GB/T 24810.1-2009 Crane Brake Standards Explained
GB/T 24810.1-2009 "Lifting Appliances — Brakes — Part 1: General Requirements" is the foundational standard for the design and selection of crane brakes. The standard, which corresponds to ISO 15513:2000 (MOD), defines the classification, performance requirements, braking torque verification methods, and safety factor requirements for crane brakes. It applies to the design and selection of brakes for all mechanisms on overhead, gantry, tower, mobile, and jib cranes.
GB/T 24810.1-2009 serves as the core standard for crane brake design and selection, specifying brake classification, braking torque safety factors, and operating condition requirements. The brake is the most critical safety component in a crane's hoisting mechanism, and its reliability directly determines the safety of lifting operations.
Brake Types and Scope of Application
GB/T 24810.1-2009 classifies brakes by structural type into: shoe brakes (which generate braking torque by symmetrically clamping the brake wheel with brake shoes — simple in construction and easy to maintain, widely used across all mechanisms on overhead and gantry cranes), disc brakes (which axially clamp the brake disc with friction linings, delivering high braking torque with excellent heat dissipation — ideal for high-speed and frequent braking duty), and band brakes (which produce friction braking torque by wrapping a steel band around the brake wheel — compact in design but generating radial forces during braking, typically found on older tower cranes and certain mobile cranes). By control method, brakes are divided into normally closed brakes (spring force closes, electromagnetic or hydraulic force releases — the safest and most common type used on cranes) and normally open brakes (closed by operating force — used only in special working conditions).
The standard mandates that hoisting mechanisms must use normally closed brakes — the brake must automatically engage and hold the load in the event of any power source failure.
Braking Torque and Safety Factors
The standard specifies minimum braking torque safety factors: for hoisting mechanisms — the maximum working braking torque must be no less than 1.5 times the rated hoisting torque (the torque generated by the rated load). When two brakes are fitted to the mechanism, each brake must deliver no less than 1.25 times the rated hoisting torque (i.e., the combined capacity of the dual-brake configuration must be ≥2.5 times the rated value).
For travel mechanisms — the braking torque must be no less than 1.25 times the travel resistance torque (including friction and slope resistance), while also satisfying braking distance requirements.
For slewing mechanisms — the braking torque must be no less than 1.5 times the slewing resistance torque.
For luffing mechanisms — the braking torque must be no less than 1.5 times the luffing resistance torque. For hoisting mechanisms handling molten metal, the standard raises the safety factor to 2.0 and requires two independent brakes (dual-brake configuration). The standard also specifies the number of working cycles for brakes — the reliable number of brake actuations over the design life must not be less than 1,000,000 cycles (for electromagnet brakes) or 500,000 cycles (for hydraulic thrust brakes).
Brake Operating Conditions
The standard sets clear requirements for the brake's working environment: ambient temperature — the brake must operate normally within a temperature range of -20°C to +40°C (outside this range, special measures such as low-temperature heating or high-temperature insulation are required). Relative humidity — must not exceed 90% (non-condensing). Protection rating — the brake's electromagnet or hydraulic push rod must have a protection rating of at least IP54 (dustproof and splash-proof). The brake's installation position must allow easy access for inspection and adjustment, and the friction linings must be replaceable without disassembling the entire brake. Exposed rotating parts of the brake wheel or brake disc must be fitted with a protective cover to prevent foreign objects from entering and to protect personnel from accidental contact. The standard places particular emphasis on heat dissipation — during frequent braking, the surface temperature of the brake wheel (or disc) must not exceed 200°C (for resin-based friction materials) or 250°C (for metal-ceramic friction materials). Exceeding these limits can cause a sharp drop in the friction coefficient (thermal fade).
Kelude heavy industry cranes come standard with dual brakes on the hoisting mechanism, meeting the safety requirements for molten metal lifting.
