker setter can hook any log he can reach with the 20 foot choker. Once hooked, the skyline is raised to provide lift and the mainline is reeled. This rigging configuration usually does not provide full suspension of the logs, but it is a very simple rigging system. The carriages usually weight from 500 to 2000 lbs depending on how much line they need to pull. Yarding distances under 600 feet are preferred and it needs to be downhill all the way to the tail hold. Since there is no lateral yarding ability, road changes must be frequent, A swing yarder an provide some lateral movement, and walking guylines can facilitate the movement of the yarder.

The rider blocks for the carriage are often Tommy Moore blocks. I'm not sure where the name came from, but a Tommy Moore Block is is a wide 'v' shaped pulley, the idea being that it can pass through its throat cable splices or even shackles. This means that if the skyline comes up short, as it often does, you can extend it and the carriage will 'jump' the shackle.

To create a 'walking' guyline, you simply put a block on the end of the guyline from the yarder. Then you loop a line through the block and anchor the respective ends of the loop well to the rear and well to the sides of the yarder. If the yarder is working down a ridge top road it can move several times down the road before the guylines must be reset. This is important in the Gravity carriage logging operation as you will be moving the yarder perhaps only 50 feet per setting. In the ideal situation you have the tail hold on a dozer and move the yarder and the dozer alternately

A similar carriage can be used with a running skyline serving as a haulback line. This is useful if the setting is too flat for the carriage to extend the mainline by gravity. The skyline in this instance instead of being anchored at the back end of the job is turned back toward the yarder with a tail block and hooked to the carriage. This way you can pull the carriage out by taking up the skyline. This method of logging requires that one drum be taking up line whenever the other is feeding out line, and unless the outfeed is held back everything lays on the ground. This implies a yarder with an interlock to keep the dynamics of this working. However historically, this has often been accomplished with a Wichita brake. The Wichita (a brand name owned by Dana) is a water cooled friction brake designed for high head dissipation.

Manually Clamping Carriages

As we have seen above the gravity logging system is simplicity itself. but it has sever limitations. It doesn't work on flat ground and is not suitable under conditions where it is possible to hang the skyline all the way across the ravine and anchor it on top of the next ridge. This ridge to ridge rigging provides the needed deflection to make a cable logging system work efficiently, but the carriage won't roll up the other side by gravity. This implies the use of a haulback.

More to the point of this article, however, is the fact that in many situations particularly as the distance gets out there, the frequent road and yarder changes become impractical. The Gravity carriage, or even a gravity carriage with a haulback has no provision for reaching to the side of the line. You can get the logs directly under the skyline easily, but the side reach is limited by the length of your choker, and if you use a long choker, you compromise the lift, in that the carriage has to be that much higher before it lifts the log off the ground, and no log is ever far enough off the ground.

There have been a lot of logs moved with cable logging systems in the last hundred years, and a lot of very innovative people have sought to make a better mousetrap. The clamping carriage is one of those mousetraps. You see a classic dumb carriage free wheels on the skyline. It is only held in place for hooking by the main line (and possibly the haulback if one is used). This means that you can't provide any slack in the main line to facilitate hooking because the carriage will go bye-bye.

Enter the Clamping carriage. If you can lock the carriage to the skyline, then you can slack the mainline without the carriage taking off. This is the very first requirement for side yarding is to get the carriage to stay put while the main line is slacked. I have seen a couple of approaches to manual clamping carriages. One solution is to put a 'dog knot' on the skyline which serves as a carriage stop/latch. With this approach the carriage runs out until it hits the dog knot bolted to the skyline and it latches to the dog knot. The main line can then be slacked and the carriage won't run off because it is hooked on the 'stop'.

The main line, instead of being anchored to the carriage passes through the carriage and has the chokers on the end of it (with suitable butt rigging so that the main line won't pull through the carriage and come in without the carriage. The choker setter can then get some slack by manually pulling on the end of the main line and assuming he is strong enough and the rigging is light enough and close enough to the yarder, and the yarder brake isn't dragging, he can actually get some extra wire out of the carriage which he can drag off to the side to reach more logs. Once the logs are hooked, the main line is taken up, first pulling the logs to the carriage, and when the but rigging hits the carriage, it releases the latch and the carriage and the logs go on in to the landing.

An alternative to this, is a hydraulic clamping carriage. We have on of those and it simply has a hydraulic 'port-a-power' pump in it. You let out the carriage and drop the skyline to where the choker setter can reach it. He pumps the hand pump a few strokes which closes a hydraulic vise on the skyline. Then it works like the dog knot/latching carriage. Slack is manually pulled, and the clamp is released by the butt rigging. This design seems to have an advantage over the dog knot in that it is more flexible. The dog knot must be attached to the skyline ahead of time,, and if the yarder engineer misjudges the location of the dog knot, the result is not different from what happens in a rail road yard when a locomotive engineer is humping freight. In either case, however, the limitation is related to the ability of the choker setter to manually pull the main line (short distances, light rigging, and down hill all are factors in the feasibility), which of course brings us to the next classes of carriages that can actually pull slack under power instead of just making it possible for the choker setter to pull it manually.

