Single-Girder vs Double-Girder Ponte Rolante: Which to Buy
If you are specifying an overhead crane for a workshop, warehouse, or production bay, the first structural decision is almost always the same: single-girder or double-girder? The answer drives cost, building height requirements, hook approach, and how the crane behaves under daily load cycles. This article compares the two configurations using real Chunhua Guindaste models — the LD single-girder and the LH/QD double-girder lines — so you can match the machine to your building and duty cycle rather than over- or under-buying.
What "Single-Girder" and "Double-Girder" Actually Mean
A single-girder crane uses one main box girder spanning the runway. The hoist trolley runs along the bottom flange of that girder. Chunhua's LD series covers 0.5–20 tonnes with spans tipicamente up to about 22.5 m, and it is the standard choice for light-to-medium workshops.
A double-girder crane uses two parallel main girders with the trolley running on rails mounted on top of them. The LH hoist double-girder covers 5–50 tonnes, and the QD universal double-girder covers 5–150 tonnes for heavier and higher-duty service. Because the trolley sits between or on top of the girders, the hook can be raised higher relative to the building, and heavier capacities are structurally practical.
Capacidade: Where the Crossover Sits
- 0.5–20 T: LD single-girder is usually the most economical correct answer. At 10 T and below, a single girder is rarely the limiting factor.
- 20–50 T: This is the transition zone. An LD can be built to 20 T, but if you are regularly at 15–20 T or need frequent lifts, an LH double-girder is the more durable choice.
- 50–150 T: QD universal double-girder. Single-girder designs are not offered here for good reason — deflection and fatigue life become unmanageable.
For metallurgical or high-temperature environments, the YZ series (5–125 T) is a double-girder platform built for severe duty. For automated warehouses, the QDS smart unmanned double-girder integrates positioning and anti-sway control.
Headroom and Hook Approach: The Hidden Cost Driver
This is where buyers most often get surprised. On an LD single-girder crane, the hoist hangs below the girder, so the hook cannot rise as close to the roof. If your building has limited height and you need to lift tall loads, you may be forced into a double-girder design — or into a more expensive building modification.
Double-girder cranes place the trolley on top of the girders, giving a shorter headroom dimension and a higher maximum hook height for the same building. They also generally offer better hook approach to the end walls, which matters when loads must be positioned close to columns.
Practical advice: Before choosing, measure your actual available headroom from the runway rail top to the lowest obstruction (roof truss, lighting, sprinkler). Then confirm the crane's "headroom" and "hook approach" dimensions against that number. A 20 T LD that fits your capacity but not your headroom is the wrong crane.
Cost: Not Just the Preço do Guindaste
A single-girder LD is tipicamente 20–35% lower in crane cost than an equivalent-capacity double-girder machine. But the total installed cost comparison includes:
- Runway and building structure: Double-girder cranes are heavier and impose higher wheel loads, which can require a stronger runway beam and columns.
- Foundation and civil work: Heavier cranes may need upgraded building steel.
- Installation: Double-girder cranes require more assembly time and rigging.
- Energy and maintenance: Single-girder cranes have fewer components and simpler maintenance; double-girder cranes have two drive sides and more wear points, but better duty-cycle tolerance.
If your duty cycle is light (FEM 1.001 / DIN 15018 light or moderate, CMAA #70 Class A–B), the LD is often the better financial decision. If you run near-continuous shifts, handle 20 T+ regularly, or need precise load positioning, the double-girder premium pays back through longer service life and less downtime.
Duty Class and Normas
Chunhua designs to GB/T 3811 as standard, with FEM 1.001, DIN 15018, or CMAA #70 on request. Steel is Q345B/Q235B, and electrical components are sourced from Schneider, Siemens, ABB, and SEW. Certificações available include CE, CCC, EAC (TR CU 010/020), GCC/SASO, SONCAP, and KEBS — relevant if you are importing into the EU, Russia/CIS, the Gulf, or África.
Quick Selection Guide
- Under 20 T, light/moderate duty, adequate headroom: LD single-girder.
- 5–50 T, higher duty or tight headroom: LH hoist double-girder.
- 5–150 T, general heavy-duty workshop: QD universal double-girder.
- Metallurgical / high-temp: YZ double-girder (5–125 T).
- Automated / unmanned: QDS smart double-girder.
Buying De Chunhua Guindaste
Chunhua Guindaste (chinacraneexporter.com) works with Hefei Chunhua Hoisting Machinery Co., Ltd (founded 2003), located in the Anhui industrial crane manufacturing belt, and serves 60+ countries across 5 categories and 81 standard models. There is no MOQ, quotes are returned within a 4-hour SLA, production runs 30–45 days, and every crane carries a 12-month warranty.
To get an accurate single- vs double-girder recommendation, send your capacity, span, lifting height, duty cycle, and building headroom. Contato us on WhatsApp +86 193 9277 7259 or email yuhua0095@gmail.com.