{"id":2573,"date":"2026-07-01T06:03:16","date_gmt":"2026-07-01T06:03:16","guid":{"rendered":"https:\/\/hydrauliccylindersprice.com\/product\/mobile-crane-telescopic-cylinder\/"},"modified":"2026-07-01T06:03:29","modified_gmt":"2026-07-01T06:03:29","slug":"mobile-crane-telescopic-cylinder","status":"publish","type":"product","link":"https:\/\/hydrauliccylindersprice.com\/es\/product\/mobile-crane-telescopic-cylinder\/","title":{"rendered":"Mobile Crane Telescopic Cylinder"},"content":{"rendered":"

<\/p>\n

<\/p>\n

\n \"Mobile<\/p>\n
\n Mobile Crane Cylinder<\/span><\/p>\n

Mobile Crane Telescopic Cylinder<\/h2>\n

22 metres of stroke. Hidden inside the boom. The multi-stage telescopic cylinder extends the boom sections one by one \u2014 transforming a 12-metre travel-length boom into a 60-metre working reach. The longest stroke and the highest pressure in the entire mobile crane cylinder family.<\/p>\n

\n
22,000mm<\/span>Max Stroke<\/span><\/div>\n
42 MPa<\/span>Highest Pressure<\/span><\/div>\n
75\u2013360mm<\/span>Bore Range<\/span><\/div>\n<\/p><\/div>\n<\/p><\/div>\n<\/section>\n

<\/p>\n

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How a 12-Metre Boom Becomes a 60-Metre Reach<\/span><\/h2>\n
\n \"Mobile<\/p>\n

A mobile crane must travel on public roads \u2014 where legal width is 2.5\u20133.0 metres and legal length is 12\u201316 metres depending on the country. The boom must fit within these transport dimensions. But once on site, the same crane must reach 40, 50, or 60 metres to place steel beams on the tenth floor of a building under construction. The telescopic cylinder solves this contradiction.<\/p>\n<\/div>\n

Inside the boom, 3\u20136 nested tube sections slide inside each other \u2014 like a radio antenna. The telescopic cylinder pushes these sections outward, one at a time or simultaneously, extending the boom from its transport length to its full working length. The cylinder itself is also telescopic \u2014 its nested stages match the boom sections, with each stage pushing the corresponding boom section outward. A 5-section boom with 4 telescopic stages produces up to 22 metres of total cylinder stroke.<\/p>\n

Korea Ever-Power manufactures the telescopic cylinder as the longest-stroke component in the mobile machinery hydraulic cylinder<\/a> range.<\/p>\n<\/section>\n

<\/p>\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>\nMobile Crane Telescopic Cylinder<\/td>\n<\/tr>\n
Function<\/td>\nLinear telescopic extension of the boom sections<\/td>\n<\/tr>\n
Bore Diameter<\/td>\n75 mm \u2013 360 mm<\/td>\n<\/tr>\n
Rod Diameter<\/td>\n50 mm \u2013 320 mm<\/td>\n<\/tr>\n
Stroke<\/td>\n\u2264 22,000 mm (multi-stage)<\/td>\n<\/tr>\n
Working Pressure<\/td>\nMaximum 42 MPa (highest in family)<\/td>\n<\/tr>\n
Application<\/td>\nMobile Crane (truck, all-terrain, rough-terrain, crawler)<\/td>\n<\/tr>\n
Certification<\/td>\nISO 9001 \u00b7 100% hydrostatic tested<\/td>\n<\/tr>\n<\/tbody>\n<\/table><\/div>\n<\/section>\n

<\/p>\n

\n \"Mobile
\n<\/section>\n

<\/p>\n

\n
\n

Multi-Stage Construction \u2014 Nested Tubes That Multiply Stroke<\/h2>\n

A single-stage hydraulic cylinder produces stroke equal to its barrel length. A 5-metre cylinder produces 5 metres of stroke. To produce 22 metres of stroke from a single-stage design, the cylinder would need to be 22 metres long \u2014 far too long to fit inside any boom. The multi-stage telescopic cylinder solves this by nesting multiple stages inside each other:<\/p>\n

