This thread reminds me of other safety aids that have been tried. Back in the days before plows with automatic reset bottoms, hooking a big rock would bend/break the plow. The first attempt at a fix was the latch type plow hitches that would unhook when a obstruction (big rock) stopped the plow. The problem was that with rocky ground, you had to back up and re hook the plow and trip rope/hyd hoses, that got old real fast if it happned 3-4 times per round. One fairly good working fix was the locally built "Steinman hitch" This was a telescoping plow hitch with huge coil springs in it that would allow the hitch to streach when you hit a rock. There was a cable and pulley affair that connected to the tractor clutch linkage that released the clutch when the plow struck a rock and the hitch telescoped. This worked pretty well with a few exceptions,one was the two cyl JD tractors with that long "crow bar" clutch lever. You quickly learned to keep your right knee out of the line of travel of the clutch if you had a Steinman automatic declutcher installed. all it took was one time of being whacked in the knee by that big steel lever when the Steinman declutcher jerked it to the release position.The Steinman automatic declutcher hitches had an extra little latch affair for the foot clutch tractors to hold the clutch in the realeased position after striknig a rock with the plow. The memory of my BIL trying out his latest proud auction sale find leaves me laughing every time I think of it, even 30 years later. He hooked his Steinman hitch equipped auction sale plow to his W9 IH tractor and headed out to do a little plowing. He rigged the clutch release cable to the W9 foot clutch pedal,but being the plow used to be pulled by a 2 cyl JD, there was no clutch release lock. BIL did not think he needed that,after all, he would just put his foot on the clutch to hold it released, right?. Everything went just fine until the plow hooked a big solid rock,the hitch telescoped and released the W9 clutch. From that instant on, things went very badly. BIL had no clue how quickly those big springs in the plow hitch would pull the W9 back once the clutch was released. The tractor/plow went into an about once per second cycle of release the clutch, roll back which reenguaged the clutch,leap forward until the clutch released. That old W9 would have made the meanest rodeo bull look tame. It was all BIl could do to hang on to the steering wheel while the tractor wildly bucked until the rear wheels dug holes deep enough to high center it. That setup never ran again until the correct clutch lock was installed. ;-))))
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