block and tackle

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.

boom

The lifting arm of a crane or derrick.

bosun's chair

A small swinging scaffold similar to a climbing harness, except that it has a rigid seat.

bottle jack

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.

bottom winding

Winding rope from the bottom of the drum. Also known as underwinding.

breech

The side opening in the side of the sheave opposite the rope.

bridge

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.

chassis

The framework for supporting an object.

clamp

An end fitting used to secure hardware to the end of a rope.

compound block and tackle

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.

crane

A machine for lifting and moving extremely heavy loads. A crane provides both vertical and horizontal movement of heavy and oversized loads.

crawler-mounted

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.

cribbing block

Rigid rectangular materials used to support a load as it is being lifted, moved, or leveled.

derrick

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.

diameter

The width of a circle.

drum

A spool-like cylindrical object with flat ends extending beyond the center's diameter. Drums are used to store and spool rope.

flanges

The sides that project from each end of a drum and contain the rope.

forklift

A small industrial truck used for carrying, lifting, and stacking materials.

fulcrum

A pivot point of a lever, or the point around which an object turns.

gantry crane

A crane with a bridge supported on two or more legs running parallel on fixed rails.

groove

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.

guy

A rope or cable that is used to secure something.

hoist

A lifting device that exerts vertical forces for lifting and lowering, usually from a position that is directly above the load.

hook

A lifting device used to pick up loads with eyebolts attached. Hooks are usually used with chains, hoists, and slings.

hydraulic jack

A type of jack that has a pump plunger that forces a fluid through a cylinder.

jack

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.

jib

A horizontal arm that attaches to the boom of a crane.

lattice

A reinforcing structure that provides support to the mast of a crane.

lever

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.

lift capacity

The maximum lifting force of the jack.

lift stroke

The difference between the fully retracted and fully extended positions of the jack.

lifting medium

The component that provides the vertical raising and lowering of a load. Wire rope and chain are commonly used lifting mediums.

load

The opposition to applied force, such as a weight to be carried or moved.

mast

A long, vertical pole used to support a structure.

maximum height

The distance from the base of the jack to the lifting element when it is fully extended.

mechanical advantage

The difference between the applied force and the work accomplished. Mechanical advantage allows machines to perform more work with less effort.

minimum height

The distance from the base of the jack to the lifting element when it is fully retracted.

mobile crane

A crane designed to travel to different parts of a job site. Mobile cranes can be truck-mounted, wheel-mounted, or crawler-mounted.

moveable pulley

A circular lever that rotates around the fulcrum. A block and tackle is an example of a moveable pulley.

operation type

The type of power provided to the lifting device. Lifting devices are powered electrically, manually, or by air pressure.

OSHA

Occupational Safety and Health Administration. A government agency dedicated to reducing injuries, illnesses, and deaths in the workplace.

overhead crane

A crane with a movable bridge carrying a movable or fixed hoisting mechanism and traveling on an overhead fixed runway structure.

overwinding

Winding rope from the top of the drum. Also known as top winding.

protection fan

A structure that extends from the perimeter of the scaffold to protect people from falling objects and debris.

ratchet jack

A type of jack that has a lever that raises the jack up or down with each downstroke.

reeving

The process of passing rope through a sheave. When reeving, make sure the sheave and rope are appropriately sized.

rigging

The process of lifting and moving heavy loads with ropes, chains, and mechanical devices.

roller

A cylindrical device that rotates to move a load. Rollers are often used in combination with skids.

safety net

A length of mesh installed under a scaffold to provide fall protection to workers.

scaffold

A platform that riggers stand or sit on while performing work.

screw jack

A type of jack that consists of a threaded cylinder that is moved up or down when the handle of the jack is turned.

sheave

The freely moving wheel that is part of a moveable pulley. The sheave usually contains a groove to hold a rope or chain.

shell

The outer covering on a moveable pulley.

simple block and tackle

A pulley system that consists of a single line with one or more blocks.

skid

A wooden plank used for form tracks for moving heavy objects. Skids are used in combination with rollers.

socket

A type of fitting that can be installed and removed quickly and easily.

stationary scaffold

A fixed scaffold that is built on the job site. Stationary scaffolds are often used for long-term or large-scale jobs.

suspended crane

A crane with a movable bridge carrying a movable or fixed hoisting mechanism and traveling on an overhead fixed runway structure.

suspended scaffold

A mobile scaffold that is suspended from ropes or cables. Also known as a swinging scaffold.

suspension type

The mounting or method used to suspend the hoist. Common suspension types include hook mounted, lug mounted, trolley mounted, and wall mounted.

swinging scaffold

A mobile scaffold suspended from ropes or cables. Also known as a suspended scaffold.

top winding

Winding rope from the top of the drum. Also known as overwinding.

tower crane

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.

trolley

The unit that travels on the bridge rails of a crane and carries the hoisting mechanism.

truck-mounted

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.

underwinding

Winding rope from the bottom of the drum. Also known as bottom winding.

wheel-mounted

A type of mobile crane that is mounted on a chassis, which may or may not be self-propelled.

winch

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.