\n
\n
1<\/div>\n
Outermost stage (largest bore)<\/strong><\/p>\n

The first stage has the largest bore diameter (up to 360 mm) and the thickest walls. It is fixed to the boom base section. When pressurised, it pushes the second stage outward \u2014 which in turn pushes the first movable boom section. This stage produces the highest force (largest piston area \u00d7 system pressure) and extends first under load.<\/p>\n<\/div><\/div>\n

\n
2<\/div>\n
Intermediate stages<\/strong><\/p>\n

Each subsequent stage nests inside the previous one \u2014 smaller bore, thinner walls, lighter weight. Each stage pushes the next boom section. The bore decreases from the base to the tip \u2014 which means the available force decreases at each stage. This is acceptable because each successive boom section is lighter (shorter, thinner-walled) and carries less load (the outer sections only support themselves plus the hook load, not the entire boom).<\/p>\n<\/div><\/div>\n

\n
3<\/div>\n
Innermost stage (smallest bore)<\/strong><\/p>\n

The final stage extends the boom tip section \u2014 the lightest section, carrying only the hook and the load. Its smaller bore produces less force, but less force is needed. When fully extended, all stages are deployed end-to-end, and the total stroke is the sum of all individual stage strokes. Contact the Korea Ever-Power engineering team<\/a> for multi-stage telescopic cylinder design.<\/p>\n<\/div><\/div>\n<\/p><\/div>\n<\/p><\/div>\n<\/section>\n

<\/p>\n

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42 MPa \u2014 Why the Telescopic Cylinder Needs More Pressure Than Any Other Crane Cylinder<\/span><\/h2>\n
\n \"Multi-stage<\/p>\n

The luffing cylinder (#17) operates at 36 MPa. The telescopic cylinder operates at 42 MPa \u2014 17% higher. The reason is friction. When the telescopic cylinder extends the boom, each nested boom section slides against the section inside it. The sliding friction between boom sections \u2014 steel on polymer wear pads, across contact areas of several square metres \u2014 produces a resistance force that the cylinder must overcome in addition to the gravitational load.<\/p>\n<\/div>\n

On a 5-section boom, the telescopic cylinder must overcome the friction of 4 sliding interfaces simultaneously. Each interface adds 5\u201315% to the required extension force. The cumulative friction of all 4 interfaces can add 20\u201350% to the gravitational load \u2014 which is why the telescopic cylinder needs higher system pressure than the luffing cylinder despite often having a similar or smaller bore diameter.<\/p>\n

The 42 MPa rating also provides a force margin for extending the boom while the crane is lifting \u2014 a “telescoping under load” operation that some crane configurations require. Telescoping under load is the most demanding operating condition for the telescopic cylinder, and the 42 MPa pressure ensures adequate force even at the innermost (smallest-bore) stage.<\/p>\n<\/section>\n

<\/p>\n

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Boom Section Sequencing \u2014 Which Section Extends First, and Why It Matters<\/span><\/h2>\n

The boom sections do not all extend simultaneously. The extension sequence \u2014 which section moves first, second, third \u2014 is controlled by the cylinder’s internal sequencing mechanism and affects the crane’s stability, load capacity, and boom deflection:<\/p>\n

\n
\n Sequential extension (section-by-section)<\/strong><\/p>\n

The outermost section extends fully before the next section begins. This produces the stiffest boom geometry at each intermediate length \u2014 because each extended section is fully supported by the section behind it before the next section begins moving. Most crane manufacturers specify sequential extension for maximum structural rigidity.<\/p>\n<\/p><\/div>\n

