How should a double-rail single-cylinder freight elevator be installed?

The elevator has two guide rails but only one hydraulic cylinder doing the lifting.
In this setup, the biggest challenge is keeping the platform level during travel, since only one side is being directly pushed by the cylinder. The other side must be synchronized mechanically so it doesn't lag or tilt.
Here's how the installation differs from a normal double-rail double-cylinder elevator:
Key Principles for Double-Rail Single-Cylinder Installation
One cylinder is mounted on one side (usually centered along one rail or close to it).
The lifting force is transferred evenly to both sides of the platform via a chain or steel wire rope balance system.
Guide rails still ensure vertical alignment and prevent sway.
Cross-shaft & chain system is the heart of the design - it ensures both sides rise/lower together.
---Installation Steps
1. Shaft & Pit Preparation
Prepare the pit and shaft walls as per the manufacturer's drawing.
Ensure strong anchor points for both rails and balance shaft bearings.
2. Install Double Guide Rails
Position and fix both guide rails vertically on opposite sides of the shaft.
Maintain perfect parallel alignment - tolerance is very tight (<= 2 mm over full height).
Anchor rails to the wall/frame at regular intervals.
3. Install Hydraulic Cylinder


Indirect push via chain/pulley from the cylinder's piston to a cross-shaft.
Ensure cylinder base is bolted to a reinforced pit foundation.
4. Install Cross-Shaft & Balance Chain System
At the top of the shaft, mount a horizontal cross-shaft connecting both sides of the elevator frame.
Fit sprockets on both ends of the shaft.
From each sprocket, run a steel chain down to the platform frame.
When the cylinder pushes one side, the chain system rotates the cross-shaft, lifting the other side at the same speed.
This ensures both sides stay level without needing a second cylinder.
5. Install Platform Frame
Position platform between rails using lifting equipment.
Attach guide shoes/rollers to the platform and engage them into the rails.
Connect the lifting side to the cylinder piston rod (direct) or chain anchor (indirect).
Connect the opposite side to the balance chain.
6. Install Hydraulic Power Unit
Place the pump station near the shaft base or in a nearby room.
Connect hydraulic hose from pump to cylinder.
Fill with recommended hydraulic oil.
7. Electrical & Safety Wiring
Install limit switches on both rails.
Connect door interlocks, emergency stop, overload protection.
Install call stations on each landing.
8. Testing & Adjustment
Run slow-speed no-load tests first to check synchronization.
Adjust chain tension until both sides rise evenly without tilt.
Perform load testing to confirm stability and safety.
Main difference from a normal double-cylinder system:
Instead of two cylinders lifting each rail side independently, a mechanical balance system links both sides so that one cylinder's motion drives the entire platform evenly.