Last Updated: January 2025 | Reading Time: 25 minutes | Audience: Appointed Persons, Lifting Supervisors, Site Managers
Quick Answer
Tower crane lifting accessories—including chain slings, wire rope slings, textile slings, shackles, lifting beams, concrete skips, and crane forks—form the critical interface between crane and load. In the UK, all lifting accessories must comply with LOLER 1998 (requiring thorough examination every 6 months) and follow BS 7121 safe lifting practices. Selection depends on load weight, centre of gravity, surface characteristics, and environmental factors. The Appointed Person (AP) is legally responsible for selecting appropriate accessories and calculating the Safe Working Load (SWL) based on the manufacturer's Working Load Limit (WLL) derated for sling angles and conditions.
In This Guide
Direct Answer: The tower crane is merely the prime mover—the safety, efficiency, and legality of every lifting operation is determined by the "below-the-hook" equipment. A failure at height releases potential energy that can cause catastrophic structural damage and multiple fatalities. The selection, maintenance, and use of lifting accessories is not a logistical task but a statutory imperative requiring deep technical competence.
The modern UK construction landscape—characterised by vertical urban development and complex infrastructure projects—relies fundamentally on tower cranes. These machines dictate the tempo of progress on any major site. Yet the crane itself is only part of the equation.
Every load that leaves the ground passes through a critical interface: the lifting accessories. From high-tensile steel chains to complex self-levelling pallet forks, these components connect the dynamic forces of the crane to the static mass of the load. Get it wrong, and the consequences are severe.
Consider this: a 500kg concrete lintel dropped from 30 metres generates impact forces equivalent to several tonnes. A cut textile sling, a side-loaded shackle, or a worn chain link can trigger exactly this scenario. Unlike machinery failures that might cause gradual breakdown, lifting accessory failures tend toward the catastrophic and instantaneous.
This is why the UK's regulatory framework—LOLER 1998, PUWER 1998, and BS 7121—treats lifting accessories with such rigour. And it's why Appointed Persons, lifting supervisors, and site managers must understand not just what accessories exist, but how they work, when they fail, and how to select the right tool for each specific lift.
Direct Answer: LOLER 1998 governs lifting operations, requiring thorough examination of accessories every 6 months and mandating that every lift be properly planned by a competent person. PUWER 1998 ensures equipment is suitable for purpose. BS 7121 provides the technical methodology for compliance—courts treat it as the benchmark of good practice, and deviation places the burden of proof on the defendant.
The HSWA establishes the foundation, placing a general duty on employers to ensure the health, safety, and welfare of employees and the public "so far as is reasonably practicable." In lifting terms, this clause means cost is not a defence against using sub-standard equipment. If a safer accessory exists—such as using a lifting beam instead of a multi-leg sling for a long, flexible load to prevent buckling—the Act implies it should be used.
The Lifting Operations and Lifting Equipment Regulations 1998 are the primary regulations governing tower crane accessories.
Key LOLER Regulations
Regulation 4 - Strength and Stability
Lifting equipment must be of adequate strength and stability for each load, accounting for stress at mounting points. This is the legal basis for "derating"—understanding not just static weight but dynamic amplification factors such as shock loading from sudden hoist stops or centripetal forces during slewing.
Regulation 8 - Organisation of Lifting Operations
Every lifting operation must be properly planned by a competent person, appropriately supervised, and carried out in a safe manner. This essentially prohibits ad-hoc lifting. Selecting the wrong accessory (such as a webbing sling on a sharp steel edge) constitutes a planning failure under Regulation 8, not merely operator error.
Regulation 9 - Thorough Examination
Creates the statutory inspection regime. Lifting accessories must be thoroughly examined at least every 6 months. An examination is also triggered immediately following any event that may jeopardise safety—overload, impact, or significant modification.
