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angular gear train
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A type of gear with slanted teeth that is designed to allow power transmission between gears of intersecting shafts. Some examples of angular gear trains are bevel gears and miter gears.
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applied force
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The energy or effort provided to a machine to perform work. Applied force has many forms, from the power of an electric motor to the push from human hands.
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axis
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The center around which a wheel or component rotates.
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axle
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The center post of a wheel. The axle is positioned on the wheel's axis.
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bearing
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A rotating support placed between components to increase movement and reduce friction. Ball bearings are a common type of this device.
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belt
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An endless loop of material used to transmit motion between two or more pulleys. Belts require friction to stay in contact with the pulleys.
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bevel gear
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A type of gear with cone-shaped teeth that are cut at an angle. Bevel gears are often used in angular gear trains.
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block and tackle
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The common name for a moveable pulley.
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brake
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A device used to stop motion.
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breech
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The side opening on a moveable pulley that provides access to the sheave.
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cam
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A low-friction, circular lever consisting of a lobe and a shaft that transforms circular motion into linear motion. Cams are often used in combustion engines.
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clutches
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Devices used to engage or disengage rotating parts.
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delivered force
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The result of the effort applied to a machine, such as a weight rising in the air or a wheel turning. Delivered force is the resulting movement or work performed by a machine.
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distance
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The space between two points or objects. Distance is the amount of space through which the supplied and delivered forces travel, which is a requirement for mechanical advantage.
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doorstop
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A wedge used to hold open a door by placing it between the bottom of the door and the floor.
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drive gear
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The gear that is attached to the power source, such as an electric motor. Drive gears transmit power to driven gears to perform work.
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driven gear
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The gear that receives motion from the drive gear on a machine. Driven gears often turn tools or components.
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driven pulley
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The pulley on a machine that receives power from the driver pulley via a belt.
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driver pulley
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The pulley on a machine that is attached to the power source, such as an electric motor.
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effort
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The force applied to an object or machine to cause motion.
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first-class lever
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A lever in which the fulcrum is positioned between the load and the effort. A crowbar is an example of a first-class lever.
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fixed block
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A type of moveable pulley that is fixed to a point overhead. One end of the rope is then attached to the load, while the free end is pulled to raise the load.
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fixed pulley
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A device consisting of a wheel rigidly fixed to a shaft that is used with a belt to transmit energy and motion to another fixed pulley.
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follower
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A device that works with a cam to transform circular motion into linear motion. The follower, which is attached to a shaft, stays in contact with the lobe and moves the shaft up and down as the lobe rotates.
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four-bar linkage
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A multi-lever device used to convert rotary motion into reciprocating motion.
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friction
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A force that resists motion between two objects that are in contact with each other. Smoother surfaces exhibit less friction, while rougher surfaces exhibit more friction.
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friction-based machine
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A machine that requires some amount of friction to function. Friction-based machines, such as screws, require friction to keep from slipping or moving.
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fulcrum
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A pivot point of a lever, or the point around which an object turns.
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gear
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A disc or wheel that contains evenly spaced teeth around its perimeter. Gears are usually used in pairs to transmit energy and motion.
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helical gear
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A type of gear with slanted teeth. Helical gears are quieter than spur gears.
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herringbone gear
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A type of gear that has angled teeth in the shape of a letter "V." Herringbone gears resist side loading.
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inclined plane
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A simple machine consisting of a flat, angled surface used to raise objects. The mechanical advantage of an inclined plane increases with its length.
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jack
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A device that consists of a large screw used to raise a heavy object, such as a car or building.
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lever
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A type of simple machine consisting of a rigid bar that pivots on a fulcrum. Levers are used to transmit motion and alter mechanical advantage.
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linear motion
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Motion that takes place in a straight line rather than in a circle around an axis.
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load
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The opposition to applied force, such as a weight to be carried or moved.
