What Is And Isn't A Windlass Tourniquet

What Is And Isn't A Windlass Tourniquet

March 28, 2018 0 Comments

When it comes to tourniquets on of the most common words heard is Windlass. This is because a windlass is a style of tourniquet that uses a device to tighten, but what exactly is a windlass? We will first examine what are simple machines, windlass definitions, windlass types, real world examples, and tourniquet applications.

 

SIMPLE MACHINES

Simple Machines

“A Simple Machine is a mechanical device that changes the direction or magnitude of a force. Defined as the simplest mechanisms that use mechanical advantage or leverage to multiply force. (Wikipedia, 2018).”

 

WINDLASS DEFINITIONS

 

Dictionary.com defines a windlass as:

 

“A device for raising or hauling objects, usually consisting of a horizontal cylinder or barrel turned by a crank, lever, motor, or the like, upon which a cable, rope, or chain winds, the outer end of the cable being attached directly or indirectly to the weight to be raised or the thing to be hauled or pulled; winch.”

 

 

Merriam-Webster Dictionary defines a windlass as:

 

“Any of various machines for hoisting or hauling: such as 

A: a horizontal barrel supported on vertical posts and turned by a crank so that the hoisting rope is wound around the barrel. 

B: a steam or electric winch with horizontal or vertical shaft and two drums used to raise a ship's anchor.”

 

Wikipedia defines a windlass as:

 

“The windlass is an apparatus for moving heavy weights. Typically, a windlass consists of a horizontal cylinder (barrel), which is rotated by the turn of a crank or belt. A winch is affixed to one or both ends, and a cable or rope is wound around the winch, pulling a weight attached to the opposite end. The oldest depiction of a windlass for raising water can be found in the Book of Agriculture published in 1313 by the Chinese official Wang Zhen of the Yuan Dynasty (fl. 1290–1333). Archimedes was the inventor of windlass.”

 

ENGINEERING

 

WINDLASS TYPES

 

DIFFERENTIAL / CHINESE:

“In a differential windlass, also called a Chinese windlass, there are two coaxial drums of different radii. The rope is wound onto one drum while it unwinds from the other, with a movable pulley hanging in the bight between the drums. Since each turn of the crank raises the pulley and attached weight by only π(r − r′), very large mechanical advantages can be obtained (Wikipedia, 2018).”

 

SPANISH:

“A Spanish windlass is a device for tightening a rope or cable by twisting it using a stick as a lever. The rope or cable is looped around two points so that it is fixed at either end. The stick is inserted into the loop and twisted, tightening the rope and pulling the two points toward each other. It is commonly used to move a heavy object such as a pipe or a post a short distance. It can be an effective device for pulling cars or cattle out of mud. A Spanish windlass is sometimes used to tighten a tourniquet or a straitjacket. A Spanish windlass trap can be used to kill small game. An 1898 report to the US Senate Committee on Foreign Relations about an American vessel captured by a Spanish gunboat described the Spanish windlass as a torture device. One of the captives' wrists was tied together. The captor then twisted a stick in the rope until it tightened and caused the man's wrists to swell (Wikipedia, 2018).”

 

SOME REAL WORLD WINDLASS EXAMPLES

 

ANATOMY

Windlass mechanism is a process by which the plantar fascia arch is stretched for a brief moment as the mid foot and hind foot are bent like a bow before relaxing as the weight is taken off the foot as the foot lifts into the air during a step (when the heel is raised and your big toe is touching the ground). This mechanism allows for an ingenious means of adding more force to a stride — the natural way providing efficiency in movement with our feet as we walk.”

 

BOATING

A Windlass is commonly seen on boats in vertical and horizontal configurations used to raise and lower anchors, sails, etc.

 

CROSSBOWS

TOURNIQUETS

 

WINDLASS BAR: Classified as a Spanish Windlass. Uses the Simple Machine Screw (mechanical advantage) mechanism. It’s 1” wide webbing is threaded through the center of a bar, which when twisted causes the webbing to create a knot or binding point underneath the windlass bar, thus shortening the circumference of the loop by pulling the strap into 1 central binding point from both sides. When this mechanism is applied to a limb it creates compression to occlude arterial blood flow.

RATCHET AND LADDER STRAP: This tourniquet style uses the Simple Machine Friction (mechanical advantage) mechanism. When attached to webbing typically 1.5” or 2” wide this tourniquet reduces the length of the webbing by moving the ladder strap through the fixed point ratchet, thus shortening the circumference of the loop by pulling the strap into the 1 central binding point from both sides (The movement of the ladder strap through the ratchet and the ratchet moving towards the fixed end of the ladder strap creates the force to pull from both sides to compress a limb and occlude arterial blood flow.

 

SUMMARY

 

  • The term Windlass applies to a specific style of simple machine that uses rotational screw force for mechanical advantage.

 

  • A ratchet and ladder strap tourniquet is a specific style of simple machine that uses friction force for mechanical advantage

 

  • Both Windlass and Ratcheting Tourniquets have 1 central binding point, and use mechanical advantage to pull from 2 sides to create compression.

 

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