{"id":2257,"date":"2026-06-25T08:33:01","date_gmt":"2026-06-25T08:33:01","guid":{"rendered":"https:\/\/hydrauliccylindersprice.com\/?post_type=product&p=2257"},"modified":"2026-06-25T08:33:01","modified_gmt":"2026-06-25T08:33:01","slug":"boom-aerial-work-vehicle-upper-arm-hydraulic-cylinder","status":"publish","type":"product","link":"https:\/\/hydrauliccylindersprice.com\/et\/toode\/boom-aerial-work-vehicle-upper-arm-hydraulic-cylinder\/","title":{"rendered":"Boom Aerial Work Vehicle Upper Arm Hydraulic Cylinder"},"content":{"rendered":"
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<\/div>\n
Articulating Boom \u00b7 Jib Section \u00b7 Knuckle Joint \u00b7 Up-and-Over Reach<\/div>\n

Boom Aerial Work Vehicle
\nUpper Arm Hydraulic Cylinder<\/h2>\n

The lower arm cylinder lifts the entire boom. The upper arm cylinder does something the lower arm cannot \u2014 it bends the boom at the knuckle, folding the jib section upward, downward, or horizontally to reach work areas that are above, below, or behind obstacles. This up-and-over capability is the defining advantage of an articulating boom lift over a straight telescopic boom, and the upper arm hydraulic cylinder is the actuator that makes it possible. At \u03a6110 bore \u2014 the largest in the entire aerial work vehicle cylinder range \u2014 the GTHZ210C-620500-000 produces both the extension force to push the jib upward and the retraction force to pull it actively downward, giving the operator precise, bidirectional control of the jib angle at any boom elevation.<\/p>\n

\n
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\u03a6110<\/div>\n
Bore \u2014 Largest<\/div>\n<\/div>\n
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\u03a675<\/div>\n
Rod (mm)<\/div>\n<\/div>\n
\n
815<\/div>\n
Stroke (mm)<\/div>\n<\/div>\n
\n
23 MPa<\/div>\n
Highest in Range<\/div>\n<\/div>\n
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100 kg<\/div>\n
Weight<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/section>\n

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Technical Specification \u2014 GTHZ210C Upper Arm Cylinder<\/h2>\n
\n\n\n\n\n\n
Cylinder Name<\/th>\nDrawing Number<\/th>\nBore (D)<\/th>\nRod (d)<\/th>\nStroke (S)<\/th>\nInstall Dist (L)<\/th>\nPressure<\/th>\nPorts (M)<\/th>\nWeight<\/th>\n<\/tr>\n<\/thead>\n
Upper arm cylinder<\/td>\nGTHZ210C-620500-000<\/td>\n\u03a6110<\/td>\n\u03a675<\/td>\n815<\/td>\n1433<\/td>\n23 MPa<\/td>\n2-\u03a69<\/td>\n100 kg<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n
\n\n\n\n\n\n\n\n\n\n\n
Function<\/td>\nJib articulation \u2014 up-and-over positioning at the knuckle joint<\/td>\n<\/tr>\n
Acting Type<\/td>\nDouble-acting (raise jib & lower jib under full hydraulic control)<\/td>\n<\/tr>\n
Rod-to-Bore Ratio<\/td>\n0.68 \u2014 optimised for balanced extend\/retract force<\/td>\n<\/tr>\n
Port Style<\/td>\n2-\u03a69 banjo fitting ports (high-flow)<\/td>\n<\/tr>\n
Body Material<\/td>\n20# \/ 45# \/ Q345B steel<\/td>\n<\/tr>\n
Seal Options<\/td>\nParker, NOK, Hallite, Busak Shamban<\/td>\n<\/tr>\n
Certification<\/td>\nISO 9001:2015, ISO 14001, ISO 45003<\/td>\n<\/tr>\n
MOQ \/ Warranty<\/td>\n1 piece \/ 1 year<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/section>\n

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What the Upper Arm Cylinder Does \u2014 Jib Articulation at the Knuckle Joint<\/h2>\n

An articulating boom lift has two main boom sections connected by a knuckle joint \u2014 a large pin-connected hinge that allows the upper section (jib) to pivot independently of the lower section. The upper arm cylinder spans this knuckle, extending to push the jib upward and retracting to pull it downward. This articulation gives the boom lift its defining capability: up-and-over reach. The platform can go up to clear a building parapet, over the parapet wall, and then back down to work on the building facade \u2014 a manoeuvre that a straight telescopic boom cannot perform.<\/p>\n

