Introduction: Load testing of mobile cranes is required by many safety regulations and national consensus standards. The purpose of the load test is to verify that the crane is functionally capable over the range of loads that the manufacturer specifies for the particular crane. Another purpose of the load test is to verify the appropriateness of the load chart. Finally, the purpose of the load test is to ascertain that the crane is structurally capable of handling the rated loads. The associated condition inspection is to ensure that the overall structural, mechanical, and electrical components of the equipment have been maintained in safe and serviceable condition and are functioning properly according to the original equipment manufacturer’s specifications.
The application of this standard is for boom-type mobile cranes of the following configurations:
1. Motor Truck Mounted Conventional Cranes
2. Crawler Mounted Conventional Cranes
3. Motor Truck Mounted Hydraulic Cranes
4. Crawler Mounted Hydraulic Cranes
5. Rough Terrain Hydraulic Cranes
6. Wheel Mounted Cranes
7. Locomotive Mounted Cranes
The following procedure is established to provide a method which will meet the most stringent requirements that apply to this type of crane. The methods herein recommended are intended to provide a safe and effective means by which load tests can be conducted.
1. Pre-test Procedures (Back to Top)
1-1. Check that an operator’s manual and load chart for the crane in the configuration that it will be tested is available and review same for operational limitations.
1-2. Determine that lifting gear to be used with the crane in normal duties or for the purpose of testing the crane has already been tested independently. Check that all lifting attachments are clearly marked with their safe working load.
1-3. Review previous test and inspection certificates, wire rope inspections, and deficiency reports and determine that any necessary corrections have been made.
1-4. Review periodic inspection reports, maintenance records and documentation of repairs to determine that all work was in order.
1-5. Choose appropriate proof loads for the test based on the manufacturer’s load ratings for the condition of use. These shall consist of the application of proof loads as close as possible to, but not exceeding, 110% of the load ratings for the boom on the crane. Proof loads shall be applied at the design maximum and minimum boom angles or radii or as close to these as practicable and at such intermediate radii as the certificator may deem necessary to verify the load chart and to verify line pull on all load hoists. A test load must also be selected for the partial load test which is done prior to the proof load tests. An intermediate proof load at less than rated radius can be used for this purpose. Reeving configuration must be recorded.
1-6. If the crane is equipped with a jib or rated on rubber in addition to outriggers, specific proof loads shall be chosen which will provide an appropriate test for the alternative condition in accordance with the load chart. (NOTE: Extreme caution must be exercised when testing on rubber. Tire pressures and work areas noted on load charts must be strictly followed.)
1-7. Rigging which conforms to safety standards for a safe lift must be selected for the test loads.
1-8. The crane shall be set up level in all directions, within acceptable tolerances, with suitable clearance from any obstructions. The operating surface should be firm and give sufficient support for the bearing pressures that will be
generated during the testing procedures. Care must be exercised in following the manufacturer’s instructions for proper set-up.1-9. Barriers should be set up around the operating perimeter if there is any possibility that personnel or vehicles will intrude into the operating region.
1-10. A pre—test conference should be arranged with the operator, the riggers, and the signalman to establish how the test will be conducted and to review the signals to be used.
1-11. Inspect the crane in its entirety according to the checklist normally used for that type of crane. Particular attention should be given to the structural elements of the crane which will be subjected to stress during the load testing procedure. Any evidence of degradation among the structural elements should be evaluated and a determination made as to the suitability of the crane’s condition for load testing and the need for nondestructive testing or dismantling for detailed examination.
1-12. The crane should be operated without a load through its full range of operation. All safety devices should be checked for appropriate function, including accuracy of all safety indicators.
2. Load Test (Back to Top)
2-1. The first test should be the functional load test. A partial load must be applied to both the main and auxiliary lines (if so equipped) and appropriate intermediate sized loads should be used. If the auxiliary line is used the chosen load should be the one intended to test the rated line pull of the auxiliary line. Swinging of a rated load at its rated radius should be accomplished from the least stable orientation to the most stable orientation of the boom.
2-3. Attach the appropriate hook to the rigging with the load located at a radius less than the maximum rated radius for that load. Take up the slack in the rigging to be sure that the load is seated properly in the rigging.
2-4. Raise the load 6" to 8" off the ground and hold it to determine if the crane is functioning properly with the load and to be sure that the load is still seated properly in the rigging.
2-5. Operate the crane through all its motions in accordance with the work area chart to ensure that the load is applied to all parts. Determine that all controls and functions are operating properly and that all components are performing as intended.
2-6. Swing the load to one side, still within the operating radius for that load size, until it is perpendicular to the center line of the carrier.
