arnd
CHOKER SETTER
Posts: 79
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Post by arnd on Aug 18, 2012 23:38:34 GMT -8
Hi all Sorry it’s me again with some technical questions. As far as I am not working in the timber industry I have my knowledge about logging trucks from pictures and articles. I want to know a bit more about the head and the hitch between the truck and the trailer. I know that the reach has to have the possibility to get longer and shorter when the trailer is hooked up and loaded. On the next photo we can see that the hitch on the truck is so build that it can move out and in. Does it have a spring to get back in the “in position”? Then I can see a pin holding the hitch in position. What is the use of it? Thanks a lot for your efforts. So long Arnd
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Post by Ryan Rønning on Aug 20, 2012 9:07:16 GMT -8
No there is no spring to pull it back in. The trailer straitening back out after a turn will push it back closed and vice versa if the compinsator were mounted in the reach of the trailer.
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Post by tufftin on Aug 20, 2012 12:04:28 GMT -8
Kind of a goofy looking hitch set up. To short for a log truck. You need a stinger 3 or 4 feet out from the rear of the frame. On the trailer is a simple "O" to hook into the pintal on the truck but the "O" is attached to a compensator pin that can stretch out of the reach to make corners. This is known as stinger steered. Hope this helps a little. Mike
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Post by Muleskinner on Aug 31, 2012 19:56:29 GMT -8
Arnd,
That is a common old style Link and pin wrist mount used on older off Hwy rigs here on the West Coast and else where. It iis made to where it will move in and out and will turn completely around in its socket when the wrist pin is pulled on it which is in the second photo with the flat top ring. This one is made for a heavy trailer with coupler guides on top and bottom to assist in getting the heavier trailer reach coupled to the rig. (The Two outward jutting fingers, which are actually guide trays.) Once the trailer is coupled, then the wrist pin is pulled.
Becuase of the massive top heavy loads which an off Hwy rig carries, This coupler design was implimented so as to keep the main rig up right if the trailer was to go over on its side. the coupler in the tail of the rig would swivel around in its socket and add a magin of safety to keep the tractor upright, unless of course the trailer went over a hill which is bad news for rig and driver. On your top picture you can see where the cap, which is hidden back by the drivers has slammed at on time into the pivot point and caused a dent in the top of it.
The trailer reach also has a long swiveling compensator going up into it with the loop couple attached to it which helps in the steering of the trailer around corners and keeps it fairly in line with the main rig. This unit is also pinned in the travel position and unpinned in the haul postion. If the trailer is to return to the woods in the down position the driver would merely back the rig up until the compensators of both truck and trailer were pushed back in side and then take a Hogger Bar and rotate the coupler until the pins could once more be reset thus locking the compensators in place.
This is a very old set up and was eventually replaced by the longer stinger which Mike mentioned, that did away with this type of coupler. But they did last a while even after the change over. I can remember seeing these same type couplers on GP and PALCO rigs in Northern California on a few rigs back in the early Sixties, but even they surcomed to the newer type Hook and loop pintal type. Hope this helps a little bit in answering your question.
William
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Post by tufftin on Sept 1, 2012 8:27:51 GMT -8
Today, with a compensator, the trailer could go over and the truck reamain up right.. Mike
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