Winches come in many designs, from tiny, lightweight hand-wound to enormous installations that may need one hundred person-hours or more to wind up and power.
Capstan winch is a type of winch that works on a capstan and shaft mechanical winching model.
Capstan winches are considered cheap alternatives to conventional rope and chain systems, but also their simple construction and fast performance have gained wide application in different situations.
The axial flow motor drives the wheeled mechanism by means of coupling gears, making the operation speed faster than other types of winches.
Best Points Of A Capstan Winch
The best torque at low speed is its strong point.
Because of this design, the torque could be built-up quickly with lightning spool load; this allows them to handle very difficult operations with heavyweight loads, especially those having small bearing surfaces.
They can work without difficulties on dead weights even when one gear gets stuck on another gear or cable winding head.
Therefore they have a good start/stop function which reduces downtime considerably.
Furthermore, they are considered compact construction because they use basic components such as no transmission chain, clutch plate, etc.
Our design offers reliable working at extreme climatic conditions.
It uses fully shielded motors that operate even under ice-covered wheels and drives with strong shafts and minimal heat dissipation due to steel cables running through ducts made of carbon graphite materials.
This makes it highly immune to electric shocks and solid contaminants entering its sensitive moving parts.
The continuous rotational speed could be changed easily by adjusting the gearbox output ratio with adjustable brakes or drum motors to maintain constant high speeds under variable loads.
Why To Have One
Self-Start
When the line becomes loose from a bollard due to boat pitching or just wind drifting, a manual push-button switch triggers a capacitor discharging circuit in the drive system, igniting the motor’s self-starter winding.
Thus, it rotates quickly enough to re-tension the cable line and relieve it from tensioning device (main stop brake).
The rest of the procedures follow our model installation procedure manual.
No Friction Loss Of Movement
- As all power is delivered by motors directly from the ship’s engines
- There is no slippage between transmissions or gears in motion
- As in common diesel motors
- Thus the motor doesn’t consume fuel at constant torque mode
- If the load does not change significantly during rotation
- Its idle mode is more efficient than standard engine idling
- even though both provide similar torques
This could save huge fuel expenses in huge long sailing distances and seasons with less expensive fuels
Lubrication System
A pressure lubrication system supplies grease through two nozzles inside a large hollow piston connected to the main shaft of the motor.
where its centrifugal force allows lubrication on demand through port valves inside a rubber hose extending out from the unit’s end cover.
As an added advantage of such a lubrication system, grease being carried by oil jets blows back into the piston cavity from ports along its perimeter during operation, thereby flushing away foreign material like fine sand particles, etc.
Thus providing longer operating life for bearings and their clearances.
In many marine applications, this feature may also help extend gearbox service life by allowing easy flushing of heat-affected parts without lubrication every time the gearbox has to run dry.
Moreover, this feature prevents dirt ingress into the gearbox, which could otherwise increase noise level or lead to premature wear of moving parts due to sticking friction between metal surfaces and gearing due to dirt deposits on those surfaces.
Advantages Of Capstan Winch
Capstan Winches offer several advantages over hydraulic systems for hoisting heavy loads in seawater:
- These Wines have far fewer moving parts than hydraulic winches and hence can work at greater speeds and for longer periods without mechanical wear or trouble.
- Due to lower energy losses, they require less maintenance than hydraulic winches. Winches use considerably less fuel than hydraulic winches, and they are safer as no open flames are involved.
- They offer increased productivity compared to other winches due to easy manoeuvrability and reduced drag while lifting heavy loads.
- Moreover, due to the ability to be driven with either standard diesel engine starters or permanent magnet AC motors, these winches can be used in different marine environments with minimum equipment modifications
Types Of Capstan Winches
Several capstan winches are based on different technologies, i.e.,
- Electromechanical
- Magnetic
- Electromagnetic pneumatic
Electromechanical Capstan Winches
Electromechanical capstan winches utilize a series wound DC motor coupled to a speed reducer, driving the winding drum through reduction gearing.
Speed reducers usually consist of worm gear arrangement or harmonic drive system, which increases its output torque by up to 20 times while reducing its speed by 5 times.