\"Boom<\/p>\n

The upper arm cylinder cycles more frequently than the lower arm cylinder because jib articulation is the primary positioning tool \u2014 operators constantly adjust the jib angle to reach different work points on a structure, while the main boom elevation stays relatively constant. On a typical work shift involving facade inspection or electrical installation, the upper arm cylinder may cycle 50\u2013100 times compared to 5\u201310 cycles for the lower arm. This higher cycle frequency drives faster seal wear and makes the upper arm cylinder a more frequent replacement item than the lower arm on the same machine.<\/p>\n<\/section>\n

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Why \u03a6110 \u2014 A Larger Bore Than the Lower Arm, Despite Carrying Less Weight<\/h2>\n

The upper arm cylinder has a \u03a6110 bore \u2014 10% larger than the lower arm’s \u03a6100. This seems counterintuitive: the upper arm carries less mass (only the jib, platform, and personnel \u2014 not the entire boom), so why does it need a larger bore? The answer lies in the retract direction.<\/p>\n

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Extend: Pushing the Jib Up<\/h3>\n

When the upper arm cylinder extends, it pushes the jib upward against gravity. The full piston area (\u03a6110 = 9,503 mm\u00b2) is available for this push. At 23 MPa, the extend force is approximately 219 kN \u2014 more than sufficient to raise the jib, platform, and rated personnel load through the full articulation arc.<\/p>\n

Full bore area \u00b7 219 kN \u00b7 Against gravity<\/div>\n<\/div>\n
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Retract: Pulling the Jib Down<\/h3>\n

When the upper arm cylinder retracts, it pulls the jib downward \u2014 with gravity assisting, but against the inertia and wind resistance of the jib section. The retract force comes from the annular area (bore area minus rod area). With the \u03a675 rod, the annular area is 5,085 mm\u00b2, producing a retract force of approximately 117 kN at 23 MPa. If the rod were \u03a680 (like the lower arm), the annular area would drop to 4,476 mm\u00b2 \u2014 a 12% reduction in retract force that would slow jib descent and reduce the operator’s downward positioning control.<\/p>\n

Annular area \u00b7 117 kN \u00b7 With gravity + against inertia<\/div>\n<\/div>\n<\/div>\n
The design trade-off: <\/strong>
\nThe lower arm cylinder prioritises buckling resistance (\u03a680 rod, ratio 0.80) because it operates at low angles with long rod extension. The upper arm cylinder prioritises balanced extend\/retract force (\u03a675 rod, ratio 0.68) because the operator needs strong bidirectional control at the knuckle. Different engineering priorities \u2192 different bore\/rod combinations, even though both cylinders serve the same machine.<\/span><\/div>\n<\/section>\n

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Upper Arm vs Lower Arm \u2014 Engineering Comparison<\/h2>\n
\n\n\n\n\n\n\n\n\n\n\n\n\n
Parameter<\/th>\nUpper Arm (this product)<\/th>\nLower Arm<\/th>\n<\/tr>\n<\/thead>\n
Bore<\/td>\n\u03a6110 (larger)<\/td>\n\u03a6100<\/td>\n<\/tr>\n
Rod<\/td>\n\u03a675<\/td>\n\u03a680 (thicker)<\/td>\n<\/tr>\n
Rod-to-bore ratio<\/td>\n0.68 (force-balanced)<\/td>\n0.80 (anti-buckling)<\/td>\n<\/tr>\n
Stroke<\/td>\n815 mm<\/td>\n1,458 mm (longer)<\/td>\n<\/tr>\n
Pressure<\/td>\n23 MPa (higher)<\/td>\n21 MPa<\/td>\n<\/tr>\n
Weight<\/td>\n100 kg<\/td>\n137 kg (heavier)<\/td>\n<\/tr>\n
Cycle frequency<\/td>\nHigh (50\u2013100\/shift)<\/td>\nLow (5\u201310\/shift)<\/td>\n<\/tr>\n
Design priority<\/td>\nBalanced bidirectional force<\/td>\nExtreme buckling resistance<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n

\"Double-acting<\/p>\n<\/section>\n

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Up-and-Over Reach \u2014 The Capability That Only the Upper Arm Cylinder Provides<\/h2>\n

A telescopic boom lift can reach high and far \u2014 but only in a straight line from the machine’s base. It cannot reach over a wall, behind a structure, or into a recessed area below the boom elevation. The upper arm cylinder<\/a> on an articulating boom lift unlocks these work positions by folding the jib section independently of the main boom angle.<\/p>\n

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Over a parapet wall<\/strong><\/p>\n

The lower arm raises the boom above the wall height. The upper arm cylinder then extends to angle the jib downward over the wall, positioning the platform on the building side. This is the most common up-and-over manoeuvre \u2014 used for rooftop HVAC maintenance, window installation on set-back floors, and building facade work above overhanging structures.<\/p>\n<\/div>\n

