"When bodies of equal weight are supported by the arms of a lever, they will balance each other when placed at equal distances from the fulcrum." —Quackenbos 1859

Balance

"When bodies of equal weight are supported by the arms of a lever, they will balance each other when…

A bridge which may be drawn up or let down to admit or hinder communication, or to leave a transverse passage free.

Draw Bridge

A bridge which may be drawn up or let down to admit or hinder communication, or to leave a transverse…

"... shows one of the commonest (sic) forms in which this kind of lever appears,-the crowbar. The power is applied at the handle. The weight is at the other end, and consists of something to be moved. The fulcrum is a stone on which the crowbar rests." —Quackenbos 1859

Crowbar

"... shows one of the commonest (sic) forms in which this kind of lever appears,-the crowbar. The power…

Pliers are a hand tool used to hold objects firmly, or for cutting and bending tough materials such as wire. Generally pliers consist of a pair of metal first class levers joined at a fulcrum positioned closer o one end of the levers, creating short jaws on one side of the fulcrum, and longer handles on the other side.

Cutting Pliers

Pliers are a hand tool used to hold objects firmly, or for cutting and bending tough materials such…

"A lever is an inflexible bar freely movable about a fixed axis called the fulcrum. If the fulcrum is between the power and weight, the lever is of the first class." — Avery, 1895

First Class Lever

"A lever is an inflexible bar freely movable about a fixed axis called the fulcrum. If the fulcrum is…

"A Lever of the First Kind is one in which the fulcrum is between the power and the weight... where F represents the fulcrum, P the power, and W the weight." —Quackenbos 1859

First Class Lever

"A Lever of the First Kind is one in which the fulcrum is between the power and the weight... where…

In the first order of levers, the fulcrum is between the power and the weight.

First Orders of Lever

In the first order of levers, the fulcrum is between the power and the weight.

"In mechanics, the point of rest about which a lever turns in lifting a body; also, a prop or support for a lever at this point. F, Fulcrum; L, lever." -Whitney, 1911

Man with Lever and Fulcrum

"In mechanics, the point of rest about which a lever turns in lifting a body; also, a prop or support…

"E represents the scape-wheel turning in a minute, and e its pinion, which is driven by the wheel D having a pinion d driven by the wheel C, which we may suppose to turn in an hour. The arbors of the scape-wheel and hour-wheel are distinct, their pivots-meeting in a bush fixed somewhere between the wheels. The pivots of the wheel, D are set in the frame AP, which rides on the arbors of the hour-wheel and scape-wheel, or on another short arbor between them. The hour-wheel also drives another wheel G, which again drives the pinion f on the arbor which carries the two arms f A, f B; and on the same arbor is set a fly with a ratchet, like a common striking fly, and the numbers of the teeth are so arranged that the fly will turn once for each turn of the scapewheel. The ends of the remontoire arms f A, f B are capable of alternately passing the notches cut half through the arbor of the scape-wheel, as those notches successively come into the proper position at the end of every half minute; as soon as that happens the-hour-wheel raises the movable wheel D and its frame through a small angle; but nevertheless, that wheel keeps pressing on the scape-wheel as if it were not moving, the point of contact of the wheel C and the pinion d being the fulcrum or center of motion of the level A d P." — Encyclopedia Britanica, 1893

Gravity Train Remontoire

"E represents the scape-wheel turning in a minute, and e its pinion, which is driven by the wheel D…

"The object W to be lifted is called the weight; the force is represented by P; the point, or pivot, F is called the fulcrum." —Hallock 1905

Lever

"The object W to be lifted is called the weight; the force is represented by P; the point, or pivot,…

"The object W to be lifted is called the weight; the force is represented by P; the point, or pivot, F is called the fulcrum." —Hallock 1905

Lever

"The object W to be lifted is called the weight; the force is represented by P; the point, or pivot,…

"The object W to be lifted is called the weight; the force is represented by P; the point, or pivot, F is called the fulcrum." —Hallock 1905

Lever

"The object W to be lifted is called the weight; the force is represented by P; the point, or pivot,…

Illustration of a lever with fulcrum F. W represents the weight lifted, P is the force that does the lifting, D is the distance from the fulcrum to the point of application of the force, and d is the distance from the fulcrum to the point where the weight is attached. In all possible relations of the fulcrum, weight, and force the following proportion holds: P:W = d:D.

Lever and Fulcrum

Illustration of a lever with fulcrum F. W represents the weight lifted, P is the force that does the…

Lever of the first class.

Lever of the first class

Lever of the first class.

Lever of the second class.

Lever of the second class

Lever of the second class.

Lever of the third class.

Lever of the third class

Lever of the third class.

