Large Excavator · 1st of 4

Large Excavator Bucket Cylinder

14× the force. 2.5× the stroke. 3.4× the bore. Everything about the large excavator bucket cylinder is a scale-up from the small — except the engineering approach, which is fundamentally different. At this scale, the bucket holds 4–7 m³ of rock, and each curl stroke generates forces that would tear a small excavator cylinder apart.

200–360mmBore

3,561 KNMax Thrust

35 MPaPressure

≤2,500mmStroke

The Scale Jump — From Mini Excavator to Mining Machine

The small excavator bucket cylinder (#1) has a maximum bore of 105 mm and produces 255 KN of curl force — enough to dig residential foundations and utility trenches. The large excavator bucket cylinder starts where the small one ends and scales up to a different world: mining faces, quarry blasts, highway cuts, and dam foundations where the excavator loads 30–50 tonne dump trucks with 4–7 cubic metres per bucket.

Parameter	Small (#1)	Large (#6)	Scale Factor
Max Bore	105 mm	360 mm	3.4×
Max Stroke	1,000 mm	2,500 mm	2.5×
Thrust	255 KN	3,561 KN	14×
Pressure	29.4 MPa	35 MPa	1.2×

The thrust increase (14×) far outpaces the bore increase (3.4×) because force scales with the square of the bore diameter — and the pressure also increases from 29.4 to 35 MPa. Korea Ever-Power manufactures the large excavator bucket cylinder as the first of four large excavator hydraulic cylinders.

Technical Specifications

Parameter	Specification
Product	Large Excavator Bucket Cylinder
Function	Control the action of the bucket (curl / dump)
Bore Diameter	200 mm – 360 mm
Rod Diameter	140 mm – 260 mm
Stroke	≤ 2,500 mm
Max Thrust	3,560.8 KN (bore 420 mm / 35 MPa at largest configuration)
Application	Large Excavator (20–100+ tonne class)
Certification	ISO 9001 · 100% hydrostatic tested

Mining and Quarrying — Where Rock Replaces Soil and Force Replaces Finesse

The small excavator digs soil, clay, and gravel — materials that yield to moderate force. The large excavator digs blasted rock, frozen ground, cemented aggregate, and heavy clay with embedded boulders — materials that resist with peak forces 5–10× higher than soil. The 35 MPa system pressure and 360 mm bore provide the brute force to penetrate these materials.

Blasted rock — irregular, interlocking fragments

After quarry blasting, the rock pile consists of jagged fragments interlocking like a 3D puzzle. The bucket must break these interlocks — the curl force must overcome not just the fragment weight but the shear strength of the interlocking surfaces. Peak pressure spikes during bucket penetration into a blast pile can reach 90–100% of system pressure for 0.5–2 seconds per curl stroke.

Frozen ground — seasonal challenge at northern mines

In Arctic and subarctic mining regions, the top 0.5–3.0 metres of ground freezes solid in winter — with compressive strength approaching that of concrete. The bucket cylinder must curl through this frozen layer before reaching the unfrozen ore below. The cylinder seals must maintain 35 MPa performance at -40 °C ambient temperature — requiring FKM or special low-temperature NBR compounds. Contact Korea Ever-Power for cold-climate large excavator specifications.

Large excavator bucket cylinder working blast pile

Manufacturing Process

Korea Ever-Power large excavator cylinder manufacturing

The bore (200–360 mm) is deep-hole bored and honed to Ra 0.2–0.4 µm. At these diameters, seamless tube may not be available — Korea Ever-Power uses precision deep-hole drilling from solid bar or welded tube with full-penetration welds, followed by stress-relief heat treatment and ultrasonic inspection. Chrome plating is 80 µm (mining/quarry standard). Rod straightness ≤0.1 mm/metre across the 2,500 mm stroke.

The rod eye is forged from a single billet — not welded — because the bucket cylinder's impact loading at the rod end (direct rock strikes through the bucket linkage) demands a joint free of weld-heat-affected zones. Seals are polyurethane + NBR or FKM (for cold-climate versions), rated for 35 MPa. Heavy-duty quad-lip wipers for rock-dust contamination.

Every large excavator bucket cylinder is hydrostatic tested at 1.5× rated pressure (52.5 MPa) and full-stroke tested under simulated digging loads.

OEM & ODM

What You Provide

Excavator model and weight class, bucket size and weight, digging material (rock/soil/frozen ground), required breakout force, bore/rod/stroke, system pressure, temperature range, pin diameters, and the bucket linkage assembly drawing.

What the Factory Delivers

Engineering drawing with bore, rod (forged eye), stroke, deep-hole bored barrel, 80 µm chrome, quad-lip wiper, cold-climate seal option, and mounting dimensions. Hydrostatic + full-stroke test. Seal kits. Browse the mobile machinery hydraulic cylinder family and the Korea Ever-Power catalogue.

Workshop

FAQ

Why does the large excavator need 35 MPa instead of 29.4 MPa?

The materials are harder. Blasted rock, frozen ground, and cemented aggregate require breakout forces that the lower 29.4 MPa pressure cannot achieve at practical bore sizes. Increasing the system pressure from 29.4 to 35 MPa adds 19% more force from the same bore — enough to penetrate these harder materials without requiring an even larger (heavier, bulkier) cylinder.

How does the 2,500 mm stroke compare to the small excavator's 1,000 mm?

The longer stroke accommodates the larger bucket arc — a 7 m³ bucket on a 20-metre stick sweeps through a much larger angular range than a 0.3 m³ bucket on a 3-metre stick. The 2,500 mm stroke allows the bucket to curl through its full 160–180° rotation arc, ensuring complete filling in hard materials that require aggressive curl angles.

Can Korea Ever-Power supply the complete large excavator cylinder set?

Yes — bucket (#6), boom (#7), stick (#8), and tightening (#9) cylinders are available as a matched set for large excavator OEMs. All four share the 35 MPa pressure rating and are manufactured with forged rod eyes, 80 µm chrome, and mining-grade contamination protection. Browse telescopic cylinders and industrial engineering cylinders.