EOT Cranes Glossary
Decode the jargon. The complete A-Z dictionary of EOT crane terminology, abbreviations, and standards.
A
Auxiliary Hoist
A secondary lifting mechanism used for lighter loads on the same trolley as the main hoist. It allows for faster lifting speeds for smaller loads.
Anti-Collision Device
Sensors (laser or infrared) that prevent multiple cranes on the same runway from colliding.
Anti-Two Block
A safety system that prevents the hook block from colliding with the hoist drum or upper block.
Anemometer
A device that measures wind speed, often used on outdoor gantry cranes to trigger alarms when wind speeds exceed safe limits.
ACEM Brake
Alternating Current Electro-Magnetic brake. A fast-acting holding brake used in hoist and travel motions.
Arm Chair Control Desk
An ergonomic operator station in a crane cabin with integrated joystick controllers for managing all motions.
B
Bridge
The main structural component of an EOT crane that spans the width of the building. It carries the trolley/crab and travels along the runway.
Bridge Drive (Long Travel)
The motor and gearbox assembly that moves the entire crane longitudinally along the runway.
Busbar (DSL)
Down Shop Leads. A rigid, insulated power rail system installed along the runway to provide continuous power to the moving crane.
Bumper (Buffer)
An energy-absorbing device (rubber, hydraulic, or spring) located at the ends of the bridge or trolley to reduce impact force.
C
Camber
The slight upward vertical curve built into the bridge girder to compensate for deflection caused by the load.
Crab (Trolley)
The unit that travels across the bridge rails (Cross Travel) and carries the hoisting mechanism.
Cross Travel (CT)
The movement of the crab/trolley perpendicular to the crane runway.
Cross Shaft
A shaft extending across the bridge used to transmit torque from a central motor to the drive wheels at both ends.
Control Panel
The central enclosure housing the VFDs, PLC, contactors, and relays.
Current Collector
A sliding contact (often with carbon brushes) that picks up electricity from the DSL as the crane moves.
C-Rail / C-Track
A "C" shaped profile used to support and guide festoon trolleys that carry electrical cables.
Cabin
An enclosed operator's station attached to the crane bridge or trolley, providing visibility and controls.
Copper Headed Rail
A specialized runway rail with a copper head to improve electrical conductivity for current collectors.
Contactors
Heavy-duty electromagnetic switches used for starting and reversing large crane motors.
D
Duty Cycle (CMAA Classes A-F)
A classification based on the frequency and intensity of use, ranging from Standby (Class A) to Continuous Severe Service (Class F).
Dead Load
The weight of the crane itself and any permanent attachments, excluding the lifted load.
Diaphragm
A vertical plate or partition placed between the girder webs to distribute rail loads and prevent web buckling.
Dynamic Braking
A method of using the motor as a generator to slow the motion, dissipating heat through resistors.
DC Brake
Direct Current brake. Known for smooth and quiet operation, often used in precision lifting.
Drum Brakes
A type of friction brake where shoes press against the inner or outer surface of a cylindrical drum.
E
EOT Crane
Electric Overhead Traveling Crane. A crane that travels on elevated rails and is powered by electricity.
End Carriage (Truck)
The structural units at both ends of the bridge that house the wheels and drive motors for Long Travel (LT).
End Tie
A structural member that connects the ends of the bridge girders to maintain the squareness and alignment of the crane.
Emergency Stop (E-Stop)
A manual "kill switch" that immediately halts all crane power and motion.
Electrohydraulic Thruster
An actuator that uses a small electric motor and centrifugal pump to generate oil pressure for releasing large capacity brakes.
F
FEM
Fédération Européenne de la Manutention. A European organization that sets rigorous standards for material handling equipment design and safety.
Festoon System
A cable management system using flexible flat or round cables suspended from trolleys to provide power to the moving trolley.
Fleet Angle
The angle between the centerline of a sheave and the wire rope leading to the drum; it must be kept small (typically 0.5° to 2°) to prevent rope wear.
Flame Proof Equipment
Electrical components designed to operate safely in hazardous, explosive environments (ATEX/IECEx certified).
G
Gantry Crane
A crane similar to an EOT crane but supported by legs that travel on floor-mounted rails rather than elevated runways.
Girder
The main horizontal beam of the crane bridge. Can be Single Girder (I-beam or box) or Double Girder.
Gearbox (Reducer)
A mechanical unit that reduces the motor's high-speed rotation to a lower-speed, high-torque output needed for heavy lifting.
Gravity/Hammer Limit Switch
A backup hoist limit switch triggered by the physical contact of the load block.
H
Hoist
The machinery unit that performs the lifting and lowering of the load using wire rope or chain.
Hook Block (Load Block)
The assembly of hook, swivel, bearings, and sheaves suspended from the hoisting ropes.
Hoist Motor
An electric motor, often high-torque or slip-ring type, that provides the power for lifting.
Hook
The forged steel interface that attaches to the load.
Hook Approach
The minimum horizontal distance the hook can reach relative to the side walls or runway rails.
Headroom
The vertical distance from the hook’s highest position to the lowest part of the building or crane structure.
