Single Spring Shock Absorbing Caster Heavy Duty Red Iron Core PU 250kg 4 inches CNCEngraverCaster

4" A02 Single Spring Shock Absorbing Caster | Heavy Duty Red Iron Core PU | 250kg

Home / Heavy Duty Casters / A02 Korean Style Series / 4 Inch (100mm)

PRODUCT OVERVIEW

The A02 Series is our Korean-style heavy duty shock absorbing caster built around one clear idea: protect the equipment above while the wheel below rolls over rough floors.

This 4 inch (100 mm) model combines:

• RED CAST IRON CORE PU wheel, polyurethane tread cast directly onto a solid iron hub
• GALVANIZED STEEL BRACKET with a built-in SINGLE COMPRESSION SPRING
• 6203 precision ball bearing for low rolling resistance

The single spring sits pre-loaded between the top plate and the yoke. As the caster rolls over a floor joint, threshold or chip pile, the spring compresses vertically and absorbs the impact BEFORE it reaches the machine frame. The result: less vibration, quieter operation, longer bearing life, and a smoother push for the operator.

The 4 inch size is the lowest-profile model in the A02 family — 174 mm installed height, 250 kg per wheel (approx. 1,000 kg on a 4-wheel set). It is made for compact, standalone equipment that moves short distances inside one workshop bay: small CNC engravers, tool chests, lab trolleys, electronics racks, bench lathes.

Common search terms covered: single spring caster wheels for industrial equipment, Korean style red iron core caster, galvanized bracket shock absorbing caster, 4 inch 250kg PU caster, A02 series caster, CNC engraving machine wheels, Shore A 95-98 PU wheel, spring loaded caster.

TECHNICAL SPECIFICATIONS

Mounting options : Rigid (Fixed) · Swivel · Swivel with Brake · Central Hole
Temperature range: -20 °C to +80 °C (standard PU; short peak +100 °C)
Floor fit: Concrete, painted steel, epoxy, PVC tile — indoor dry use

MATERIAL ADVANTAGES

[1] RED CAST IRON CORE PU WHEEL — Shore A 95-98

• Polyurethane is CAST (poured liquid) onto the iron hub, not glued. The bond is permanent — the tread can never delaminate under load.
• Shore A 95-98 is the upper end of the industrial hardness scale:
  • highly resistant to cutting, chunking and wear from metal chips
  • non-marking on epoxy, painted and PVC floors
  • oil, grease and most solvent resistant
• The RED colour is not just cosmetic — it acts as a visual wear indicator. When the black iron core starts to show through the red tread, you know it is time to replace, before the wheel fails in service.
• Cast iron core = zero radial deformation under load, superior heat dissipation versus aluminium, and a rigid centre that keeps the 6203 bearing perfectly aligned.

[2] GALVANIZED STEEL BRACKET (5.0 mm pressed steel)

• Hot-dip galvanized coating protects the bracket against rust and corrosion far better than painted brackets (paint chips; zinc does not).
• 5.0 mm steel plate for both top plate and yoke = high structural strength, resists bending under off-centre shock loads.
• Clean, bright industrial finish that matches the red wheel visually — looks professional on customer-facing equipment.

[3] SINGLE SPRING SHOCK ABSORPTION (A02 defining feature)

• A single heavy-duty coil spring is pre-loaded inside the bracket, between the top plate and the yoke.
• As the wheel hits a floor joint, threshold, chip pile or uneven slab, the spring compresses VERTICALLY and cushions the impact.
• Vibration is greatly reduced before it reaches:
  • CNC spindles and linear guides
  • laser tubes and optical components
  • electrical control cabinets and VFD drives
  • precision measuring instruments
  • the operator pushing the trolley
• Result: quieter operation, less floor marking, longer bearing life, lower pushing effort, and protection for sensitive equipment above.

⚠ Honest note (builds trust, reduces returns):
The SINGLE SPRING provides VERTICAL shock absorption.
- Need side-thrust / anti-side-shock protection? → Choose our DOUBLE SPRING series.
- High-speed towing or continuous dynamic load? → Contact us to select the correct spring rate (spring stiffness).

[4] 6203 PRECISION BALL BEARING

• 6203 ZZ sealed deep-groove ball bearing, one of the most common and serviceable bearings in industrial casters.
• Low rolling resistance → lower push/pull force → less operator fatigue.
• Standard size → easy, low-cost replacement in the field.

APPLICATION GUIDE — 4 INCH (100 mm) — WHERE AND ON WHAT

The 4" model is the lowest installed height (174 mm) and tightest turning radius in the A02 family. At 250 kg / wheel it is ideal for compact, sub-1-ton equipment that is moved occasionally within a single workshop.

