QD vs LD Bridge Crane: Tonnage, Span, and Cost Guide

Why Compare These Three Overhead Crane Types?

When selecting lifting equipment for a workshop or factory building, the QD-type double-girder bridge crane (twin-girder overhead crane), LD-type electric single-girder bridge crane, and LH-type hoist bridge crane are the three configurations you'll most often weigh. Although they all fall under the overhead crane category, they differ dramatically in main girder design, hoisting mechanism, work duty, and price—choose wrong and you'll either overspend on capacity you don't need or stall your production line. This article benchmarks them across six parameters: lifting capacity, span, lifting height, work duty, cost, and application scenarios, so procurement decision-makers can quickly zero in on the optimal fit.

Model Overview: QD, LD, and LH Cranes

QD-Type Double-Girder Bridge Crane

The QD-type double-girder bridge crane (twin-girder overhead crane) features twin main girders with a winch-based hoisting mechanism—a dedicated hoist winch assembly (motor + gearbox + drum + pulley block + hook block). It's the heavy-duty flagship of the overhead crane family. Lifting capacity ranges from 5 to 500 t, spans 10–35 m, lifting heights reach 12–32 m, and work duty classifications span A5 to A8. This is the go-to choice for continuous, high-frequency, heavy-load production environments.

LD-Type Electric Single-Girder Bridge Crane

The LD-type uses a simplified single main girder with an electric hoist for lifting. The main girder combines a box-section with an I-beam runway, and the electric hoist (CD1/MD1 models) travels along the bottom flange of the beam. Lifting capacity: 1–20 t, span: 7.5–28 m, lifting height: 6–30 m, work duty: A3 to A5. Thanks to its simple construction and low manufacturing cost, it's the most economical overhead crane option for small-to-medium workshops.

LH-Type Hoist Bridge Crane

The LH-type is the middle-ground solution: twin main girders for lateral stability and long-span capability, but with an electric hoist instead of a winch for lifting. Lifting capacity: 5–32 t (up to 50 t in select configurations), span: 10–30 m, lifting height: 6–24 m, work duty: A3 to A5. Think of it as the "upgraded" LD or the "economy" QD—it fills the gap between single-girder simplicity and winch-driven double-girder performance.

Key Comparison Parameters

Lifting Capacity Range

Bottom line: For lifting capacities up to 20 t, all three models are viable options. In the 20–32 t range, the QD and LH models compete head-to-head. Above 32 t, the QD-type double-girder bridge crane is the only suitable choice. For heavy-duty applications exceeding 50 t, the QD is the sole option.

Span Range

Bottom line: When span ≥ 28m, the LD type falls short; at span ≥ 30m, the LH type approaches its ceiling. For large spans (≥ 25m) combined with heavier lifting capacities, the QD-type double-girder bridge crane is the preferred choice—its twin main girders deliver superior bending stiffness and reduced deflection.

Lifting Height

The LD type offers a standard lifting height of 6–12m (extendable to 30m), the LH type 6–18m (extendable to 24m), and the QD type 12–16m (extendable to 32m). The QD's hoist winch mechanism achieves greater maximum lifting heights by varying wire rope winding layers and drum length, making it well-suited for high-bay factory buildings.

Bottom line: When lifting height requirements exceed 20m, the QD type holds a clear advantage.

Work Duty Classification (A3–A7)

Work duty is the most overlooked yet critical parameter in bridge crane selection: A3 (light duty) suits intermittent use with infrequent full loads; A5 (medium duty) handles moderate frequency with regular full loads; A7 (heavy duty) is built for high-frequency, continuous full-load operation.

Kelude Heavy Industry's technical lead points out: “Many customers only compare lifting capacity and price, overlooking the work duty classification. For two 20t overhead cranes, the manufacturing cost difference between A5 and A7 can reach 30–40%. Selecting a lower duty class for high-frequency, heavy-load applications will significantly shorten the equipment's service life.”

Bottom line: When the required work duty is A6 or higher, the QD Type double-girder bridge crane is the only viable option; for A3 to A5 applications, both LD and LH models can meet the demand.

