Cordless Zebra Blinds – Cordless Curtain Solution Provider | Dosron

R38L Cordless Spring Drive for Zebra Blinds

Gianna — Thu, 29 Jan 2026 07:52:14 +0000

Quick Summary

The Cordless Spring Drive is a 38mm internal spring mechanism engineered for
manual cordless zebra blinds. Built around a constant-force Spring Box and a controlled
Brake, it replaces cord lifting with a pre-tensioned force-balance architecture that
improves safety, delivers stable positioning, and scales across OEM SKUs by combining multiple Spring Boxes on one
Shaft.

Child-safe, minimalist cordless design (no exposed cords)
Modular build: up to 5 Spring Boxes per Shaft
Pre-winding with Pin for controlled stored energy
Selection by load + drop using a spring selection table

Cordless Spring Drive Product Overview

A Cordless Spring Drive is not a “cord-removed” zebra blind. Once cords are eliminated, the blind becomes a
hidden force-balance system inside the tube. This 38mm platform is designed for OEM production where
consistent hand feel, controlled stopping, and predictable configuration matter more than showroom-only smoothness.

Target customers
Zebra blind manufacturers, OEM fabricators, and system integrators.

Application
Manual cordless zebra blinds (day & night blinds).

Cordless Spring Drive System Architecture

The 38mm internal assembly uses five functional modules with clear responsibilities—so performance is engineered, not guessed.

Component	Role in the system
Spring Box	Core energy module with internal 301 stainless steel constant-force spring output.
Brake	Provides controlled holding and prevents sudden drop (anti-free-fall protection).
Shaft	Structural carrier and alignment backbone; supports multiple Spring Boxes in one tube.
Circlip	Fixes the Spring Box and Brake position to maintain consistent geometry and stability.
Pin	Locks the system after pre-winding, securing stored energy before insertion into the tube.

Pre-winding requirement: Before installation, the system must be pre-wound to store initial energy.
The Pin locks the pre-tension state, which is essential for consistent lift and hold behavior.

Spring Box Engineering Inside the Cordless Spring Drive

The Spring Box defines the force band of the entire mechanism. The Brake governs motion
inside that band—but it cannot “fix” an incorrect band. That’s why proper spring selection is the foundation of stability.

Materials & Construction

POM housing: self-lubricating, dimensionally stable, and low-noise during long-term cycling.
301 stainless steel spring strip: rolled constant-force architecture for near-flat output.

Modular Scaling: Cordless Spring Drive Configuration for OEM SKUs

One Shaft supports up to five Spring Boxes, enabling a scalable platform across different
zebra fabrics, bottom rails, and size ranges. OEM teams can standardize the tube architecture while tuning performance by
adjusting Spring Box model and quantity.

Why modular matters
Fewer unique parts, broader SKU coverage, and faster engineering iteration.

What changes per SKU
Spring Box model + quantity, based on measured load and required drop.

Cordless Spring Drive Model Logic & Selection Principles

The 38mm series includes six Spring Box variants, most visibly differentiated by spring strip thickness. Thicker strips
deliver more force, but allow fewer windable turns in a fixed volume—reducing maximum supported drop.

Model Example

38ZB-08-350-84″

Code	Meaning
08	Spring strip thickness: 0.08 mm
350	Load capacity per Spring Box: 350 g
84″	Maximum supported blind drop: 84 inches

Selection Logic (Engineering Rule of Thumb)

Thicker spring strip → higher force, fewer turns → shorter drop range
Thinner spring strip → lower force, more turns → longer drop range

Practical takeaway: Correct selection is about balance (force + travel + controllability), not maximum force.
Overpowered setups can increase stress on the Brake and raise noise risk.

Cordless Spring Drive Selection Table Placeholder

Use measured fabric + bottom rail weight and required drop to choose the Spring Box model and quantity per Shaft.
Final values are typically confirmed by sample build testing.

Drop length		Spring Spec.	Spring Force	Rebound Force
162.56cm	64″inch	0.07194000mm	165g	50g
		0.08193500mm	260g	75g
		0.09193500mm	330g	100g
		0.10193500mm	430g	125g
182.88cm	72″inch	0.07194000mm	175g	50g
		0.08193500mm	280g	75g
		0.09193500mm	350g	100g
213.36cm	84″inch	0.07194000mm	185g	50g
213.36cm	84″inch	0.08193500mm	300g	75g
218.44cm	86″inch	0.07194000mm	190g	50g
243.84cm	96″inch	0.07194000mm	200g	50g

Advantages of the Cordless Spring Drive Platform

Purpose-built for zebra blinds (manual cordless application)
Safety-driven design: no exposed cords, reduced free-fall risk
Modular scalability: up to 5 Spring Boxes per Shaft
Stable force output across travel when correctly selected
Controlled stopping through Brake authority within the force band
OEM-friendly configuration by load-based selection

Applications

Residential manual cordless zebra blinds
Child-safe window covering product lines
OEM private-label zebra blind platforms

FAQ – Cordless Spring Drive (OEM Focus)

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.

