{"id":2551,"date":"2026-07-01T06:03:16","date_gmt":"2026-07-01T06:03:16","guid":{"rendered":"https:\/\/hydrauliccylindersprice.com\/product\/large-excavator-boom-cylinder\/"},"modified":"2026-07-01T06:03:21","modified_gmt":"2026-07-01T06:03:21","slug":"large-excavator-boom-cylinder","status":"publish","type":"product","link":"https:\/\/hydrauliccylindersprice.com\/ceb\/product\/large-excavator-boom-cylinder\/","title":{"rendered":"Large Excavator Boom Cylinder"},"content":{"rendered":"

<\/p>\n
\n \"Large<\/p>\n
\n Large Excavator \u00b7 2nd of 4<\/span><\/p>\n

Large Excavator Boom Cylinder<\/h2>\n

The heaviest lifter in the family. Two boom cylinders \u2014 one on each side \u2014 hoist the complete arm assembly: 10\u201330 tonnes of boom, stick, and bucket plus 5\u201315 tonnes of payload in every swing cycle. Combined thrust: nearly 10,000 KN from a twin pair.<\/p>\n

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200\u2013420mm<\/span>Largest Bore<\/span><\/div>\n
4,847 KN<\/span>Per Cylinder<\/span><\/div>\n
\u00d72<\/span>Twin Config<\/span><\/div>\n
\u22643,500mm<\/span>Stroke<\/span><\/div>\n<\/p><\/div>\n<\/p><\/div>\n<\/section>\n
\n

Twin Cylinders \u2014 Why Large Excavators Use Two Boom Cylinders Instead of One<\/span><\/h2>\n

\"Twin<\/p>\n

\n \"Large<\/p>\n

A small excavator (#3) uses a single boom cylinder mounted on top of the boom. A large excavator uses two \u2014 one on each side. The reason goes beyond simply needing more force. A single centre-mounted cylinder on a 30-tonne arm assembly would require a bore exceeding 600 mm to produce the required lift force \u2014 impractical to manufacture, transport, and service. Two 420 mm cylinders produce the same combined force in a much more practical package.<\/p>\n<\/div>\n

The twin configuration also provides structural symmetry. On a single-cylinder machine, the lifting force applies at one point \u2014 creating a torsional moment on the boom root. On a twin-cylinder machine, the force is split equally between both sides \u2014 eliminating the torsion and distributing the stress evenly across the boom’s welded structure. This symmetric loading extends boom structural life and reduces the fatigue risk at the critical boom-to-superstructure pivot joint.<\/p>\n

Korea Ever-Power supplies boom cylinders as matched pairs within the large excavator hydraulic cylinder<\/a> range \u2014 both cylinders manufactured from the same bore batch, tested at the same pressure, and verified for matched force output to ensure symmetric boom lifting.<\/p>\n

<\/div>\n<\/section>\n
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Technical Specifications<\/span><\/h2>\n
\n\n\n\n\n\n\n\n\n\n\n\n\n
Parameter<\/th>\nSpecification<\/th>\n<\/tr>\n<\/thead>\n
Product<\/td>\nLarge Excavator Boom Cylinder<\/td>\n<\/tr>\n
Function<\/td>\nControl the lifting motion of the big arm (boom)<\/td>\n<\/tr>\n
Bore Diameter<\/td>\n200 mm \u2013 420 mm<\/td>\n<\/tr>\n
Rod Diameter<\/td>\n140 mm \u2013 300 mm<\/td>\n<\/tr>\n
Stroke<\/td>\n\u2264 3,500 mm<\/td>\n<\/tr>\n
Max Thrust<\/td>\n4,846.6 KN per cylinder (bore 420 mm \/ 35 MPa)<\/td>\n<\/tr>\n
Configuration<\/td>\nTwin-cylinder (matched pair, one per side)<\/td>\n<\/tr>\n
Certification<\/td>\nISO 9001 \u00b7 100% hydrostatic tested \u00b7 drift tested \u00b7 matched pair<\/td>\n<\/tr>\n<\/tbody>\n<\/table><\/div>\n<\/section>\n
\n
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4,847 KN \u2014 The Physics of Holding 45 Tonnes at Full Reach<\/h2>\n

