L Series Cordless Spring for Bamboo Roman

Gianna — Fri, 16 Jan 2026 09:47:17 +0000

Quick Summary

The Cordless Spring system in the L-Series is engineered for bamboo Roman shades,
integrating a constant force Spring Box, V4 Cord Base, and adjustable Cord Bundler.
It delivers stable lift, precise balance, and a clean, child-safe cordless solution
optimized for OEM production.

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

Fix the Spring Box at the center of the wooden headrail
Mount the V4 Cord Base units symmetrically on both sides
Route cords from the Spring Box through the V4 Cord Base
Guide cords downward through the bamboo Roman shade body
Secure cords at the bottom rail using the Cord Bundler
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
Name	Spring Specification	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.

Bamboo Roman Shades – Cordless Curtain Solution Provider | Dosron