CSCS Mobile Crane flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Load radius definition

The horizontal distance from the crane's center of rotation to the vertical line through the center of gravity of the load. It is measured with the boom under load, not unloaded.

Ground bearing pressure

The load per unit area transmitted to the soil by outrigger floats or tracks. Calculated as total weight divided by total bearing area, including cribbing.

Critical lift definition

A lift that meets defined criteria such as exceeding 75 percent of rated capacity, lifting over occupied areas, or involving multiple cranes, requiring an engineered lift plan.

Net capacity

The gross rated capacity from the load chart minus deductions such as the hook block, headache ball, jib, and rigging weight. This is the allowable load weight.

Interpolation rule

When the actual radius falls between chart values, capacity may be interpolated linearly only if the manufacturer permits it. Never extrapolate beyond the chart.

On-rubber capacity

The reduced rated capacity when lifting without outriggers, usually requiring the boom centered over the front or rear and travel at creep speed per the chart.

Boom length effect

At a fixed radius, increasing boom length generally reduces rated capacity because the chart accounts for boom strength and tipping moment at that geometry.

Sling tension formula

Tension per leg equals load divided by the number of legs, then divided by the cosine of the angle from vertical. Shallower angles increase tension.

Sling angle factor

A multiplier applied to sling tension based on angle from horizontal. A 30-degree angle doubles tension compared with a vertical lift.

Center of gravity

The point where the load's weight is concentrated. It must be directly below the hook, or the load tilts and legs carry unequal loads.

Working load limit

The maximum load a sling or rigging component is rated to carry in a specific configuration, accounting for angle, number of legs, and attachment method.

Tag line purpose

A rope used to control load rotation and swing from a safe distance. It must never be used to pull a load beyond the rated radius.

Hoist hand signal

Forearm raised vertically with index finger pointing up, moving in a small circular motion. The operator raises the load accordingly.

Stop hand signal

Arm extended horizontally with palm facing down, held stationary. Anyone on site may give this signal and the operator must stop immediately.

Emergency stop rule

Any person may signal stop in an emergency. The operator must stop and hold the load until the signalperson or supervisor directs otherwise.

Signalperson qualification

The signalperson must be trained and qualified in standard signals, positioned in full view of the operator, and be the single designated signal source.

Anti-two-block device

A safety device that prevents the hook block from contacting the boom tip. It must be function-tested each shift and never bypassed or disabled.

Load moment indicator

A system that measures load, radius, and boom angle to warn and stop operations approaching rated capacity. Overrides are prohibited except per manufacturer procedure.

Side loading hazard

Pulling or dragging a load sideways places forces on the boom it was not designed for, potentially causing structural failure outside the load chart.

Swing control

Smooth swing acceleration and deceleration limit pendulum swing. Centrifugal force during rapid swings increases load radius and capacity demand.

Outrigger float pressure

Soil pressure under a float equals load per outrigger divided by float area. Doubling float dimensions quarters the pressure on the soil.

Leveling requirement

The crane must be level within the manufacturer's tolerance, commonly one percent, before lifting. Use a bubble level or inclinometer on the carrier.

Counterweight configuration

Counterweight must match the load chart selected. Adding or removing counterweight changes rated capacity and requires the corresponding chart.

Assembly barricade

The assembly and disassembly area must be barricaded and controlled so only the assembly director and crew enter the boom and counterweight zone.

Pre-shift inspection

A documented check before each shift covering wire rope, hook, rigging, outriggers, levels, LMI, anti-two-block, brakes, and fluid levels.

Hook throat opening

A hook must be removed from service when the throat opening increases beyond the manufacturer's limit, commonly 15 percent of the original opening.

Wire rope removal criteria

Criteria include broken wires per lay, diameter reduction, corrosion, kinking, and birdcaging. Exceeding any manufacturer limit requires removal from service.

Periodic inspection

A documented inspection at defined intervals and after any incident, shock load, or modification. Records include date, inspector, findings, and corrective action.

Power line contact response

If the crane contacts a power line, the operator stays in the cab and warns others away. If evacuation is required, jump clear and shuffle away.

Swing radius barricade

The area swept by the counterweight and the area under the load must be barricaded. No personnel may stand under a suspended load.

Emergency lowering

A procedure using the manufacturer's emergency pump or lowering valve to bring the boom down if hydraulic power is lost. Must be known before operation.

Personnel platform rules

Personnel platforms require manufacturer approval, a fall protection system, and reduced capacity per the platform chart. Free fall of the platform is prohibited.