8 hours ago
What Happens If a Boom Cylinder Line Fails While Lifting a Load
In modern hydraulic cranes, boom cylinder lines are protected by factory-installed holding valves. These valves are designed to prevent uncontrolled descent of the boom in the event of a hydraulic line failure. If a line ruptures while a load is suspended, the holding valve should automatically lock the cylinder in place, preventing the boom from dropping and averting a catastrophic accident.
However, this assumes the valve is functioning correctly and the system has been maintained. In older cranes or poorly serviced units, the absence or failure of a holding valve could result in rapid boom descent, potentially damaging the load, the crane, or nearby structures. This is why regular inspection of hydraulic components and valve integrity is critical.
A crane operator in Kansas once experienced a partial line rupture during a lift. Thanks to the holding valve, the boom held position long enough for the crew to safely lower the load using auxiliary controls. The incident led to a company-wide review of hydraulic safety protocols.
What Is Cabling and How Can It Be Prevented
Cabling refers to the twisting or tangling of multiple parts of line during a lift, especially when using multi-part reeving. It typically occurs when the load block spins instead of the hook, causing the lines to twist together. This can lead to binding, uneven load distribution, and even refusal of the block to descend properly.
Preventive strategies include:
In one lift involving a 90,000-pound load and 300 feet of line, a crew in Florida experienced severe cabling. The block twisted, and the load refused to descend. After running the block up to the two-block position and back down, the twist cleared. The team later adjusted their reeving and added tag lines to prevent recurrence.
What Must Be Done When Adding an Air Compressor to the Rear of a Crane
Adding an air compressor or any auxiliary equipment to the rear of a crane alters its counterweight configuration. This modification must be approved by the crane’s manufacturer and documented in the load chart or operating manual. Failure to do so can invalidate the crane’s rated capacities and compromise safety.
Steps include:
A crane rental company in New York added a hydraulic power pack to the rear of a lattice boom crane. After consulting the manufacturer, they removed an equivalent amount of counterweight and issued a revised load chart. The crane passed inspection and performed flawlessly on a six-month bridge project.
Conclusion
These questions—about boom cylinder failure, cabling, and rear-mounted equipment—highlight the complexity and nuance of crane operation. While technology has improved safety and control, operator knowledge remains the cornerstone of safe lifting. Understanding hydraulic safeguards, line behavior, and load chart integrity ensures that cranes perform reliably under pressure. Whether preparing for certification or refining field practices, revisiting these fundamentals keeps crews sharp and lifts secure.
In modern hydraulic cranes, boom cylinder lines are protected by factory-installed holding valves. These valves are designed to prevent uncontrolled descent of the boom in the event of a hydraulic line failure. If a line ruptures while a load is suspended, the holding valve should automatically lock the cylinder in place, preventing the boom from dropping and averting a catastrophic accident.
However, this assumes the valve is functioning correctly and the system has been maintained. In older cranes or poorly serviced units, the absence or failure of a holding valve could result in rapid boom descent, potentially damaging the load, the crane, or nearby structures. This is why regular inspection of hydraulic components and valve integrity is critical.
A crane operator in Kansas once experienced a partial line rupture during a lift. Thanks to the holding valve, the boom held position long enough for the crew to safely lower the load using auxiliary controls. The incident led to a company-wide review of hydraulic safety protocols.
What Is Cabling and How Can It Be Prevented
Cabling refers to the twisting or tangling of multiple parts of line during a lift, especially when using multi-part reeving. It typically occurs when the load block spins instead of the hook, causing the lines to twist together. This can lead to binding, uneven load distribution, and even refusal of the block to descend properly.
Preventive strategies include:
- Using tag lines to control load rotation
- Lashing the block to the hook or rigging to prevent spin
- Pulling slack through the block before reeving to remove twists
- Ensuring balanced reeving across sheaves
- Using rotation-resistant wire rope (with caution)
In one lift involving a 90,000-pound load and 300 feet of line, a crew in Florida experienced severe cabling. The block twisted, and the load refused to descend. After running the block up to the two-block position and back down, the twist cleared. The team later adjusted their reeving and added tag lines to prevent recurrence.
What Must Be Done When Adding an Air Compressor to the Rear of a Crane
Adding an air compressor or any auxiliary equipment to the rear of a crane alters its counterweight configuration. This modification must be approved by the crane’s manufacturer and documented in the load chart or operating manual. Failure to do so can invalidate the crane’s rated capacities and compromise safety.
Steps include:
- Manufacturer approval of the modification
- Load chart amendment or replacement
- Rebalancing counterweights if necessary
- Ensuring leads or auxiliary lines do not interfere with boom movement
- Verifying stability with the added mass
A crane rental company in New York added a hydraulic power pack to the rear of a lattice boom crane. After consulting the manufacturer, they removed an equivalent amount of counterweight and issued a revised load chart. The crane passed inspection and performed flawlessly on a six-month bridge project.
Conclusion
These questions—about boom cylinder failure, cabling, and rear-mounted equipment—highlight the complexity and nuance of crane operation. While technology has improved safety and control, operator knowledge remains the cornerstone of safe lifting. Understanding hydraulic safeguards, line behavior, and load chart integrity ensures that cranes perform reliably under pressure. Whether preparing for certification or refining field practices, revisiting these fundamentals keeps crews sharp and lifts secure.
