Glossary O-P-q-R-S-T-U-V-W (no x,y,z)

O

OPERATORS CAB: The operator's compartment from which movements of the crane are controlled.

OVERLOAD PROTECTION (OVERCURRENT): A device operative on excessive current to cause and maintain the interruption or reduction of current flow to the equipment governed.

P

PATENTED TRACK: A generic term referring to crane and monorail equipment built in accordance with the MMA specification utilizing a composite track section incorporating a proprietary bottom flange shape.

PENDANT PUSHBUTTON STATION: A control station suspended from the crane for operating the crane from the floor or other levels beneath the crane.

PLAIN REVERSING CONTROL: A reversing control which has identical characteristics for both directions of motor rotation.

PROTECTIVE PANEL: An assembly containing overload and under voltage protection for all crane motions.

R

RATED LOAD: The maximum load which the crane is designed to handle safely

REMOTE CONTROLS: Devices used to operate a crane or hoist from a remote location.  Normally refers to a radio control with a receiver mounted on the crane and a transmitter held by the operator.

RESISTOR RATING: Rating established by NEMA which classifies resistor according to percent of full load current on first point and duty cycle.

REVERSING CONTACTOR: An electro-magnetic device for reversing the direction of a motor.

ROVING PENDANT: A pushbutton station suspended from an independent track allowing the pendant to “move” along the bridge independent of the hoist.

ROTATING AXLE: An axle which rotates with the wheel.

RUNWAY: The rails, beams, brackets and framework on which the crane operates.

RUNWAYS or RUNWAY BEAMS: The structural elements that run parallel to each other and upon which the crane runs.

RUNWAY CONDUCTORS: The main conductors mounted on or parallel to the runway which supply current to the crane.

RUNWAY RAIL: The rail supported by the runway beams on which the bridge travels.

S

‘S’ SECTION: A standard “I” beam shape as defined by the American Institute of Steel Construction.

SAFETY LUG: A mechanical device fixed securely to the end truck or trolley yoke which will limit the fall of the crane or carrier in case of wheel or axle failure.

SHALL: This word indicates that the adherence to the particular requirement is necessary in order to conform to the specification.

SHOULD: This word indicates that the requirement is a recommendation, the advisability of which depends on the facts in each situation.

SINGLE GIRDER CRANE: An electric overhead traveling crane having one main girder which supports a fixed hoist or a hoist mounted on an under running trolley. An auxiliary girder may be provided to reduce the torsional stresses on the main girder.

SPAN: The horizontal distance center-to-center of runway rails or beams.

SPARK RESISTANCE: Refers to mechanical components only and their ability to avoid sparking.  Normally consists of non-iron bearing metals and non metals.  Not governed by NEC.  See Explosion Proof.

SPUR GEAR: A gear typified by straight cut teeth.

STATIC CONTROL: A method of switching electrical circuits without the use of contacts.

STEPPED CONTROLS: A type of control system with three or more speed points.

STOP: A device to limit travel of a trolley or crane bridge. This device normally is attached to a fixed structure and normally does not have energy absorbing ability.

STRENGTH, AVERAGE ULTIMATE: The average tensile force per unit of cross sectional area required to rupture the material as determined by test.

STRESS: Load or force per unit area tending to deform the material usually expressed in pound per square inch.

SWEEP: Maximum lateral deviation from straightness of structural member, measured at right angles to the Y-Y axis.

T

TOP RIDING CRANE: An overhead traveling crane having the end trucks running on rails attached to the top flange of the crane runway beams.

TORQUE, FULL LOAD (MOTOR): The torque produced by a motor at its rated horsepower and speed.

TRAVELING PENDANT: A pushbutton station suspended from an independent track allowing the pendant to “travel” along the bridge independent of the hoist.

U

UNDER RUNNING CRANE: An overhead traveling crane having the end trucks running on the bottom flanges of the runway beams.

UNDER VOLTAGE PROTECTION: A device operative on the reduction or failure of voltage to cause and maintain the interruption of power in the main circuit.

V

VARIABLE FREQUENCY: A method of control by which the motor supply voltage and frequency can be adjusted.

VFD or VFC: Variable Frequency Drive or Control.

VOLTAGE DROP: The loss of voltage in an electric conductor between supply tap and load tap.

W

‘W’ SECTION: A wide flange beam shape as defined by the American Institute of Steel Construction.

WEB PLATE: The vertical plate connection the upper and lower flanges or cover plates of a girder.

WHEEL BASE: Distance from center to center of outermost wheels.

WHEEL LOAD: The load without impact on any wheel with the trolley and lifted load (rated capacity) positioned on the bridge to give maximum loading.