While LOLER focuses on the lifting operation, PUWER focuses on equipment fitness for purpose. Regulation 4 requires equipment to be suitable for intended use. A concrete skip must not only be strong enough to hold concrete (LOLER) but designed so the discharge mechanism doesn't jam, forcing a worker to place hands in a crush zone (PUWER). PUWER also mandates that instructions are available to users—a requirement often overlooked for simple accessories like plate clamps.
BS 7121 provides the technical methodology for compliance. Although following a British Standard is technically voluntary, courts treat BS 7121 as the benchmark of good practice. Deviation places the burden of proof on the defendant to demonstrate their alternative method was equally safe.
Key Parts of BS 7121
Part 1 - General Recommendations
Establishes the management structure and introduces the pivotal role of the Appointed Person (AP). The AP has overall authority for lifting operations and must have theoretical and practical knowledge to plan lifts, select cranes, and—crucially—select accessories.
Part 5 - Tower Cranes
Addresses unique interactions between accessories and tower crane mechanics: long hoist ropes introducing elasticity and potential for "cabling" (twisting), strict communication protocols for blind lifting, and more frequent inspection requirements for high-intensity operations like concrete skipping.
CE and UKCA Marking
Following Brexit, the UK introduced UKCA marking to replace CE marking. However, to prevent supply chain disruption, the UK government announced indefinite recognition of CE marking for lifting equipment in Great Britain. Businesses can use either UKCA or CE marked accessories, provided equipment is accompanied by a Declaration of Conformity (DoC).
Important: "Own-use" is not an exemption. If a construction company fabricates a lifting beam in their own workshop, they become the "manufacturer" legally. They must create a technical file, issue a DoC, and affix UKCA/CE marking. Failure renders the equipment illegal to use.
Direct Answer: Working Load Limit (WLL) is the maximum mass an accessory can sustain in a straight vertical pull under ideal conditions—a fixed value stamped on the gear. Safe Working Load (SWL) is the maximum mass for a specific operational configuration, calculated by the Appointed Person by derating WLL for sling angles and environmental factors. LOLER requires SWL to be marked; for multi-leg slings, tags typically display SWL at the "standard" 0-45° rating angle.
Confusion between WLL and SWL causes accessory failures. Understanding the difference is fundamental to safe lifting.
WLL vs SWL Explained
Working Load Limit (WLL)
Safe Working Load (SWL)
When a sling is used in any configuration other than vertical, tension in the sling leg exceeds the portion of load weight it supports due to trigonometric force resolution.
The 90° Rule
An included angle of 90° (45° from vertical) is the "golden angle." At this angle, load on each leg of a two-leg sling is 0.707 of total load. Most multi-leg slings are rated for use up to this angle.
Above 90°: Tension increases exponentially. At 120° included angle, tension in each leg equals the total load weight. Lifting above 120° is generally prohibited in UK construction—even minor dynamic movements can instantly overload the sling.
*Theoretical basket hitch is 2.0, but practical use limits this to 1.4 due to radius of curvature and non-vertical legs.
Worked Example: 4-Leg Chain Sling
A 4-leg chain sling with 2-tonne WLL per leg:
| At 0-45° included angle | SWL = 2t × 2.1 = 4.2 tonnes |
| At 45-60° included angle | SWL = 2t × 1.5 = 3.0 tonnes |
| Above 60° | Consult manufacturer—may require 1.0 factor |
The AP must verify included angles before every lift. A wider-than-expected spread can reduce capacity by 50% or more.
Direct Answer: Chain slings (Grade 8 or Grade 10 steel, BS EN 818) are valued for durability and abrasion resistance. Grade 10 offers 25% more capacity than Grade 8 at equivalent weight. Chains can operate up to 200°C without derating, making them essential for hot works. Rejection criteria: >3% elongation indicates overload; >8% diameter reduction from wear; any bent links or twisted master links require immediate scrapping.
The industry standard is Grade 8 (T) steel, but Grade 10 (V) is increasingly common. Grade 10 provides 25% more lifting capacity for the same chain weight, reducing manual handling burden on slingers. Grade 100 and 120 exist for specialised heavy lifts but are less common in general construction.