Under a soffit or overhang<\/strong><\/p>\n

The lower arm raises the boom to the underside of the overhang. The upper arm cylinder retracts to fold the jib horizontally, sliding the platform underneath the structure. This is used for bridge inspection, canopy maintenance, and industrial pipeline access where the work area is below and behind the structural element.<\/p>\n<\/div>\n

Into a confined vertical space<\/strong><\/p>\n

The lower arm extends horizontally to position the knuckle above the target area. The upper arm cylinder then extends to lower the jib vertically downward into the space \u2014 like lowering a platform into a pit, a shaft, or an atrium from above. The 815 mm stroke allows the jib to articulate through approximately 135\u00b0 of total travel at the knuckle \u2014 from fully elevated to near-vertical descent.<\/p>\n<\/div>\n<\/div>\n<\/section>\n

\"hydraulic-cylinder-1-4\"<\/p>\n

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Upper Arm Cylinder \u2014 Technical Questions<\/h2>\n
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Can I interchange the upper arm cylinder and the lower arm cylinder?<\/h3>\n

No. Despite sharing the same GTHZ210C platform designation and the same 2-\u03a69 port style, the two cylinders have different bore, rod, stroke, pressure rating, and installation distance. The upper arm cylinder (\u03a6110\/\u03a675\/815 mm) is dimensionally incompatible with the lower arm mounting (which requires \u03a6100\/\u03a680\/1,458 mm). Even if a physical fit were possible, the different rod-to-bore ratios would produce incorrect force characteristics \u2014 the upper arm cylinder’s lower buckling resistance would be dangerous in the lower arm position.<\/p>\n<\/div>\n

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The jib descends faster than it rises \u2014 is this normal?<\/h3>\n

Yes \u2014 within limits. The retract annular area (5,085 mm\u00b2) is smaller than the extend full-bore area (9,503 mm\u00b2). At the same flow rate, the retract stroke moves faster because the same volume of oil fills a smaller area. Additionally, gravity assists the downward jib movement. The combination makes the jib descend approximately 50\u201380% faster than it ascends. This is a designed characteristic, not a fault. However, if the descent speed has increased noticeably compared to when the machine was newer, the upper arm cylinder may have internal seal bypass allowing oil to bypass the piston during extension \u2014 check by performing a hold test at mid-jib angle under load.<\/p>\n<\/div>\n

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Should I replace the upper arm cylinder and lower arm cylinder at the same time?<\/h3>\n

Not necessarily. Unlike forklift tilt cylinders<\/a> that must be replaced as a matched pair for symmetry, the upper and lower arm cylinders are independent actuators serving different joints. They wear at different rates (the upper arm cycles more frequently and typically fails first). Replace each cylinder on its own failure timeline. However, if both cylinders are showing symptoms simultaneously and the boom lift is scheduled for a major service, replacing both during the same downtime event saves the labour cost of a separate boom teardown.<\/p>\n<\/div>\n

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Why is the upper arm cylinder’s working pressure 23 MPa \u2014 the highest on the boom lift?<\/h3>\n

The upper arm cylinder operates at the highest system pressure because it must provide adequate retract force from a reduced annular area. On the extend stroke, the full \u03a6110 bore at 21 MPa would produce 200 kN \u2014 already sufficient. But on the retract stroke, the annular area at 21 MPa would produce only 107 kN. The additional 2 MPa (23 MPa total) raises the retract force to 117 kN, ensuring the jib can be pulled down smoothly even when wind or inertia oppose the movement. Contact Korea Ever-Power<\/a> for a replacement quotation.<\/p>\n<\/div>\n<\/div>\n<\/section>\n

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Customer Reviews<\/h2>\n
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Daniel F.<\/strong>
\nVerified Purchase \u00b7 June 2025<\/span><\/div>\n
\u2605\u2605\u2605\u2605\u2605<\/div>\n

Replaced the upper arm cylinder on our GTHZ210C articulating boom after the original started drifting at the knuckle \u2014 the jib would slowly drop about 5\u00b0 over 10 minutes when we were doing facade work at 18 metres. Extremely unsettling for the guys in the basket. The Ever-Power replacement eliminated the drift completely. Jib now holds rock-solid at any angle. The \u03a6110 bore is impressive \u2014 this is a big, serious cylinder. Needed a forklift to unload it from the truck. Installation took about 3 hours including bleeding the circuit. Back in service and working perfectly.<\/p>\n<\/div>\n

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Highrise Access NZ<\/strong>
\nVerified Purchase \u00b7 April 2025<\/span><\/div>\n
\u2605\u2605\u2605\u2605\u2605<\/div>\n

We specialise in high-rise building maintenance in Auckland using articulating boom lifts. The upper arm cylinder fails before the lower arm on every machine in our fleet \u2014 we estimate roughly 2:1 replacement ratio. The Ever-Power GTHZ210C-620500-000 gives us a viable alternative to the OEM channel, which in New Zealand means 8\u201312 week shipping from Europe or the US. Ever-Power delivers to Auckland in about 4 weeks, and the price difference funds the air freight if we need to expedite. Two units installed, both performing well after 5 months of daily use.<\/p>\n<\/div>\n

