A grab bucket overhead crane is a double-girder bridge crane fitted with a grab bucket instead of a hook. It engages bulk material by opening the bucket, lowering it onto the pile, closing the jaws to bite into the material, and lifting the load. One operator can handle hundreds of tons per shift without additional ground crew, which is why this machine is standard equipment in power plants, coal yards, ports, grain terminals, and industrial storage facilities.
The Weihua QZ series grab bucket overhead crane is designed specifically for this duty cycle — A6 heavy-duty classification, four-rope grab mechanism, and spreader hoisting speeds optimized for repetitive bulk loading cycles.
What Buyers Often Miss About Rated Capacity?
The rated capacity stamped on the nameplate includes the dead weight of the grab bucket itself. A 10 t grab bucket overhead crane does not lift 10 t of coal — it lifts 10 t total, grab bucket included. The actual payload per cycle is the rated capacity minus the grab bucket weight listed in the technical specification. Keep this in mind when calculating throughput.
Technical Specifications — QZ 5–10t and 16–20t
QZ 5–10t Class
Lifting capacity: 5–10 t (grab weight included)
Span: 10.5–31.5 m
Max. lifting height: 20 m (5–10t at spans 10.5–28.5m), 18 m (5–10t at 31.5m span)
Working class: A6 (heavy duty)
Hoisting speed: 39.2 m/min
Trolley travelling speed: 44.6 m/min (5t), 45.9 m/min (10t)
Crane travelling speed: 93.6 m/min (5t), 101–113.6 m/min (10t)
Steel track recommended: P43 or QU70
Power supply: 3-phase AC 380V 50Hz
QZ 16–20t Class
Lifting capacity: 16–20 t (grab weight included)
Span: 16.5–31.5 m
Max. lifting height: Up to 28 m
Working class: A6 (heavy duty)
Hoisting speed:41.8 m/min (16t), 45.7 m/min (20t)
Trolley travelling speed: 43.2 m/min
Crane travelling speed: 87.3–98 m/min
Steel track recommended: QU70 or 90×90 square steel
Power supply: 3-phase AC 380V 50Hz
Grab Type Selection — Four-Rope vs Hydraulic
Four-rope grab (standard). Two ropes from the hoisting mechanism and two from the closing mechanism share the load. The design is mechanically simple, durable under A6 duty, and easy to maintain. It is the default choice for most bulk material handling applications.
Hydraulic grab. Recommended when the operator needs precise opening control — for example, when feeding material into a hopper at a controlled rate. It also suits applications where a lighter overall crane structure is desired. Maintenance requires hydraulic system knowledge, and spare parts are different from the four-rope type.
For sticky or abrasive materials. Materials such as wet ash, clay, or corrosive slag require custom jaw shapes and high-manganese steel or abrasion-resistant liners. The standard bucket design may clog, wear unevenly, or fail prematurely in these conditions. The supplier should be informed at the quotation stage, not after delivery.
Duty Class — When A6 Is Worth the Cost
The QZ series is classified A6 (heavy duty) by design. This means the crane is rated for 2.5–4.0 million load cycles with a load spectrum factor that assumes regular full-capacity lifts.
If your site runs the crane 6–8 hours per day or less, the A6 classification includes a built-in safety margin equivalent to about 30–40% fatigue life reserve over a standard industrial crane. You can discuss an A5 configuration with the supplier to reduce upfront cost — but only if the operating intensity is low.
If the crane runs 16–24 hours per day, do not downgrade the duty class. A crane that fails prematurely in high-frequency grab service will cause shutdowns that far exceed the initial savings on a lower-rated model.
Runway Rail — What to Check Before Installing
The QZ grab bucket overhead crane generates high wheel loads due to the combined weight of the crane, the grab mechanism, and the lifted material.
•5 t class: max wheel load 75–130 kN (depending on span and motor configuration)
•10 t class: max wheel load 113–180 kN
•16 t class: max wheel load 206–269 kN
•20 t class: max wheel load 229–293 kN
Standard rail recommendations: P43 (43 kg/m) for 5–10 t models, and QU70 or 90×90 square steel for 16–20 t models.
