Winches

I'm pretty sure the average B&S engine is governed at 3600 RPM full-throttle. That would give me 144 RPM at the drum, or 348 feet per minute. Waaaaa aaaay too fast.

I'm thinking perhaps 10 feet per minute?

Those Ramsey's and Warn's are for emergency use and work around the limitiations of 12 volt supply. Geared waaay down....

For a production winch, you might consider engineering your winch from the 'maximum line pull' point of view... take the torque rating of that engine and multiply it by the reduction down through your geartrain.. down to the effective working radius of your drum... and engineer to meet the line pull you figure you need....

Leave plenty of reserve..

A Couple other thoughts....

How are you clutching it ? Is there any give in the system ? (watch out for shock loads)
Does this winch have a brake.. to hold load...
and how are you gonna spool out ?

Sounds like a fun project.
-- bb

After considerable thought, and peeking at the balance in the ol' checkbook, here's how I plan to do it.

Prime mover will be a Briggs and Stratton 11 hp electric start twin. Entire assembly will be on a cart, which will be chained to a deadman, and used to haul a tri-hull catamaran sailboat out via a marine railway.

I will put a shaft mounted centrifugal clutch on the motor, and chain-drive with a 4:1 reduction to the input of a compact car transmission. My research indicates that 1st gear on most car transmissions run between 2.5 and 3:1. The output shaft of the trans will be gear-and-chain to the input of the winch, 4:1 reduction. The winch has a 25:1 planetary reduction.

Thus, with the transmission in first, assuming a 2.8:1 first gear, drum speed on the winch would be 4 RPM, with the engine running at rated speed of 3600. That gives me approximately 10 FPM line speed. That should give me plenty of grunt.

If faster line speed is desired, the transmission can be shifted. In high gear at 1:1, I get a line speed of about 30 FPM.

The transmission also gives me the option of power out.

The winch has a band brake and a ratchet brake.

Sure hope this works...

Using your figures of cascaded reductions of 4:1, 2.8:1, and 25:1 I come up with a total reduction of 280:1 which I then come up with 12.8 RPM at the winch drum when the engine is at 3600. It has been a while since I have done a power transmission system calculation but if I remember how to do it here are the figures I come up with based on your data. The engine at 3600 RPM and 11 HP would deliver 16 Foot Pounds of Torque that would result in a mathematical figure of 280 * 16 = 4,480 to the winch shaft, since you would probably use up about 20% of that torque turning all of those gears and shafts you will realize about 80% of that calculated torque at the winch say 3,584 Foot Pounds.
Using an Drum RPM of 12.8
At core diameter of 5.5" I calculate a capacity of 15,639 Pounds at 18.5 Foot per Min.
At core diameter of 9.25" I calculate a capacity of 9,299 Pounds at 31.25 Foot per Min.
At core diameter of 13" I calculate a capacity of 6,617 Pounds at 43.7 Foot per Min.

I can't guarantee the accuracy of these figures but I think they are in the ballpark. If the winch capacity will do the job I think your plan will work. If you need more capacity you will either need to use a double line on a snatch block or work out more gear reduction.

Hope this helps Tom R

'preciate the engineering. With the extra reduction, it should give me plenty of capacity. If not, as you said, we can always used a snatchblock and double the line.

Thanks again,

Paul

You are really getting into some serious winching capabilities. Do you have any idea as to what the rated capacity of your winch is? I sure you have considered this but I bring it up for safety reasons since I can't see your winch very well from this keyboard. But when I see the winching capabilities you are proposing I envision some pretty healthy Iron to withstand those kinds of forces.

Sorry about my goof up, Good luck with your very interesting project: Tom R.

• hilliardcorp

• gates

T_Bone

Look at the way a crane is rigged to lift maxmium. We 4part the head block for maxmium lift, two part for medium lift, single line for hauling butt.

T_Bone