Chain slings are modular systems comprising a master link (top connection to crane hook), connecting links, chain legs (load-bearing elements), and hooks terminating each leg.
Hook Types
Sling Hook
Spring-loaded safety catch—standard for general use.
Self-Locking Hook
Closes under load, requires trigger to open—preferred for tower crane work as it cannot accidentally detach if loads snag or rope goes slack.
Shortening Clutches
Allow adjustment of individual leg lengths for asymmetric loads (e.g., precast stair units where centre of gravity isn't central). The chain must sit correctly in the clutch pocket—incorrect seating reduces strength by 30-50% due to point loading.
Chain slings are unique in their heat resistance. They can operate at temperatures up to 200°C without any reduction in WLL, and up to 400°C with derating (consult manufacturer tables). Above 400°C is not permitted. This makes chain the only choice for foundry-adjacent work or hot material handling.
Chains don't show fatigue as visibly as wire ropes. Critical rejection criteria must be understood and applied rigorously during pre-use checks and thorough examinations.
Critical Point
A chain stretched beyond 3% has entered plastic deformation and cannot be returned to service—its internal structure has permanently changed. This is not visible to the naked eye, which is why accurate measurement during thorough examination is essential.
Direct Answer: Wire rope slings (BS EN 13414) offer high capacity at lower weight and cost than chain. Typically 6x19 or 6x36 construction—higher wire counts provide flexibility but less abrasion resistance. Terminations are almost universally ferrule-pressed (talurit). Rejection criteria: broken wires (6 in 6×diameter or 14 in 30×diameter randomly distributed), bird-caging, core protrusion, or concentrated wire breaks near terminations.
Wire rope slings are manufactured from stranded wire. The most common types are 6x19 class (6 strands with 19 wires per strand, good abrasion resistance) and 6x36 class (6 strands with 36 wires per strand, greater flexibility, less abrasion resistance). Terminations are almost universally a turn-back loop secured with compressed aluminium or steel ferrule (talurit pressing). Hand-spliced eyes are rare in modern UK construction due to difficulty certifying termination efficiency.
Wire rope excels for choke hitch lifts of bundled materials, scaffolding tubes, rebar bundles, pipe runs. The wire "bites" into bundles better than chain, providing secure grip without slippage.
Wire ropes degrade through fatigue and abrasion. Unlike chains, damage is often visible—but requires knowledge of what to look for.
What is Bird-caging?
Bird-caging occurs when strands open up to resemble a birdcage. It's caused by sudden tension release (shock loading) or forcing twisted rope through a sheave. It destroys the structural integrity of the core and mandates immediate scrapping—there is no repair.
Direct Answer: Textile slings (BS EN 1492) are lightweight and surface-friendly, preventing load damage. Webbing slings are colour-coded by capacity (Violet=1t through Red=5t). Roundslings offer exceptional strength-to-weight ratio—a 10-tonne roundsling is easily carried by one person. Critical vulnerability: susceptibility to cutting on sharp edges (mandatory engineered edge protection required) and UV degradation from sunlight exposure.
Woven from high-tenacity polyester with reinforced eyes at each end. Flat webbing slings are colour-coded for capacity, allowing quick identification across the industry.
Roundslings consist of a continuous hank of load-bearing polyester yarn encased in a protective (non-load-bearing) sleeve. They're exceptionally strong for their weight—a 10-tonne roundsling is easily carried by one person, whereas a 10-tonne chain sling would require mechanical handling.
⚠️ Critical Safety Issue
The Sharp Edge Problem
The fatal flaw of textile slings is cutting susceptibility. A tower crane lifting a steel beam with sharp flanges can cut through a textile sling instantly if the load slips or shifts.
BS 7121 and industry best practice mandate engineered edge protection (sleeves or corner guards) whenever textiles contact non-rounded loads. Using cardboard or scrap wood is considered insufficient—purpose-designed edge protectors are required.