If you already have a runway from a previous crane installation, ask the supplier to evaluate whether the existing rail profile and supporting structure can carry the new QZ crane. The rail type, rail clamps, and foundation bolts should all be reviewed, especially if local codes specify different standards.
Motor and Drive Configuration
The QZ series uses YZR series wound-rotor induction motors designed for repeated start-stop and reversing duty. These motors are standard for A6 applications because they tolerate high starting torque and dissipate heat effectively during rapid cycling.
•Hoisting motors: 5–10 t models use YZR motors matched to the grab hoisting and closing mechanism. 16–20 t models use YZR315M-10 motors — 75 kW × 2 for 16t, 90 kW × 2 for 20t.
•Trolley travel motors: YZR160M2-6 / 7.5 kW for 16–20 t models.
•Crane travel motors: YZR180L-8 / 11 kW × 2 or YZR200L-8 / 15 kW × 2, depending on span.
If your site requires variable speed for smooth grab positioning or reduced sway during travel, frequency inverter drives can be added. This is not standard but is available by request.
Information Needed for a Quotation
Preparing a complete RFQ avoids back-and-forth and produces a more accurate price. The following information should be included in your initial inquiry:
1.Material characteristics — type, bulk density (t/m³), handling rate (t/h), and whether the material is sticky, abrasive, or corrosive.
2.Capacity requirement — maximum net payload per cycle, not counting grab weight.
3.Span — distance between rail centers, in meters.
4.Lifting height — from floor to required hook/grab position at the highest point.
5.Runway condition — existing rail type and profile, or confirmation that new rail will be installed.
6.Local power supply — voltage, frequency, and phase (standard: 3-phase AC 380V 50Hz; other voltages available on request).
7.Local applicable standards — if your country or project requires CE, AS 1418, GOST, or other certifications, mention this at the RFQ stage.
Total Cost of Ownership
A grab bucket overhead crane operates under higher stress and more cycles per day than a standard hook crane. The long-term cost difference between a well-built and a marginal crane is mainly determined by:
•Crane structure: Welded box girder with internal diaphragms resists the fatigue from repeated grab loading better than a simplified design.
•Motor quality: YZR series motors with proven insulation and cooling last 6–8 years under A6 duty before requiring rewinding.
•Spare parts availability: Grab buckets, wear pads, brake linings, and wire ropes are consumables. If the destination lacks a local supplier, ordering a 2-year consumables kit with the crane avoids downtime later.
Frequently Asked Questions
Q1: What materials can a grab bucket overhead crane handle?
Loose bulk materials such as coal, coke, sand, gravel, ore, grain, cement clinker, ash, and slag. For sticky, abrasive, or corrosive materials, the grab jaws and lining can be customized to extend service life.
Q2: Does the lifting capacity include the grab weight?
Yes. The rated capacity covers the grab bucket plus the material. When requesting a quotation, specify the maximum material payload you need per cycle, and we will recommend the appropriate capacity with a safe margin.
Q3: What is the difference between a light-type and heavy-type grab?
The difference is the bucket volume and material density range they are designed for. A light-type grab for ≤1 t/m³ material (e.g., grain, coal) has a larger volume. A heavy-type grab for >1.7 t/m³ material (e.g., iron ore) has a smaller volume but stronger structure. The crane capacity and grab type must be selected together based on the material density.
Q4: Is the grab bucket overhead crane suitable for outdoor use?
Yes. The QZ series can be used outdoors. The electrical components and crane structure are designed for outdoor service. When ordering for outdoor installation, specify this requirement so that weatherproofing measures — such as IP-rated electrical enclosures and corrosion-resistant paint — can be included.
Q5: Can the crane use an existing runway?
It depends on the rail profile, supporting steel structure condition, and foundation load capacity. Provide the existing rail type and span to the supplier for assessment.
