- Today, I'm helping you understand some
of the most frequently asked basic rigging questions
and terms.
(upbeat music)
If you work in the industry,
then many terms are second nature.
But that can cause a lot of confusion
for someone who is not as familiar with the work.
If you are looking for more in-depth understanding,
we dive into all these topics extensively
in our Learning Center at mazzellacompanies.com.
So, let's get into it.
What is an overhead crane?
An overhead crane is a machine or piece of equipment
that allows you to lift and move heavy material
from one location to another in a precise manner.
There are many different designs
and configurations, capacities, spans, and uses.
Unlike the cranes you see on construction sites,
the majority of overhead cranes are not mobile
and are permanent fixtures.
The different types
of overhead cranes are bridge cranes, gantry cranes,
monorail cranes, jib cranes, and workstation cranes.
What is a jib crane?
A jib crane is a type of overhead lifting device
that's often used in a smaller work cell area
for repetitive and unique lifting tasks.
Jib cranes are extremely versatile and can also be paired
with overhead bridge cranes to maximize production.
They can have capacities ranging anywhere
from 250 pounds to 15 tons.
They come in different types, designs, capacities and spans
but the main feature
of a jib crane is its ability to rotate.
Depending on the type of jib crane,
the boom can rotate anywhere
from 180 degrees to 360 degrees within your workspace.
What is a gantry crane?
A gantry crane is a type of overhead crane
with a single or double girder configuration supported
by free-standing legs that move
on wheels or along a track or rail system.
Gantry cranes are usually considered
when there is a reason not
to incorporate an overhead runway system.
Larger gantry systems may run
on a rail or track embedded in the ground
typically in a straight line in a dedicated work area.
Smaller portable gantry systems run on casters
or wheels and can be moved about the facility
for maintenance or light fabrication work.
There are a few different kinds of gantry cranes,
full gantry cranes, semi-gantry cranes,
portable gantry cranes and adjustable gantry cranes.
What is a shackle?
A shackle is a U-shaped load-bearing connecting device
designed to be used with a removable pin.
Shackles can be used in a variety of different applications
including rigging, towing or pulling, lifting,
hoisting and tie down applications.
There are bow type shackles, which can be side loaded
and chain shackles that can only be used
with inline tension.
Pins can be screw pin,
round pin or bolt type depending on your application.
There are also numerous different specialty shackles
for specific applications.
What is a lifting sling?
A lifting sling is used with a crane
or other type of lifting device to lift objects.
They're used to attach loads to the lifting device
such as a crane hook or below the hook device.
They're generally made of metal or synthetic material.
There are wire rope slings,
alloy chain slings, metal mesh slings,
synthetic web slings, synthetic round slings,
high performance round slings, and synthetic rope slings.
That can be made and used in different configurations,
assemblies and hitches to balance and lift a load.
What is a turnbuckle?
A turnbuckle is a rigging device that is used
to adjust tension and reduce slack in a rope, cable
or a similar tensioning assembly.
They're often used in the tensioning
of fence or perimeter cables,
suspension bridges or buildings, aircraft construction
or probably their most famous application,
the tensioning of ropes in a boxing or wrestling ring.
The end fittings can consist of different combinations
of either a hook end, jaw end, or an eye end depending
on your application.
The end fittings are opposite threaded
so when they're connected to their assembly,
you can turn the body to take up or let out slack.
What is a spreader bar?
A spreader bar, also known as a spreader beam,
is a type of below the hook lifting device.
It is used to stabilize
and support a load during an overhead lift.
They keep the lifting slings
below the device at or near a 90 degree angle.
Spreader bars are often confused with lifting beams.
Both stabilize the load and keep the slings
around a 90 degree angle under the beam.
The difference is the type of forces applied to them.
A spreader bar is connected to the crane hook
by two slings set at an angle using two lifting points
at either end of the beam.
The load mainly puts a compressive stress on the beam.
A lifting beam is connected to the crane hook
by a single lifting point centered on the top of the beam.
The load mainly puts a bending stress on the beam.
What are chain grades?
The number in the title of a welded chain,
grade 80 alloy, grade 43, grade 70,
transport chain, et cetera,
refers to the grade of the chain.
The higher the grade is,
the stronger and more resistant to bending
and breaking the chain is.
Welded chain comes in various different strengths referred
to as grades on the market.
The grade is indicated
by a number and represents the strength
or means of stress value of the chain.
As the chain grade number increases,
the material of the chain is typically harder
and more resistant to abrasion.
The strength to weight ratio increases
and the working load limit increases.
The grade of a chain refers
to the strength of the chain and can indicate the type
of material that it's manufactured from.
What are eye bolts?
Used as a lifting or securement point, eye bolts are one
of the most popular types of rigging hardware.
Eye bolts can be used as a connection point for rigging,
anchoring, pulling, pushing, or hoisting applications.
They can be shouldered or non shouldered
and have a forged eye or a bent eye.
There are nut eye bolts secured with a nut,
machinery eye bolts that are secured
into specifically engineered tapped holes,
and screw eye bolts for wood applications not used
in overhead lifts or with heavy loads.
What is duty cycle?
Duty cycle is the amount of time
that a machine or device is in operation
versus the total amount of time it is available for use.
A motor may have a 40% duty cycle
meaning it's made to be ran up to 40% of the time
such as four minutes out of 10.
When it comes to cranes, to determine duty cycle,
you need to estimate the number
of loads lifted at or near the crane's capacity,
the total number of hours it will be in operation per day,
the number of lifts, and trolley and bridge movements
per hour, and the average length of each movement.
Based on duty cycle, a crane will fall
into six different service classifications specified
by the CMAA.
Class A1 and 2 standby service and infrequent use,
Class B, light service,
Class C, moderate service, Class D, heavy service,
Class E, severe service,
and Class F, continuous severe service.
To determine the classification of a crane,
you need to see how the load class
and the load cycle correlate.
This can be determined based off of a table provided
by the CMAA.
Mazzella's sales staff is a wealth of information
and can help you no matter where you're at
with your rigging expertise.
If you're interested in learning more
or scheduling a consultation,
then contact one of our specialists
in our Lifting and Rigging division linked
in the description below.
Below are also links to some more in-depth articles
and videos to help you understand each of these subjects.
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My name is Ben and I'll see you in the next one.