These motors need to be rated high enough for both load and duty cycle requirements to achieve the required power ratings.
This will mean large space requirements, low efficiency, and large start-up inertia requiring large electric starters, requiring special air cooling systems to prevent overheating.
Such systems also suffer from vibration problems in harsh marine environments, oil leakage from gearboxes, and the very high initial cost of capital equipment and installation costs
Magnetic Capstan Winches
On the other hand, Magnetic capstan winches have a small AC induction motor permanently magnetized by induction magnets fixed on the motor shaft and hence require no starter or alternator to function.
Due to this unique energy conversion method, there is no reduction gearing or belt drive between motor and drum, thus making them the most efficient capstan winches in the market.
The main disadvantage of magnetic capstan winches is their small duty cycle capacity as they are most suitable for very light loads only.
In addition, due to lower rotational speed, they require bigger gearboxes than conventional electric motor-driven capstan winches, thus increasing the overall cost of operation
Applications Of Capstan Winches
As discussed earlier, there are numerous applications of capstan winches in many industries, including
- Marine
- Offshore
- Mining
- Petroleum
- Shipbuilding
- Towing
- Industrial
Offshore Vessels
Capstan winches are preferred for offshore vessels because of their ease of maintenance, better mechanical efficiency, and superior corrosion resistance than conventional hydraulic or pneumatic systems.
However, one needs to bear in mind that despite their superiority over conventional systems, they still need an ample electricity supply for the long run.
This will be impractical for those applications where the low-frequency current is not available.
They are, however, highly recommended for loads such as boats that may stay idle for months together with large ships with few sails or smaller cargo ships that travel mostly during daylight hours.
Crane Systems
Capstan winches can be considered as part of crane systems. The load hoisting system includes multiple pulleys with tensioned wire rope attached to each pulley.
Wire rope ends fixed on clevis hooks and cranes fitted with different sized sheaves at different points along with its boom and load hooking means.
which helps to tension the wire rope from the bottom end as the hoisting system operates from the top end.
The method is advantageous because there is no danger of tangling or mishandling.
Therefore, these systems are often used in the coal mining industry. Where capstan winches are most suitable because of their safety, versatility, and low maintenance costs.
The wires attached to the hoisting drum using sheaves help to make it easier to remove the loaded parts without putting undue stress on the system.
Because they do not directly haul on the hoisting drum but pull it down through sheaves. Thus saving in consumption of energy.
Most cranes, however, use pneumatic cylinders instead of electric motors to move the sheaves up and down. It allows more flexible operation and handling of heavier loads than other methods.
Still, due to the high-pressure air supply, regular maintenance is necessary
Marine Usage
Sailing vessels like racing yachts or pleasure cruisers generally require frequent winding and topping up their electrical batteries.
Capstan winches come in handy in such conditions. As they provide an automatic method of managing such situations by helping to replace batteries quickly without manual assistance.
And provide full power in a very short time when recharging is required.
Bowlines used for mooring purposes also need frequent attention because they tend to slacken over time due to weathering effects.
When capsizing happens, capstan winches save them from drowning by wrapping around them. Keeping them safe from slipping into the water.
They can thus assist ships at sea with lowering anchors in heavy weather conditions. It rescues them during storms, avoiding vessel collisions, etc.
They can also be used for dragging anchors or picking up drifting objects such as bottles etc. The tension maintained by these devices can also be utilized for deploying booms.
And tarpaulins for loading or unloading cargoes or even preventing fouling by trawling with similar cables or other accessories
Conclusion
For many purposes, capstan winches have become an indispensable tool. That enables easy deployment of boats with
- Less effort
- Lowering anchors
- Unloading cargoes
Without such tools, the sailing craft will remain docile only while under sail.
But without further flexibility or adaptability when it comes to operations, running under oars, or operating different equipment simultaneously. So having one is a basic necessity for many heavy loaders.
I wrote a complete article for you that will be helpful in benefits and applications of capstan winch it may have a detailed information on working of capstan winch. And i also discuss about the mechanism of capstan winch.
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