Crane Brake Selection Guide: YWZ, Disc & Drum Torque
Key Points Crane brakes generally fall into three categories: ① YWZ electro-hydraulic block brakes (braking torque 80–5,000 N·m), widely used in crane bridge and hoisting mechanisms with a response time of 0.15–0.3 s; ② Disc brakes (200–10,000 N·m), designed for precise braking on large-tonnage cranes with a response time of under 0.15 s; ③ Drum brakes (20–500 N·m), integrated at the rear end of the electric hoist motor. Brake safety factors: ≥1.5 for hoisting mechanisms and ≥1.25 for travel mechanisms. Kelude Heavy Industry cranes come standard with dual brake redundancy (YWZ + disc brake), meeting the safety requirements of ISO 4301 Crane Design Standard.
Brake Types and Structures
Crane brakes are critical components for safe operation and are classified by structure into shoe, disc, and drum types. The YWZ electro-hydraulic shoe brake applies braking force through a spring and releases via an electro-hydraulic thruster, delivering high braking torque with stable performance. Disc brakes clamp the brake rotor axially for fast response and adjustable braking torque. Drum brakes are mounted at the rear of the electric hoist motor, offering a compact structure. Brake selection in engineering calculations for electric hoist hoisting mechanisms must consider both braking torque and the required brake safety factor. Kelude Heavy Industry cranes rated at 20 t and above are equipped with dual brake redundancy as standard.
| Model | Type | Braking torque(N·m) | Brake wheel Diameter(mm) | Matched With Thruster | Reference Price(CNY) |
|---|---|---|---|---|---|
| YWZ-200 | Shoe Type | 100~200 | 200 | ED-23/5 | 500~800 |
| YWZ-300 | Shoe Type | 250~630 | 300 | ED-30/5 | 800~1200 |
| YWZ-400 | Shoe Type | 630~1600 | 400 | ED-50/6 | 1200~2000 |
| YWZ-500 | Shoe Type | 1600~3150 | 500 | ED-80/6 | 2000~3500 |
| YWZ-600 | Shoe Type | 3150~5000 | 600 | ED-121/6 | 3500~5000 |
| YP-250 | Disc Type | 200~500 | 250 | Hydraulic Power Unit | 2000~4000 |
| YP-500 | Disc Type | 1500~4000 | 500 | Hydraulic Power Unit | 5000~10000 |
| YP-800 | Disc Type | 5000~10000 | 800 | Hydraulic Power Unit | 8000~15000 |
Braking Torque Selection Reference for Brakes
| crane Capacity (tonnage)(t) | mechanism | Recommended Brake | Braking torque(N·m) | Safety factor |
|---|---|---|---|---|
| ≤5 | Hoisting / Lifting | Drum Type/YWZ-200 | 80~200 | 1.5 |
| 5~16 | Hoisting / Lifting | YWZ-300/400 | 250~800 | 1.5 |
| 20~50 | Hoisting / Lifting | YWZ-500+Disc Type | 1600~3150 | ≥1.5 |
| 50~100 | Hoisting / Lifting | YWZ-600+Disc Type | 3150~5000 | ≥1.5 |
| ≤32 | Crane Bridge | YWZ-200/300 | 100~400 | 1.25 |
| 32~100 | Crane Bridge | YWZ-300/400 | 400~1200 | 1.25 |
Note: Safety factors per ISO 4301 Crane Design Standard — hoisting mechanism ≥1.5, travel mechanism ≥1.25. Kelude Heavy Industry standardizes YWZ + disc dual brake redundancy on hoisting mechanisms above 20t.
Brake Torque Calculation for Brake Selection
Brake torque calculation is the core of brake selection. The required braking torque for a hoisting mechanism is Tₚ = K × Tₙ, where K is the brake safety factor (≥1.5) and Tₙ is the rated load torque (referred to the brake wheel shaft). Tₙ = 9550 × P / n × i × η, where P is motor power (kW), n is motor speed (r/min), i is the gearbox speed ratio, and η is transmission efficiency (0.85–0.95).
Example 1: A 10t overhead crane has a hoisting motor power P = 15kW, speed n = 960r/min, gearbox ratio i = 40, and transmission efficiency η = 0.9. Calculate the required braking torque and select a suitable brake.
Solution: Tₙ = 9550 × 15 / 960 × 40 × 0.9 ≈ 9550 × 0.0156 × 40 × 0.9 ≈ 537N·m.
Required braking torque: Tₚ = K × Tₙ = 1.5 × 537 = 805N·m.
From the YWZ series selection table: YWZ-400 offers a braking torque range of 630–1600N·m, which covers 805N·m. Therefore, select YWZ-400.
Example 2: A 32t double-girder bridge crane has a hoisting motor P = 37kW, n = 740r/min, i = 50, η = 0.88.
