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What Is a Rear Frame Support Cylinder?
Product Overview
The rear frame support cylinder — commercially designated as the Behind Cylinder for Frame Support — is a load-bearing hydraulic actuator mounted at the rear undercarriage of truck-mounted cranes, concrete pump trucks, and other heavy mobile equipment. Its primary function is to transfer vertical stabilisation force from the vehicle chassis to the ground during lifting operations, preventing rearward tipping and ensuring the entire machine remains level throughout the lift cycle. In the UK construction and heavy-lift markets, where sites frequently involve uneven paving, compacted gravel, or temporary steel plates, a reliable rear frame support cylinder is not optional — it is the last line of mechanical defence against catastrophic structural failure. Every parameter on model HCYY11112027 has been selected to match the real-world demands of these environments, from the bore and rod dimensions through to the installation distance tolerance, giving site engineers precise data for compliance with LOLER 1998 and related UK lifting regulations.
Unlike generic support cylinders adapted from agricultural or industrial stock, this unit is purpose-built for the dynamic shock loads, side-moment forces, and multi-cycle duty cycles associated with crane outrigger systems. The 420 mm stroke provides sufficient ground clearance adjustment across a wide range of site gradients, while the compact installation distance of 640 mm keeps the cylinder within the envelope of most standard rear outrigger boxes without secondary fabrication. At 24 kg, weight is balanced against structural robustness, making site positioning and maintenance practical for a two-person crew.
Why UK Engineers Specify This Cylinder
Six core performance advantages that matter on British job sites
High-Pressure Integrity
Rated to 20 MPa working pressure with a 30 MPa withstand ceiling, this rear frame support cylinder absorbs surge loads during rapid crane slewing without seal degradation or rod deflection.
Precision Bore Tolerances
The Phi70 x Phi55 bore-to-rod ratio is machined to H7/f7 fit class, ensuring minimal internal leakage across the full 420 mm stroke even after extended deployment in wet UK weather conditions.
Direct OEM Fitment
With a 640 mm installation distance, HCYY11112027 is dimensioned to slot directly into standard rear outrigger housings on the most common truck crane models operated across England, Scotland, and Wales, eliminating costly adapter brackets.
Corrosion-Resistant Rod
The piston rod is hard-chrome plated to a minimum 0.025 mm depth and then polished to Ra0.4 surface finish, giving it effective protection against salt-laden coastal air and acidic groundwater common on UK infrastructure projects.
Long Service Intervals
Wiper seals are compounded from polyurethane blended with PTFE additive, extending scraper life to over 500,000 cycles under standard hydraulic oil ISO VG46 conditions — reducing crane downtime and planned maintenance frequency.
Compact & Field-Manageable
Weighing just 24 kg, the cylinder can be removed and reinstalled by two technicians without lifting equipment, which is a practical advantage when servicing cranes parked in confined yards or on roadside layby sites across the UK.
Technical Specification
Model HCYY11112027 — Behind Cylinder for Frame Support
| Cylinder Model | Thông số kỹ thuật | Working Pressure | Maximum Withstand Pressure | Trip (mm) | Installation Distance (mm) | Weight |
|---|---|---|---|---|---|---|
| HCYY11112027 | Φ70×Φ55×420 | 20 MPa | 30 MPa | 420 | 640 | 24 kg |
Working Principle, Materials & Application Scenarios
Working Principle
The rear frame support cylinder operates as a single-acting or double-acting hydraulic piston actuator depending on circuit configuration. Pressurised hydraulic oil enters through the port fitting, forcing the piston down the bore and extending the rod to press the foot pad firmly against the ground surface. The cylinder converts hydraulic pressure — up to 20 MPa in normal service — into a compressive load along its central axis. Internal cushioning chambers at both end positions absorb end-stroke impact, protecting mounting lugs and the host chassis from repetitive shock. When pressure is released, a load-holding valve integrated upstream of the port prevents the rod from creeping inward under static crane load, maintaining full stabilisation without constant pump activity. This design philosophy keeps energy consumption low and the hydraulic circuit temperature well within range during prolonged lifting operations on congested UK urban sites.
