Overload Testing Disadvantages

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Questions and Answers

What is one of the reasons some manufacturers do not recommend routine overload testing?

It provides mechanical benefits to the structure.

It can cause deterioration of the crane structure. (correct)

It is always necessary for all cranes.

It reveals all defects in the crane.

Which of the following circumstances is considered acceptable for overload testing?

Before routine operational use

After structural modifications (correct)

Regular operational checks

Daily routine maintenance

What is a potential consequence of a crane failing during overload testing?

It provides valuable data for future tests.

It confirms the crane's reliability.

It poses danger and incurs high costs. (correct)

It offers an opportunity for redesigning the crane.

What do authoritative bodies state about the benefits of overload testing?

There is no defined benefit to the practice. Signup and view all the answers

What examination must be conducted before applying a load during crane testing?

Thorough examination of the crane Signup and view all the answers

Which of the following is NOT listed as a circumstance when overload testing might be justified?

Daily operational efficiency check Signup and view all the answers

What should the competent person do before determining the nature of the load test?

Seek advice from the manufacturer or design authority. Signup and view all the answers

Repeated overloads on a crane may lead to which of the following issues?

Fatigue that could go unrevealed Signup and view all the answers

Which checks should be performed to ensure the rated capacity of the crane is accurate?

Check the load radius indicator and the operator’s cab capacity table. Signup and view all the answers

What should a competent person validate during a functional test with no load applied?

The operation of controls, switches, and limit switches. Signup and view all the answers

How do variations in counterweight affect crane performance?

They significantly affect the crane's stability. Signup and view all the answers

What should be marked clearly on the outrigger for operational safety?

Intermediate extension position for the outrigger. Signup and view all the answers

Which of the following is NOT a factor that affects the stability and strength of a mobile crane?

Available operator training. Signup and view all the answers

Why is it essential for the manufacturer’s duty charts to provide specified intermediate extensions?

To prevent overload conditions during extended operations. Signup and view all the answers

What factor should be taken into account during overload testing?

All support systems affecting crane stability. Signup and view all the answers

What is the function of the RCI/RCL during the operational safety checks?

To provide real-time load measurements. Signup and view all the answers

What is the primary purpose of functionally testing a crane without a load applied?

To ensure proper working condition of the crane Signup and view all the answers

Which step should be taken after the functional tests without a load applied?

Test the efficiency of the crane’s hoist brake with maximum line pull Signup and view all the answers

What should occur when the hoist brake is applied after lifting the load clear of the ground?

There should be no fall back or creep Signup and view all the answers

What is crucial to check when lifting the load during the test program?

The load must be raised clear of the ground Signup and view all the answers

What is the significance of raising the load until every tooth in the train of the hoist gears has been subjected to overload?

To confirm that gear engagement is robust enough under stress Signup and view all the answers

Why is it important to maintain the crane setup within the rated capacity during the test program?

To ensure stable operation and safety Signup and view all the answers

What indicates the need for further testing if the load does not lower smoothly?

The brake mechanism may be malfunctioning Signup and view all the answers

What should be checked if the control is returned to neutral after lowering the load?

The load must not collapse instantly Signup and view all the answers

Study Notes

Disadvantages of Routine Overload Testing

Minimal benefits to routine overload testing, with significant drawbacks.
Manufacturers often advise against overload tests except in specific situations, such as overload, jib clash, collision, arduous duties, structural component failure, excessive weather conditions, or substantial modifications.
Repeated overloads may degrade crane structures over time.
Fatigue-related defects often remain undetected during overload testing.
No defined structural or mechanical advantages recognized by authoritative bodies.
Failures during testing pose safety risks and financial burdens.

Preparation for Load Testing

Competent personnel should consult manufacturers or design authorities about testing specifics, including load magnitude and methodologies.
A thorough visual inspection of the crane and testing area is required before starting the test.
Ensure compliance with manufacturer’s rigging instructions prior to load application.
Long jibs may lead to instability if jib angles are below specified minimums.

Sequence of Supplementary Load Testing

Functional tests without load to confirm proper crane operation.
Evaluate hoist brake efficiency using maximum line pull before applying load.
The load should be elevated clear of the ground, with the brake engaging upon neutral control return to prevent fall back or creep.
The process includes re-hoisting and re-applying the brake to test the capability to lift again.
Lowering the load should be executed while maintaining clear ground clearance with neutral controls.
Requirements include no over-run or creep during operations.
Each test configuration must keep the load within the crane's rated capacity.
Elevate the load slightly off the ground and extend the crane to the radius where overload conditions apply as per manufacturer specifications.

Ensuring Rated Capacity Consistency

The competent person must verify that rated capacity corresponds across all manufacturer documentation, including certificates, load radius indicators, and operator’s cab displays.

Functional Testing Procedures

Conduct a functional test without load to check the operation of controls, switches, and limit devices.
Verify adjustments and performance of brakes and limit switches.
Stability factors for mobile cranes include varied support systems such as crawler tracks, tires, outriggers, and configurations that impact strength and stability.

Outrigger Considerations in Load Testing

Intermediate outrigger extension positions must be clearly marked.
Manufacturer's duty charts must reflect the correct rated capacities for various outrigger extensions.
Duty charts should detail specified intermediate extensions as well.

Impact of Counterweights

Variations in counterweight influence crane stability.
Manufacturer duty charts define applicable ratings related to different counterweight configurations.

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Description

This quiz explores the disadvantages of routine overload testing in various manufacturing contexts. It highlights that many manufacturers only recommend such tests in exceptional circumstances, including overload, structural failures, and extreme weather. Understanding these limitations is essential for safe and effective testing practices.