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Hi all I have a fair amount of oak log to fell, Done a bit just skidding behind the tractor but as we seem to be getting more of this sort of work I am thinking of getting a 3 point linkage winch. But am not sure what size or make to go for? Any advice would be great!

I am in the process of understanding and selecting winching equipment. I want to ensure that the equipment I put together is all compatible and fits in with best practice guidelines. Ultimately I can see several sets of equipment being helpful given the different sizes of challenges winches can be applied to. I am considering the Tirfor with a working load limit of 1600kg. I understand that this winch is designed to fail at 50% overload via a shear pin. This should mean that the pin fails at 2400kg. Is this correct? As I understand it strops, shackles and pulleys are designed to fail at 400/500% overload. For example a 2000kg strop in good condition and used 'sensibly' shouldn't fail before its loaded to approximately 8000kg. Is this correct? Given the redundancy (reserve strength) in the pulleys/strops and shackles etc.) is a much bigger margin is it considered acceptable/good practice to put together 'sets' of kit together based on the redundancy or not? The winch obviously gives a mechanical advantage. When a more powerful pull is needed it is possible to use pulley systems. I have some concerns about the extent these systems dramatically increase the loads on the equipment. If I understand this correctly a two to one system based on the 1600kg winch, factoring the 50% overload can have parts of the system stressed to 3600kg before the shear pin fails. If a similar but three to one system is used part of the system can be stressed to 7200kg before the shear pin fails. I know that there are other significant factors. Including stretch, friction, wheel size in pulley etc. I am new to working with pulley systems and winches in the world of tree work. I suspect that a direct or redirected pull is most commonly used. If I understand this correctly, when a pull is simply redirected, for simple figures the maximum pre failure load in the system will be less than two times the failing capability of the winch. In this case 4800kg. (two times shear pin failure load) So, more questions: I can see a case for not using pulley systems with the mechanical advantage being already generated by the winch. In reality how often (if at all) are two to one and three to one systems used? How do I select kit to be inline with good practice? I am also interested in ensuring the right pulley selection for the cable and know very little about this. What would you good people recommend and and where can I obtain them? Any other thoughts/suggestions appreciated. Thanks for any help David