Before you do something you might regret to your traps I'd like to direct you to this on Hal Sullivan's Trapping Archives #9769, 8/12/06. You'll find all the illistrations there.
PIT Pan Tension Systems - Principles and Observations
I first saw the PIT (Paws-I-Trip) Pan system at an NTA Convention in the early 1990's. I really like this system for big traps and big animals. The PIT system creates pan tension simply by leverage. It does not require friction, or the tightening of a nut and bolt, to create pan tension.
But it still remains a mystery to most folks as to how it works. I?ve tried to explain it a hundred times. But now I'm am going to take opportunity of this media to try to explain this with the use of some visual aids.
Illustration 1
On a normal trap, the notch or release point of the pan/dog is directly above the hinge point (blue dotted line). Here a minimum of pressure on the pan is required to move the pan downward and release the dog. In order for us to get some "tension" on that pan, we have to install a nut and bolt at the pivot point and tighten it.
Illustration 2
In order to understand the PIT leverage system, it may be helpful to look at something entirely opposite. Look at the illustration above. If you had a pan system that had an engagement point behind the pivot point (closer to the jaw) -- that trap wouldn't even stay set. Look how the dog would just "upend" the pan, and fire the trap of its on accord. (I once bought some traps like this! )
Illustration 3
Now look what happens if you move the pan/dog engagement point on the other side of the pivot. While before the dog was trying to "up end" the pan, now it is trying to "pick up" the back of the pan. It is actually pulling the pan up in the air. This "pulling up" leverage is what gives you the frictionless pan tension.
Illustration 4
In order to hold the pan in place, and keep it from riding back up on the dog, a PIT dog has a bump on the end which serves as a mechanical stop. However, the bump on the dog is not the defining feature of the PIT system. If there is no mechanical advantage, there is no PIT system.
The advantage in the PIT system is that it doesn't require friction, making it very consistent from one time to the next. There is nothing to go out of adjustment. The disadvantage in the PIT system is -- there's nothing to adjust. What you see is what you get. This is why I find PIT systems more adaptable to large animals. The heavy pan tension needed for large animals is hard to maintain with a nut and bolt.
There are a number of things that will influence the resulting PIT pan tension. Spring strength is one. Stronger springs mean more tension. Four-coiled PIT traps will have a higher pan tension than 2 coiled.
Illustration 5
Another major influence is where, between the eye of the dog and the engagement point, the jaw actually lies. Given a dog of equal length, the further the jaw is from the eye of the dog, the more force it will exert on the pan. This can be a consideration especially with inside laminated or wide faced jaws.
Illustrations 6
There is one other way to change the pan tension. If you can move the engagement point back a little closer to the pivot, the pan tension will decrease. Again the problem is that these systems are not adjustable.
I could be mistaken here (but I don't think so). I think that all the PIT pans are spun off one die. This is the one that establishes the "kicked back" legs which moves the engagement point forward, thus making the pan tension. And that is designed to produce about three or four pounds of pan tension given "average" circumstances. This is the pan you'll see on a #5 or a CDR. From this point forward, the remaining pans are made simply by cutting down the target area of the #5 pan.
These pans all have different target areas, but note that the legs are all the same.
I do realize the economy of this enterprise. Dies ain't cheap. But if there were a second pan, with less angled legs, as in the middle on Illustration 6, it would be more suitable to lighter pan tensions. Say the two pound range.
Of course if you move the engagement point all the way back to the pivot point, like at the bottom of the illustration, you no longer have any leverage advantage at all.
Illustration 7
Another way to increase or decrease PIT tension is ostensibly by bending up or down on the end of the dog. But this has its limitations.
(continued
Last edited by Seldom; 10/12/21 09:19 AM.
