Overhead Crane Design Classification

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Questions and Answers

How much load can a 5t WLL crane lift for 70% of its daily operating cycles?

Full load (correct)

More than 5t

Up to 3t

Exactly 1t

What percentage of the crane's daily operating cycles involves lifting less than 1t?

70%

50%

10%

30% (correct)

What is the main purpose of establishing the class of utilization for a crane mechanism?

To ensure compliance with safety regulations

To determine the resale value of the crane

To assist in designing parts of the mechanism (correct)

To optimize operational efficiency

What does the total duration of use refer to in the context of crane design?

The theoretical basis for design parts Signup and view all the answers

Which of the following is not true about the loading state of a crane?

It determines the resale value of the crane. Signup and view all the answers

What is a requirement for the Competent Person conducting the thorough examination of the crane?

They should not have been involved in crane maintenance. Signup and view all the answers

Which factor should the Competent Person consider when determining the scope of the thorough examination?

The likelihood of failure and associated risks. Signup and view all the answers

When should the maximum intervals for thorough examination of a crane be reduced?

To accommodate environmental factors. Signup and view all the answers

What should be included in the thorough examination scope before putting an OTC into use for the first time?

The condition and age of the crane since manufacturing. Signup and view all the answers

Who is responsible for putting together the scope of the thorough examination following installation?

The Competent Person. Signup and view all the answers

What is one of the key responsibilities during a thorough examination of a crane?

Determine whether all safety devices are functioning correctly Signup and view all the answers

How often should competent persons be re-assessed after the initial appointment?

At regular intervals not exceeding 4 years Signup and view all the answers

What is the purpose of witnessing any testing during the thorough examination?

To evaluate the results of the testing conducted Signup and view all the answers

What should employers document to assess the competence of their employees?

A formally documented assessment process Signup and view all the answers

What should be established for all personnel carrying out thorough examinations?

A comprehensive individual training record Signup and view all the answers

Why must any shortfalls in competency be addressed before a person conducts thorough examinations unsupervised?

To ensure the safety of personnel and operation Signup and view all the answers

What is necessary to specify during a thorough examination of a crane?

Any limitations on the use of the crane Signup and view all the answers

What should be verified regarding warning notices during a thorough crane examination?

If they are correctly fixed and legible Signup and view all the answers

What is the preferred joint for offsetting rail joints from the girder splice?

45° scarf joint Signup and view all the answers

Who is responsible for the design of gantry foundations?

Civil Engineer Signup and view all the answers

What is a requirement when setting the position of foundation bolts?

A template must be used. Signup and view all the answers

What should the competent person refer to for crane running tolerances?

Manufacturer’s specifications Signup and view all the answers

What can cause the gantry alignment tolerances to be exceeded over time?

Settlement of the structure and vibrations Signup and view all the answers

What type of grout is typically used to set anchors into the foundation?

Non-shrink grout Signup and view all the answers

What happens after grouting the stanchion bases is completed?

Loose bolts are tightened up. Signup and view all the answers

What is the purpose of the cones in some foundation anchors?

To allow movement for alignment Signup and view all the answers

What is the primary purpose of classification for design purposes in overhead travelling cranes?

To analyse the design and verify its capability to achieve the desired life under expected conditions Signup and view all the answers

What are the two factors used to determine the group classification of a crane?

Class of utilisation and state of loading Signup and view all the answers

What is an operating cycle in the context of crane classification?

The period from when a load is ready for hoisting to when it is ready to hoist the next load Signup and view all the answers

According to ISO 4301, what is the maximum number of operating cycles for a class U4 crane?

2.5 x 10^5 Signup and view all the answers

What is the state of loading (load spectrum) in crane classification?

The weight of the load relative to the rated capacity of the crane Signup and view all the answers

A 10t WLL overhead crane lifts 2.5t for 80% of its total number of operating cycles per day. What is the state of loading for this crane?

The crane is operating within its rated capacity Signup and view all the answers

How is the total number of operating cycles in the life of the crane usually determined?

By the total operating hours per day and number of cycles per hour Signup and view all the answers

What is the purpose of determining the class of utilisation of a crane?

To determine the expected number of operating cycles over the duration of the crane life Signup and view all the answers

Study Notes

Classification for Design Purposes

Design classification enables analysis and verification of a crane's ability to meet life expectancy under expected service conditions.

Group Classification of the Whole Crane

Classification relies on two main factors: class of utilization and state of loading.

Class of Utilization

Defined by the anticipated number of operating cycles over the crane's lifespan.
An operating cycle begins when a load is ready for hoisting and ends when it’s ready for the next load.
Calculation of total operating cycles involves total operating hours per day and cycles per hour.
Example: A class U4 crane can handle a maximum of 250,000 operating cycles throughout its expected lifetime.

State of Loading (Load Spectrum)

Examines frequency of lifting specific weights in relation to the crane's rated capacity.
Example scenarios:
- A 10t WLL crane may lift 2.5t for 80% of operations and 10t for 20%.
- A 5t WLL crane might operate near full load for 70% of cycles and under 1t for 30%.

Group Classification of a Mechanism

Characterized by total assumed duration of use measured in hours, derived from daily use and expected service years.
Total duration is theoretical and aids in the design of parts but does not guarantee mechanical service life.
Purpose of total duration includes operational assessment, defect identification and rectification, safety device checks, and compliance with regulations.

Assessment of Competence

Employers should document a formal assessment of individual competencies for crane examination roles.
Competence assessments required upon hiring, within the first year, and periodically every four years.
Shortfalls in competency must be addressed before allowing unsupervised examinations.

Training Records

Establish comprehensive training records for personnel conducting thorough examinations.
Records must reflect training adequacy considering environmental factors and crane condition.

Selection of the Competent Person

The Competent Person conducting thorough examinations must not have been involved in the crane's maintenance activities.

Scope of Thorough Examination

Developed by the Competent Person, considering failure likelihood and associated risks, especially regarding the crane's age and condition.
Examination scope applies before initial use and after installation, focusing on structural integrity and operational safety.

Gantry Foundation Design

Civil engineers are tasked with foundation design, incorporating proper load bearings and utilizing template guidance for bolt positioning.
Foundations require grouting and bolt tightening for stability, with exposure checks post-erection.

Gantry Alignment

Gantry alignment adheres to manufacturer specifications and general standards (BS466, ISO12488) for crane tolerances.
Over time, structure settlement and operational stresses may require reevaluation of alignment and tolerances.

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Description

This quiz focuses on the classification of overhead cranes for design purposes. It covers factors such as class of utilization and state of loading, crucial for ensuring cranes meet operational requirements. Test your knowledge on the principles that guide crane design verification.