Winch

[|Winch] - a mechanical device that is used to pull in (wind up) or let out (wind out) or adjust the "tension" of a rope or wire rope or cable.

In its simplest form it consists of a spool and attached hand crank. In larger forms, winches are the main component of machines as diverse as tow trucks, steam shovels and elevators. The spool is also known as the winch drum. More elaborate designs have gear assemblies and can be powered by electric, hydraulic, pneumatic or internal combustion drives. Some may include a solenoid brake and/or a mechanical brake or ratchet and pawl device that prevents it from unwinding unless the pawl is retracted.

Earliest wooden winches were used to tighten the cables for a pontoon bridge across the Hellespont in 480 B.C. By the 4th century BC, winch and pulley hoists were in common use for building.

[|Crane] - a type of machine, generally equipped with a hoist, wire ropes or chains, and sheaves, that can be used both to lift and lower materials and to move them horizontally. It is mainly used for lifting heavy things and transporting them to other places. It uses one or more simple machines to create mechanical advantage and thus move loads beyond the normal capability of a man. Cranes are commonly employed in the transport industry for the loading and unloading of freight, in the construction industry for the movement of materials and in the manufacturing industry for the assembling of heavy equipment.

Winches are used in many applications
 * boating - adjusting sail trim, dock lines
 * towing - pulling vehicles to safety
 * [|gliding] - Powered-aircraft and winches are the two most common means of launching gliders. These and other launch methods require assistance and facilities such as airfields, tugs, and winches.

[|Winching with Synthetic winch rope (video 2:25)] - In this case, the vehicle was positioned for the demonstration so it could be winched out but not driven out forward.
 * What's the problem?**
 * **Ask** -  The vehicle is equipped with a winch on the front. How does the driver use the winch to get out of the ditch?
 * **Imagine** - For off-roading, drivers have to rely on themselves and the equipment they have with them. What types of equipment would be useful? Can it be designed to be carried in the vehicle at all times? Does the need for this function justify the cost?
 * **Design, Build** - For the winch to get the vehicle un-stuck, it has to have enough power to tow the weight of the vehicle over obstacles and up inclines. What materials can be used for the tow line? How is the towline secured to an anchor? What safety precautions need to be taken?
 * **Improve** - For many years, wire rope or cable was used for vehicle winches. What are the characteristics of the synthetic rope that are suitable for this application?


 * That's engineering**
 * [|mechanical advantage] - the factor by which a machine multiplies force. The mechanical advantage of a machine can be used to find out how well a machine works and whether it can perform a particular job.

> gear, ratchet, pawl, drum, mechanical advantage
 * Engineering ideas**

Challenges for you to work on...
 * Do It**
 * [|build this winch simple machine]. Using recycled items for STEM activities is an awesome way to re-use and re-purpose common items you would normally recycle or throw away.
 * [|Build a Crank Mechanism] - Build a simple machine that transfers rotational motion into linear reciprocating motion (repetitive back and forth motion).
 * build a crane with a winch component
 * [|Heavy Lifting] - Build a cardboard crane and see how heavy a load it can lift.


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