capstan winch has a 8 or 10 sided drum and was designed for laid rope,
not multiplait (multiplait should be used on a smooth drum). Manilla
(a sort of grass) is best for hauling since it will stretch before breaking
unlike hemp. Generally synthetic ropes should not be used as the heat
generated whilst it is slipping can melt the rope and damage it. The
only disadvantage of capstan winches is that the engine must be running
to use it.
- Light weight.
- Easy to use. 100% reliable, works under water or mud.
- No drain on electrical system.
- Precise control of the load and line speed - in or out.
- It's a working winch - you can use it all day long.
- Difficult to use if rope is wet or frozen.
- Only works if engine is running.
- Must be engaged with the engine stationary, though it can be disengaged
- Line pull limited to 3,000lbs on some versions, though this can be
almost doubled with a snatch block.
There are two shear pins on the Fairey winch: One is part of the drive
shaft to the winch from the starter dog, one is part of the capastan
itself. The first one is the weakest one of the two.
They are not too difficult to replace, so long as you get the outer
and inner parts of the shaft (which the pins connect to operate the
winch) lined up, and so long as you can get at the underneath of the
winch (i.e. just in front of the front chassis cross member). You can
easily line up the holes using a steel version of the shear pin, which
you can make up yourself. Such a pin will also allow you to hand crank
the engine without risking breaking the shear pin. It should not be
used for winching of course!
You should be able to winch 1.5 ton objects up steep 1:2 or 1:1 slopes,
with a thick nylon rope. The farey capstan winch, if used with a steel
shear pin has a load capcaity of 10 000 Pounds!
Take 3 turns upwards round the capstan and tail the rope from the side,
far enough away in case anything lets go. When in use with proper rope,
you will find that the the turning of the drum as you tail the winch
will cause the turns of rope to ride up. The further up the drum the
rope goes, the steeper the taper becomes, so the top turns of rope bind
tighter onto the lower ones. This reduces the force you need to put
in tailing. Most capstans on ships have a limit to the torque they can
generate, either because of the motor power if electric or steam, or
a pressure relief if hydraulic. The Land-Rover one has, as far as I
can remember, a shear pin. Rather terminal!
Note: If you use mm, then you are talking diameter, but if
you talk inches then it is circumfence. So, a 3/4" rope
will be rather small, about 6mm diameter actually. You should want something
like a 20mm rope.
HEMP / MANILA:- Since both these are made from natural materials, they
tend to rot with age and their strength can be adversely affected with
no visible signs of deterioration.
NYLON / Terilyne:- Good strength but too springy/elastic,
the outer covering will melt due to friction on the drum.
Kevlar:- Excellent strength, no stretch, does
have a synthetic outer so it will melt under heavy friction, when it
snaps, it goes with a bang, suddenly.
Poly cotton/terilyne inner:- Like that used by
Yachties for "sheets", High strength, low stretch, soft to
handle, not cheap.
Never use wire on an ordinary capstan, wire should be greased to preserve
it and it would not drive properly, it will not bend tightly enough
if of large enough diameter for the capstan, the turns can bind or lock
preventing you from releasing it, and it will quickly wear out the ridges
on the drum. The main reason is safety though, imagine a snapped cable
with you standing in front holding the tail end!
After a short while, wire will form into coils as it
wraps round the drum, thus becoming awkward to handle and sprigs of
wire will break, shredding your hands in the process. Also the friction
of a rope round the drum is greater (3 turns) than you can get with
wire, and far more handleable.
BT cable pulling gangs use 16mm dia. poly covered kevlar stranded rope,
SWL 3Tonnes, that should be enough for most people.