Prolonged sunlight exposure degrades polymer chains (photolysis). Signs include chalky, powdery surface texture, stiffening of the sling body, and colour fading. Slings left on a crane hook exposed to sun for weeks can lose significant strength. Store in dark, dry conditions when not in active use.
Textiles are also vulnerable to chemical attack. Acids damage both polyester and polyamide, alkalis damage polyamide more than polyester, and solvents can weaken the yarn structure. Any sling showing signs of chemical burns (discolouration, unusual stiffness, surface damage) must be scrapped regardless of apparent physical condition.
Direct Answer: Shackles (BS EN 13889) are essential connectors. Bow shackles (O-shaped) accept loads from multiple angles up to 45° from centreline—essential for multi-leg sling connections. Dee shackles (D-shaped) are for in-line tension only—side-loading causes body twist or pin shear. Pin types: screw pins must be moused (secured with wire) for extended use; safety bolt pins (nut and cotter) are mandatory for permanent installations or rotating loads.
Shackle Types Explained
Bow Shackles (Anchor Shackles)
Dee Shackles
Selection Rule
If sling legs will pull at angles to the shackle centreline, use a bow shackle. Dee shackles are only appropriate when all loading is directly in line with the pin axis.
Shackle Pin Types
Screw Pin
Safety Bolt (Nut and Cotter Pin)
Important
Never substitute pins between shackles—pins are matched to their body and mixing can result in inadequate thread engagement or incorrect material specification.
Direct Answer: Lifting beams and spreader bars (BS EN 13155) handle long or flexible loads, preventing crushing forces and bending. Spreader bars use top sling arrangements (bar in compression)—lightweight but require headroom. Lifting beams attach directly to crane hooks (beam in bending)—minimal headroom needed but heavier and costlier. Modular systems can be configured for different spans but require strict adherence to manufacturer torque and configuration specifications.
Key Differences
Spreader Bars
Lifting Beams
The industry has moved toward modular beams that can be bolted together for different spans. This flexibility offers significant advantages but introduces assembly risk.
⚠️ Critical Requirements
A modular beam assembled at the wrong span or with under-torqued bolts becomes a single point of failure for the entire lift.
Direct Answer: Crane forks lift palletised bricks, blocks, and bagged materials. Self-levelling mechanisms adjust the lifting eye position to maintain horizontal tines—but require minimum load (typically 20% WLL) to function; lifting empty pallets can cause dangerous tip-back. UK best practice and HSE enforcement require secondary restraint systems (brick guards/cages or integrated nets)—lifting loose materials with forks alone is a severe LOLER breach.
Modern crane forks use spring-loaded or hydraulic slides that adjust the lifting eye position relative to the load's centre of gravity. This ensures tines remain horizontal regardless of where the load sits on the forks.
Critical Limitation
Self-levelling mechanisms require a minimum load (typically 20% of WLL) to engage. Lifting an empty or very light pallet can be dangerous as the mechanism may not function, causing the forks to tip backwards uncontrollably.
⚠️ HSE Enforcement Point
It is a critical requirement in the UK—often enforced by HSE prohibition notices—that crane forks must be used with a secondary restraint system.
Acceptable options:
Lifting a pallet of loose bricks with just forks and no restraint is a severe breach of LOLER. A single brick falling from tower crane height is lethal.
The self-levelling mechanism is a moving part susceptible to concrete dust ingress. It requires regular lubrication and function checks before each shift. If the slide jams, self-levelling fails completely. Annual overhaul is recommended for high-use environments.
Direct Answer: Concrete skips experience "high intensity operations"—rapid cycling near capacity creates fatigue stress distinct from occasional heavy lifts. Types include column skips (vertical discharge, bale arm lifting) and boat skips (lay flat for filling, self-right when lifted). The bale arm is a critical fatigue point—cracks develop at weld points. Never hammer jammed discharge gates while suspended. Tremie pipes add significant weight that must be included in calculations.
Concrete Skip Types
Column Skips
Boat Skips
Concrete skipping is one of the most demanding applications for lifting accessories. The skip is filled heavy (often near maximum capacity) and emptied light, hundreds of times per day. This cycling induces fatigue stresses that develop differently from occasional heavy lifts.