\n Synchronous extension (all sections together)<\/strong><\/p>\n

All sections extend simultaneously at proportional speeds. This is faster (the boom reaches full length in less time) but produces a less rigid intermediate geometry. Some cranes use synchronous extension for the initial deployment and switch to sequential control for fine-length adjustment under load.<\/p>\n<\/p><\/div>\n<\/p><\/div>\n

The sequencing mechanism \u2014 typically a system of internal pins, cams, or sequencing valves \u2014 is integrated into the telescopic cylinder and the boom sections. Korea Ever-Power designs the cylinder staging and port arrangement to match the crane manufacturer’s specified sequencing logic.<\/p>\n<\/section>\n

<\/p>\n

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Actuator and Structure \u2014 The Cylinder That Becomes Part of the Boom<\/span><\/h2>\n
\n \"Telescopic<\/p>\n

Most hydraulic cylinders are pure actuators \u2014 they produce force and motion, but the structure they are attached to carries the load. The telescopic cylinder is different. When fully extended inside the boom, its nested stages form a continuous column from the boom base to the boom tip. This column carries a portion of the boom’s bending load \u2014 the cylinder is simultaneously an actuator (providing the extension force) and a structural member (supporting the boom).<\/p>\n<\/div>\n

This dual role imposes structural requirements that no other cylinder in the mobile machinery hydraulic cylinder family<\/a> shares: the cylinder stages must be stiff enough to resist lateral deflection under the boom’s bending loads, the stage overlap joints must transmit shear forces without excessive play, and the entire column must remain straight under combined axial compression and lateral bending.<\/p>\n

Korea Ever-Power verifies the structural performance of every telescopic cylinder design using FEA \u2014 modelling the combined axial, bending, and pressure loads at the most severe boom angle and load configuration in the crane’s load chart.<\/p>\n<\/section>\n

<\/p>\n

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

\"Korea<\/p>\n

Each stage of the telescopic cylinder is manufactured as a precision tube \u2014 bore honed to Ra 0.2\u20130.4 \u00b5m, outer diameter chrome-plated (each inner stage slides inside the next outer stage, so the outer surface of each stage is a bearing surface). The concentricity between bore and outer diameter of each stage is held to \u22640.1 mm TIR \u2014 any eccentricity creates uneven wear on the guide rings and seals, leading to premature leakage.<\/p>\n

Stage overlap length (the distance each stage remains inside the next when fully extended) is a critical design parameter \u2014 longer overlap = more structural support but less usable stroke. Korea Ever-Power optimises the overlap for each crane application, balancing maximum stroke against structural stiffness. Seals between stages use combined pressure seal + wiper + guide ring sets rated for 42 MPa and -30 \u00b0C to +80 \u00b0C outdoor service. Every telescopic cylinder is hydrostatic tested at 1.5\u00d7 rated pressure (63 MPa) at each stage individually, then functionally tested for full sequential and simultaneous extension and retraction.<\/p>\n<\/section>\n

<\/p>\n

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

Crane model, boom section geometry (number of sections, section lengths, section inner\/outer diameters), required total stroke, extension sequencing logic (sequential\/synchronous\/hybrid), system pressure, extension speed, retraction speed, telescoping-under-load requirement (if applicable), and the boom cross-section drawing showing the cylinder envelope (the available space inside the boom for the cylinder).<\/p>\n<\/div><\/div>\n

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

Engineering drawing with stage diameters, stage strokes, stage overlap, sequencing port arrangement, seal specification per stage, chrome plating (bore and OD), structural analysis summary (FEA on request), and mounting dimensions. Hydrostatic test per stage + full-assembly functional test. Seal kits. Browse the industrial engineering cylinders<\/a> and the complete Korea Ever-Power hydraulic cylinder catalogue<\/a>.<\/p>\n<\/div><\/div>\n<\/p><\/div>\n