Brake Adjustment Requirements
The standard sets out systematic requirements for routine brake adjustment: brake clearance — the gap between the brake shoe and the brake wheel (in the released state) must remain uniform, with the per-side clearance determined by the brake wheel diameter: 0.5–0.8 mm for wheel diameters ≤200 mm, 0.8–1.2 mm for diameters between 200 and 500 mm, and 1.2–1.5 mm for diameters ≥500 mm. The difference between the four side clearances must not exceed 0.1 mm (i.e., the clearance on both sides of the brake shoe relative to the brake wheel must be consistent — excessive deviation causes uneven brake lining wear). Spring adjustment — the braking torque is set by adjusting the compression of the closing spring. The spring compression must be set according to the manufacturer's marked scale; over-compressing the spring to achieve torque above the rated value is prohibited (over-compression leads to premature spring fatigue fracture and harsh braking impact).
Brake shoe release — after the brake is released, the clearance between the brake shoe and the brake wheel should be adjusted to the minimum value at which the shoe just clears the wheel. Excessive clearance increases the brake's idle stroke (response latency), while insufficient clearance can cause dragging and overheating.
Brake Inspection and Troubleshooting
The inspection items specified by the standard include: braking torque test — each brake must undergo a sampling inspection for braking torque before delivery (sampling rate of no less than 10% per batch); if any sample fails, every unit in the batch must be tested individually. Brake spring fatigue test — after 300,000 compression cycles under maximum working load, the spring's permanent deformation must not exceed 1% of its free height. Brake lining life — under rated conditions, the wear life of the brake lining must be no less than 200,000 braking cycles.
Common Faults and Solutions: Brake dragging (brake shoe fails to fully disengage from the brake wheel) — caused by insufficient clearance adjustment or inadequate stroke of the electromagnetic/hydraulic push rod. Readjust the clearance and opening stroke. Insufficient braking torque (load slipping) — caused by inadequate spring compression or excessive wear on the friction lining. Adjust the spring or replace the lining. Braking noise — caused by oil contamination on the friction surface or uneven contact between the lining and the brake wheel. Clean the surface or re-scrape the lining for proper contact.
Excessive brake temperature rise — caused by braking frequency exceeding the design rating or poor heat dissipation. Inspect the braking frequency or add additional cooling measures.
| Parameter | Shoe brake | Disc Brake | Band brake |
|---|---|---|---|
| Braking torque Range | Medium(~5000Nm) | Large(~50000Nm) | Medium(~3000Nm) |
| Heat Dissipation Performance | Fair | Good | Poor |
| Brake Gap Adjustment | Requires Periodicadjustment | Automatic Compensation | Requires Periodicadjustment |
| Radial Force | None(Symmetric Clamping) | None(Axial Clamping) | Yes(Impact Bearing) |
| maintenance convenience | Good(Easily Replaceable Liners) | Medium(Requires Disassembly) | Medium |
| Application Scenarios | bridge and gantry crane All Mechanisms | High-Speed Frequent Braking | Legacy Tower Crane Mobile Hoist |
Brake FAQ: Selection, Inspection & Safety
Q: Why is a normally closed brake mandatory for hoisting mechanisms?
A: A normally closed brake is held engaged by spring force and releases only when power is applied. Any power interruption automatically applies the brake, safely holding the load in place. With a normally open brake, a power loss would release the brake and allow the load to drop. This is a core principle of crane safety design.
Q: What is the recommended inspection interval for brakes?
A: Perform a daily inspection to verify proper operation and check for abnormal noise or dragging. Measure brake shoe clearance weekly to confirm it stays within the standard range. Verify braking torque and lining wear monthly. Kelude provides brake inspection record sheets to support your maintenance program.
Q: How do I select the right brake type for different operating conditions?
A: Shoe brakes are applicable to all mechanisms on bridge and gantry cranes in duty classes A1 through A5. Disc brakes suit duty class A5 and above, where high-speed, frequent braking is required — typical in steel mills and other heavy industries. Band brakes are mostly found on older tower cranes. For lifting and transport of molten metal, two independent brakes are mandatory, each with a safety factor of 2.0 or higher.
Q: What are the consequences of brake wheel overheating?
A: When the brake wheel temperature exceeds 200°C (392°F) for resin-based linings or 250°C (482°F) for metal-ceramic linings, the friction coefficient drops from 0.35 to below 0.15, resulting in a braking torque loss of more than 50%. Overheating is typically caused by braking frequency exceeding the design value or by continuous dragging. Kelude performs a thermal capacity verification during the brake selection process to prevent this condition.