Holding Brake
An automatically applied friction brake (electromagnetic or hydraulic) that holds the load securely when power is off.
I
Idler Wheels
Non-driven wheels that provide additional load support.
J
Joystick Controller
A multi-axis control lever used for precise, stepless control of crane motions.
L
Limit Switch
An electrical device that cuts power at the ends of travel. Variants include Rotary and Gravity types.
Long Travel (LT)
The movement of the crane bridge along the length of the runway rails.
Load Test
A mandatory test where the crane lifts a load (usually 125% of SWL) to prove structural and mechanical integrity.
Longitudinal Stiffeners
Horizontal members attached to the web of the bridge girder to prevent it from buckling under high stress.
Lang’s Lay
A wire rope construction where the wires are at a 45-degree angle to the rope axis, offering better wear resistance.
Load Cell (Pin and Wire Rope)
A sensor that measures the tensile force on the wire rope or the shear force on a pin to detect the weight of the load.
Load Controller
An electronic unit that processes signals from load cells to display weight and prevent overloads.
M
Main Hoist
The primary lifting mechanism of a crane, designed for the maximum rated capacity.
Mechanical Load Brake
An automatic friction device in the hoist drivetrain that provides a "fail-safe" for controlling the load during lowering.
Master Controller
A heavy-duty switch used to control the speed and direction of crane motors, often found in cabins.
MCB (Miniature Circuit Breaker)
An electrical safety device that protects circuits from overcurrent or short circuits.
MCCB (Molded Case Circuit Breaker)
A larger circuit breaker used for higher current ratings and adjustable trip settings.
O
Overload Limiter
A sensor (Load Cell) that prevents the hoist from lifting if the load exceeds the rated capacity.
OLR (Overload Relay)
A protective device that shuts down a motor if it draws excessive current for too long, preventing burnout.
P
Pendant Station
A handheld pushbutton controller suspended from the crane for floor-level operation.
Plugging (Counter-torque)
Reversing the motor's electrical power to create torque in the opposite direction for rapid stopping.
Pendants
Handheld pushbutton controllers suspended from the crane for floor-level operation (also known as Pendant Stations).
PLC (Programmable Logic Controller)
A specialized computer used to automate crane functions, safety interlocks, and diagnostics.
Protective Panel
An electrical enclosure containing fuses, circuit breakers, and isolators to protect the crane's entire electrical system.
R
Runway
The assembly of rails, beams, and columns on which the entire crane travels throughout the length of the building.
Regular Lay (Ordinary Lay)
Wire rope construction where wires appear parallel to the rope axis; commonly used for general hoisting.
Rail Sweeper
A device attached to the front of end trucks to clear debris from the rails, preventing derailment or wheel damage.
Radio Remote Control
A wireless transmitter that allows the operator to control the crane from a distance.
Regenerative Braking
An electrical braking method that feeds generated power back into the electrical grid.
Rotary Limit Switch
Monitors the number of drum rotations to set upper and lower hoist limits.
Relays
Electromagnetic switches used to control high-power circuits with low-power signals.
Resistance Box
A series of resistor grids used with slip-ring motors to control starting torque and speed during acceleration.
S
SWL (Safe Working Load)
The maximum load weight that the crane is certified to lift safely under normal conditions. Also known as WLL (Working Load Limit).
Span
The horizontal center-to-center distance between the runway rails.
Skewing
A condition where one end of the bridge moves ahead of the other, causing lateral forces on the rails and excessive wheel wear.
Safety Latch
A spring-loaded device that closes the hook throat to prevent accidental detachment of the load.
Slip Ring Motor
A type of induction motor used for high-duty cycles where external Resistance Boxes are used to control starting torque and speed.
Solenoid Brakes
A type of electromagnetic brake where a solenoid coil provides the force to release or apply the brake.
T
Trunnion
The supporting member that allows the hook to swivel within the block.
Two-Blocking
The hazardous condition of the load block making physical contact with the upper block.
Trolley (Crab)
The unit that carries the hoist and moves horizontally along the bridge girders (Cross Travel).
Thruster Brakes
Brakes released by an electrohydraulic thruster, offering smooth and reliable braking for high-torque applications.
U
Upper Block
A fixed assembly of sheaves located on the trolley frame that supports the load block.
V
VFD (Variable Frequency Drive)
A motor controller that adjusts frequency and voltage to provide smooth acceleration, deceleration, and infinite speed control.
W
Wheel Load
The vertical force exerted by a single crane wheel on the runway rail. Critical for building design.
Wire Rope Guide
A ring mechanism on the rope drum that ensures the rope coils neatly into the grooves and prevents overlapping.
Wire Rope Drum
A grooved cylindrical spool that winds and unwinds the wire rope to raise or lower the load.
Wire Rope
A lifting medium made of twisted metal strands, categorized by its "lay" (direction of twist).
Wheels
Includes Drive Wheels (power-driven) and Idler Wheels (non-driven) that support the crane’s weight and motion.
Web Bracket
A structural component used to reinforce the connection between the bridge girder and the end carriage.