\"Korea
\n<\/section>\n

<\/p>\n

\n

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

How does the telescopic cylinder differ from the luffing cylinder?<\/h3>\n

The luffing cylinder<\/a> changes the boom angle (up\/down rotation) \u2014 it is a single-stage cylinder mounted externally between the superstructure and the boom base. The telescopic cylinder changes the boom length (extension\/retraction) \u2014 it is a multi-stage cylinder mounted internally inside the boom. The luffing cylinder has the largest bore (560 mm); the telescopic cylinder has the longest stroke (22,000 mm) and the highest pressure (42 MPa).<\/p>\n<\/p><\/div>\n

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Can the crane telescope the boom while lifting a load?<\/h3>\n

Some cranes permit telescoping under load at reduced capacity \u2014 the load chart specifies a lower maximum load for telescoping operations. The telescopic cylinder must produce enough force to extend the boom section against both the boom weight and the suspended load’s gravitational moment. This is the most demanding condition for the telescopic cylinder and drives the 42 MPa pressure rating. Not all crane models allow telescoping under load \u2014 some restrict telescoping to the unloaded (boom-only) condition.<\/p>\n<\/p><\/div>\n

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What sealing challenges are unique to multi-stage telescopic cylinders?<\/h3>\n

Each stage-to-stage interface requires a complete seal set (pressure seal + guide ring + wiper) that must withstand 42 MPa while allowing smooth sliding at speeds up to 10 m\/min. The number of seal interfaces multiplies with the number of stages \u2014 a 4-stage cylinder has 4 sets of seals in series, and any single seal failure causes the entire cylinder to leak. Korea Ever-Power uses progressive seal stacks with pressure-staging grooves to distribute the 42 MPa pressure across multiple seal lips \u2014 reducing the stress on any single seal. Browse telescopic cylinders<\/a> and forklift cylinders<\/a> for other multi-stage applications.<\/p>\n<\/p><\/div>\n<\/p><\/div>\n<\/section>\n

<\/p>\n

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Related Categories<\/span><\/h2>\n
\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>
\n <\/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>
\n <\/p>\n

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

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

<\/p>\n

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

Mobile crane telescopic cylinder \u2014 the multi-stage hydraulic cylinder hidden inside the boom that extends the boom sections to their full working length. Stroke up to 22,000 mm (22 metres) \u2014 achieved through multiple nested stages sliding inside each other. Working pressure 42 MPa \u2014 the highest in the mobile crane cylinder family \u2014 because extending the boom under load requires overcoming both the boom weight and the friction of each nested section. The telescopic cylinder is both the actuator that extends the boom and a structural column that supports it when extended. Bore 75\u2013360 mm. Korea Ever-Power. ISO 9001. OEM & ODM.<\/div>","protected":false},"featured_media":2574,"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-2573","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\/es\/wp-json\/wp\/v2\/product\/2573","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/hydrauliccylindersprice.com\/es\/wp-json\/wp\/v2\/product"}],"about":[{"href":"https:\/\/hydrauliccylindersprice.com\/es\/wp-json\/wp\/v2\/types\/product"}],"replies":[{"embeddable":true,"href":"https:\/\/hydrauliccylindersprice.com\/es\/wp-json\/wp\/v2\/comments?post=2573"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/hydrauliccylindersprice.com\/es\/wp-json\/wp\/v2\/media\/2574"}],"wp:attachment":[{"href":"https:\/\/hydrauliccylindersprice.com\/es\/wp-json\/wp\/v2\/media?parent=2573"}],"wp:term":[{"taxonomy":"product_brand","embeddable":true,"href":"https:\/\/hydrauliccylindersprice.com\/es\/wp-json\/wp\/v2\/product_brand?post=2573"},{"taxonomy":"product_cat","embeddable":true,"href":"https:\/\/hydrauliccylindersprice.com\/es\/wp-json\/wp\/v2\/product_cat?post=2573"},{"taxonomy":"product_tag","embeddable":true,"href":"https:\/\/hydrauliccylindersprice.com\/es\/wp-json\/wp\/v2\/product_tag?post=2573"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}