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Marco B.<\/strong>
\nVerified Purchase \u00b7 February 2025<\/span><\/div>\n
\u2605\u2605\u2605\u2605\u2606<\/div>\n

Functionally excellent. The jib articulation is smooth and precise \u2014 better than the original cylinder at 6,000 hours. My only concern is cosmetic: the paint finish on the barrel was slightly uneven in one area, with a visible run mark. It doesn’t affect performance or durability, but on a 100 kg cylinder that costs this much, the finish should be consistent. I’d give five stars if the paint quality matched the machining quality, which is outstanding.<\/p>\n<\/div>\n

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Khalid A.<\/strong>
\nVerified Purchase<\/span><\/div>\n
\u2605\u2605\u2605\u2605\u2605<\/div>\n

We ordered the upper arm and lower arm cylinders together for a complete boom rebuild at 10,000 hours. Both arrived in one shipment, 26 days to Jeddah. Our technician installed both in a single day \u2014 having both cylinders ready at the same time meant we only needed to crane-support the boom once instead of twice. Combined cost was about 45% of the OEM equivalent for both cylinders. The boom lift has been back in service for 4 months with zero issues on either cylinder.<\/p>\n<\/div>\n<\/div>\n<\/section>\n

<\/p>\n

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Complete Boom Lift Cylinder Set<\/h2>\n
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\"Lower<\/p>\n
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Lower Arm Cylinder<\/h3>\n

\u03a6100, 1,458 mm stroke, 137 kg. Main boom elevation.<\/p>\n<\/div>\n<\/div>\n

\"Floating<\/p>\n
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Floating & Steering<\/h3>\n

Platform levelling (60 mm) and front-axle steering (320 mm).<\/p>\n<\/div>\n<\/div>\n

\"HCYY<\/p>\n
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HCYY-Series AWV Cylinders<\/h3>\n

OEM replacement cylinders for specific AWV platforms.<\/p>\n<\/div>\n<\/div>\n<\/div>\n<\/section>\n<\/div>","protected":false},"excerpt":{"rendered":"

The upper arm cylinder articulates the jib section of an articulating boom lift \u2014 the second boom section that pivots at the knuckle joint to reach over, around, and behind obstacles that the main boom alone cannot access. At \u03a6110 bore, this is the largest-bore cylinder in the Korea Ever-Power aerial work vehicle range \u2014 larger even than the lower arm cylinder’s \u03a6100. The reason is not load weight (the upper arm carries less mass), but retract-force demand: the upper arm cylinder must actively pull the jib downward against its own weight, and the annular retract area must be large enough to provide this pulling force smoothly and controllably. 815 mm stroke, 23 MPa, 100 kg, 2-\u03a69 banjo ports.<\/div>","protected":false},"featured_media":2255,"comment_status":"open","ping_status":"closed","template":"","meta":{"_et_pb_use_builder":"","_et_pb_old_content":"","_et_gb_content_width":""},"product_brand":[],"product_cat":[849],"product_tag":[],"class_list":["post-2257","product","type-product","status-publish","has-post-thumbnail","product_cat-aerial-work-vehicle-hydraulic-cylinders","first","instock","shipping-taxable","product-type-simple"],"_links":{"self":[{"href":"https:\/\/hydrauliccylindersprice.com\/et\/wp-json\/wp\/v2\/product\/2257","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/hydrauliccylindersprice.com\/et\/wp-json\/wp\/v2\/product"}],"about":[{"href":"https:\/\/hydrauliccylindersprice.com\/et\/wp-json\/wp\/v2\/types\/product"}],"replies":[{"embeddable":true,"href":"https:\/\/hydrauliccylindersprice.com\/et\/wp-json\/wp\/v2\/comments?post=2257"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/hydrauliccylindersprice.com\/et\/wp-json\/wp\/v2\/media\/2255"}],"wp:attachment":[{"href":"https:\/\/hydrauliccylindersprice.com\/et\/wp-json\/wp\/v2\/media?parent=2257"}],"wp:term":[{"taxonomy":"product_brand","embeddable":true,"href":"https:\/\/hydrauliccylindersprice.com\/et\/wp-json\/wp\/v2\/product_brand?post=2257"},{"taxonomy":"product_cat","embeddable":true,"href":"https:\/\/hydrauliccylindersprice.com\/et\/wp-json\/wp\/v2\/product_cat?post=2257"},{"taxonomy":"product_tag","embeddable":true,"href":"https:\/\/hydrauliccylindersprice.com\/et\/wp-json\/wp\/v2\/product_tag?post=2257"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}