Cordless Spring systems have become a baseline requirement for bamboo Roman shades
in the US and European markets. Beyond safety compliance, consistent hand feel,
balanced lift, and long-term stability are now critical performance expectations.

The L-Series Cordless Spring platform is designed as a system-level solution,
ensuring predictable mechanical behavior across different shade sizes,
materials, and installation conditions.

Cordless Spring Installation Overview

1. Fix the Spring Box at the center of the wooden headrail
2. Mount the V4 Cord Base units symmetrically on both sides
3. Route cords from the Spring Box through the V4 Cord Base
4. Guide cords downward through the bamboo Roman shade body
5. Secure cords at the bottom rail using the Cord Bundler
6. Fine-tune final tension via the Cord Bundler

Cordless Spring Selection Guide（Taking L4-2 as an Example）

Proper Cordless Spring selection is based on two key parameters:
total shade weight and shade width.

Name	Spring Specification	L4Spring box0R+V4-2.0Cord base0R		L4Spring box0.5R+V4-2.0Cord base0R		L4Spring box0R+V4-2.0Cord base0.5R		L4Spring box0.5R+V4-2.0Cord base0.5R
		Maximum bear weight/g	Minimum  Down rail weight/g	Maximum bear weight/g	Minimum  Down rail weight/g	Maximum bear weight/g	Minimum  Down rail weight/g	Maximum bear weight/g	Minimum  Down rail weight/g
L4-2	0.1	850	250	1050	200	1250	150	1550	100
	0.11	950	250	1200	200	1400	150	1700	100
	0.12	1150	300	1350	300	1700	200	2050	150
	0.13	1350	400	1650	350	1950	250	2350	200
	0.14	1650	550	1950	500	2350	300	2900	250
	0.15	1750	600	2100	550	2600	350	3150	300

Cordless Spring System Architecture

• Spring Box – constant force energy and balance module
• V4 Cord Base – cord routing and load distribution interface
• Cord Bundler – bottom-rail fixation and tension adjustment

The Spring Box is installed centrally on the headrail.
Cords extend from both ends, pass through the V4 Cord Base,
and continue downward to the bottom rail,
where the Cord Bundler secures and adjusts final tension.

The Core of the Cordless Spring: Constant Force Spring Box

The Spring Box uses a constant force spring to maintain near-uniform output
throughout the entire lifting range.
This minimizes uneven lift, mid-height drift, and excessive pull force.

The housing is manufactured from engineering-grade POM,
offering low friction, dimensional stability, and long service life.
The flat-profile geometry integrates naturally with wooden headrails
used in bamboo Roman shades.

Model Example

The L4 Spring Box measures approximately
168.5 × 38 × 21.5 mm,
making it suitable for compact bamboo Roman shade constructions.

Cordless Spring Configuration Options

Spring Thickness

• 0.09 mm
• 0.10 mm
• 0.11 mm

Cord Quantity

• 2-cord system
• 3-cord system
• 4-cord system

Spring thickness is selected according to shade weight,
while cord quantity is determined primarily by shade width.

Frequently Asked Questions (FAQ)

Q1: How do I choose the correct Cordless Spring model?

Selection is based on total shade weight and finished width.
Spring thickness defines lifting force, while cord quantity ensures
balanced load distribution across wider bamboo Roman shades.

Q2: Can one Cordless Spring system fit different bamboo materials?

Yes. The L-Series Cordless Spring platform supports a wide range of bamboo
and fabric combinations by adjusting spring thickness and cord count
without changing the system layout.

Q3: Why is constant force important for bamboo Roman shades?

Bamboo Roman shades experience changing load as material stacks during lifting.
A constant force Spring Box maintains stable output,
preventing drift, uneven lift, and inconsistent hand feel.

Q4: What role does the V4 Cord Base play in system performance?

The V4 Cord Base controls cord routing and load symmetry.
It actively reduces left-right force imbalance caused by width,
material variation, or installation tolerance.

Q5: Is on-site adjustment possible after installation?

Yes. Final tension can be adjusted at the bottom rail
using the Cord Bundler, eliminating the need for spring replacement
or re-routing cords during installation.

Field Insight

In bamboo Roman shade applications, long-term performance is determined by
how force generation, cord routing, and tension adjustment work together as a system.
The L-Series Cordless Spring platform approaches this challenge by integrating
the Spring Box, V4 Cord Base, and Cord Bundler into a unified mechanical architecture.

