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block and tackle
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A moveable pulley that is used to raise and lower loads. More lines on a block and tackle allow you to do more work with less effort.
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boom
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The lifting arm of a crane or derrick.
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bosun's chair
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A small swinging scaffold similar to a climbing harness, except that it has a rigid seat.
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bottle jack
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A type of hydraulic jack that is placed in a horizontal position. Bottle jacks are preferred for their high leverage and ability to fit into small spaces.
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bottom winding
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Winding rope from the bottom of the drum. Also known as underwinding.
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breech
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The side opening in the side of the sheave opposite the rope.
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bridge
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The part of the crane which carries the trolley. Bridges consist of girders, trucks, end ties, footwalks, and the drive mechanism that carries the trolley.
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chassis
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The framework for supporting an object.
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clamp
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An end fitting used to secure hardware to the end of a rope.
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compound block and tackle
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A pulley system that consists of two or more ropes with two or more blocks. A compound system is made up of two or more simple systems.
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crane
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A machine for lifting and moving extremely heavy loads. A crane provides both vertical and horizontal movement of heavy and oversized loads.
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crawler-mounted
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A type of mobile crane that is mounted on a chassis with caterpillar tracks. Crawler-mounted cranes are used for jobs that require a high level of stability and traction.
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cribbing block
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Rigid rectangular materials used to support a load as it is being lifted, moved, or leveled.
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derrick
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A lifting device with a mast held at the head with guys or braces. Derricks come with or without a boom for use with a hoisting mechanism and operating ropes.
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diameter
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The width of a circle.
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drum
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A spool-like cylindrical object with flat ends extending beyond the center's diameter. Drums are used to store and spool rope.
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flanges
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The sides that project from each end of a drum and contain the rope.
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forklift
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A small industrial truck used for carrying, lifting, and stacking materials.
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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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gantry crane
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A crane with a bridge supported on two or more legs running parallel on fixed rails.
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groove
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The channel in a sheave through which rope is passed. Always choose a sheave that is at least 1½ in. wider than the rope's diameter.
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guy
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A rope or cable that is used to secure something.
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hoist
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A lifting device that exerts vertical forces for lifting and lowering, usually from a position that is directly above the load.
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hook
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A lifting device used to pick up loads with eyebolts attached. Hooks are usually used with chains, hoists, and slings.
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hydraulic jack
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A type of jack that has a pump plunger that forces a fluid through a cylinder.
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jack
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A tool used for lifting large or heavy objects. Jacks are used for items that cannot, or should not, be lifted with a crane or hoist.
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jib
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A horizontal arm that attaches to the boom of a crane.
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lattice
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A reinforcing structure that provides support to the mast of a crane.
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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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lift capacity
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The maximum lifting force of the jack.
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lift stroke
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The difference between the fully retracted and fully extended positions of the jack.
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lifting medium
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The component that provides the vertical raising and lowering of a load. Wire rope and chain are commonly used lifting mediums.
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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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mast
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A long, vertical pole used to support a structure.
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maximum height
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The distance from the base of the jack to the lifting element when it is fully extended.
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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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minimum height
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The distance from the base of the jack to the lifting element when it is fully retracted.
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mobile crane
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A crane designed to travel to different parts of a job site. Mobile cranes can be truck-mounted, wheel-mounted, or crawler-mounted.
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moveable pulley
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A circular lever that rotates around the fulcrum. A block and tackle is an example of a moveable pulley.
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operation type
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The type of power provided to the lifting device. Lifting devices are powered electrically, manually, or by air pressure.
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OSHA
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Occupational Safety and Health Administration. A government agency dedicated to reducing injuries, illnesses, and deaths in the workplace.
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overhead crane
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A crane with a movable bridge carrying a movable or fixed hoisting mechanism and traveling on an overhead fixed runway structure.
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overwinding
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Winding rope from the top of the drum. Also known as top winding.
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protection fan
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A structure that extends from the perimeter of the scaffold to protect people from falling objects and debris.
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ratchet jack
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A type of jack that has a lever that raises the jack up or down with each downstroke.
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reeving
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The process of passing rope through a sheave. When reeving, make sure the sheave and rope are appropriately sized.
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rigging
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The process of lifting and moving heavy loads with ropes, chains, and mechanical devices.
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roller
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A cylindrical device that rotates to move a load. Rollers are often used in combination with skids.
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safety net
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A length of mesh installed under a scaffold to provide fall protection to workers.
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scaffold
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A platform that riggers stand or sit on while performing work.
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screw jack
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A type of jack that consists of a threaded cylinder that is moved up or down when the handle of the jack is turned.
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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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simple block and tackle
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A pulley system that consists of a single line with one or more blocks.
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skid
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A wooden plank used for form tracks for moving heavy objects. Skids are used in combination with rollers.
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socket
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A type of fitting that can be installed and removed quickly and easily.
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stationary scaffold
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A fixed scaffold that is built on the job site. Stationary scaffolds are often used for long-term or large-scale jobs.
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suspended crane
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A crane with a movable bridge carrying a movable or fixed hoisting mechanism and traveling on an overhead fixed runway structure.
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suspended scaffold
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A mobile scaffold that is suspended from ropes or cables. Also known as a swinging scaffold.
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suspension type
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The mounting or method used to suspend the hoist. Common suspension types include hook mounted, lug mounted, trolley mounted, and wall mounted.
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swinging scaffold
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A mobile scaffold suspended from ropes or cables. Also known as a suspended scaffold.
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top winding
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Winding rope from the top of the drum. Also known as overwinding.
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tower crane
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A stationary crane with an extremely long vertical mast. Tower cranes are used in construction for large structures such as bridges and hi-rise buildings.
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trolley
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The unit that travels on the bridge rails of a crane and carries the hoisting mechanism.
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truck-mounted
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A type of mobile crane that is self-powered and mounted on a truck bed. The truck can be driven anywhere that a truck would normally go.
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underwinding
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Winding rope from the bottom of the drum. Also known as bottom winding.
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wheel-mounted
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A type of mobile crane that is mounted on a chassis, which may or may not be self-propelled.
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winch
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A drum mounted on a frame with a motor on one end and gears on the other. Winches are often used as inexpensive alternatives to other lifting devices.
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