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lobe
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The portion of a cam that intersects with the follower to transmit motion. Lobes are commonly shaped like an oval.
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low-friction machine
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A machine that functions best when minimal friction is present. Low-friction machines, such as levers, maximize mechanical advantage.
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lubrication
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The use of a slippery substance, such as oil or graphite, placed between two moving surfaces that are in contact with each other. Lubrication minimizes friction, which aids movement and reduces heat.
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machine
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A device whose primary purpose is to transform energy into motion to accomplish some form of useful work.
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mechanical advantage
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The difference between the applied force and the work accomplished. Mechanical advantage allows machines to perform more work with less effort.
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mechanical system
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A collection of machines functioning together to perform useful work.
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miter gear
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A type of bevel gear used in pairs with intersecting shafts at 90° angles. Both the driving gear and driven gear in a miter gear pair have the same diameter, same number of teeth, and a mechanical advantage of 1.
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moveable pulley
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A device consisting of a shell, a moveable wheel, and a rope that is used to raise a load. Moveable pulleys, also known as block and tackle, may be attached overhead or to the load itself.
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nut
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A fastening device containing a hole and internal threads that mate with a screw or bolt.
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perpendicular
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An intersection of two lines or objects at right angles. The delivered forces exerted by a wedge are perpendicular to its direction of travel.
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physical science
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The study of non-living matter. Physical science includes physics, chemistry, astronomy, and geology.
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pulley
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A circular device that is used to raise or lower a load or transmit motion. A pulley may be moveable or fixed.
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rack and pinion
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A type of gear that consists of a rack, which is a bar containing teeth, and a pinion, which is a round gear. Rack and pinion devices are commonly used on automotive steering mechanisms.
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ramp
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A type of inclined plane. A ramp is often used to load materials onto a truck bed or to allow pedestrians to walk from one level to another.
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reciprocating
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Alternating or back and forth.
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resistance
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The opposition to a force, such as the weight of a load or friction to movement.
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runner
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A type of moveable pulley that is attached to the load. One end of the rope is fixed to a point overhead, while the other is pulled to raise the load.
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screw
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A type of inclined plane set around a cylinder. Screws are often used to fasten materials or transmit motion.
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second-class lever
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A lever in which the load lies between the fulcrum and the effort. A wheelbarrow is an example of a second-class lever.
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see saw
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A long, narrow board equally balanced in the middle on a fulcrum.
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shaft
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A long cylindrical device such as a rod or pole. On a wheel, the shaft extends from the center of the wheel along its axis.
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sheave
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The freely moving wheel that is part of a moveable pulley. The sheave usually contains a groove to hold a rope or chain.
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shell
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The outer covering on a moveable pulley.
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shim
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A thin wooden wedge used in woodworking to tighten and fill gaps in loose wooden parts.
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side load
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A force that occurs when gears are meshed together at an angle, which can lead to deflection and wear.
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speed
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The rate at which an object travels. Speed describes the rate at which supplied and delivered forces move.
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spring
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A flexible device used to apply force, control motion and vibration, and store energy.
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spur gear
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A type of gear that has straight, flat-topped teeth set parallel to the shaft. Spur gears are good for transferring motion.
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third-class lever
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A lever in which the effort is placed between the fulcrum and the load. A baseball bat is an example of a third-class lever.
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thread
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The wedge-shaped circular feature on a screw that serves as the inclined plane.
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valve stem
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A moveable shaft commonly used with a follower and cam to open and close holes in a device such as an engine.
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wedge
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A friction-based inclined plane used to spread apart two opposing forces. A wedge is often used to split wooden logs.
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wheel
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A circular machine that turns on a center axis. A wheel is a circular lever.
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wheel and axle
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A wheel that is rigidly fixed to a central post that rotates with the wheel. A fixed pulley is an example of a wheel and axle.
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work
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The result of a force applied to an object and the distance through which the force is applied. In an equation, work is force multiplied by distance.
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