Insights / Technical guide · 2026-10-23
Rigid Chain Lift Systems: Loads, Safety Design and Testing
A rigid chain lift raises a stage platform, orchestra pit floor or industrial table with a chain that becomes a solid column as it leaves the drive. It is a compact alternative to hydraulic cylinders and screw jacks, but only when the load, travel and safety functions are specified correctly. This article explains how these systems carry load, how to read their ratings, which safety features to ask for and what a sensible test plan looks like. Figures quoted are from Zhonghui's 30A–100A rigid lifting chain documentation; everything else is general engineering guidance, and final values always come from the drawings approved for a specific project.
How a rigid chain carries load
A normal roller chain can only pull. A rigid chain has links shaped so that, once they are guided out of the drive unit, they interlock on the load side and act as a push-and-pull column. The drive pinion pushes this column up; on the way down, the links unlock and fold into a chain storage box beside or below the drive. Because the chain is stored rather than telescoped, the closed height of the machine stays low while the travel can be long. In Zhonghui's range, the minimum installation height runs from 200 mm (30A) to 650 mm (100A), while maximum travel reaches up to 10 m depending on model and load.
Static versus dynamic load — and why they are not the same number
Every rigid chain size has two load ratings:
- Static load — what the chain can hold when the platform is stationary, for example a parked stage lift carrying scenery.
- Dynamic load — what it can move while travelling.
Dynamic ratings are lower because moving loads add acceleration forces and the guided column must stay stable while links are engaging. Both ratings also fall as travel increases: a taller unsupported column is more sensitive to buckling and side load. That is why Zhonghui publishes two pairs of values for each size:
| Model | Max. static load / allowed travel | Allowed static load / max. travel | Max. dynamic load / allowed travel | Allowed dynamic load / max. travel | Rated speed |
|---|---|---|---|---|---|
| 30A | 10 kN / 1.2 m | 10 kN / 1.2 m | 8 kN / 1.2 m | 8 kN / 1.2 m | 150 mm/s |
| 35A | 12 kN / 1.5 m | 12 kN / 1.5 m | 10 kN / 1.5 m | 10 kN / 1.5 m | 200 mm/s |
| 40A | 40 kN / 2 m | 25 kN / 4 m | 30 kN / 2 m | 15 kN / 4 m | 300 mm/s |
| 60A | 90 kN / 2 m | 35 kN / 5 m | 60 kN / 2 m | 25 kN / 5 m | 300 mm/s |
| 80A | 130 kN / 2 m | 35 kN / 8 m | 95 kN / 3 m | 35 kN / 8 m | 300 mm/s |
| 100A | 200 kN / 3.5 m | 20 kN / 10 m | 150 kN / 5 m | 20 kN / 10 m | 300 mm/s |
Read the table as two ends of a curve: a 100A chain can hold 200 kN at 3.5 m, or 20 kN at 10 m — not 200 kN at 10 m. When you send an RFQ, give load and travel together so the right point on that curve can be checked. The rigid chain systems page lists the full data, including chain weight, pitch, drive weight and rise per revolution.
From one chain to a complete lift
A finished lift is rarely a single chain. A rigid chain lift table such as the SL500 (≤500 kg, 1450 × 1100 mm platform, 500 mm stroke) or a large stage elevator combines several elements:
- Lifting points. Large platforms use two, four or more chains. Load distribution decides how much each point carries, so an off-centre load (a piano at one edge, a set wagon parked on one side) must be part of the calculation.
- Synchronisation. Several lifting points can be driven by one motor through mechanical shafts, or by separate drives synchronised electronically with encoder feedback.
- Guidance. The chain is designed to push, not to resist large side loads. Guides or a scissor frame keep the platform level and take horizontal forces.
- Drive selection. Motor, gearbox and brake are sized to the dynamic load, speed and duty cycle (moves per hour and operating hours).
Safety design: what to specify
Safety on a stage lift comes from the whole system, not from the chain alone. When reviewing a proposal, check that it covers:
- Load margin. Select a chain size whose rating at the required travel is comfortably above the moving load, including the platform's own weight and the worst-case load position.
- Holding brake. A brake on the drive holds the platform when the motor stops or power is lost.
- Travel limits. Upper and lower limits, with a separate final limit beyond the operating limit, stop the drive before mechanical end positions.
- Emergency stop. E-stop circuits reachable by operators, wired into the control system so all lifting points stop together.
- Position feedback. Encoders or similar feedback for each lifting point allow the control to detect synchronisation errors and stop before the platform twists.
- Edge and under-platform protection. Where people can reach the moving edge or the space below, the risk assessment should define guarding or sensing measures.
- Control interface. Define whether the lift runs standalone or under the venue's stage control system, and how interlocks with neighbouring machinery work.
No single list replaces a project risk assessment; the exact functions and their implementation follow the approved drawings and the rules that apply where the venue is built.
Testing before handover
A useful test plan treats mechanics, electrics and controls as one system. Zhonghui's commissioning checklist for rigid chain lifts covers:
- Before powered movement: installation interfaces, fasteners, guides, guarding, clearances, chain path, drive alignment and inspection access checked against approved documents.
- Functional tests: unloaded and loaded travel, stopping behaviour, limits, emergency-stop response, feedback signals and synchronised lifting, with notes on abnormal noise or vibration.
- Handover records: approved drawings, test records, control backups, operating instructions, maintenance responsibilities and the contact route for engineering support.
In the factory, lift tables are run before dispatch — singly and in groups — so motion and synchronisation can be observed before the equipment reaches site.
Maintenance planning
Base the plan on the approved system manual, operating frequency and environment. Typical inspection points are the chain path, drive and guides, fasteners, lubrication points where specified, limits, sensors, brakes, guarding and safety circuits. Record findings and corrective actions, and do not replace project-specific intervals with a generic one.
Rigid chain or another drive?
Rigid chain lifts need no hydraulic oil on stage and achieve long travel from a low closed height. Hydraulic systems can suit some very high loads where a pit or plant room is available; scissor tables suit short strokes; screw jacks tie travel to screw length. The comparison on our lift table page summarises the trade-offs. For actuator-only supply to integrators and OEMs, see the 30A–100A rigid chain actuators.
Send your project inputs
To size a rigid chain lift, send the moving load and its distribution, required travel, platform size, target speed, duty cycle, available pit or installation height, and the control interface. Use the RFQ form on our contact page. We reply within 24 hours on business days (GMT+8).