Q6: Why use POM for the Spring Box housing?

POM offers low friction, dimensional stability, and lower noise potential during long-term cycling versus common plastics.

Q7: What is the role of the Circlip?

The Circlip fixes geometry between the Spring Box and Brake to prevent shifting that can cause instability or inconsistent feel.

Q8: Is this platform suitable for larger / heavier zebra blinds?

Yes—within the boundaries of correct spring model and quantity selection. Modular scaling supports heavier builds when properly configured.

Final Note / Practical Takeaway:

A zebra blind without cords is not a simplified product—it becomes a force-balance mechanism. A well-built
Cordless Spring Drive is engineered so the force band stays stable and the Brake can govern motion predictably.

Spring Box sets the force band (energy output)
Brake controls motion and anti-drop behavior within the band
Shaft maintains alignment and supports modular scaling (up to 5 Spring Boxes)
Pre-winding + Pin establishes stored energy before tube insertion
Correct selection (load + drop) drives long-term stability more than friction tuning

38ZB Cordless Spring System for Zebra Shades

Gianna — Fri, 12 Dec 2025 09:07:23 +0000

Quick Summary

The DOSRON Cordless Spring System built around the 38ZB spring box is the zebra-specific module in the R38 cordless spring mechanism. With a POM housing and 301 stainless-steel constant-force spring, it is mounted in series on a shaft together with a brake and fixed by circlips, then inserted into a Ø38 mm aluminum tube. Two shaft options support up to 2 or 5 spring boxes per blind, so OEM brands can tune lift force to the zebra fabric and bottom rail weight while keeping a clean, cordless appearance.

Cordless Spring System Overview for 38ZB Zebra Blinds

The 38ZB spring box is a dedicated in-tube spring module for cordless zebra blinds using 38 mm aluminum tubes.
It belongs to the R38 Cordless Spring System family, where 38RB modules are optimized for roller blinds and
38ZB modules are optimized for zebra (day & night) fabrics. Within this Cordless Spring System, each 38ZB module combines a low-friction POM outer shell with an internal 301 stainless-steel spiral spring that provides near constant lifting force across the stroke.

Internal Architecture: Shaft, Spring Boxes, Brake and Circlips

Shaft – the “bamboo skewer” core: A precision R38 shaft runs through the center, but with a mechanical profile rather than a bamboo look. It defines the positions for each 38ZB spring box and the brake inside the Cordless Spring System.
38ZB spring boxes – the “hawthorns” on the stick: One or more 38ZB modules are threaded onto the shaft in series. Each module adds lifting capacity in the Cordless Spring System, just like adding another hawthorn on the skewer.
Brake – the tail piece of the skewer: The Brake is central to the shade’s safe and graceful operation. It ensures the shade descends at a steady, elegant pace, preventing rapid falls and guaranteeing reliable performance.
Circlips – the invisible stoppers: Once the spring boxes and brake are positioned, circlips are locked into the shaft grooves above and below the stack, fixing the positions and preventing movement during operation.
Aluminum tube – the outer shell: The fully assembled spring set (shaft + 38ZB modules + brake + circlips) is then pushed into a Ø38 mm aluminum tube like a plug, creating a compact, sealed cordless lift core for zebra blinds within the Cordless Spring System.

There are two shaft versions in the R38 system: one designed to hold up to 2 pcs of 38ZB spring boxes, and one that can hold up to 5 pcs. The actual number of spring boxes used is selected according to the zebra fabric weight and bottom rail mass for each blind size.

Key Features & Benefits of the Cordless Spring System

Fabric Length
Fabric Length (Unit: ” /CM)		A	B	C	D	E	F	G	H	I	G	L
		36″	36″	48″	54″	60	64	72	84	86	96	Top 40CM rebound force	Unit
		91.44CM	91.44CM	121.92CM	137.16	152.4	162.56	182.88	213.36	218.44	243.84
ITEM	Spring Spec.	Spring Force
1	0.07194000mm	154	175	200	213	225	234	251	276	280	301	50	g
2	0.08193500mm	212	236	264	279	293	303	322	350			75	g
3	0.09193500mm	272	300	333	350	367	378	400				100	g
4	0.10193500mm	331	362	400	418	437	449					125	g
5	0.11193000mm	436	470	509	529	549						175	g
6	0.12192600mm	570	616	671	698							225	g

Engineered for Zebra Fabrics

Zebra-specific tuning: The 38ZB module is calibrated for the layered double fabric and typical weight distribution of zebra blinds, improving balance and hold at any position within the Cordless Spring System.
Modular lift capacity: By combining 1–5 38ZB spring boxes on a single shaft, OEMs can cover a wide range of blind widths and drops without redesigning the mechanism.
Consistent feel: The constant-force 301 stainless-steel spring delivers nearly uniform lift force, so the blind feels similar at the first pull and at full extension.