On a 100-tonne excavator with a 12-metre boom and a full 7 m\u00b3 bucket, the arm assembly (boom + stick + bucket + payload) totals approximately 30\u201345 tonnes \u2014 hanging at the end of a 12-metre lever arm. The gravitational moment at the boom pivot can reach 3,000\u20135,000 KNm. Each boom cylinder must produce enough force, multiplied by its lever arm (typically 1.5\u20133.0 metres), to counteract half this moment.<\/p>\n

\n
\n Lift at worst angle \u2014 horizontal boom = maximum load<\/strong><\/p>\n

When the boom is horizontal, the gravitational moment is maximum (full weight \u00d7 full lever arm). This is the design condition that sets the 420 mm bore and 35 MPa pressure. As the boom rises toward vertical, the moment arm shortens and the required cylinder force decreases \u2014 the same cylinder that strains at horizontal cruises comfortably at 60\u00b0 elevation.<\/p>\n<\/p><\/div>\n

\n Controlled lowering \u2014 regenerative energy management<\/strong><\/p>\n

When the boom lowers, gravity does the work \u2014 the cylinders retract under the arm’s weight. Modern large excavators use boom-down energy regeneration: the oil displaced from the boom cylinders is redirected to assist the boom-up stroke of the next digging cycle, saving 5\u201315% of the machine’s fuel consumption. The boom cylinder’s port sizing is optimised for this regenerative flow. Contact Korea Ever-Power engineering<\/a> for boom cylinder specifications.<\/p>\n<\/p><\/div>\n<\/p><\/div>\n<\/p><\/div>\n<\/section>\n

\n \"Large
\n<\/section>\n
\n

Manufacturing Process<\/span><\/h2>\n

The 420 mm bore \u2014 the largest single-bore excavator cylinder Korea Ever-Power produces \u2014 is deep-hole bored and honed to Ra 0.2\u20130.4 \u00b5m. The barrel wall thickness exceeds 50 mm to contain the 35 MPa working pressure with the required safety factor. Chrome plating 80 \u00b5m. Rod straightness \u22640.1 mm\/metre over 3,500 mm. Rod eyes forged from single billets \u2014 not welded \u2014 because the twin-cylinder boom pivot joint carries the full arm weight under continuous cyclic loading.<\/p>\n

Every boom cylinder pair is hydrostatic tested at 52.5 MPa (1.5\u00d7), drift-tested (both cylinders loaded identically, position monitored for 10 minutes), and force-matched \u2014 verifying that the two cylinders produce equal thrust at the same input pressure, ensuring symmetric boom lifting. Seal kits are supplied per pair.<\/p>\n<\/section>\n

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OEM & ODM<\/span><\/h2>\n
\n
\n
What You Provide<\/strong><\/div>\n
\n

Excavator model and weight class, boom length and weight, combined arm assembly weight (with rated payload), required lift force per cylinder, bore\/rod\/stroke, system pressure, regenerative flow requirement, drift limit, pin diameters, and the boom pivot assembly drawing.<\/p>\n<\/div>\n<\/div>\n

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What the Factory Delivers<\/strong><\/div>\n
\n

Matched pair with engineering drawing, 420 mm bore, forged rod eyes, 80 \u00b5m chrome, force-matching certificate, drift test certificate, and mounting dimensions. Hydrostatic + drift + pair-matching test. Seal kits. Browse the mobile machinery hydraulic cylinder family<\/a> and the Korea Ever-Power catalogue<\/a>.<\/p>\n<\/div>\n<\/div><\/div>\n

\"Workshop\"
\n<\/section>\n

\n

FAQ<\/span><\/h2>\n
\n
\n

Why twin cylinders instead of one larger single?<\/h3>\n

A single cylinder producing 9,700 KN would need a bore exceeding 600 mm \u2014 impractical to manufacture and too heavy to service in the field. Two 420 mm cylinders produce the same total force, weigh less per unit, and can be replaced individually if one is damaged. The twin arrangement also eliminates the torsional loading that a single centre-mounted cylinder would impose on the boom structure.<\/p>\n<\/div>\n

