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Definitions

 

sheave, nonrunning (equalizer)

upper block


sheave, nonrunning (equalizer): a sheave used to equalize tension in opposite parts of the rope. Because of its slight movement, it is not termed a running sheave.

sheave, running: a sheave that rotates as the load block is lifted or lowered.

should: this word indicates that a rule is a recommendation, the advisability of which depends on the facts in each situation.

side pull: the portion of the hoist pull acting horizontally when the hoist lines are not operated vertically.

sills: horizontal structural members that connect the lower ends of two or more legs of a gantry crane on one runway.

slash (/): a slash (/) denotes and/or and indicates that two words are to be taken together or individually.

span: the horizontal distance, center to center, between runway rails.

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.

switch (valve): a device for making, breaking, or changing the connections in an electric, hydraulic, or pneumatic circuit.

switch, emergency stop: a manually actuated switch to disconnect power independently of the regular operating controls.

switch, limit: a device that is actuated by the motion of a part of a power-driven machine or equipment to alter or disconnect the electric, hydraulic, or pneumatic circuit associated with the machine or equipment.

switch, main (crane disconnect): a switch on the crane controlling the main power supply from the runway conductors.
switch, master: a switch that dominates the operation of contactors, relays, or other remotely operated devices.

switch, master, spring-return: a master switch that, when released, will return automatically to a neutral (off) position.

switch, runway disconnect: a switch, usually at floor level, controlling the main power supply to the runway conductors.

trolley: the unit that travels on the bridge rails and supports the load block.

trolley travel: the trolley movement.

truck: a unit consisting of a frame, wheels, bearings, and axles that supports the bridge girders, the end ties of an overhead crane, or the sill of a gantry crane.

unattended: a condition in which the operator of a crane is not at the operating control devices. However, on a floor-operated crane, if the operating control devices are within sight of the operator and within a distance equal to the span of the crane, the crane should be considered at tended.

upper block: a fixed block located on a trolley that, through a system of sheaves, bearings, pins, and frame, supports the load block and its load.