SWL of winch cable

Submitted: Saturday, Mar 29, 2008 at 22:45

ThreadID: 56058 Views:4105 Replies:3 FollowUps:5

This Thread has been Archived

mitch

looking at a new winch , all the specs are there but no mention of the capacity of the cable itself.

A 10,000 lb winch with a snatch block for a double pull could give a mighty heave on a steep hill or well bogged 60.

Its not in the specs and l get a non confedent answer from the staff , it should be an easy to find thing on a new winch.

Back Expand Un-Read 0 Moderator Share

Reply By: mike w (WA) - Saturday, Mar 29, 2008 at 23:03

Saturday, Mar 29, 2008 at 23:03

Not sure if this helps, but as a guide in the absence of a definitive number from the manufacturer, if you know the diameter of the rope, you can use thie following equation:

Diameter x Diameter x 8 = SWL (in tons)

If there is a sharp bend in the wire i.e. damage, divide the SWL by one third

AnswerID: 295502

Reply By: John S (NSW) - Saturday, Mar 29, 2008 at 23:21

Saturday, Mar 29, 2008 at 23:21

mitch,

One would hope that the winch would have a cable rated to the winch itself. A 10,000lb winch has a SWL of 4500kg, with a typical cable diameter of 8/8.5mm. (12,000lb/5400kg - 9.5mm cable). In fact the cable would be rated just above the winch capacity.

Using a snatch block - then a 10,000lb winch has a SWL of 9000kg, but personally I try to keep under 80% of capacity for safety, and for less stress on the winch.

AnswerID: 295507

Follow Up By: Member - andrew B (Kununurra) - Sunday, Mar 30, 2008 at 08:38

Sunday, Mar 30, 2008 at 08:38

Gday Mitch, a snatch block should make little diferance to the load on the winch or the cable, as its operation almost doubles the pulling force, but in doing so also doubles the cable (their would be some losses and extra strains on the area of the pulley etc, but they would be minimal)

Where there is aditional stresses is at the anchor point, so if the cable goes from the bulbar to a tree to the winch, there may be 4500kg of strain on the cable, the winch, and the hook on the end of the cable, but there would be 9000kg of strain on the entire bullbar and the tree/anchor point at the snatch block.

Cheers Andrew

FollowupID: 561554

Follow Up By: obee - Sunday, Mar 30, 2008 at 16:43

Sunday, Mar 30, 2008 at 16:43

The same amount of work will be done but less load and more time.

Newtonian physics

Owen

FollowupID: 561630

Follow Up By: mitch - Sunday, Mar 30, 2008 at 23:02

Sunday, Mar 30, 2008 at 23:02

l cant see how a snatch block would do anything other than reducing the load on the winch buy giving it a mechanical advantage over the amount of work that needs to be done , the trade off is to halve the load on the winch and double the time.

lf there is 6000kg of resistance then the link between the winch doing the work and the tree or whatever we are pulling against , must have that load against it , no matter how many pullies or whatever we put in to lessen the load on the winch.

the same amount of work will be done in a greater time , ok ,but the link between the winch and the tree have to feel the 6000kg it takes to move the load

FollowupID: 561738

Follow Up By: Member - Andrew (QLD) - Monday, Mar 31, 2008 at 00:13

Monday, Mar 31, 2008 at 00:13

Adding a snatchblock to a wirerope winch also doubles the cable length unspooled, thereby allowing to apply a load closer to its rated line pull (based on the first layer of the drum) in some cases. As an example, a Warn XD9000 is rated from 4100kg (9000lbs) on its 1st layer down to 2990kgs if used on its 5th layer.

Andrew

FollowupID: 561744

Reply By: Member - Kiwi Kia - Sunday, Mar 30, 2008 at 07:52

Sunday, Mar 30, 2008 at 07:52

Hi Mitch,

Everything you want to know should be found at the following web site;

http://www.pirate4x4.com/tech/billavista/Recovery/index.html

Be aware that any termination splice or compressed fitting where a hook is attached will de-rate the actual SWL of the cable. I use synthetic cable myself, it's thinner, it floats and I can get a lot more on the drum.

AnswerID: 295518