Critical Inspection Point
The bale arm is the critical stress point. Fatigue cracks develop at weld points connecting the arm to the skip body. Thorough examination must specifically check these welds using appropriate NDT methods where warranted.
Common Hazards to Manage
Jammed gates
Concrete curing inside discharge gates causes jams. Operators must never use a hammer to force a gate open while the skip is suspended—this is a common cause of serious hand injuries and sudden uncontrolled discharge.
Tremie pipes
Flexible hoses for deep pours add significant weight and drag. This weight must be accounted for in the net weight of the accessory assembly.
Wash-out neglect
Regular cleaning is critical to prevent weight build-up (hardened concrete) and mechanism failure. A skip not properly cleaned can gain 100kg+ of "dead weight" over time.
Direct Answer: Lifting people with tower cranes is a high-risk activity strictly controlled by LOLER Regulation 5 and BS 7121. It's only permitted in "exceptional circumstances" where no safer method (scaffold, MEWP, passenger hoist) is practicable. Man baskets (BS EN 14502-1) require distinct WLL marking, inward-opening auto-locking gates, overhead protection, and harness anchor points. Hoisting speed is limited to 0.5 m/s with "dead man" controls. The hoisting rope safety factor increases to 10:1, effectively derating crane capacity by 50%.
⚠️ The Exceptional Circumstances Rule
HSE guidance is clear: cranes should not be used to lift people if a safer method exists. Personnel lifting is reserved for:
"It's quicker" or "it's more convenient" are not valid justifications.
Mandatory Requirements
When Lifting Personnel
Every personnel lift requires a specific risk assessment, method statement, permit to work (on most sites), records of basket examination, and competence records for all personnel involved.
Direct Answer: Load control prevents dangerous spinning, swinging, and collision during lifting. Basic taglines (hemp or polypropylene ropes) guide loads manually but have limitations in high winds or tight tolerances. Advanced systems like the Vita Load Navigator use powered tagline winches for precision control in challenging conditions—enabling operations that would otherwise be impossible due to wind effects or proximity constraints.
Suspended loads are inherently unstable. Without control, loads spin from rope twist or off-centre rigging, wind causes lateral movement, long hoist ropes amplify oscillation, and building aerodynamics create unpredictable turbulence. On congested sites with tight tolerances, uncontrolled loads risk collision with the structure, adjacent buildings, or workers.
Simple hemp or polypropylene ropes attached to the load, held by ground personnel to guide positioning. Limitations include limited control force available from human strength, ineffectiveness in high winds, requiring personnel in the load landing zone (risk exposure), and inability to address load spin during long vertical travel.
Advanced load control systems, such as the Vita Load Navigator (VLN), use powered tagline winches mounted on the load or lifting frame. These provide controlled rotation and orientation, active damping of swing, precision positioning in tight tolerances, and continued operation in higher wind conditions.
Case Study
Chapter London Bridge: Precision Lifting in Challenging Conditions
At Chapter London Bridge—a 39-storey student accommodation tower for Mace—the site's tiny footprint required WOLFFKRAN 355B and 630B luffing cranes to be positioned on steel cantilevers alongside the building. The Vita Load Navigator (VLN) was deployed to enable precision lifting despite wind tunnel effects from adjacent buildings.
Results:
"There was a very small margin of error for lifting loads, and the proximity of the next building created a wind tunnel effect. The VLN enabled us to control our loads with precision."
— Mohammed Jaan, AP, Pro-Lifting UK
The VLN transformed what could have been a schedule-critical constraint into a competitive advantage, demonstrating how the right accessories don't just enable safe lifting—they unlock operational efficiencies that directly impact project outcomes.
Direct Answer: Pre-use checks are user-level visual/tactile inspections before every shift—slingers verify no obvious defects and check the identification tag is present and legible. Thorough examinations are statutory engineering inspections by competent persons producing legal documentation. The RGBY colour code system (Blue/Yellow/Green/Red quarterly rotation) enables instant verification of examination currency across thousands of accessories on large sites.