An illustration of a lever with weights m and n with distances a and b from fulcrum. Illustration could be used with proportions.

Lever Balanced on fulcrum With Weights

An illustration of a lever with weights m and n with distances a and b from fulcrum. Illustration could…

"The lever of the first class has the fulcrum between the power and the weight." Examples: a common crowbar, a pump handle, scissors, a seesaw. -Foster, 1921

First Class Lever

"The lever of the first class has the fulcrum between the power and the weight." Examples: a common…

"In straight levers of the first kind, the fulcrum is between the power and the resistance, as in fig 1, where F is the fulcrum of the lever AB; P is the power, and W the weight or resistance."—Pettigrew, 1874

First Kind of Lever

"In straight levers of the first kind, the fulcrum is between the power and the resistance, as in fig…

Illustration of a hammer being used as a lever. F represents the fulcrum.

Hammer Used as a Lever

Illustration of a hammer being used as a lever. F represents the fulcrum.

"The lever of the second class has the weight between the power and the fulcrum." Examples: a nutcracker, a wheelbarrow. -Foster, 1921

Second Class Lever

"The lever of the second class has the weight between the power and the fulcrum." Examples: a nutcracker,…

"In the second order of levers, the resistance is between the fulcrum and the power; and, as before, P : W :: BF : AF, but the pressure of the fulcrum is equal to W-P, or the weight less the power."—Pettigrew, 1874

Second Kind of Lever

"In the second order of levers, the resistance is between the fulcrum and the power; and, as before,…

Illustration of an ordinary steel-yard being used as a lever. F represents the fulcrum. Weight P is used to balance weight W.

Steel-yard Used as a Lever

Illustration of an ordinary steel-yard being used as a lever. F represents the fulcrum. Weight P is…

"The lever of the third class has the power between the weight and the fulcrum." Examples: sewing machine treadle, forearm. -Foster, 1921

Third Class Lever

"The lever of the third class has the power between the weight and the fulcrum." Examples: sewing machine…

"In the third order of lever the power acts between the prop and the resistance, where also P : W :: BF : AF, and the pressure on the fulcrum is P-W, or the power less the weight."——Pettigrew, 1874

Third Kind of Lever

"In the third order of lever the power acts between the prop and the resistance, where also P : W ::…

Images of different points about a fulcrum F. P is the power exerted on the object, W is the weight.

Simple Machines

Images of different points about a fulcrum F. P is the power exerted on the object, W is the weight.

This is a corkscrew type bottle opener, or a device that enables the removal of metal bottle caps from bottles.

Bottle Opener

This is a corkscrew type bottle opener, or a device that enables the removal of metal bottle caps from…

An instrument for making a reduced, enlarged, or exact copy of a plane figure

Pantograph

An instrument for making a reduced, enlarged, or exact copy of a plane figure

Illustration of a hydraulic machine. "A principle known as Pascal's Law states that pressure exerted on a liquid in a closed vessel is transmitted equally and undiminished in all directions." If a, A, p, and P respectively represent the areas and pressures, then the following proportion holds: a:A = p:P.

Hydraulic Machine Exerting Pressure

Illustration of a hydraulic machine. "A principle known as Pascal's Law states that pressure exerted…

"In the single fixed pulley (fig. 1) there is no mechanical advantage, the power and weight being equal. It may be considered as a lever of the first kind with equal arms. In the single movable pulley (fig. 2) where the cords are parallel there is a mechanical advantage, there being an equilibrium when the power is considered as a lever of the second kind, in which the distance of the power from the fulcrum is double hat of the weight from the fulcrum." -Marshall

Pulley

"In the single fixed pulley (fig. 1) there is no mechanical advantage, the power and weight being equal.…

"In a system of pulleys (figs. 3,4) in which the same string passes round any number of pulleys, and the parts of it between the pulleys are parallel, there is an equilibrium when the power is to the weight as 1 to the number of strings at the lower block" -Marshall

Pulley

"In a system of pulleys (figs. 3,4) in which the same string passes round any number of pulleys, and…

"In a system in which each pulley hangs by a separate cord and the strings are parallel (fig. 5), there is an equilibrium when the power is to the weight as 11 to that power of 2 whose index is the number of movable pulleys." -Marshall

Pulley

"In a system in which each pulley hangs by a separate cord and the strings are parallel (fig. 5), there…

"A common scale-beam, used for weighing, is a lever, suspended at the centre of gravity, so that the two arms balance each other. Hence the machine is called a balance. The fulcrum, or what is called the pivot, is sharpended, like a wedge, and made of hardened steel, so as much as possible to avoid friction." -Comstock 1850

