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When a standard off-the-shelf spring just won't cut it, engineers, mechanics, and serious DIYers reach for a purpose-matched compression spring. These 300mm length compression springs are designed for applications where a longer travel range and consistent load response are non-negotiable — whether you're building custom machinery, repairing industrial equipment, or prototyping a mechanical assembly.
Each spring is formed from spring steel wire, available in wire diameters of 2.0, 2.5, 3.0, 3.5, 4.0, and 4.5 mm (approximately 0.079–0.177 in), with a fixed body length of 300 mm (11.81 in). Outer diameters vary by wire size and coil count — see variant options for exact OD dimensions. The closed-end coil construction provides stable seating on flat surfaces without additional hardware.
Typical use cases include linear actuator return mechanisms, valve spring replacements in pneumatic systems, suspension damping assemblies in light machinery, and custom jig or fixture clamping setups where a long-travel spring is required.
Formed from carbon spring steel wire for consistent elastic return and resistance to set under repeated compression cycles.
Long 300 mm (11.81 in) body provides extended travel range — ideal for machinery, fixtures, and custom mechanical assemblies.
Available in 2.0, 2.5, 3.0, 3.5, 4.0, and 4.5 mm wire diameters to match varying load and deflection requirements.
Closed and ground ends ensure flat, stable seating on spring plates and guide rods without rocking or misalignment.
Surface treated to provide baseline protection against oxidation during storage and light-duty indoor use.
Uniform coil pitch delivers a linear spring rate across the compression stroke, supporting predictable force calculations in engineering applications.
| Material | Carbon spring steel |
|---|---|
| Wire Diameter | 2.0 / 2.5 / 3.0 / 3.5 / 4.0 / 4.5 mm (0.079–0.177 in) |
| Free Length | 300 mm (11.81 in) |
| Outer Diameter | See variant options |
| Inner Diameter | See variant options |
| End Type | Closed ends (typically ground) |
| Spring Rate | See variant options |
| Surface Finish | Oxidation-resistant treatment |
| Pack Size | 1 pc per unit |
Wire diameter directly affects the spring rate and load capacity. Thinner wire (2.0–2.5 mm) suits lighter loads and lower spring rates, while thicker wire (3.5–4.5 mm) handles heavier loads and stiffer deflection requirements. Calculate your required spring rate and maximum load, then select the wire diameter that falls within that range. If you are unsure, contact us with your load and deflection specs.
The size format shown in the variant selector follows the pattern: Wire Dia × Outer Dia × Free Length (all in mm). For example, "2.0×10×300 mm" means wire diameter 2.0 mm, outer diameter 10 mm, free length 300 mm. Select the variant that matches your bore or guide rod clearance.
These springs are made from carbon spring steel with a surface treatment that provides basic oxidation resistance. They are suitable for indoor and dry environments. For outdoor, high-humidity, or chemically aggressive environments, consider stainless steel springs or apply an additional protective coating after installation.
These 300mm compression springs are well-suited for light machinery, pneumatic valve returns, fixture clamping, and prototype assemblies. For safety-critical automotive suspension applications, always verify the spring rate, load capacity, and fatigue life against your engineering requirements before use.
Measure your guide rod outer diameter — the spring inner diameter should be slightly larger than the rod for a sliding fit (typically 0.5–1.5 mm clearance). Measure your bore inner diameter — the spring outer diameter should be slightly smaller than the bore (typically 0.5–2 mm clearance). Refer to the variant size format to identify the outer diameter before ordering.
The three numbers represent: Wire Diameter × Outer Diameter × Free Length, all in millimeters. So "2.0×10×300 mm" is a spring with 2.0 mm wire, 10 mm outer diameter, and 300 mm free length. Use this format to match the spring to your application's dimensional requirements.
Each unit contains 1 piece (1 pcs) as shown in the Pack Size option. If you need multiple springs, simply adjust the quantity in your cart before checkout.
