CSCS Tower Crane flashcards
CSCS Tower Crane · Build recall with a focused review session.
34 cards. Read the term and the definition here. The deck at the top of this page is optional.
- Hammerhead tower crane
- A tower crane with a fixed horizontal jib and counter-jib; a trolley travels along the jib to change the working radius.
- Luffing jib crane
- A tower crane whose jib pivots up and down to change radius, allowing it to work in tight sites without a horizontal jib sweep.
- Slewing unit
- The turntable assembly between mast top and jib that allows the jib and counter-jib to rotate together through 360 degrees.
- Counterweight function
- Counterweights on the counter-jib balance the overturning moment created by the jib and its load, keeping the crane stable.
- Trolley carriage
- The wheeled carriage running along the jib that carries the hoist rope sheave and positions the hook at the required radius.
- Climbing crane
- A tower crane supported by a climbing frame attached to the building structure; mast sections are added as the building rises.
- Foundation reactions
- The vertical load, overturning moment, and horizontal shear a crane base imposes on its foundation; the foundation must be designed for these.
- Erection sequence
- Typical order: base, mast, slewing unit, cab and turntable, counter-jib with counterweights, jib, then rope reeving.
- Free-standing height
- The maximum mast height a crane can stand without being tied to a structure; set by the manufacturer.
- Wall tie/tie-in
- A structural connection between the crane mast and the building that stabilises the crane above its free-standing height.
- Dismantling order
- Dismantling reverses erection: remove jib, then counterweights, then counter-jib, then mast sections using a mobile crane or self-lowering system.
- Rated capacity
- The maximum load a crane may lift at a given radius and configuration, as stated in the load chart, including all deductions.
- Load moment
- The product of load and working radius; the load chart primarily limits the overturning moment plus structural capacity.
- Working radius
- The horizontal distance from the crane's slewing centre to the centre of gravity of the suspended load.
- Sling leg tension
- Tension in each sling leg equals load divided by (number of legs times the sine of the leg angle to horizontal).
- Critical lift
- A lift exceeding a defined percentage of rated capacity (often 75%) or involving multiple cranes or personnel; requires a lift plan.
- Reeving parts
- The number of rope falls between trolley and hook block; more parts increase capacity but reduce hook height and speed.
- Hook inspection
- Daily check of the hook for cracks, deformation, throat opening, and a safety latch that closes and seats correctly.
- Limit switch check
- Daily verification that hoist high/low, trolley, and slewing limit switches and the overload limiter function correctly.
- Anemometer check
- Confirm the wind-speed instrument reads correctly; it is a primary safety device governing when operations must stop.
- Brake inspection
- Check hoist, slewing, and trolley brakes for holding ability and adjustment, and for oil or grease on braking surfaces.
- Inspection log
- A written record of daily and periodic checks; safety-related defects must be reported and the crane taken out of service.
- Single signaler rule
- Only one designated signaler directs the crane at a time; the operator obeys that person unless anyone gives a stop signal.
- Stop hand signal
- A raised clenched fist is the standard stop signal; anyone may give it and the operator must obey immediately.
- Tag line use
- A rope attached to the load to control rotation and swing; it keeps personnel from having to touch or guide the load directly.
- Suspended load rule
- Never leave the controls with a load suspended; lower the load, set the brake, and shut down per procedure.
- Wind speed limit
- The manufacturer's maximum wind speed for operation; operations stop when it is reached, and out-of-service limits also apply.
- Out-of-service position
- The manufacturer's specified park position for the jib and slewing brake (often free-slew) when the crane is not in use.
- Power line clearance
- The minimum approach distance to overhead lines set by local rules; lines are treated as live until confirmed de-energized.
- Wind load scaling
- Wind force on the jib and load increases with the square of wind speed, so doubling wind speed quadruples the force.
- Brake adjustment
- Maintaining the correct air gap or clearance so hoist and slewing brakes hold rated load without slipping.
- Wire rope lubrication
- Applying the manufacturer-specified lubricant at set intervals to reduce wear and corrosion; broken-wire counts govern replacement.
- Thorough examination
- A statutory inspection of the crane by a competent person at defined intervals, with records kept as legal evidence.
- Operator's authority
- The operator must refuse unsafe lifts and may stop operations when conditions or defects make the lift unsafe.