Tₙ = 9550 × 37 / 740 × 50 × 0.88 ≈ 9550 × 0.05 × 50 × 0.88 ≈ 2101N·m.
Tₚ = 1.5 × 2101 = 3152N·m.
A single brake cannot meet this requirement. Kelude Heavy Industry standardizes a dual brake configuration: YWZ-500 (1600–3150N·m) + YP-500 disc brake (1500–4000N·m), providing a combined braking torque of 3100–7150N·m — satisfying the ≥3152N·m requirement while maintaining braking capability even if either brake fails.
Thruster Selection and Electrical Control System
The electro-hydraulic thruster (ED series) is the release actuator for YWZ brakes. Thruster models must match the brake: YWZ-200 pairs with ED-23/5, YWZ-300 with ED-30/5, YWZ-400 with ED-50/6, YWZ-500 with ED-80/6, and YWZ-600 with ED-121/6. Thrusters operate under duty classification S3 at 60% duty cycle, with a maximum of 720 electrical operations per hour. Applications exceeding this frequency require a higher-capacity model.
Brake electrical control is available in AC-driven and DC-driven configurations. AC-driven systems use a rectifier to convert AC 380V to DC 170–220V for the thruster motor; DC-driven systems (DC 220V) are used for special applications such as metallurgy. Rectifier failure is a common cause of electrical faults in brake systems, typically presenting as the brake failing to release or releasing incompletely when power is applied. Kelude Heavy Industry brake control cabinets come standard with a rectifier status indicator light for rapid troubleshooting.
Contactors control the brake power supply. When the hoisting contactor opens, the brake contactor de-energizes simultaneously, and the spring applies the brake. Contactor contact welding (fused contacts) can leave the brake in the released state after power-off, causing load slipping. Kelude Heavy Industry uses a power-off limit switch as the final protection against contact welding.
Brake Selection Quick Reference Table
The following is a quick-reference guide for hoisting mechanism brake selection (Kelude Heavy Industry recommended solution):
| Capacity Range | Recommended Brake Configuration | Braking Torque Range |
|---|---|---|
| ≤5t | Drum brake (integrated on electric hoist motor rear shaft) or YWZ-200 | 80–200N·m |
| 5–16t | YWZ-300/400 | 250–800N·m |
| 20–50t | YWZ-500 + YP-500 disc (dual brake) | 3100–7150N·m combined |
| 50–100t | YWZ-600 + YP-800 disc (dual brake) | 8150–15000N·m combined |
| ≥100t | Large disc brakes (2–4 sets) | ≥20000N·m |
Brake Selection and Maintenance Precautions
Frequently Asked Questions
Q: What is the correct brake clearance for a YWZ brake, and how often should it be adjusted?
A: The normal clearance for a YWZ brake is 0.6–1.5 mm total (release gap), with 0.3–0.8 mm per side. Kelude Heavy Industry recommends a monthly inspection of brake clearance, with timely adjustment as linings wear. Fine adjustments can be made via the adjusting nut on the brake; after adjustment, use a feeler gauge to confirm even clearance on both sides.
Q: What should I do if the electric hoist brake fails to hold the load?
A: Common causes of drum brake failure on electric hoists include: ① Excessive brake clearance — readjust as needed; ② Oil-contaminated friction linings — remove and clean with alcohol or replace; ③ Spring fatigue — Kelude springs are rated for 100,000 cycles and typically require replacement every 2–3 years; ④ Worn brake wheel — restore by turning or replace the wheel.
Q: Why is a dual brake system required on hoisting mechanisms?
A: ISO 4301 Crane Design Standard requires a brake safety factor of ≥1.5 for hoisting mechanisms, but cranes handling molten metal must be equipped with dual brakes. Kelude Heavy Industry also fits dual brakes as standard on general-purpose cranes above 20 t (YWZ plus disc brake), so the load remains safely held even if one brake fails — effectively doubling the safety factor.
Q: What advantages does a disc brake offer over a YWZ brake?
A: Disc brakes respond faster (<0.15 s vs. 0.15–0.3 s for YWZ), offer a wider range of braking torque adjustment, and exert no radial force on the motor shaft. The trade-offs are higher cost (roughly 3–4 times that of a YWZ brake) and shorter friction lining replacement intervals. Kelude Heavy Industry typically specifies disc brakes for large-tonnage or high-speed hoisting applications.
This completes our technical guide to selecting among the three main crane brake types — YWZ electro-hydraulic block brakes, disc brakes, and drum brakes. Kelude Heavy Industry matches every crane with the most suitable braking solution, with dual brake redundancy as standard on units above 20 t, and offers a full range of brake components and maintenance services. For brake selection assistance, contact the Kelude Heavy Industry technical team.
