Counterweight and Ballast Configuration 1 Flashcards

What is the key difference between a crane's counterweight and its ballast?

Answer: Counterweight is attached to the rotating superstructure, while ballast is fixed weight added to the carrier or crawler carbody to improve stability

Counterweight is mounted on the rotating superstructure (upper works) to offset the load moment, while ballast is fixed weight — typically added to the carrier, carbody, or outrigger pads — to improve overall machine stability without rotating with the crane.

A crane operator is preparing to travel a mobile crane on a public road with the counterweight installed. What is the most important concern?

Answer: Traveling with full counterweight may exceed axle load limits and the crane's travel configuration weight restrictions

Traveling on public roads with counterweight installed often exceeds legal axle weight limits and may violate the manufacturer's travel configuration requirements. The operator must consult the crane manual and local regulations — counterweight is frequently removed and transported separately for road moves.

During a lift, a crane operator notices the machine is becoming unstable in the backward direction (tipping away from the load). Which condition most likely explains this?

Answer: The counterweight is too heavy relative to the load being lifted at that radius

Backward (rearward) tipping occurs when the counterweight moment exceeds the load moment — meaning the counterweight is too heavy for the load being lifted at that working radius. This is a real hazard when operating with a light load and maximum counterweight at a short radius.

On a crawler crane, what is the purpose of the carbody counterweight (also called carbody ballast)?

Answer: It is fixed weight mounted on the lower carbody to increase overall machine stability and improve traction on soft ground, independent of the rotating superstructure counterweight

Carbody counterweight is fixed ballast on the lower works of a crawler crane that improves machine stability and ground bearing characteristics. It does not rotate with the superstructure and works in addition to — not instead of — the upper works counterweight.

A load chart specifies a rated capacity at a given radius with 'counterweight removed.' Why would a manufacturer publish capacities for this configuration?

Answer: To allow the crane to work in confined spaces where the rear swing radius of the counterweight would create a hazard, accepting a reduced load rating

Some job sites — such as inside buildings, near walls, or in tight urban settings — cannot accommodate the rear swing radius of a large counterweight. Manufacturers publish reduced-capacity ratings for counterweight-removed configurations so operators can legally work in these constrained environments.

When adding or removing counterweight segments on a lattice boom crane, in what order must the work generally be performed?

Answer: The manufacturer's specific sequence in the operator's manual must be followed, as incorrect order can create unbalanced loads that damage the crane or cause tipping

Counterweight installation and removal sequences are specified by the manufacturer because incorrect sequencing can create structural overloads on mounting pins and connecting plates, or shift the machine's center of gravity in a way that causes tipping. Always follow the crane manufacturer's procedure exactly.