CSCS Crawler Crane cheat sheet

A crawler crane carries its load on a lattice or telescopic boom mounted on a rotating upperworks supported by two endless crawler track assemblies.

Boom length = base boom section + inserted lattice sections; effective radius is measured horizontally from the crane's rotation center to the load's center of gravity.

Boom angle is the angle between the boom centerline and horizontal; radius increases and capacity decreases as boom angle decreases.

The load moment indicator (LMI) or rated capacity limiter compares actual load moment to the chart value and warns or locks out before overload.

Counterweight reduces forward tipping moment; counterweight and carbody weight are fixed chart inputs and must match the configuration listed.

Boom foot pins, boom top sheaves, and the boom hoist (pendant or luffing) system transfer boom loads to the upperworks; pendant lines are fixed-length, luffing cylinders/ropes are variable.

A jib or fly extension adds reach at reduced capacity; jib capacity is charted separately and is typically a small fraction of main boom capacity.

Track shoes, grousers, and track width determine ground bearing pressure and flotation; wide shoes reduce pressure but do not increase chart capacity.

Ground bearing pressure (psf or kPa) = total weight carried by a track divided by the effective track contact area; compare to the soil's allowable bearing capacity.

Crawler cranes must sit on level, uniformly supporting ground; typical manufacturer limit is 1% out-of-level for the crane's longitudinal and transverse axes unless the chart states otherwise.

Mats, timber, or steel plates spread load: pressure under a mat is roughly total load divided by mat area, and mats must be sized so subgrade capacity is not exceeded.

Tipping is governed by load moment about the tipping axis (track edge or outrigger line); the crane tips when load moment exceeds the resisting moment of crane weight and counterweight.

Keep the swing path clear of excavations, buried utilities, slopes, and backfilled trenches; crane track pressure can extend well beyond the track footprint into the soil.

Boom deflection and side loading reduce stability; the crane must be set so the boom can swing freely through the full working arc without contacting obstructions.

Crawler crane travel with a load is only permitted within charted pick-and-carry ratings, on firm level ground, with the boom in the specified travel position.

Wind acts on boom and load sail area, increasing load moment and side load; stop operations when wind exceeds the manufacturer's limit or when the load cannot be controlled.

Rated capacity = the lesser of the structural limit (boom, pins, wire rope) and the stability limit for the given radius, boom length, and configuration.

Total load = load weight + rigging and sling weight + hook block and headache ball weight + any attached below-the-hook device; deduct all of these from gross chart capacity.

Radius is the horizontal distance from the crane's rotation center to the vertical line through the load's center of gravity - not to the boom tip.

For capacities between charted radii, use the next longer radius (lower capacity); never interpolate upward.

For boom lengths between charted values, use the next longer boom length; for multiple part lines, use the reeving that matches the chart block.

Deductions for jib, auxiliary head, and stowed attachments must be applied exactly as the notes specify; chart notes override the table.

Operating radius changes with boom deflection and load swing; the loaded radius is greater than the unloaded geometric radius, so verify the loaded radius.

Line pull and parts of line: required line pull = total load / number of parts of line; the hook block capacity and rope breaking strength must both exceed the load with the required design factor.

Sling tension in a two-leg bridle: tension per leg = (load / 2) / sin(angle from horizontal); flatter angles sharply increase leg tension.

Sling angle factor: capacity of a multi-leg sling is reduced by the sine of the angle to horizontal; a 60-degree leg uses about 0.866 of its vertical rating, 45 degrees about 0.707, 30 degrees 0.5.

Vertical hitch uses full sling capacity; choker hitch is typically rated about 75-80% of vertical; basket hitch can be up to 200% only if legs are vertical and the load is balanced.

Shackle and hook ratings are based on the pin or bowl, not the body; the working load limit must equal or exceed the load, and hooks need a functioning latch.

Center of gravity must be below or at the lift point to avoid load rotation; off-center lifts require calculated tag lines and load control.

Wire rope inspection rejects rope with broken wires exceeding the specified count per lay, kinking, crushing, bird-caging, or corrosion/heat damage.

Tag lines control rotation and swing but are not rigging; they must be long enough to keep personnel clear of the load and swing radius.

Shock loading, side pulls on the hook, and dragging loads are prohibited because they impose loads the chart and rigging are not rated for.

Daily pre-shift inspection covers wire rope, sheaves, hook and latch, boom pins and lacings, track condition, fluid levels, brakes, and the LMI/anti-two-block function.

Anti-two-block device must be tested before each shift; it stops hoist before the hook block contacts the boom tip.

LMI calibration and load cell zero must match the installed configuration; an uncalibrated or bypassed LMI removes the crane from service.

Boom assembly checks: all pins fully inserted and secured, lacing pins in place, pendant lines properly tensioned, and boom stop adjusted.

Wire rope end connections, wedge sockets, and dead-end anchorages must be inspected for correct assembly and broken wires at the termination.

Track tension and undercarriage: check for loose or missing track shoes, worn pins and bushings, and fluid leaks in the travel drives.

Functional checks before lifting: hoist, boom, swing, and travel brakes; travel alarm; horn; and all limit switches.

Maintenance records document inspections, repairs, and load test results; an annual or periodic inspection by a qualified person is required in addition to daily checks.

Standard hand signals include hoist, lower, boom up/down, swing, stop, and emergency stop; the operator follows only one designated signal person.

The operator stops immediately on a stop signal from anyone; only the designated signal person may direct other motions.

Before lifting, confirm the load weight, radius, chart capacity, rigging, and swing path; lift a few inches and verify stability and brake holding.

Smooth starts and stops prevent load swing; swing the load with the boom, not by dragging or by swinging the load ahead of the boom.

Never leave the operator's station with a load suspended; if the operator leaves, the load is landed and the controls are secured.

Travel with a suspended load only when the chart permits, with the boom in the specified position and the load kept low and controlled.

Radio communication must be dedicated to the lift; hand signals are used when radios fail or when the signal person is in direct view.

Multiple crane lifts require a written plan, a designated lift director, and load sharing calculated so neither crane exceeds its chart.

Power line approach: maintain the required minimum clearance from all energized lines; if contact occurs, the operator stays in the cab and warns others to stay clear until the line is de-energized.

If the crane contacts a power line and fire forces exit, jump clear without touching the crane and the ground at the same time, then shuffle away.

Personnel must never stand or walk under a suspended load, in the swing radius, or between the load and a fixed object.

Load drop or runaway load: sound the alarm, clear the area, and lower the load only if it can be done without endangering anyone.

Crane tipping or structural failure warning signs include LMI alarms, unusual boom deflection, and load swing; the operator lowers the load and stops.

Fire extinguisher must be on the crane and accessible; fuel only with the engine off and no ignition sources nearby.

Emergency shutdown: disengage the clutch/hoist, set brakes, lower the load if safe, and secure the controls before leaving the cab.

Incident reporting: any contact with power lines, dropped load, two-blocking, or overload must be reported and the crane inspected before returning to service.