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Jib
Crane Terminology
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| Anchor
Bolt Load: |
The
total amount of force that is applied to each supporting anchor
bolt; usually measured in kips. |
| Axial
Load: |
The
total vertical force applied to the supporting structure. |
| Formula: |
Axial load = (overall weight of the crane) + (design factor
x weight of load) |
| Boom: |
The
horizontal beam (track) upon which the hoist trolley travels. The
“jib” of the jib crane. |
| Bracket
Center: |
The distance, center line to center line, between two supporting
brackets of a wall mounted jib crane (i.e. the distance between
the two wall mounting points). |
| Capacity: |
The
maximum live weight that the crane is designed to support. For jib
cranes, the design load is based on the capacity, plus a hoist &trolley
allowance (15% of capacity) and an impact allowance (25% of capacity).
The allowable deflection of the crane is calculated using the design
load plus the hoist allowance. Load testing can be performed to
125% of rated load capacity. Standard Gorbel jib cranes are available
in capacities up to 5 tons (4536 kg). |
| Deflection: |
The
difference in elevation at the tip of the boom between an unloaded
crane and a fully loaded crane; usually measured in inches. Gorbel
tends to have stricter deflection criteria than others in the industry.
Typical deflection of Gorbel designs (where L = span of the crane
in inches):
WC200, FS300, FS350, FS350S, MT400: L/150 WB100: L/450 |
| Foundation: |
Free
Standing jib cranes require that a special foundation, usually of
concrete and steel, be used to support the crane and prevent the
crane from tipping over. Foundation recommendations can be found
in the price pages and in the installation manual. |
| Height
Under Boom (HUB): |
The
distance from the floor to the underside of the crane's boom. The
minimum height under boom equals the height of the load, plus the
maximum distance the load is to be lifted, plus the headroom required
for the hoist, trolley, and attachments. |
| Mast:
|
The
vertical steel component of the jib crane which supports the crane.
Free Standing jib cranes (including Work Station Jibs) have a circular
pipe for a mast, Wall Cantilever cranes have standard I-beams, and
Mast Type cranes have wide flange beams. Wall Bracket cranes do
not have a mast.
Overall Height: The distance to the highest point on the jib crane
(should include hardware). A minimal clearance (nominally 3 inches)
is required from any obstructions above the boom or tie rod assembly
throughout the entire rotation of the crane. |
| Span: |
For
a jib crane, span is the distance from the center of the pivot point
to the end of the boom. Note that "span" is greater than
actual “working span” or “hook coverage.”
Supporting Structure: For a free standing jib crane (FS300, FS350,
FS350S) the supporting structure is the foundation which the crane
is bolted to or implanted in. For a wall bracket or wall cantileverjib
crane (WB100 or WC200), the supporting structure is the wall or
column to which the crane is bolted. Mast type jib cranes have a
supporting structure at both the ceiling and the floor. |
| Thrust
& Pull: |
Forces
exerted by a crane on its supporting structure. Thrust is the pushing
(or compressive) force exerted on the structure, while Pull is the
tensile force. Thrust and Pull are thus equal (but opposite in direction)
to each other. The maximum thrust & pull occurs when the crane
is loaded at full capacity. |
| Working
Span: |
The
working span (or hook coverage) is less than the span of the crane.
It is a function of the maximum hook reach and the ability to get
the trolley close to the mast. working span = (distance between
trolley stops) - (hoist trolley length) |
