DYNEST™

A spring-elastomer composite that responds progressively

DYNEST™ Elastomer-Encapsulated Spring Technology is a spring-elastomer composite developed and licensed by DJLL Holdings LLC of Landenberg, Pennsylvania. A coil spring is cast inside an elastomer part and geometrically confined by it. The confinement holds back the outward bulge that lets an elastomer shed load, so the element delivers a rising, progressive response neither component produces alone.

In steel-polyurethane elements, the measured spring rate is 2.6 to 3.3 times what the rule of mixtures predicts, in an unchanged envelope.

Cast polyurethane is the matrix in production today. The same architecture extends to silicone and other elastomers across the durometer range.

Illustration of a DYNEST element, a coil spring inside a translucent cone-shaped elastomer part, beside a schematic force-displacement chart in which the DYNEST curve rises progressively above the straight line of a conventional elastomer. Same envelope, same bore, a different curve. Illustrative, axes unscaled.

How it works

A compression spring is cast fully inside a solid elastomer, and the two work as a single element. As the element compresses, the gaps between the coils close and the elastomer between them becomes progressively confined. Deep in the stroke the same material behaves like a much firmer one, and resistance climbs beyond what the spring and the elastomer would give added together.

Read "How DYNEST Works" on the Hamboards blog

The DYNEST Blog: spring-elastomer technology articles

Line drawing of a DYNEST element under axial load next to an elastomer part with no spring. With the coil spring present, outward displacement of the elastomer is largely inhibited and occurs only as small lobes between adjacent coils. Without the spring the part bulges uniformly like a barrel.

Measured results for DYNEST steel-polyurethane elements: stiffness 2.6 to 3.3 times the rule-of-mixtures prediction; the steel spring carries 2.6 to 6.0 percent of the load directly; about 3 times change in rate from elastomer hardness alone with the same spring

The three DYNEST design variables. Matrix: elastomer chemistry and hardness set the baseline compliance and the early stroke. Spring: wire and geometry set the rate and where the response stiffens, in compression, tension or torsion. Confinement geometry: how tightly the matrix is held against outward displacement.

Where it stands

In production as spring bushings for skateboard trucks, licensed to Hamboards Holdings LLC
In development for automotive suspension bushings, mounts and isolators, with industrial, medical and aerospace applications open to explore
Cast polyurethane is the matrix in production; silicone and other elastomers fall within the same architecture
More than 100 US contract molders identified as candidate manufacturing partners, across cast polyurethane, liquid silicone injection and press-molded bonded rubber
Force-displacement characterization, including work on an ISO/IEC 17025 NVLAP-accredited instrument
Presented to composites professionals at SAMPE, September 2026
US patents pending: 18/785,017 and 19/794,207
DYNEST™ trademark application filed

In production today

DYNEST elements in four polyurethane grades, Shore 50A to 80A. Same spring, different matrix. The coil shows through the translucent elastomer.

Four DYNEST HST spring-elastomer elements in polyurethane grades from Shore 50A to 80A, with the steel coil spring visible through the translucent elastomer

Questions and answers

What is DYNEST?

DYNEST™ Elastomer-Encapsulated Spring Technology is a spring-elastomer composite. A coil spring is cast inside an elastomer part so that the spring confines the elastomer around it. The result is a higher and more progressive spring rate in the same outside diameter, bore and height.

Which elastomers does it use?

Parts in production today use cast polyurethane from Shore 50A to 80A. The architecture also covers silicone and other elastomers. The measured results published so far are for steel springs in polyurethane.

What do the measurements show?

In steel-polyurethane elements, the measured spring rate is 2.6 to 3.3 times the rule-of-mixtures prediction. The steel spring carries 2.6 to 6.0 percent of the load directly. Changing the elastomer hardness alone, with the same spring, changes the rate about threefold. Each figure is a ratio measured within one test series on one instrument.

What are the three design variables?

Matrix: elastomer chemistry and hardness set the baseline compliance and the early stroke. Spring: wire and geometry set the rate and where the response stiffens, in compression, tension or torsion. Confinement geometry: how tightly the matrix is held against outward displacement, which has no analogue in a conventional part.

Who owns DYNEST?

DJLL Holdings LLC of Landenberg, Pennsylvania owns the technology and the DYNEST trademark. U.S. Application No. 18/785,017 and U.S. Application No. 19/794,207 are pending. Skateboard applications are licensed to Hamboards Holdings LLC.

What is on sale today?

DYNEST spring bushings for skateboard trucks, in HST, longboard and street formats, sold by Hamboards. No production parts exist in other fields yet.

Which fields is DJLL looking to explore?

Automotive suspension bushings, mounts and isolators, industrial equipment, medical devices, aerospace hardware, microelectronics and bicycles.

Who manufactures DYNEST parts?

DJLL writes the specification and qualifies manufacturing partners against it. A 2026 survey of public sources identified more than 100 US contract molders in 33 states as candidates. They work in cast polyurethane, liquid silicone injection and press-molded bonded rubber. DJLL is looking for manufacturing partners as well as new applications.

How do I work with DJLL?

Send a load range, a displacement and an envelope to info@dynest.tech. We will tell you whether a DYNEST element fits and what it would take to prove it.

Page updated

Report abuse