ENGINEERING STRUCTURAL BREAKDOWN

Spring System Works in Real Operation
NOTE
  •  ANSI/WCMA A100.1(U.S. Window Covering Safety Standard)
  • CPSC 16 CFR 1260(U.S. Federal Mandatory Cordless Rule)
  • EN 13120(European Child Safety Standard for Window Coverings)
  • AS/NZS 60335.2.97(Australia & New Zealand Safety Standard for Motorized Blinds)

At DOSRON, our cordless systems are engineered to eliminate exposed cords and hazardous loops — reducing strangulation risks at the source. Every architecture is developed in alignment with key global child-safety standards:

  • ANSI/WCMA A100.1(U.S. Window Covering Safety Standard)
  • CPSC 16 CFR 1260(U.S. Federal Mandatory Cordless Rule)
  • EN 13120(European Child Safety Standard for Window Coverings)
  • AS/NZS 60335.2.97(Australia & New Zealand Safety Standard for Motorized Blinds)

Because protecting children is not a feature upgrade.It is the starting point of responsible engineering.

Quick Summary

The R38L Spring Lift Mechanism is a professional-grade cordless system for roller shades.
Built around a POM Spring Box with an internal 301 stainless steel constant force spring,
the system delivers controlled lift, reliable braking, and scalable load capacity.
Designed for OEM manufacturers, the R38L supports up to five Spring Boxes on a single Shaft,
making it ideal for wide and heavy roller shade applications.

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.

R38L Spring Lift Mechanism for Cordless Roller Shades
 

 

 

 

 

 

 

 

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

Spring Box Constant Force Spring

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.

Fabric/inch
/cm
36 48 54 60 64 72 84 86 96 102 112″ Top rebound force Unit
91.44 121.92 137.16 152.4 162.56 182.88 213.36 218.44 243.84 259.08 284.48
Spring  mm
0.09*19*2000 180 207 220 234 243 260 287 292 314 327 350 50 g
0.10*19*2000 274 315 335 356 370 397 438 445 480 500 75 g
0.11*19*2000 382 426 448 470 484 513 557 565 600 125 g
0.12*19*2000 482 526 548 570 584 613 657 665 700 175 g

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

Roller Blinds
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 Blind
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

Roller Blind in Office
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

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.

Field Insight

A Spring Lift Mechanism is not defined by strength alone.
Long-term reliability depends on force matching, braking authority,
and correct spring selection.

  • R38L enables scalable load design using multiple Spring Boxes
  • Constant force springs improve stability across full travel
  • Integrated Brake prevents sudden drop in heavy shades
  • Correct selection is critical for performance and durability

Capacity & Drop

R32 spring box Capacity & Drop

Spring Box PN.

Maximum Capacity /g

Support Maximum Drop /inch

Support Maximum Drop /cm

0.07*16*2000

   

0.08*16*2000

   

0.09*16*2000

   

0.10*16*2000

   

0.11*16*2000

   

 

R38 spring box Capacity & Drop

Spring Box PN.

Maximum Capacity /g

Support Maximum Drop /inch

Support Maximum Drop /cm

0.09*16*2000

   

0.10*16*2000

   

0.11*16*2000

   

0.12*16*2000

   

Why Us?

This will help you understand the differences between our products and those currently on the market.

Item

Electric tubular motors for cordless Spring Mechanism Roller BlindVSElectric tubular motors for cordless Spring Mechanism Roller BlindVSElectric tubular motors for cordless Spring Mechanism Roller Blind

Stablity

   

Force compensate

   

Assembly Safety

   

SKU

   

Lifecycle

   

Cost

   

Operation

   

Patents & Certifications

We design and manufacture cordless spring mechanisms and tubular motors for roller shades, honeycomb shades, zebrablinds, and venetian blinds,roman shades and more. Trusted by top international brands, DOSRON delivers scalableOEM/ODM solutions worldwide.

Get in touch

If you are interested in our solutions, please leave us a message. Let us provide a complete solution tailored to your specific situation.

Frequently Asked Question about Dosron

Q1: Is this Cordless Spring Drive suitable for motorized zebra blinds?

No. This system is engineered for manual cordless zebra blinds. Hybrid motor-spring platforms use different control logic.

Q2: How many Spring Boxes should I use?

It depends on measured fabric + bottom rail weight and required drop. Use the selection table to choose model and quantity per Shaft.

Q3: Why is pre-winding required before installation?

Pre-winding stores initial energy so the system enters the intended force band immediately. The Pin locks the pre-tension state.

Q4: Can a stronger Brake solve drift if the spring is mismatched?

Not reliably. The Spring Box defines the force band; the Brake only governs motion within it. Correct selection comes first.

Q5: Can different Spring Box models be mixed on one Shaft?

Yes, but only with proper load calculations to keep force distribution stable across the full travel.

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