\n

What is boom-down energy regeneration?<\/h3>\n

When the boom lowers, the arm’s gravitational potential energy is converted into hydraulic energy (pressurised oil flowing out of the boom cylinders). Instead of dumping this oil through a valve to tank (wasting the energy as heat), regenerative systems redirect the oil to assist the next boom-up stroke \u2014 effectively recycling the potential energy. This reduces fuel consumption by 5\u201315% on continuous-digging operations.<\/p>\n<\/div>\n

\n

How does the boom cylinder compare across the small and large families?<\/h3>\n

Small excavator boom (#3): 125 mm bore, 361 KN, single cylinder. Large excavator boom (#7): 420 mm bore, 4,847 KN per cylinder \u00d7 2 = 9,694 KN total. That is a 27\u00d7 force increase \u2014 reflecting the 10\u201320\u00d7 increase in machine weight and the exponential increase in arm assembly weight with boom length. Browse telescopic cylinders<\/a> and forklift cylinders<\/a>.<\/p>\n<\/div>\n<\/div>\n<\/section>\n

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Related Categories<\/span><\/h2>\n
<\/p>\n
\n
\"Telescopic\"<\/div>\n
\n
Telescopic Hydraulic Cylinders \u2192<\/div>\n
Dump truck, trailer, hoist.<\/div>\n<\/div>\n<\/div>\n

<\/a><\/p>\n

\n
\"Forklift\"<\/div>\n
\n
Forklift Hydraulic Cylinders \u2192<\/div>\n
Lift, tilt, steer \u2014 OEM.<\/div>\n<\/div>\n<\/div>\n

<\/a><\/p>\n

\n
\"AWV\"<\/div>\n
\n
Aerial Work Vehicle Cylinders \u2192<\/div>\n
Scissor, boom, platforms.<\/div>\n<\/div>\n<\/div>\n

<\/a><\/div>\n<\/section>\n

<\/main><\/p>","protected":false},"excerpt":{"rendered":"

Large excavator boom cylinder \u2014 the highest-force cylinder in the large excavator family, lifting the entire arm assembly (boom + stick + bucket + payload) on 20\u2013100+ tonne excavators. Bore up to 420 mm, thrust 4,846.6 KN, stroke \u22643,500 mm at 35 MPa. Unlike the small excavator which uses a single boom cylinder, large excavators use a twin-cylinder configuration \u2014 two boom cylinders mounted on either side of the boom, sharing the gravitational load and providing redundancy. Korea Ever-Power. ISO 9001. OEM & ODM.<\/div>","protected":false},"featured_media":2552,"comment_status":"closed","ping_status":"open","template":"","meta":{"_et_pb_use_builder":"","_et_pb_old_content":"","_et_gb_content_width":""},"product_brand":[],"product_cat":[854],"product_tag":[],"class_list":["post-2551","product","type-product","status-publish","has-post-thumbnail","product_cat-mobile-machinery-hydraulic-cylinders","pa_editor-cxm","first","instock","product-type-simple"],"_links":{"self":[{"href":"https:\/\/hydrauliccylindersprice.com\/ceb\/wp-json\/wp\/v2\/product\/2551","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/hydrauliccylindersprice.com\/ceb\/wp-json\/wp\/v2\/product"}],"about":[{"href":"https:\/\/hydrauliccylindersprice.com\/ceb\/wp-json\/wp\/v2\/types\/product"}],"replies":[{"embeddable":true,"href":"https:\/\/hydrauliccylindersprice.com\/ceb\/wp-json\/wp\/v2\/comments?post=2551"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/hydrauliccylindersprice.com\/ceb\/wp-json\/wp\/v2\/media\/2552"}],"wp:attachment":[{"href":"https:\/\/hydrauliccylindersprice.com\/ceb\/wp-json\/wp\/v2\/media?parent=2551"}],"wp:term":[{"taxonomy":"product_brand","embeddable":true,"href":"https:\/\/hydrauliccylindersprice.com\/ceb\/wp-json\/wp\/v2\/product_brand?post=2551"},{"taxonomy":"product_cat","embeddable":true,"href":"https:\/\/hydrauliccylindersprice.com\/ceb\/wp-json\/wp\/v2\/product_cat?post=2551"},{"taxonomy":"product_tag","embeddable":true,"href":"https:\/\/hydrauliccylindersprice.com\/ceb\/wp-json\/wp\/v2\/product_tag?post=2551"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}