Telescopic Sections for Telescopic Booms

Product Specifications

Technical details and manufacturing context for Telescopic Sections (for telescopic booms)

Definition

Telescopic sections are the individual, concentrically arranged segments that form the extendable structure of a telescopic boom. They slide within one another, typically using hydraulic cylinders or other actuators, to provide variable reach and lifting height for equipment such as cranes, aerial work platforms, and material handlers. As part of the Main Boom, they are critical for the machine's operational flexibility and range. These sections are manufactured from high-strength steel (e.g., Weldox, Hardox) or aluminum alloy for lighter booms, and are designed to withstand significant bending and compressive loads. The sections are typically box-shaped or cylindrical, with dimensions such as section width and height ranging from 200 to 600 mm, and wall thickness from 4 to 12 mm. The number of sections typically ranges from 3 to 6, allowing for a total extended boom length of 5 to 20 meters. The minimum overlap between sections for stability is 0.8 to 1.5 meters. The material yield strength for load-bearing sections is typically 550 to 700 MPa, and surface hardness on sliding surfaces is 45 to 55 HRC. Straightness tolerance is 0.5 to 1.5 mm/m to ensure smooth extension and alignment. The weight per section ranges from 200 to 800 kg, affecting total boom weight and crane capacity. Telescopic speed is typically 0.1 to 0.5 m/s, limited by hydraulic flow, and operating pressure is 20 to 35 MPa. Operating temperature range is -20 to 80°C. These sections are critical for the machine's operational flexibility and range. When selecting telescopic sections, it is essential to verify model-specific values and standards with the legal manufacturer or supplier, as the provided ranges are for reference only.

Working Principle

Multiple sections (typically 2-5) are nested, with the smallest section innermost. A hydraulic cylinder or chain system attached to the base or an inner section provides the force to extend or retract the sections sequentially or simultaneously, guided by wear pads, rollers, or sliding surfaces to ensure smooth, aligned movement and structural stability under load. The extension and retraction are controlled by hydraulic pressure, typically 20-35 MPa, and the speed is limited by hydraulic flow. The sections are designed to maintain a minimum overlap for stability, and the straightness tolerance ensures proper alignment. Wear on sliding surfaces is mitigated by surface hardness and wear pads, which require periodic inspection and maintenance.

Common Materials

High-strength steel (e.g., Weldox, Hardox), Aluminum alloy (for lighter booms)

Technical Parameters

Parameter	Typical range	Notes & selection driver
Boom Length	5–20 m	Total extended length of the telescopic boom.
Section Count	3–6	Number of telescopic sections; more sections reduce retracted length.
Section Overlap Length	0.8–1.5 m	Minimum overlap between sections for stability.
Section Wall Thickness	4–12 mm	Determines strength and weight; thicker for higher loads.
Material Yield Strength	550–700 MPa	High-strength steel for load-bearing sections.ISO 6892-1
Section Width	200–600 mm	For box-section; affects bending stiffness.
Section Height	200–600 mm	For box-section; affects bending stiffness.
Telescopic Speed	0.1–0.5 m/s	Extension/retraction speed; limited by hydraulic flow.
Operating Pressure	20–35 MPa	Hydraulic pressure for actuation; higher for heavy loads.
Operating Temperature	-20–80 °C	Material and seal performance limits.
Surface Hardness	45–55 HRC	Wear resistance on sliding surfaces.ISO 6508-1
Straightness Tolerance	0.5–1.5 mm/m	Ensures smooth extension and alignment.ISO 1101
Weight per Section	200–800 kg	Affects total boom weight and crane capacity.

Ranges are indicative industry figures for RFQ preparation, not a supplier commitment. Confirm every value and standard with the legal manufacturer before ordering.

Components / BOM

Wear Pad / Slide Block Part
Reduces friction and wear between sliding sections, ensuring smooth extension/retraction and alignment.

Material: UHMW-PE, nylon, or bronze composite
Seal / Wiper Part
Prevents ingress of dirt, moisture, and debris into the space between sections to protect sliding surfaces and internal components.

Material: Rubber or polyurethane
Lifting Lug / Attachment Point Part
Provides a connection point for the hydraulic cylinder, chain, or cable that drives the section's movement.