Quiet, Cordless Spring System User Experience

No external cords or chains: The R38 38ZB Cordless Spring System supports fully cordless zebra blinds, reducing entanglement risks and eliminating bead-chain rattling.
Low-friction POM housing: The POM shell provides self-lubricating contact surfaces, reducing internal friction and helping to keep the lift motion smooth and quiet.
Brake and damping integration: The R38 brake and controlled spring release help avoid “snap-up” behavior.

OEM-Friendly Platform

Standardized R38 platform: Share the same shaft, brake and circlip logic between 38RB and 38ZB variants; only the spring box type changes between roller and zebra programs in the Cordless Spring System.
Inventory simplification: Two shaft types (2-spring and 5-spring) plus a defined set of 38ZB modules allow you to cover most zebra blind SKUs with fewer mechanism SKUs.
Ready for automation and volume: The sealed module design and clear assembly steps are suitable for high-volume production lines and automated pressing equipment.

Application Scenarios

Premium living rooms and bedrooms: Smooth, quiet Cordless Spring System zebra blinds that match modern interior design.
Nursery and family spaces: No exposed cords; compliant, child-friendly hardware when paired with suitable headrails and components.
Offices and hospitality: Unified R38 platform for large projects that require consistent operation across many windows.
Smart-ready programs: The same R38 mechanical core can be combined with suitable tubular motors in hybrid designs, sharing the load and improving motor life.

Installation & Fabrication Notes for Cordless Spring System Zebra Blind Manufacturers

Step 1 – Confirm tube and blind specs: Use Ø38 mm tubes and calculate total load (fabric + bottom rail) for the target zebra blind size.
Step 2 – Select shaft type: Choose the 2-spring shaft for lighter, smaller blinds or the 5-spring shaft for wider, heavier blinds or denser fabrics.
Step 3 – Decide the number of 38ZB modules: Based on load charts and your key SKUs, configure the shaft with the appropriate number of 38ZB spring boxes to balance the blind without over-pulling.
Step 4 – Assemble the spring pack: Thread the 38ZB modules onto the shaft “in series”, add the R38 brake at the tail, then lock their positions using the specified circlip grooves.
Step 5 – Insert into the tube: Push the assembled spring shaft into the aluminum tube like a plug, mount the corresponding end caps, and integrate into your zebra blind headrail.
Step 6 – Pre-tension and test: Apply the recommended number of pre-tension turns, cycle the blind several times, and fine-tune pre-tension to achieve stable stop at any height.

FAQ

Q1: Can the 38ZB Cordless Spring System be used for roller blinds?
A1: No. The 38ZB spring box in the Cordless Spring System is tuned for zebra (day & night) fabrics. For roller blinds, DOSRON provides the matching 38RB spring box within the same R38 platform.

Q2: How do I decide how many 38ZB spring boxes to use?
A2: Selection is based on zebra fabric weight, bottom rail mass and blind size. The R38 Cordless Spring System offers shafts for up to 2 or 5 spring boxes; your final configuration should follow DOSRON’s load chart and your key SKUs.

Q3: Is the Cordless Spring System child-safe?
A3: The R38 Cordless Spring System eliminates external lift cords and chains at the user interface, helping brands design child-safe cordless zebra blinds. Final compliance still depends on the complete blind design and local regulations.

Q4: Can DOSRON customize the Cordless Spring System for my zebra blind range?
A4: Yes. DOSRON can adjust spring specification, pre-tension range and shaft configuration within the Cordless Spring System to match your target fabric weights, sizes and market requirements for OEM/ODM projects.

Q5: Can I combine the Cordless Spring System with a tubular motor?
A5: The 38ZB Cordless Spring System can be used in hybrid spring + motor architectures, where the spring shares the lifting load with a tubular motor to reduce torque demand and improve motor life.

Q6: What maintenance does the 38ZB Cordless Spring System require?
A6: The 38ZB spring box is a sealed POM module and normally does not require lubrication in use. Routine checks should focus on the overall blind: tube connection, end caps, brackets and correct pre-tension settings.

Field Insight

Separating 38RB for roller blinds and 38ZB for zebra blinds allows OEM brands to keep one R38 Cordless Spring System while still tuning the spring behavior to different fabrics. The shaft with multiple 38ZB spring boxes, a brake at the end and circlips fixing every position gives engineers a clear, modular way to scale from small residential blinds to wider project windows without redesigning the core mechanism. For factories, this means fewer SKUs and faster assembly; for end users, it means a zebra blind that feels consistently smooth, quiet and safely cordless.