Gear Winches
Gear
winch is a stationary machine, which is either motor driven or hand powered.
Winch is a kind of mechanical device that is used to turn wire rope about
something fixed. A simple gear winch consists a spool and an attached crank.
Another name of the spool is winch drum. In a complex form of winch, a winch
consists gear assemblies and these gear assemblies are powered by hydraulic,
electric, internal combustion or a pneumatic drive. Solenoid brakes may also
be there in some gear winches. Apart from solenoid brakes, there may have
ratchets or mechanical brakes.
These brakes prevent the winches from unwinding. It is used for either
raising-up or for dragging/pulling the load. It has a drum around of it
which is warped a chain or rope attached to the load that has to be moved.
The drum (spool) around of the gear winch must be movable and a drawing
force is generated when the drum starts to rotate. The force is produced at
the end of the chain or the rope. Another similar device like the gear winch
is a windlass. The only difference between a winch and a windlass is that
windlass is always hand driven, but gear winch may be motor driven also.
Therefore, a windlass is less sophisticated than a winch.
Peripheral Devices of a Common Gear Winch
The normal devices which are attached with a winch are: a ratchet wheel and
a pawl. These two devices prevent the load from being slipped. The other
devices which are also equipped with a winch are:
- Brake It helps in controlling the rate of coming down of the
load.
- Hoist It helps in the movability of the winch. Example, A
traveling crane, in cargo controlling like in factory, ship, warehouse.
Applications of Gear Winches
Gear
Winch is used in a car puller with a vertical drum axis. It is used in
positioning the railroad cars in freight yards. Another category of winch is
engine-powered winch and this type of winch is used in certain construction
vehicles and military vehicles which are used for off-road purposes. As an
element of backstage machine, winches are used quite frequently. Here,
winches are used for lifting and moving large scenery. Winches are often
fixed into the stage floor and used in moving large set pieces on and off.
Along with industrial applications, winches are also used in cars, gliders
and boats for towing purpose. Almost on every ship or boat, there are
several winches. The winches in ships and boats are used for pulling anchor
or mooring lines, sheets and halyards.
Calculating Winch Power
The winch power is calculated in the following process: Calculate the
fore-triangle area in sq.feet and then multiply it by 6. Fore-triangle area
means the bounded area by foredeck, forestay and mast in sq.meter. Now,
divide the product by 35. At the time of multiplication, number 6 is taken
because 6 accounts for sail force and frictional force. At the time of
division, number 35 is taken, because the maximum input force value in pound
is 35. The final result that will be obtained in this way, will be the
optimum rated mechanical advantage in the second gear (low gear) of a
optimum powered winch. Say for example, if the fore-triangle area is 300
sq.feet, then multiply it with 6: 300*6=1,800. now, divide it by 35. the
quotient will be 51.4. It means that the winch has advantage of 50:1
approximately. Similarly the calculation of the maximum handle load on the
winch, more or less is same as to winch power calculation. The only
difference is that despite of fore-triangle area, sail area has to be taken
into consideration.
