precast lifters safety is not an accident. it is the ... · using clutches with lifters since the...

Driver & Crane Operator Training Program

1Developed with: OVERTON Safety Training, Inc.

Precast Lifters

Safety is not an accident. It is the responsibility of all employees to ensure

we all go home as healthy as when we arrived for work.

Even though you may not be part of the production team we feel it is

important that you understand the principles behind the use of lifters in our

products.

This Section on Lifter Safety is designed to provide Users with a better

understanding of the use of lifters and how recognize potential hoisting

problems and how to safely attach to and use them.



Lifters

Key points covered in this section:

1. Basic knowledge on the concept of

lifters.

2. Lifters have higher capacity if they

are reinforced. That Oldcastle

Precast requires all lifters be

reinforced with rebar.

3. Problems with 4-way lift gear and

insert placement.

4. Problems with cable lifters, ‘A’

anchors, and other types of lifters.

5. Affects of lift gear chain angles on

increasing the loads.

6. Handling issues with Center of

Gravity (CG) being offset.



Lifter Rating

• Just because a lifter uses a "4 Ton" lifting clutch, does not mean it will lift

4 Tons!

• The lifter label typically refers to the lift clutch system – not the lifter’s capacity.

• Here are some "4 Ton" lifter types:

The "4 Ton" lifters shown vary in their lifting

capacity. Below are Capacity Ratings from the Lifter

Manual:



Lifter Rating

Below are Capacity Ratings from the Lifter Manual:

Anchor Type Tension Rating at 3500 PSI

4 Ton Spread Anchor (#79113) 2670 Lbs. = (1.34 Tons) Not 4 Tons!

4 Ton Plate Anchor (#79044) 4732 Lbs. = (2.37 Tons) Not 4 Tons!

4 Ton Plate Anchor w/rebar (#79044) 8000 Lbs. = (4 Tons)

4 Ton Tech Anchor (#79544) 4305 Lbs. = (2.15 Tons) Not 4 Tons!

Which lifter has the FULL rated capacity of the lifting clutch at 3500 PSI?

Only the 4 Ton Plate Anchor, with the additional rebar reinforcement, is

rated at full capacity of 4 Tons.

Consequently, many lift insert manufacturers have revised the name of the inserts for example from a "4 Ton" lift insert to a "4T" insert. Regardless, it is critical to know the actual allowed capacity or rating of the lift insert being used within the precast product



The capacity of a lifter may be

increased by using reinforcement

around the lifter. The ‘Plate Anchor’

and ‘Flat Foot Anchors’ are examples

of lifters that this rule applies to.

This is easy to do by making #4 x 18”

leg rebar ‘hairpins’ that can be tied to the anchor…



IMPORTANT NOTE:

Precast requires lifters on the unformed (top) surfaces prior to casting to be tied-in to reinforcing, or attached to the forms

regardless of the manufacturer’s requirements. This ensures the lifter

is in the correct position, and the lifter is not dislodged by contacting

concrete, rebar or a vibrator.



Center of Gravity of Loads

Many products have holes, or can be made as irregular shapes. These

changes will affect the Center of Gravity (CG) of the product.

The CG will always be a point directly under the hook when the product is

lifted.



For a symmetrical product (the same on both sides) this is always in the

center of the product.

Examples of symmetrical products, which has a CG target directly under the

hook:



If the product has an offset hole, it will have an off center CG:

In order to pick this product in a level manner, the lifters need to be moved,

or the length of the chains adjusted. Engineering will determine the location

of lifters.



In order to pick this product in a level manner, the lifters need to be moved,

or the length of the chains adjusted. Engineering will determine the location

of lifters.

In this case the lifters will be moved to allow this bridge to pick level, and

give equal load on the lifters.

Many times the most severe load on a lift insert or lifting device will occur during product movement out of a form or product tipping in the yard. The specific inserts used for this purpose need to be designed for that special loading.



Rolling blocks and cables, or spreader bars, can also be used to equalize the

load to the lifters. This pick also requires “rolling blocks” to equalize the

loads on the lifters….



Using Clutches with Lifters

Since the majority of the lifters we install in our concrete products are

recessed, clutches are utilized to provide a “link” between the sling and the

lifter.

Example of using clutches with lifters installed on the top of the product.

• Clutch Example




• Points for lifters to be

installed on top of product




• Close-up of installed lifter.

Ensure there are no visible

severe cracks or defects in

the concrete around the

lifter that would cause you

to doubt the strength.




• Attaching clutch to lifter as

a “link” between the lifter

and the sling.



4 Way Chain Sling Picks

Many products are handled using 4 lifters and a 4-way chain or cable sling. It

is critical to get each leg of the 4 way pick to pick equal load. If a lifter is

misplaced it will only have 2 legs of the 4 way picking the product:

All employees need to be able to

recognize when a 4 way pick has

2 legs loose, and must stop lifting

the product until the lifting is equalized.



One way to solve this is to use the

correct lift gear. The 4-way sling

shown below has a large hook eye,

with 2 smaller eyes holding the chain.

The smaller eyes will correct for slight

errors (about 1”) in the placement of

lifters.

The Production Manager will make

sure your plant has this type of lift

gear.



Here is an example of using the 4-way chain sling, with proper tension being

equalized on all four legs.




Having chains at a small Sling Angle will increase the load on the lift gear

and the lifter.

Here is a chart showing the Tension on the lift gear and the lifter, as the angle

decreases:

Many precast plant production policies normally specify a 60 degree, or

greater, sling angle. As shown in the table above, this increases the load on

the lifters and chain by 16% from a straight vertical lift. (Tip: If your sling

leg is long enough when laid down to reach pick point A to B then the

horizontal angle will be at least 60 degrees).

A 30 degree angle will increase the tension by 2 times the load on the lifter, and lift gear.




If the lift gear has sling angles less than 60 degrees, STOP and consult with

engineering to determine if the additional load has been accounted for.

Here is an example

of using the 4-way chain

sling, with at least a

60 degree horizontal sling

angle being utilized.

(you can see he could

easily touch from pick

point "A" to pick point "B"with a single leg of the

sling).

A B



Using 4 Way Chain Slings

Many of the loads we produce and deliver will require the use of a 4 way

chain sling to place them at the site. Here are some basic steps for safe

hoisting using these systems.

• Install the clutches on each of the

4 lifters. Ensure they are locked

into place correctly.




Safely and slowly position the crane

hook and 4 way slings directly over

the center of gravity of the load.

Provide enough slack in the slings

for proper attachment to the

clutches.




• Lay out the slings in proper

position to be attached to the

clutches.




• Ensure the hooks on the

slings are facing outward and

the locking mechanism on

the hooks is closed.



Most rigging problems with lifters can be solved by following:

• Check sling angles are 60 degrees or greater

• Check tension is equal on lift gear legs of a 4 way

• Make sure your lifters account for offset Center of Gravity

• Visually check the lifter and concrete around it for any signs of failure or

severe issues that would cause you to doubt the strength prior to elevating

the load.



Safe lifts are everyone's responsibility! Follow your company policy and

procedure for the correct use of rigging and attachment to lifters at all times.

precast lifters safety is not an accident. it is the ... · using clutches with lifters since the...

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