★ MACHINING & METAL FABRICATION

• Benchtop CNC engraving machine (6090, 3040, 4060, 6040)
• Mini CNC milling machine, bench lathe, mini milling/drilling machine
• Toolroom surface grinder stand, pedestal drill press base
• Small parts washing tank trolley, deburring station cart

★ ELECTRONICS & SMT

• SMT magazine cart / feeder cart, PCB turnover trolley
• Electronics assembly rack dolly, component storage bin wagon
• Lab instrument trolley (spectrometer, oscilloscope, precision balance)

★ WORKSHOP & MAINTENANCE

• Industrial sewing machine base (garment / upholstery workshop)
• Mechanics tool chest, roller cabinet, service cart
• Portable workbench, fitter's bench, welding positioner base
• Maintenance & repair trolley (MRO cart)

★ CONTROL & POWER (light)

• Small electrical control cabinet, VFD / PLC panel base
• Battery bank trolley, UPS power cabinet dolly

★ WOODWORKING (small)

• Benchtop sliding table saw stand, thickness planer base
• Woodworking jig / fixture trolley

★ MEDICAL & LAB (indoor dry only)

• Portable X-ray / ultrasound cart, lab analysis instrument trolley

WHY 4 INCH:
Lowest mounted height keeps compact machines stable and ergonomic; smallest swivel radius for tight workshops; 250 kg capacity is more than enough for sub-1-ton equipment. The Shore A 95-98 PU absorbs spindle vibration and protects painted / epoxy floors — a direct fit for CNC engravers, tool chests and SMT carts.

WHY CHOOSE THE 4 INCH A02 (vs 5", 6", 8")

• Lowest installed height (174 mm) → maximum stability for short equipment
• Smallest swivel radius → turns inside narrow workshop aisles
• Lightest caster → lowest added height and weight to the machine
• 250 kg/wheel still covers most compact industrial equipment
  → When floor clearance and tight turning matter more than maximum load, the 4" is the right choice.

KEY FEATURES

1. Single spring shock absorption built into galvanized bracket
2. Red cast iron core PU wheel — Shore A 95-98, non-marking
3. Cast PU permanently bonded to iron core (no delamination)
4. Hot-dip galvanized 5.0 mm steel bracket — rust resistant
5. 6203 precision ball bearing — smooth roll, low push force
6. Rigid / Swivel / Swivel+Brake / Central Hole options
7. Load capacity 250 kg / wheel (≈ 1,000 kg system)
8. Red tread acts as visual wear indicator
9. Oil, grease and solvent resistant tread
10. Quiet operation, floor protective
11. Standard 6203 bearing — easy field replacement
12. OEM/ODM customization available

LONG-TAIL SEO PARAGRAPH

The A02 4 inch single spring shock absorbing caster is designed for compact industrial equipment that needs occasional mobility without sacrificing stability. Built around a red cast iron core polyurethane wheel (Shore A 95-98) and a galvanized steel bracket with integrated coil spring, it is widely used on CNC engraving machines (6090 / 3040 / 4060), bench lathes, mini milling machines, tool chests, roller cabinets, SMT magazine carts, PCB turnover trolleys, electronics racks, lab instrument trolleys, industrial sewing machine bases, portable workbenches, small electrical control cabinets and maintenance trolleys. The iron core carries the load; the high-hardness PU tread cushions spindle and motor vibration while leaving no black mark on epoxy or painted floors; the single spring absorbs impacts from floor joints and thresholds so vibration is not transferred into the machine frame. Working temperature -20 °C to +80 °C covers cold mornings and hot workshops alike.

FREQUENTLY ASKED QUESTIONS

Q1: What machines use the 4 inch 250 kg A02 caster?
A: Small CNC engravers (6090/3040), bench lathes, tool chests, SMT carts, electronics racks, lab trolleys, portable workbenches and sewing machines.

Q2: Is Shore A 95-98 too hard for an epoxy floor?
A: No. 95-98A is the industrial standard for heavy load — hard enough to carry 250 kg without deforming, soft enough to be non-marking on epoxy, painted concrete and PVC tile.

Q3: How does the single spring help on a small CNC engraver?
A: It absorbs bumps from floor joints and chip piles, so vibration does not reach the spindle or linear guides — better surface finish, longer tool life.

Q4: Can the 4 inch replace stainless casters in a washdown area?
A: No. The galvanized bracket is for dry indoor industrial use. For food, washdown, seawater or outdoor use, use our 304 stainless steel series.

Q5: What is the 4-wheel system capacity?
A: Approximately 1,000 kg on a 4-wheel set (250 kg × 4), on flat, level floor with evenly distributed load.

CUSTOM ORDER — WELCOME TO CUSTOMIZE

We are a professional industrial caster manufacturer with MORE THAN 10 YEARS of factory experience. We operate our own production lines and quality control lab, and we welcome OEM / ODM orders for any combination of wheel and bracket.

We can customize:

• Wheel material: PU / TPR / Rubber / Nylon / PP / Phenolic
• Wheel hardness: Shore A 70 – 100 (including softer anti-vibration grades)
• Wheel colour: Red / Orange / Black / Grey / Blue / Custom
• Core material: Cast iron / Aluminium / Nylon
• Bracket / fork finish: Galvanized / Zinc-plated / Powder coated / 304 SS / 316 SS
• Mounting type: Top plate / Threaded stem / Expanding stem / Central bolt hole
• Brake / lock: Total lock / Directional lock / Side lock / No brake
• Bearing: 6202 / 6203 / 6204 / 6303 / stainless sealed
• Load rating: From 100 kg up to 1,000 kg+ per wheel
• Special features: Anti-static (ESD) / High-temp / Food-grade / Conductive / Flame-retardant / Explosion-proof / Dual wheel

Tell us your application, required load, wheel diameter and mounting style — we will engineer the right wheel-and-bracket combination for you.

TAGS

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