Cost & Price Comparison

Estimated based on a 10t lifting capacity, 22.5m span, and 12m lifting height:

The higher cost of the QD type comes down to three factors: the twin main girders require 2 to 2.5 times more steel than a single-girder design; the hoisting mechanism—complete with its own motor, gearbox, drum, pulley block, and brake—is far more complex than an electric hoist; and it also demands twin trolley rails plus a more sophisticated electrical control system.

Bottom line: If your budget is tight and lifting capacity requirements are modest, go with the LD type. When you need the stability of a double-girder crane but have limited funds, the LH type is the sweet spot. For heavy-duty, high-frequency operations, the QD-type double-girder bridge crane is the only real choice.

Application Scenarios

• QD-type double-girder bridge crane: Steel mill foundries (handling ladles of molten steel or iron), heavy machinery workshops (large workpiece assembly), hydroelectric power stations (turbine installation and maintenance), shipyards (sectional hoisting), and high-capacity warehouses—in short, any facility that runs at full load day in and day out should prioritize the QD type.
• LH type: Medium-sized steel fabrication shops, general machine shops, equipment installation and repair, and mid-size warehouses—applications with moderate duty cycles and lighter loads that still need the span of a double-girder crane.
• LD type: Light assembly lines, small repair workshops, basic warehouses, school training labs, and other intermittent light-duty applications.

Full Parameter Comparison Table

3-Step Crane Selection Process

Step 1: Filter by Lifting Capacity

• ≤5t: LD Type is the priority choice (lowest cost, fully sufficient). For capacities above 20t, skip the LD option entirely.
• 5–20t: All three models remain viable candidates—proceed to Step 2.
• 20–32t: Eliminate the LD Type. Choose between the QD Type Double-Girder Bridge Crane and the LH Type.
• ≥32t: Go directly with the QD Type—the LH Type is no longer economically justifiable at this capacity.

Step 2: Confirm by Work Duty Classification

• If the required work duty is A6/A7/A8, select the QD Type Double-Girder Bridge Crane directly—neither the LD nor LH Type supports these classifications.
• For work duty A3–A5, keep all candidate models and proceed to Step 3.

Step 3: Decide Based on Budget and Application

• Sufficient budget (≥¥250,000 per unit) with a focus on full-lifecycle reliability: Choose the QD Type Double-Girder Bridge Crane. Although the initial investment is 40–60% higher, the hoist winch mechanism delivers over 30% lower combined maintenance costs over a 10-year operating period compared to electric hoist types (the gearbox, brake, and wire rope on electric hoists require far more frequent replacement than winch systems).
• Mid-range budget (¥120,000–180,000 per unit) with moderate lifting capacity: Choose the LH Type, which uses a double-girder configuration for better operational stability and smoother trolley travel.
• Limited budget (≤¥100,000 per unit) with low usage frequency: Choose the LD Type for the best cost-performance ratio. For intermittent duty cycles not exceeding 2,000 hours per year, the LD Type saves ¥10,000–30,000 annually in maintenance costs compared to over-investing in a double-girder system.

Kelude Heavy Industry—Full-Series Bridge Crane Selection Support

Henan Kelude Heavy Industry Co., Ltd. (k.qizhongji.com) offers design, manufacturing, and installation services for the complete range of bridge cranes, including the QD Type Double-Girder Bridge Crane, LD Type, LH Type, and explosion-proof/metallurgical models. For projects where crane selection is uncertain, the Kelude Heavy Industry sales engineering team provides complimentary selection assistance—simply supply the lifting capacity, span, lifting height, annual operating hours, and duty frequency, and an engineer will issue a detailed model recommendation, preliminary configuration proposal, and budget estimate within 24 hours. Call or chat online with our support team to get started.

To compare specifications and pricing across the full bridge crane series, see the Bridge Crane Full-Series Comparison Chart—a single table that breaks down the differences between the LD, QD, LH, LB, and LDY models.

Frequently Asked Questions