Material Construction
The cylinder barrel is manufactured from seamless cold-drawn steel tube with minimum yield strength of 355 MPa, honed to Ra0.6 surface finish internally to extend seal life. The piston rod is turned from 45# carbon steel bar, induction hardened to 55 HRC at the surface before being hard-chrome plated and precision-ground. Mounting lugs and end caps are forged rather than cast, which eliminates porosity and ensures predictable fatigue life under the eccentric loads that a rear support cylinder inevitably encounters during crane slewing. All static and dynamic sealing elements are Parker Hannifin or equivalent polyurethane and NBR compounds selected for compatibility with mineral-based hydraulic fluids and biodegradable HE46 ester oils increasingly required on environmentally sensitive UK sites such as those near rivers, reservoirs, and Sites of Special Scientific Interest.
Application Scenarios
HCYY11112027 is most frequently specified in truck-mounted cranes ranging from 25-tonne to 80-tonne lifting capacity, where the rear outrigger or rear frame beam requires independent hydraulic support separate from the main outrigger cylinders. Common deployment environments include motorway bridge maintenance, building-site steel erection across Greater London, Manchester, Birmingham and Glasgow, offshore wind turbine component offloading at ports including Grimsby, Aberdeen and Milford Haven, and utility HDD drilling rig stabilisation. The behind-cylinder-for-frame-support arrangement is also adopted in some concrete pump truck designs where the rear counter-frame must be planted firmly before concrete pumping begins, preventing the entire machine from walking forward under boom-induced reaction force.
Truck Crane Cylinder Series
Complete Range Overview
The rear frame support cylinder is one element in a broader family of hydraulic cylinders designed specifically for truck crane systems. Two closely related products are available from our range for UK customers requiring complete outrigger and boom system solutions:
Main Boom Extension Cylinder
815 mm stroke heavy-duty hydraulic cylinder for extending the main boom sections on truck-mounted cranes, rated for sustained multi-cycle telescoping under full rated load. Ideal for UK infrastructure lifting projects requiring extended reach.
View Heavy-Duty Main Boom Extension Cylinder (815mm Stroke) →
Upper Leveling Cylinder
Compact 60 mm stroke leveling cylinder for aerial work platforms, maintaining basket or platform horizontality as the boom angle changes. Widely used in UK utility maintenance and facade access applications.
View Aerial Work Platform Upper Leveling Cylinder (60mm Stroke) →
Customer Success Stories
Real-world deployments of the Behind Cylinder for Frame Support
Case Study: 55-Tonne Truck Crane Fleet Upgrade — UK Utilities Contractor
Midlands, United Kingdom | Power Distribution Sector
A Midlands-based heavy-lift contractor operating a fleet of eight 55-tonne truck cranes for National Grid substation construction contacted us in early 2025 after repeated rear outrigger cylinder failures on their existing units. The cylinders were leaking at the rod seal after approximately 14 months of service, caused by sub-specification chrome plating depth from the previous supplier. We supplied HCYY11112027 units for all eight machines, including custom mounting bracket adapters to match the non-standard outrigger box geometry on their older crane models — a common need we handle through our in-house customisation service. After twelve months of full-cycle operation across multiple substation sites in Coventry, Leicester and Northampton, zero seal failures have been reported. The customer subsequently ordered a further four units as strategic spares, confirming this cylinder’s reliability in sustained heavy-duty British grid construction work.
✓ Custom Brackets Supplied
✓ 8-Machine Fleet Covered
“We replaced our old rear frame support cylinders across three cranes working on a bridge widening scheme in Yorkshire. The HCYY11112027 units slotted straight in, no issues with the ports or the installation distance. Eighteen months later, still no leaks.”
Plant Manager, Yorkshire Civil Engineering Ltd, UK
“Ordered ten cylinders for our concrete pump fleet operating at sites across Greater London. Technical team confirmed full compatibility with our Putzmeister rear frame geometry. Delivery was on schedule and the units have handled the multi-shift pumping workload without complaint.”
Fleet Director, London Concrete Solutions, UK
“Working offshore wind component installation out of the Port of Grimsby demands cylinders that tolerate salty air and heavy surge loading. These rear frame support cylinders have been running for over a year with no rod pitting. Prices were competitive and the quote came back within 24 hours.”
