Counterweight and Ballast Configuration Flashcards

According to ASME B30.5, what must occur if the crane's counterweight configuration is changed between lifts on the same job site?

Answer: A new load chart review must be conducted and the lift plan updated to reflect the new configuration

Any counterweight configuration change alters the crane's rated capacities and stability, requiring a new load chart review and lift plan update before proceeding.

A counterweight slab is found to have a visible crack through its mounting pin hole. What is the correct action?

Answer: Remove the slab from service and quarantine it for manufacturer evaluation or replacement

A cracked counterweight slab must be removed from service immediately; structural integrity of counterweight components is critical for safe operations and no field repair is permitted.

What is the primary reason crane manufacturers specify different counterweight configurations for different boom lengths?

Answer: Longer booms shift the lifted load further forward, increasing the forward tipping moment that must be counterbalanced

As boom length increases, the load's moment arm from the tipping fulcrum grows, requiring greater counterweight to maintain the required stability margin.

When a crane is configured with an overhauling ball (no load) and full counterweight, which stability concern is most relevant during slow swing?

Answer: Backward tipover because the counterweight moment exceeds the front-side restoring moment with no load

With no load to provide a front restoring moment, the counterweight can dominate the balance equation, raising the risk of backward tipover especially on uneven ground.

How does using a longer boom pendant (backstay) affect the effective counterweight moment on a lattice boom crane?

Answer: A longer pendant allows a higher boom angle, which reduces the horizontal distance of the counterweight and decreases its moment

Longer pendants raise the boom to steeper angles, which brings the counterweight closer horizontally to the tipping fulcrum and reduces its stabilizing moment.

A job requires installing 80,000 lb of counterweight on a crane. The crane's counterweight mounting system is rated for 75,000 lb maximum. What must happen before the lift can proceed?

Answer: An engineering modification or a different crane must be used; the rated structural limit cannot be exceeded

Exceeding the mounting system's structural rating risks catastrophic failure of the counterweight tray or brackets; a different crane or manufacturer-approved modification is required.

In NCCCO written examinations, which document is the definitive authority for determining permissible counterweight configurations for a specific crane model?

Answer: The crane manufacturer's load chart and operator manual for that specific crane model and serial number

The crane manufacturer's load chart and operator manual, specific to the model and serial number, are the authoritative documents for all configuration and capacity decisions.