• System stability starts with constant force.
  The constant force Spring Box maintains a near-flat output curve,
  reducing drift, uneven lift, and position instability over time.
• Balanced lift depends on controlled cord paths.
  The V4 Cord Base actively manages load distribution,
  minimizing left–right imbalance caused by width or material variation.
• Installation variability must be adjustable.
  The Cord Bundler allows final tension tuning at the bottom rail,
  eliminating on-site improvisation or component replacement.
• Flat-profile integration supports natural materials.
  The compact Spring Box geometry fits wooden headrails
  without compromising the visual character of bamboo Roman shades.
• A platform approach reduces lifecycle risk.
  Treating the Cordless Spring as a system—not a single part—
  improves OEM consistency, scalability, and long-term reliability.

Spring System Overview for Cordless Roman Blinds

This Spring System integrates four key components inside the headrail to keep the lift cords fully internal
while maintaining controlled, repeatable motion:

• T1 Spring Box — constant-force spring module defining the system force band
• Cord Reel — manages cord winding/unwinding as shade travel changes
• Cord Bundle — secures cords at the bottom rail and allows tension adjustment
• Fiber glass Hexagonal rod — mechanical coupling shaft that synchronizes rotation

A common layout uses one centrally mounted T1 Spring Box with Cord Reels on both sides.
The Fiber glass Hexagonal rod passes through all rotating parts, linking them into one coherent Spring System.

T1 Spring Box: The Force Source of the Spring System

The T1 Spring Box is the core of this Spring System. Inside it, a constant-force spring
provides stable lifting assistance across travel, reducing sensitivity to fabric stacking changes and minimizing position drift.

In practical terms, the T1-based Spring System is engineered to keep the user experience consistent:
smooth lift, predictable lowering, and reliable stop-at-any-height behavior.

Cord Management Inside the Spring System

Cord Reel + Cord Bundle: Controlled Winding and Tension

In this Spring System, lift cords are anchored inside the Cord Reel and wound around its spool.
The cords then route through the bamboo/fabric structure (slats or lift passages) and terminate at the bottom rail where the
Cord Bundle locks and fine-tunes cord tension.

When the blind is fully lowered, most of the cord length is extended through the shade body, leaving fewer wraps on the Cord Reel.
As the blind is raised, cord wraps increase on the Cord Reel, and the rotation is transferred through the Fiber glass Hexagonal rod.

Fiber glass Hexagonal rod: Rotation Synchronization

The Fiber glass Hexagonal rod ensures synchronized rotation across the entire Spring System.
This rigid coupling helps prevent phase drift, uneven winding, or left–right imbalance during travel—especially valuable for OEM builds
where repeatability matters.

How the Cordless Spring System Operates

This is an externally cordless Spring System: no exposed pull cords or chains. Users operate the Roman blind by
pulling the bottom rail up or down. Releasing the rail causes the Spring System to stop immediately, enabling
“pull-and-stop” positioning.

During motion, cord wrap count changes on the Cord Reel, and the Fiber glass Hexagonal rod rotates accordingly.
This rotation coordination keeps the system behavior smooth and predictable across the full stroke.

Applications of the Spring System

This Spring System is designed for OEM Roman blind programs requiring clean aesthetics, internal cord routing,
and controlled manual operation. Typical applications include:

• Bamboo Roman blinds
• Fabric Roman blinds
• Residential cordless window coverings
• OEM private-label Roman blind platforms

Spring Lift Mechanism System Overview

The R38L Spring Lift Mechanism is a mechanical cordless lifting system installed inside aluminum roller tubes.
It replaces traditional cords or chains while improving safety, stability, and user experience.

The complete system consists of:

• Spring Box – Core energy storage unit
• Brake – Anti-drop holding component
• Shaft – Structural carrier for multiple Spring Boxes
• Circlip – Fixing component between Spring Box and Brake
• Pin – Locking pin used during pre-winding

Spring Lift Mechanism Installation Overview

Step 1: Spring Box and Shaft Assembly

Install the required number of Spring Boxes onto the Shaft in sequence
and secure each unit using the appropriate Circlip.

Step 2: Brake Installation

Mount the Brake at the end of the Shaft to complete the assembly.

Step 3: Pre-Winding

Pre-wind the Spring Lift Mechanism by three turns and lock it using the Pin.

Step 4: Tube Installation and Testing

Insert the assembled system into the aluminum roller tube
and test lifting smoothness.

Step 5: Activation

Remove the Pin to activate the Spring Lift Mechanism after final testing.