2-7. Slowly move the load out to a radius which will achieve 110% of rated capacity condition for that load. Hold the load at that radius for at least ten (10) minutes.
2-8. Move the load in toward the crane, by elevating the boom, to an intermediate radius and swing the load to the other side of the crane to point where it is perpendicular to the center line of the carrier. Elevating the boom from the test position verifies the capacity of the boom hoist under rated conditions.
2-9. Slowly move the load out to a radius which will achieve 110% of rated capacity condition for that load. Hold the load at that radius for at least ten (10) minutes.
2-10. Move the load in toward the crane, by elevating the boom, to an intermediate radius and set the load down at the designated storage area in preparation for the next test.
2-11. Attach the hook on the auxiliary line to the rigging for the lightest test load and take up the slack to be sure that the load is seated properly in the rigging.
2-12. Raise the load 6" to 8" off the ground and hold it to determine if the crane is functioning properly with the load and to be sure that the load is still seated properly in the rigging.
2-13. Swing the load to one side, still within the operating radius for that load size, until it is perpendicular to the center line of the carrier.
2-14. Slowly move the load out to a radius which will achieve 110% of rated capacity condition for that load. Hold the load at that radius for at least ten (10) minutes.
2-15. Move the load in toward the crane, by elevating the boom, to an intermediate radius and swing the load to the other side of the crane to point where it is perpendicular to the center line of the carrier.
2-16. Slowly move the load out to a radius which will achieve 110% of rated capacity condition for that load. Hold the load at that radius for at least ten (10) minutes.
2-17. Move the load in toward the crane, by elevating the boom, to an intermediate radius and set the load down at the designated storage area in preparation for the next test.
2-18. Attach the main load block to the maximum load. This should be done with the load in place within the operating radius for that load and in the area of maximum stability for the particular crane. Take up the slack to be sure that the load is seated properly in the rigging.
2-19. Raise the load 6" to 8" off the ground and hold it to determine if the crane is functioning properly with the load and to be sure that the load is still seated properly in the rigging.
2-20. Slowly move the load out to the radius at which the condition of 110% rated capacity is achieved and check to see that the brakes and load bearing components are performing properly while holding the load for at least ten (10) minutes.
2-21. Elevate the boom to operating radius and swing the load to the next quadrant to be tested.
2-22. Slowly move the load out to a radius which will achieve 110% of rated capacity condition for that load. Hold the load at that radius for at least ten (10) minutes.
2-23. Move the load in toward the crane, by elevating the boom, to an intermediate radius and swing the load to the final quadrant to be tested.
2-24. Slowly move the load out to a radius which will achieve 110% of rated capacity condition for that load. Hold the load at that radius for at least ten (10) minutes.
2-25. Move the load in toward the crane, by elevating the boom, to an intermediate radius and set the load down at the designated location using the brake and/or hydraulic functions in such a way that the load is under full control of the operator while being lowered.
2-26. Disengage the rigging and make preparation to lift the test load for the jib or for other alternative configurations as appropriate.
2-27. Raise and manipulate the appropriate test loads in the same fashion described above as required for the alternative configurations. When all testing is completed, set the load down in an appropriate area clear of the crane in preparation for post—test inspection.
2-28. While performing the proof load tests, shut off the engine with the load 6"—8" off the ground, and test the function of the load check valves or hoist pawls, as appropriate, in the most severe condition for the function being tested.
3. Post-test Inspection (Back to Top)
3-1. Lower the boom to the ground or as low as possible for the crane configuration. A platform or other work surface will allow appropriate inspection of the boom and all of its fittings.
3-2. Relax all rigging and reeving to allow for inspection of the wire rope and sheaves. Check all sheaves, drums and wire rope for evidence damage or excessive wear. Open the wire rope and inspect the core at several points to determine any deterioration. Give particular attention to potential damage at end fittings and anchor points. When inspection is completed, re—wrap the cables on the drums using appropriate fleet angles and cable tension.
3-3. Inspect each element of the boom, jib, gantry, and reeving. Check all components of the crane for structural damage including cracks, weld separation, permanent deformation, paint flaking and loose fasteners. Make note of any deficiencies or damage found.
3-4. Check that all required guards are securely attached. Verify that all shafts, couplings and open gears that can be contacted by personnel are properly guarded.
3-5. Check outrigger structure for damage and hydraulic components for any evidence of damage or leaks in the hydraulic system.
3-6. Make note of any damage, deficiencies, or corrections that may
be required.3-7. Return the boom to its normal rest position and complete the report.
3-8. Conduct an exit briefing as appropriate.