Scale

"A common scale-beam, used for weighing, is a lever, suspended at the centre of gravity, so that the…

"Many instruments in common use are on the principle of this kind of lever. Scissors, consists of two levers, the rivet being the fulcrum for both. The fingers are the power, and the cloth to be cut, the resistance to be overcome." -Comstock 1850

Scissors

"Many instruments in common use are on the principle of this kind of lever. Scissors, consists of two…

"A lever is an inflexible bar freely movable about a fixed axis called the fulcrum. If the weight is between the power and the fulcrum, the lever is of the second class." — Avery, 1895

Second Class Lever

"A lever is an inflexible bar freely movable about a fixed axis called the fulcrum. If the weight is…

"Two men carrying a load between them on a pole is also and example of this [second class] kind of lever. Each man acts as the power in moving the weight, and at the same time each becomes the fulcrum in respect to the other." -Comstock 1850

Second-class Lever

"Two men carrying a load between them on a pole is also and example of this [second class] kind of lever.…

"A Lever of the Second Kind is one in which the weight is between the power and the fulcrum." —Quackenbos 1859

Second Class Lever

"A Lever of the Second Kind is one in which the weight is between the power and the fulcrum." —Quackenbos…

In the second order of levers, the weight is between the power and the fulcrum.

Second Order of Lever

In the second order of levers, the weight is between the power and the fulcrum.

This shear attachment features tensioners riveted at the fulcrum.

Tension Attachment for Shears

This shear attachment features tensioners riveted at the fulcrum.

"Any rod, or bar, which is used in raising a weight, or surmounting a resistance, by being placed on a fulcrum, or prop, becomes a lever." -Comstock 1850

Simple Lever

"Any rod, or bar, which is used in raising a weight, or surmounting a resistance, by being placed on…

"Suppose that A is the lever, B the fulcrum, D the weight to be raised, and C the power. Let D by considered three times as heavy as C, and the fulcrum three times as far from C as it is from D; then the weight and power will exactly balance each other out." -Comstock 1850

Simple lever system

"Suppose that A is the lever, B the fulcrum, D the weight to be raised, and C the power. Let D by considered…

"Suppose the weight, B to be sixteen pounds and suppose the fulrum to be placed so near it, as to be raised by the power A, of four pounds hanging equally distant from the fulcrum and the end of the lever. If now the power A be removed, and another of two pounds, C, be placed at te end of the lever, its force will be just equal to A, placed at the middle of the lever." -Comstock 1850

Simple Lever System

"Suppose the weight, B to be sixteen pounds and suppose the fulrum to be placed so near it, as to be…

"But let the fulcrum be moved along to the middle of the lever, with the weight of sixteen pounds still suspended to it, it would then take another weight of sixteen pounds, instead of two pounds, to balance it..." -Comstock 1850

Simple Lever System

"But let the fulcrum be moved along to the middle of the lever, with the weight of sixteen pounds still…

The steelyard is an instrument for weighing bodies by means of a single weight which can be hung at any point of a graduated arm.

Steelyard

The steelyard is an instrument for weighing bodies by means of a single weight which can be hung at…

"Heterocercal Caudal Fin of a Sturgeon (Acipenser brevirostris), showing the series of fulcrums, Fl, along the dorsal border." -Whitney, 1911

Shortnose Sturgeon Tail

"Heterocercal Caudal Fin of a Sturgeon (Acipenser brevirostris), showing the series of fulcrums, Fl,…

"A lever is an inflexible bar freely movable about a fixed axis called the fulcrum. If the power is between the weight and the fulcrum the lever is of the third class." — Avery, 1895

Third class lever

"A lever is an inflexible bar freely movable about a fixed axis called the fulcrum. If the power is…

"In the third and last kind of lever, the weight is placed at one end, the fulcrum at the other end and the power between them, or the hand s between the fulcrum and the weight." -Comstock 1850

Third-class Lever

"In the third and last kind of lever, the weight is placed at one end, the fulcrum at the other end…

"A Lever of the Third Kind is one in which the power is between the weight and the fulcrum." —Quackenbos 1859

Third Class Lever

"A Lever of the Third Kind is one in which the power is between the weight and the fulcrum." —Quackenbos…

In the third order of levers, the power is between the weight and the fulcrum.

Third Order of Lever

In the third order of levers, the power is between the weight and the fulcrum.

"Considered as a lever, the fulcrum is at the common axis, while the arms of the lever are the radii of the wheel and of the axle. The usual arrangement is to take ac, the radius of the wheel, as the power arm, and bc , the radius of the axle, as the weight arm." -Avery 1895

Wheel and Axle

"Considered as a lever, the fulcrum is at the common axis, while the arms of the lever are the radii…