Spring Lift Mechanism Core: Spring Box

At the core of the R38L Spring Lift Mechanism is the Spring Box.
Each Spring Box contains a precision-engineered 301 stainless steel constant force spring.

The spring strip is wound in a rolled form, similar to roller shade fabric,
allowing the spring to deliver a stable lifting force throughout the entire travel range.

The Spring Box housing is manufactured from POM engineering plastic,
selected for low friction, dimensional stability, and quiet operation.

Brake Function in the Spring Lift Mechanism

The Brake plays a critical safety role in the Spring Lift Mechanism.
Its primary function is not lifting, but holding.

By preventing sudden downward movement, the Brake ensures controlled operation,
especially for large and heavy roller shades.

Spring Lift Mechanism Assembly Structure

The R38L Spring Lift Mechanism is assembled linearly along the Shaft:

1. The Shaft acts as the structural base
2. Spring Boxes are installed sequentially
3. Each Spring Box is secured using a Circlip
4. The Brake is installed last to complete the system

Before insertion into the roller tube, the system must be pre-wound by three turns.
A Pin is used to lock the spring during installation.

After final installation and smoothness testing, the Pin is removed to activate the system.

Configurable Load Capacity for Heavy Roller Shades

The R38L Spring Lift Mechanism is designed for large and heavy roller shade systems.
A single Shaft can support up to five Spring Boxes.

The required spring configuration depends on:

• Total fabric weight
• Bottom rail weight
• Total shade drop

After weighing the fabric and bottom rail, the appropriate Spring Box model
and quantity are selected using the official selection chart.

Spring Lift Mechanism Selection Chart

Correct spring selection is essential for stable performance and long-term durability.
Please measure the combined weight of the fabric and bottom rail before selecting the configuration.

Final configurations should be validated through prototype testing.

Application Scenarios for the R38L Spring Lift Mechanism

The R38L Spring Lift Mechanism is designed for roller shade systems
where standard spring solutions reach their performance limits.
It is especially suitable for the following application scenarios:

Large-Width Roller Shades

For wide roller shades, fabric weight and bottom rail leverage increase significantly.
The R38L system supports multiple Spring Boxes on a single Shaft,
allowing OEMs to distribute lifting force evenly across the width.

Heavy Fabric Roller Shades

Roller shades made with blackout fabrics, textured materials,
or laminated fabrics place higher demands on lifting and holding stability.
The R38L Spring Lift Mechanism provides controlled lift combined with reliable braking.

Commercial and Project-Based Roller Shades

In hotels, offices, and public buildings,
roller shades are often larger, heavier, and used more frequently.
The R38L system is designed to handle these higher load and durability requirements.

Premium Cordless Roller Shade Product Lines

For manufacturers developing high-end cordless roller shades,
the R38L Spring Lift Mechanism offers a scalable and engineered solution
that balances smooth operation with long-term reliability.

FAQ – R38L Spring Lift Mechanism

Q1: What type of shades is the R38L Spring Lift Mechanism designed for?

The R38L Spring Lift Mechanism is designed for cordless roller shades,
particularly large and heavy fabric systems.

Q2: Why does the R38L system support multiple Spring Boxes?

Multiple Spring Boxes allow precise force matching for wide and heavy shades
instead of relying on a single oversized spring.

Q3: How do I select the correct Spring Box model?

Selection is based on fabric weight, bottom rail weight, and shade drop,
using the official selection chart.

Q4: What does the spring thickness code indicate?

Spring thickness determines lifting force.
Thicker springs provide higher force but shorter maximum travel.

Q5: Why do thinner springs support longer shade drops?

Thinner springs allow more winding turns within the same Spring Box,
resulting in longer usable travel.

Q6: What is the purpose of the Brake?

The Brake prevents sudden downward movement and provides holding stability.

Q7: Why is pre-winding required?

Pre-winding stores initial energy in the system and ensures proper operation after installation.

Q8: What happens if the spring configuration is incorrect?

Improper configuration may cause drifting, rebound, or heavy operation.

Q9: Is the R38L compatible with motorized systems?

The R38L is designed for manual cordless operation.
Hybrid systems require separate evaluation.

Q10: Who is the target customer for the R38L system?

The R38L Spring Lift Mechanism is supplied exclusively to OEM window covering manufacturers.

Key Features

• True Cordless Lift Control – No exposed cords or chains
• 301 Stainless Steel Constant Force Spring
• Integrated Brake System to prevent sudden drop
• 32mm Tube Compatibility for standard roller blinds
• POM Spring Box Housing for low friction and quiet operation
• Multiple Spring Force Options for different blind weights
• OEM-Friendly Assembly with pre-tension pin locking

Product Overview

The Cordless Lift Control is engineered as an internal mechanical platform
that provides both lifting force and positional stability for roller blinds.
Instead of relying on external cords, the entire load-balancing function
is handled inside the aluminum tube.