Mechanical Slack Pulling Carriages

Danabo Carriage
Danabo Mechanical Slackpuller
Yarder Logging Side
Logging side With Skagit 3 Drum

The next class of carriages that need mention are Mechanical Slack pulling carriages. Everyone has had a better idea of how to do this, but the common thread of them is that one way or another they use a third line from the yarder to pull slack. A comon approach is to have 2 main line drums which can be locked together or operated independently on the yarder. Pulling on the third line can clamp the carriage and pull slack on the main line thereby providing a length of line extending from the carriage that can be used to reach off for side yarding.

The availability of this 3rd control line represents a major benefit of the triple drum yarder over the double drum machine. This means that the 3 drum yarder can work greater distances and be much more effective at side yarding than a double drum machine. The third drum also adds an element of cost to the operation, but for working distances beyond 5-600 feet the availability of this third control line is critical, though it may not be used for slack pulling. In a standing skyline configuration the operator may use a motorized carriage and use the 3rd line for a haulback on sides where a gravity carriage is not effective.

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Both Skagit and Washington made large 3 drum yarders in their day. They were purpose built machines. Shown on the left is a Skagit GT-4, one of the larger and heavier machines that Skagit made. Assembled the machine weighs 50 or 60 tons, and holds around 1500 feet of 7/8's wire on the yarding drums. As noted it is a triple drum machine with 2 yarding drums and a larger haulback drum. It has interlocks so the two yarding drums can be turned together while the pair take up wire or let it out under a interlock with the haulback/running skyline permitting full suspension logging, or alternatively the haulback can be locked, while the two yarding lines are moved in any out. Typically one of the yarding lines runs through the carriage and is doubled back and hooked to the other yarding line allowing you to pull slack in the second line. This ability to pull slack can be to lower a drop line for side yarding or for opening a grapple

Motorized Slack Pulling Carriages

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Maki Carriage Full Side
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Maki Engine Side
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Maki - Control Side
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Hatz Diesel Engine

The next level of complexity in carriages are the motorized models. Of the motorized carriages there are really to types. The light motorized carriage sometimes called a radio controlled carriage reflecting the fact that it is radio controlled, will contain within its innards about a 10 hp engine which does a number of things. It will charge a battery which runs the radio and will likely turn a small hydraulic pump and turn a few pulleys inside the carriage. Maki is best known for this type of carriage but others make them as well. On radio command, the carriage will clamp, and the motor will pull the slack in the main line providing an alternative to the third control line required of the mechanical slack pullers and an alternative to the armstrong slack pulling on the clamping only carriages. These carriages are pricey, but not as not as expensive as the next class of carriage.

The photographs shown here (along with those at the very top of the page) are of the Maki slack pulling carriage. Maki is simply the owner of an obscure machine shop in Pierce Idaho where these were made. Quite a few were sold in the early 1990's, and as I write this I have no idea if they are still in production or not.

The collective photos here are of several different units. They weigh just over 2000 lbs and are designed to pass intermediate supports. The plate of 4 photos show the insides of the carriage without the sideskirts. The model shown here had 3 functions. It could lock on the main line, lock on the yarding line, or pull slack. The clamp on the mainline was designed to fold off the line to allow the passage of shackles and intermediate supports.

The radio system was in the 475 mhz band, and was controlled by the yarder engineer or the rigging slinger. On this particular model the engine had to be started and stopped manually at the carriage. In the photo the actually control panel is dismantled, but it had a Key switch, a prewarmer indicator for the glow plug, and an idiot light for the oil pressure as if anyone could see it. Shutdown was manual with a jerkwire. The engine normally ran at a fast idle, but had a hydraulic throttle which pushed the engine to full throttle when pulling slack.

The engine has a hydraulic pump on one end and a mechanical drive for the slack pulling on the other end. There is no winch inside this unit. In the slack pulling mode, it just grabs the yarding line and feeds it through the carriage, paying it out the bottom end of the carriage. In this fashion it is not necessary to drop the skyline for the choker setter to reach the rigging, not does the choker setter have to pull slack all the way from the yarder to get any. Of course with the carriage elevated it is easier to pull the but rigging sideways than if it is laying in the brush.

Another advantage of this type of carriage is that once hooked, you the turn gets hung up, unlike other yarding systems, it is possible to back up on it under power. In a gravity carriage operation when you are taking the turn in you have 2 wires to pull. You can pull one or the other or both, but pulling is all you can do, though tightening the skyline is suppose to help you pop the turn over obstructions, but this is of little benefit if you are short on deflection (lift). With the Maki carriage if you get hung up, you can drop the turn, pull some slack and let the carriage roll down the skyline a ways,then you can lock the carriage to the skyline and go ahead on the yarding line pulling the logs backwards and hopefully out of the hang up. Particularly if you are side yarding, this will almost always reposition them so that it will be something else that you get hung up on when you go ahead on the carriage next time. Few cable systems offer the advantage of pulling backwards, and this is a big deal.

Motorized Drop Line Carriages

The last but not least in cost is the full motorized carriage. These are seen only in the biggest and heaviest of logging operations. The carriage itself weighs several thousands of pounds and their cost is fearsome, but they can support full suspension logging at great distances for very large logs. These carriages will have a 100 hp or more diesel engine in them and a winch which will lower a drop line onto which the logs are hooked. In this configuration you are essentially sending a single drum yarder out on the skyline, and when it gets out over the logs, it lowers the skyhook and the logs are connected. The drop line is wound in lifting the logs for sailing to the landing fully suspended.

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