Rigging and Heavy Lift

Tools in this group

• Center of Gravity and Pick-Point Load Share - Load on each of two pick points and the percent imbalance from the total weight, span, and CG offset, with a flag when the CG falls outside the picks. The head rigger and the load weight govern.
• Crane Net Capacity After Deductions - Net capacity for the hook after the OSHA 1926.1417(o) deduction stack (hook block, jib, wire rope), the total hook load, the percent of net, and the 75 / 90 / 100 percent flags. The manufacturer's load chart governs.
• Crane Ground Bearing Pressure and Mat Size - Outrigger / crawler ground bearing pressure vs an allowable soil bearing, the area required to pass, and the square mat or cribbing side. A geotech source and a qualified person govern.
• Wire-Rope Sling D/d Bend Efficiency - Bend efficiency factor and reduced working load limit of a wire-rope sling from the D/d ratio, per the WRTB curve. Inspect every sling before the lift.
• Wind Force and Swing on a Suspended Load - Velocity pressure, lateral wind force, and swing angle on a suspended load from the sail area, wind speed, and shape coefficient. The manufacturer's in-service wind limit governs.
• Tag Line Pull and Handler Count - Tag-line tension to control a suspended load, the number of handlers at a safe per-person pull, and a flag when a mechanical tag is needed. The lift director governs.
• Tandem (Two-Crane) Lift Load Share - Each crane's share of a tandem lift from the CG, the derated allowable per crane, and a combined pass / fail. A designated lift director and an engineered plan govern.
• Shackle / Eye-Bolt WLL and Angular Derate - Working load limit and the angular derate of a shackle (side load) or shoulder eye bolt from the pull angle, with a pass / fail. The manufacturer's chart governs.
• Spreader Bar vs Lifting Beam Below the Hook - Top sling tension, spreader-bar axial compression, lifting-beam bending moment, and headroom for a wide load from one hook. ASME BTH-1 / B30.20 and the rating plate govern.
• Forklift Load-Center Capacity Derate - Net forklift capacity at the actual load center from the data-plate rating, a pass / fail against the load, and the remaining margin. The capacity plate is the legal rating.
• Roller / Skate / Jacking Push Force - Steady and breakaway push force to move a load on rollers or skates, the grade component, and the skate count by capacity. Verify the floor's own capacity.
• Chain / Lever Hoist Effort and Travel - Hand-pull effort, hand-chain travel for the lift, and a pass / fail against the rated WLL of a chain or lever hoist. ASME B30.16 / B30.21; the rated WLL is the ceiling.
• Rigging Block Redirect Resultant Load - Resultant force on a rigging block and its anchor when a line changes direction (up to twice the line tension when doubled back). Size for the resultant, not the line tension.
• Multi-Leg Sling Load per Leg - The tension in each sling leg of a multi-leg lift: per ASME B30.9, a rigid load on 3 or more legs is assumed to hang from only 2, so the conservative tension divides the load over 2 legs and then by sin(angle from horizontal), with an equal-share reference and the 1/sin load factor. The qualified rigger and the sling tag govern.
• Wire-Rope Breaking-Strength Estimate and WLL - A field estimate of wire-rope minimum breaking strength (construction factor x diameter^2, default 46 tons/in^2 for IPS 6x19, editable) and the working load limit at a design factor (default 5:1). An ESTIMATE only - the manufacturer's certified breaking strength governs, and unmarked or uncertified rope must not be placed in service.
• Spanned Cable Sag and Tension - The tension a horizontally spanned cable (a tramline, highline, span set, or messenger) develops from its sag: H = w L^2 / (8 d), the support tension H sqrt(1 + (4d/L)^2), and the developed length. A 100 ft span at 1 lb/ft sagging 2.5 ft runs 500 lb; pull it to a 0.5 ft sag and the tension jumps to 2,500 lb - five times the load for the same span, because tension is inversely proportional to the sag. Shallow parabola (sag under ~1/10 span), uniform load, level supports; a concentrated load is the sling-angle case. A planning screen; the rope WLL, the anchors, and the head rigger govern.
• Two-Leg Bridle Leg Tension - Each leg's tension and angle and the horizontal beam reaction of an asymmetric two-leg bridle from the apex load and the run/rise to each point. The legs never carry half each -- the steeper leg carries more, and a shallow bridle drives both legs above the hung load.
• Three-Point Bridle Leg Tension (3-D) - The exact leg tensions of a three-point bridle from the apex load and each leg's east / north / rise offsets: the 3x3 static equilibrium T1 u1 + T2 u2 + T3 u3 = (0, 0, W) solved by Cramer's rule, with each leg's length and angle. Physical only while every tension is positive - the apex must hang inside the triangle of its attachment points (a rope can only pull), and an asymmetric hang splits 1,000 lb as 497 / 419 / 244, nothing like an even 333 each. A design aid, not a rigging sign-off.
• Beam Clamp Reaction and Side-Pull Check - What a bridle leg actually does to the clamp: V = T sin(angle), H = T cos(angle), each checked against the clamp's vertical WLL and the manufacturer's side-pull allowance (zero for most beam clamps). The steep 860 lb leg of the two-leg bridle example loads its clamp to only 38% vertically but 77% of a generous 500 lb side-pull rating - the side pull governs, and on an unrated clamp the verdict is re-rig, not pass. A design aid, not a rigging sign-off.
• Winch Drum Line Pull by Layer - The derated line pull, mean diameter, and increased speed of a winch drum at a given rope layer (Pn = rated x drum / (drum + (2n-1) x rope)). The rated pull is a bare-drum first-wrap figure that fades 30-40% on the outer layers -- plan the pull for the layer you finish on, not the nameplate.
• Crane Outrigger Reaction from Lift Geometry - The maximum single-outrigger reaction over a corner from the gross load and radius, counterweight, and outrigger spread (R_max = (W+Wc)/4 + M/(sqrt(2) spread)). Not a quarter-share -- swinging over a corner can concentrate well over half the load into one outrigger. The load crane-ground-bearing asks for but never derives.
• Lifting Lug / Padeye Pin-Hole Check - Checks an engineered lifting lug or padeye against all four ASME BTH-1 pin-hole failure modes -- bearing, net-section tension, and double-plane shear tear-out -- and reports the governing capacity and DCR. The four modes trade off through hole placement; a lug sized for gross tension alone can tear out at the pin.