Two Levels of Inspection
Pre-Use Check (Every Shift)
Thorough Examination (Every 6 Months)
To manage examination validity across thousands of accessories on major sites, a colour coding system is employed. Upon passing thorough examination, accessories are tagged with a coloured cable tie or paint mark corresponding to the examination quarter.
The current valid colour is displayed on site noticeboards. Any slinger encountering wrong-coloured gear knows instantly it's out of date. This standardised sequence (Build UK standard) allows workers to transfer knowledge between sites.
Practical Requirements
Direct Answer: PUWER requires equipment storage that prevents deterioration. Best practice: A-frame racking for hanging accessories (air circulation, prevents crushing), segregation of heavy chains from delicate textiles, and a locked "red bin" quarantine area for rejected gear preventing accidental re-use. Textile slings require dark, dry conditions. Chain and wire rope benefit from light oil coating during extended storage.
Every site using tower cranes should have a dedicated lifting tackle store.
Design Principles
Heavy chain slings should be separated from textile slings to prevent abrasive damage. Different capacities should be visibly separated, and specialist gear (man baskets, specific rigging) identified and controlled.
The Red Bin
A locked "red bin" or quarantine cage is essential for rejected gear. This prevents:
Quarantined items should be physically marked (red paint, cut tag) in addition to segregation.
Storage and Care by Accessory Type
Chain Slings
Wire Rope Slings
Textile Slings
Direct Answer: Every lift must be covered by a risk assessment and method statement (RAMS), with complexity determining detail level—basic (routine/repetitive), intermediate (non-routine/complex loads), or complex (tandem lifts, live infrastructure). The Appointed Person (AP) is the lift architect responsible for planning and gear selection. The Crane Supervisor ensures the plan is followed. The Slinger/Signaller physically attaches loads and directs the crane—they're the last line of defence with authority to stop any lift.
Key Personnel in Lifting Operations
Appointed Person (AP)
Crane Supervisor
Slinger/Signaller
Minimum Content for a Lift Plan
Related Reading
For guidance on construction site power solutions including powering tower cranes, see our BESS for Construction Sites Guide.
The selection, inspection, and management of lifting accessories directly determines the safety and efficiency of your tower crane operations. Whether you're specifying equipment for a new project, reviewing your examination regime, or seeking solutions for challenging lifting conditions, expert guidance ensures compliance and operational excellence.
WOLFF Onsite supplies the full range of tower crane lifting accessories—from chain slings and shackles to specialist equipment like the Vita Load Navigator for precision load control. Our team understands the regulatory requirements and practical challenges of UK construction sites.
Part of WOLFFKRAN, trusted since 1854
From our depot to your site, every order is fully tracked and delivered on our own WOLFF Onsite vehicles or via trusted courier partners. Delivery costs are calculated based on your postcode and order size.
Pallet Delivery
Dispatched within 1–2 working days, delivered next working day between 8am–5pm, Monday to Friday. Delivery cost is based on the number of pallet spaces and your delivery zone.
Parcel Delivery
Smaller items like radio accessories and safety equipment ship via tracked courier at a flat rate. Deliveries between 8:30am–5pm, Monday to Friday.
RENTAL Delivery / Collection
All rentals are delivered and collected by the WOLFF Onsite team. We'll confirm a delivery time that works for you and arrange collection within 3 working days of your hire end date. Deliveries and collections between 8am–5pm, Monday to Friday, Saturday collections can be arranged if suitable.
Dispatch Times
Orders placed by 1pm are dispatched same day where possible. Some products carry a manufacturing lead time, this is always stated in the product description.
Need Help?
Call us: 01709 437 141
Email: hello@wolffonsite.co.uk Available 8:30am - 5pm Mon-Fri
We are happy to help with any delivery or product questions.
Part of WOLFFKRAN, trusted since 1854