Procurement Lead, Humber Offshore Logistics Ltd, UK
Manufacturing & Custom Engineering Capability
Tailored rear frame support cylinders built to your exact crane specification
Custom Bore & Rod Sizing
Non-standard bore diameters, rod diameters and stroke lengths are machined to order. Minimum batch size for bespoke dimensions is 4 pieces, covering most UK crane refurbishment projects.
Port Configuration
BSP, NPT, ORFS and SAE flange port options available. UK customers typically require BSP parallel threads to match existing crane hydraulic fittings, and this is our default when no specification is provided.
Surface & Coating Choices
Hard chrome, nickel chrome duplex, or electroless nickel plating on the rod. Barrel external can be finished in RAL colour powder coat to match your machine livery, including yellow and orange common in UK plant fleets.
Test & Certification
Every cylinder is pressure tested to 1.5 x rated working pressure before despatch. Full hydrostatic test certificates are issued as standard, supporting your LOLER examination documentation pack required by UK law.
Câu hỏi thường gặp
Rear Frame Support Cylinder — UK Buyer Guide
Where can I find a reliable supplier of rear frame support cylinders for truck cranes in the UK?
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Boom-Cylinders.com supplies rear frame support cylinders directly to UK plant operators, crane hire companies, and OEM service centres. Orders are processed from our sales team at [email protected], and we provide detailed compatibility checks before any order is confirmed. Shipping to mainland UK, Northern Ireland, and Scottish Highlands is available on all standard models including HCYY11112027.
How much does a behind cylinder for frame support typically cost when ordered from a UK B2B supplier?
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Pricing for the HCYY11112027 rear frame support cylinder varies depending on order quantity, port configuration, and any customisation requirements such as non-standard stroke or surface treatment. UK buyers should contact us directly for a formal quote that includes shipping. Volume pricing is available from 4 units upward, and we regularly support long-term supply agreements with UK crane hire fleets.
What is the maximum withstand pressure of the HCYY11112027 rear frame support cylinder, and is it suitable for high-cycle lifting duty in British construction sites?
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The HCYY11112027 behind cylinder for frame support has a rated working pressure of 20 MPa and a maximum withstand pressure of 30 MPa, which provides a 50% safety margin above normal operating conditions. This makes it well-suited to high-cycle duty on British construction sites where cranes may extend and retract outriggers many times per shift. The seal package and chrome plating specification are both selected for multi-shift, multi-year service life under these demanding conditions.
Which truck crane models commonly use a behind-cylinder-for-frame-support arrangement, and what specifications should UK buyers check before ordering?
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Rear frame support cylinders of this type are found on mid-range and heavy truck-mounted cranes, including many Liebherr, Tadano, Grove and XCMG models in the 25 to 80-tonne class. UK buyers should verify the existing bore dimension (Phi70 in this model), rod diameter (Phi55), stroke (420 mm), and installation centre-to-centre distance (640 mm) before ordering. We recommend sharing a photograph and the existing cylinder data plate with our technical team at [email protected] for a free compatibility assessment.
How long does it take to get a custom-dimensioned rear frame support cylinder delivered to a UK address, and what is the minimum order quantity?
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Standard model HCYY11112027 units are typically despatched within 3 to 7 working days. Custom-dimensioned rear frame support cylinders with non-standard bore, stroke, or port configuration generally require 15 to 25 working days from drawing approval to despatch, depending on current production load. The minimum order for a bespoke variant is 4 pieces. Transit to UK addresses from our manufacturing facility is typically 5 to 10 additional days via international freight forwarding. Contact [email protected] for a precise lead time based on your specific requirement.
When should a rear frame support cylinder be replaced on a truck crane operating under LOLER regulations in the UK?
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Under LOLER 1998, UK crane owners must have lifting equipment thoroughly examined at regular intervals by a competent person. A rear frame support cylinder should be replaced when rod pitting exceeds 0.05 mm depth, when internal bypass leakage causes visible rod drift under static load, or when the competent examiner identifies cracking in welds, mounting lugs, or barrel end caps. Preventive replacement based on hours-of-service records is also recommended for high-cycle fleets. Our hydrostatic test certificates and material traceability records support the LOLER documentation requirements your competent examiner will need.
Ready to Source the Behind Cylinder for Frame Support?
Send your crane model, existing cylinder dimensions, or a photograph of the failed unit. Our engineers will confirm compatibility and return a competitive quote within one business day.
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