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No Pulling Power

No Pulling Power

Posted by Dan Ekstrom on Jul 30th 2021

Performance LossesDoes it matter if your max line pull drops from 143,000 lbs to 64,000 lbs?

Have you ever considered that you can lose over 55% of pulling capacity simply due to wire rope and gear ratio options? The Allied W8L is a great example of this because it’s been in production since the late 70’s. Maximum line pull of the same winch goes from 143,000 down to 58,000 lbs which is a huge loss and worth looking into.

“Maximum line pull is the lessor of the breaking strength of the wire rope installed or the maximum power available from the tractor for the specified winch gear ratio. “

This statement above is key to understanding winch configuration and wire rope selection.

  • If you have 7/8” wire rope with a breaking strength of 64,000 lbs it doesn’t matter that the winch can pull 100,000+ because the wire will break once you exceed 64,000 lbs.
    • For those using anything other than a 100% efficient spelter/swage socket termination, there is also going be an efficiency loss up to 20% of pulling capacity. The wire may be rated to 64,000 lbs, but not all termination ends can hold the same loads as the wire rope. (Flemish Eye can reach 100%) 


  • If you have a slow speed PTO winch with gear ratio’s around 100:1 or slower, most dozers bare drum and full drum pulling capacity exceed the breaking strength of any wire rope on the drum. If you have a standard speed winch with gear ratio’s around 50:1 the tractor will run out of pulling power as the drum fills with rope. In this case the pulling power of the winch is limited by the torque available from the dozer

Note: If you have a Hydraulic winch, the gear ratio and tractor power have impact like a PTO winch, but not as much. A large powershift type crawler dozer may have a very small hydraulic system making winch performance poor. A hydrostatic drive crawler may have a very large hydraulic pump giving the winch hydraulic drive motor a lot of pulling power. Regardless of the type of crawler being used, and regardless of how slow the gear ratio is, hydraulic winches traditionally loose around 30-40% of their max bare drum line pull as the wire fills the winch drum.

  • -On large drum winches like the Carco HCH100 bare drum pulling power is 100,000 lbs, but full drum only 36,000 lbs. It’s rated for 1-1/4” wire rope, but you really only need ¾” wire to match the min line pull and you could nearly double the length capacity of the drum.


  • Termination:
    • For pulling power, the best wire termination is the Spelter Open Socket w/pin, but it’s heavy, bulky, and can be difficult to work with in certain applications.
      • For the best balance between convenience and power, we recommend the Flemish Eye because they are versatile and often test with higher than 90% efficiency. Some applications do not work with a eye(loop) at the end, but if you’re unsure what end to get, we recommend the Flemish Eye as a great start.
    • Wire Size: Size the wire rope for your application on what you plan to pull. On a recovery winch this usually means the maximum wire diameter allowed for the drum and approximately 2/3 capacity of length so make sure the wire fits on the spook if not wound perfectly. On a logging winch or special application winch sometimes this means you’d rather have a longer length of smaller diameter wire rope, especially on a faster gear ratio winch with less pulling power.