Users operate the blind by gently pushing or pulling the bottom rail.
The internal spring stores and releases energy smoothly,
while the brake controls motion and holding position.

System Components

• Spring Box – Core energy storage using a constant force spring
• Brake – Controls speed and prevents free fall
• Shaft – Transfers torque inside the tube
• Circlip – Fixes axial position between components
• Pin – Locks pre-tension during installation

Constant Force Spring Technology

At the heart of the Cordless Lift Control is a constant force spring
manufactured from 301 stainless steel.
The spring strip is wound into a compact spiral,
delivering near-uniform output force throughout the blind’s travel.

Compared with conventional torsion springs,
constant force springs reduce pull-force variation,
improve mid-position stability,
and enhance overall user experience.

Spring Options & Load Matching

The Spring Box is available in five force variants.
The main difference lies in the thickness of the spring strip.

Example: 0.09 × 16 × 2000

• Thickness: 0.09 mm
• Width: 16 mm
• Length: 2000 mm

Thicker springs provide higher lifting force
but allow fewer wraps within the Spring Box,
resulting in a shorter maximum blind drop.

Thinner springs support longer blind heights
with lower lifting force,
making proper selection essential for optimal performance.

Cordless Lift Control Selection Guide

Proper spring selection is critical for achieving balanced operation,
stable holding, and long service life.
The table below provides a general reference for matching spring specifications
to blind weight and drop length.

Note: Spring selection should always consider fabric weight,
bottom rail weight, tube diameter, and target user pull force.
Final validation through prototype testing is recommended.

Integrated Brake System

The Brake is responsible for controlling movement and holding position.
It prevents sudden downward acceleration
and ensures the blind remains stable when released.

The brake does not generate lifting force;
instead, it governs motion within the force range defined by the spring.

Installation & Pre-Tensioning

Before insertion into the aluminum tube,the Cordless Lift Control must be pre-wound to store initial spring energy.

The Pin locks the spring after pre-tensioning,allowing safe handling during assembly.
Once installed, the Pin is removed,and the system becomes fully operational.

Applications

• Residential roller blinds
• Commercial window shading systems
• Child-safe window coverings
• Manual cordless roller blind platforms

Why Choose This Cordless Lift Control

• Designed specifically for OEM roller blind manufacturers
• Reduces safety compliance risk
• Minimizes wear-prone external components
• Supports scalable production with consistent performance

Frequently Asked Questions

1. What type of blinds is this Cordless Lift Control designed for?

This Cordless Lift Control is specifically designed for roller blinds
using a 32mm aluminum tube.
It is not intended for Roman shades, zebra blinds, or venetian blinds.

2. Is this a complete roller blind system?

No. This product is an internal lift mechanism and belongs to the
roller blind accessory category.
Fabric, tube, bottom rail, and brackets are supplied separately by the manufacturer.

3. How does the blind stay in position without cords?

Position holding is achieved through the balance between
the constant force spring inside the Spring Box
and the integrated Brake.
The spring provides lifting force,
while the Brake controls motion and prevents sudden movement.

4. Can one spring model fit all blind sizes?

No. Different blind weights and drop lengths require different spring forces.
Selecting the correct spring thickness is essential
to avoid excessive pull force or insufficient lift.

5. What happens if the spring force is too strong?

An oversized spring may cause the blind to rise too quickly,
increase pull resistance,
or reduce usable drop length due to limited wrap capacity.

6. What happens if the spring force is too weak?

An undersized spring may result in poor lifting performance,
difficulty holding position,
or increased load on the Brake.

7. Why is pre-tensioning required before installation?

Pre-tensioning stores initial energy in the spring,
ensuring balanced operation from the first use.
The Pin temporarily locks the spring during assembly for safety and accuracy.

8. Is this system child-safe?

Yes. The Cordless Lift Control eliminates external cords and chains,
significantly reducing entanglement risks
and supporting modern child-safety requirements.

9. Can this system be used for very wide roller blinds?

Performance on wide blinds depends on proper spring selection,
fabric weight distribution,
and overall system design.
Wide applications may require careful testing and validation.

10. Do you support OEM customization?

Yes. Spring force configuration, component matching,
and packaging can be adjusted to support OEM manufacturing requirements.