Material: Steel

Application & selection

Application Fit & Sizing Matrix

Operational Limits

pressure:	Up to 300 bar (hydraulic systems)
other spec:	Max extension ratio: 4:1, Min retracted length: 1.5m, Max extended length: 20m
temperature:	-40°C to +120°C

Media Compatibility

✓ Hydraulic oil (ISO VG 46) ✓ Compressed air (dry, filtered) ✓ Water-based lubricants

Unsuitable: Abrasive slurries with >5% solids concentration

Sizing Data Required

Required extended length (m)
Maximum load moment (kN·m)
Operating pressure (bar)

Risk, maintenance & compliance

Reliability & Engineering Risk Analysis

Failure Mode & Root Cause

Seal degradation and hydraulic fluid leakage

Cause: Contamination ingress (dust, debris), improper seal material selection for operating conditions, or excessive pressure/temperature causing seal hardening or extrusion

Structural fatigue and binding

Cause: Misalignment during extension/retraction cycles, inadequate lubrication on sliding surfaces, or overloading beyond design capacity leading to deformation

Maintenance Indicators

Visible hydraulic fluid streaks or drips along telescopic sections during operation
Audible grinding, scraping, or uneven jerking motion during extension/retraction cycles

Engineering Tips

Implement regular contamination control: Use high-quality filters in hydraulic systems, maintain clean work environments during maintenance, and establish scheduled seal inspections/replacements based on operating hours.
Ensure proper alignment and lubrication: Conduct periodic alignment checks using laser tools, apply manufacturer-recommended lubricants to sliding surfaces, and train operators on smooth, controlled extension/retraction to minimize shock loads.

Indicative industry ranges for design and RFQ preparation. Confirm the exact figures and applicable standard with the manufacturer before specifying.

Compliance & Manufacturing Standards

Applicable Standards

ISO 4309:2010 (Cranes - Wire ropes - Care, maintenance, installation, examination and discard) ANSI/ASME B30.5 (Mobile and Locomotive Cranes) DIN EN 13001-3-1 (Crane safety - General design - Part 3-1: Limit states and proof of competence of steel structure)

Quoted from the published standard.

Manufacturing Precision

Bore diameter tolerance: +/-0.05mm
Section parallelism: 0.15mm per meter length

Quality Inspection

Magnetic Particle Inspection (MPI) for surface cracks
Ultrasonic Testing (UT) for internal material flaws

Procurement Evaluation Criteria

A practical evidence checklist for RFQ preparation and supplier evaluation.

Technical documentation

Request current drawings, revision history, and a signed specification sheet.

Manufacturing capability

Verify equipment lists, process limits, capacity, and representative production evidence.

Inspection readiness

Confirm test methods, calibrated equipment, sampling plans, and traceable reports.

Supplier transparency

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Manufacturers of Telescopic Sections (for telescopic booms)

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Frequently Asked Questions

What materials are telescopic sections typically made of?

Telescopic sections are commonly made of high-strength steel (e.g., Weldox, Hardox) or aluminum alloy for lighter booms. The material yield strength for load-bearing sections is typically 550-700 MPa, and surface hardness is 45-55 HRC. Always verify material specifications with the manufacturer.

How many sections are typically used in a telescopic boom?

The number of sections typically ranges from 3 to 6. More sections reduce the retracted length but may affect stability. The minimum overlap between sections is 0.8-1.5 meters. Confirm the exact count and overlap for your application.

What are the typical dimensions and weights of telescopic sections?

Section width and height typically range from 200 to 600 mm, wall thickness from 4 to 12 mm, and weight per section from 200 to 800 kg. These values affect bending stiffness and total boom weight. Verify with the manufacturer for specific models.

What standards apply to telescopic sections?

Relevant standards may include ISO 6892-1 for material yield strength, ISO 6508-1 for surface hardness, and ISO 1101 for straightness tolerance. These are verification references; confirm compliance with the supplier.

Related equipment

Applied To / Applications

This component is essential for the following industrial systems and equipment:

Main Boom

View system integration details

Industrial Ecosystem & Supply Chain Structure

Complementary Systems

Downstream Applications

Specialized Tooling

Industry Taxonomies & Aliases

Commonly used trade names and technical identifiers for Telescopic Sections (for telescopic booms).

Data Basis

Editorial classification, named public sources where available, and source-reviewed manufacturer records.

Preliminary Technical Classification

This page supports structured research, RFQ preparation, and supplier evaluation. It does not replace buyer-led supplier qualification, standards review, or technical approval.

Compiled and source-reviewed by the CNFX editorial team. Each manufacturer above links to the page on that company's own website where the product is listed, with the date we checked it. How we source and review · Page last updated 12 October 2026

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