Disassembly
Find an old box and cut a 4 3/8” diameter circle out the bottom.
Then lodge it in place over the winch.
Insert a 3/16” hex key into the capscrew that you can see when looking down into the winch and loosen it completely.
Do not remove the capscrew or its retaining washer: leave them in place.
Grip the drum itself and pull upwards very gently with steady force: do it slowly as you want to prevent pawls or pawl springs suddenly jumping out. Place the drum to one side in an upright position to prevent the loosened capscrew from falling out.
Slide the washer off the top of the base and place it aside.
Compress the pawls with your fingers and slide the top bearing upwards over the pawls. This may require some steady force as the old grease may tend to hold on to the bearings.
Remove the bearing completely and repeat the process for the bottom bearing. Place the base and pawls in a plastic sandwich bag and use a pair of pliers to pull the pawls loose through the bag. The pawl springs will most likely jump out unexpectedly: but the bag should catch them.
This is a close-up of a pawl and spring.
Your parts inventory for the base should now be the base, two pawls, two pawl springs, two bearings and a washer.
Now disassemble the drum (it was put it aside after loosening the capscrew) by slowly turning it upside-down so that the capscrew and its washer falls out:
An aside: While the drum is upside-down, take a close look to how the pawls in this top part are positioned. You’ll notice that the pawls are currently each seated in a ratchet slot inside the drum – as the top cap (the part holding the pawls) makes a full revolution, one will hear 12 clicks as the pawls snap into place.
Hold the top cap (the part holding the pawls) down with something like the handle of a screwdriver while gently pulling the drum itself upwards.
Carefully remove the pawls and springs (just as you did with the base) using a sandwich bag.
Your parts inventory for the drum housing should now be the drum, two pawls, two pawl springs, the topcap, the capscrew washer and the capscrew itself.
Clean the parts
Wash all the parts in kerosene. Use a toothbrush to remove old grease from the small rollers on the bearings. Wipe the parts dry with a lint free cloth.
Inspection
Inspect all the parts for damage, loose ratchet pawls or excessive wear. Spare parts can still be obtained from Hutton-Arco Winches in Australia. Their web address is http://www.huttonwinches.com/products/spares but other winch repair kits may also be suitable.
Lubrication
Sparingly lubricate all mating parts and bearing surfaces with a marine waterproof grease. Avoid greases with added ‘Teflon’. Lubricate the ratchet pawls and springs with a drop or two of SAE 30. Avoid grease in the ratchet pawl areas as grease will deteriorate over time and interfere with the operation of the pawls.
Re-Assembly
Slide the two bearings onto the base.
When assembling the pawls and springs note that one leg of the spring is tangential to the circumference of the spring while the other leg is perpendicular:
Also note that the tangential leg is shorter than the perpendicular leg. Be careful to place the shorter, tangential leg in the slit of the pawl when assembling.
Assemble the four pawls and springs and place two in the base and two in the topcap. Repeatedly flick the ratchet pawls to ensure free operation.
Raise the one bearing while depressing the two pawls on the base so that these pawls are held in their seated or depressed state.
Lower the drum over the base and push it down gently — the top bearing assists in engaging the pawls in the drum ratchet and it’s then pushed down by the drum into its normal position on top of the lower bearing.
An Aside : Note that only one of the two pawls is seated in a ratchet slot at a time, while the other one is halfway between two slots. So as the drum makes a full revolution around the base, one will hear 24 clicks as each pawl in turn snaps into place in a slot. Unlike the pawls on the topcap (which are exactly opposite each other and cause 12 clicks to be heard per revolution as discussed earlier), these pawls on the base are not exactly opposite each other:
Continuing with the assembly, proceed by placing the washer on top of the base inside the drum.
Wrap a strong cotton thread around the pawls in the topcap and pull it tight so that the pawls are in their seated or depressed state.
Lower the topcap into the drum: when it is nearly seated (and the pawls are now inside the drum ratchet area), relax the tension on the cotton thread.
Gently pull the cotton thread out and seat the topcap completely.
Insert the capscrew and its washer and tighten with the hex key.
Operation
Check the operation of the winch.
The base is fixed in position and by looking at the pawls when disassembled one can tell that the drum can only rotate in a clockwise direction around the base making 24 clicks per full revolution.
After the topcap is inserted, its pawls have exactly the same orientation as the pawls of the base as seen here (but they ratchet on the upper half of the drum’s ratchet slots):
But unlike the base, the topcap is not fixed and can therefore rotate inside the drum at 12 clicks per full revolution in an anti-clockwise direction. In a clockwise direction it will push against the drum’s ratchet slots, thereby rotating the drum — you’ll hear the base’s pawls clicking at a rate of 24 clicks per revolution. Of course, the topcap is rotated by using (or grinding) the winch handle.
As the topcap’s two pawls are engaging the drum ratchet slots simultaneously, there is an even and strong load distribution.
Mathematics
What follows applies mostly to this Barlow 16 Top Action Ratchet Winch and the Ericson 25 sailboat.
The size of the jib is about 140 square feet. In 20 knots of wind the load on the sail will be:
Load = .00431 * A * V ^ 2
where A = Sail Area and V = Windspeed
Thus, Load = .00431 x 140 x 20^2 = 240 lbs.
The radius of the winch handle is 10 inches while the radius of the winch drum is 1 ¼ inches thus giving a power ratio of 10 / 1 ¼ = 8 (this winch has no gears: the gear ratio in other winches would amplify this power ratio).
Once you have a few of turns of the jib sheet around the winch drum, you should be able to control the jib easily with just a minimal 30 lb. (240 lb. / 8 ) application of force on the winch handle.
The question now arises, how much holding power will the winch drum have on the jib sheet? Or, to put it another way, how much force will the cleat be expected to hold once the jib sheet is cleated off?
Too few turns on the winch drum will mean that the cleat will be expected to hold too much force.
Too many turns on the winch drum will mean that the sheet will not run out when one lets go of the cleat end.
The simplified formula for computing this holding power is based on the Capstan Equation (see Wikipedia):
H = 100 / e ^ (2 * π * t * f)
where H = holding force: percent of load force required to hold the load, e = 2.718,
π = 3.1416, t = number of full turns, and f = the friction coefficient.
The counter-intuitive aspect of this formula is that the size of the winch drum and the sheet’s diameter doesn’t matter at all!
A small or large winch, a thin or thick jib sheet, the holding force calculation is all the same: it only depends on the number of turns of the jib sheet around the winch drum and the friction coefficient between the sheet and the winch drum.
One way of looking at this is to realize that the friction depends on how tightly the surfaces of the winch and the sheet are pressed together. With a small diameter winch the sheet’s surface against the winch is more compressed than on a larger diameter winch – and this increases the friction. On the other hand, less of the sheet is actually on the drum of the smaller winch and this decreases friction. These two tendencies apparently exactly offset each other.
Here are the results, tabulated:
Assuming a coefficient of friction of 0.3, the jib sheet’s pull of 240 lbs will require the cleat to resist a pull of 15.2 % of 240 lbs. = 36.5 lbs with one turn around the winch. With two turns around the winch, this reduces to 2.3% of 240 lbs. = 5.5 lbs.
Notice how very quickly a single extra turn reduces the required holding force.
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