Hot-Dip Galvanized QP-Type Ball Eye for Insulator Strings
The QP-type ball eye is a load-bearing connection fitting designed for overhead transmission and distribution-line insulator strings. It provides a transition between an eye-type mechanical connection at the upper end and a standardized ball-and-socket connection at the lower end.
The upper circular eye can be connected to a compatible shackle, clevis, link plate or tower-side fitting. The lower ball end is inserted into the socket of a W-type or WS-type socket fitting, a ball-and-socket insulator cap or another compatible component. After assembly, the socket locking device prevents unintended separation of the ball connection.
The ball-and-socket arrangement permits controlled articulation within the insulator-string assembly, helping the connected components accommodate alignment changes and movement caused by conductor tension, wind and installation geometry.
QP-type ball eyes are available in multiple coupling designations, eye dimensions, connection heights and mechanical load classes. The selected model must match both the ball-and-socket coupling size and the mechanical rating of the complete insulator-string assembly.
Important: A ball eye does not have an independent voltage rating. Product selection is primarily based on coupling designation, mechanical load, eye diameter, connection height, material, coating and compatibility with adjacent fittings.
Key Features
- Eye-to-ball transition for overhead-line hardware assemblies
- Compatible with ball-and-socket insulator-string connections
- Allows controlled articulation within suspension and strain strings
- Available in different coupling sizes and mechanical load classes
- One-piece load-bearing steel construction
- Hot-dip galvanized surface for outdoor corrosion protection
- Permanent model marking available for product identification
- Custom dimensions, markings and packaging available according to approved drawings
Typical Technical Specifications
| Product Type | QP-Type Ball Eye / Ball-Eye Link Fitting |
|---|---|
| Connection Structure | Upper eye and lower ball end |
| Body Material | Steel according to model and approved drawing |
| Typical Manufacturing Method | Forging and machining |
| Surface Finish | Hot-dip galvanized |
| Coupling System | Standard ball-and-socket connection |
| Representative Coupling Designations | 16, 20 and 24 |
| Representative Mechanical Classes | 70, 100, 120, 160, 210 and 320 kN |
| Application | Suspension and strain insulator-string assemblies |
| Installation Area | Overhead transmission line, distribution line and substation |
| Reference Standards | DL/T 759-2023, GB/T 4056-2019, IEC 60120:2020 and IEC 61284 |
| Customization | Model, eye diameter, coupling designation, load class, coating, marking and packaging |
Representative Model Selection
| Stable-Design Model | Common Model | Eye Diameter | Connection Height | Ball Diameter | Coupling Designation | Nominal Failure Load |
|---|---|---|---|---|---|---|
| QP-0750 | QP-7 | 20 mm | 50 mm | 33.3 mm | 16 | 70 kN |
| QP-1050 | QP-10 | 20 mm | 50 mm | 33.3 mm | 16 | 100 kN |
| QP-1260 | QP-12 | 24 mm | 60 mm | 33.3 mm | 16 | 120 kN |
| QP-1660 | QP-16G | 26 mm | 60 mm | 41.0 mm | 20 | 160 kN |
| QP-2180 | QP-2120G | 26 mm | 80 mm | 41.0 mm | 20 | 210 kN |
| QP-3280 | QP-3224G | 33 mm | 80 mm | 49.0 mm | 24 | 320 kN |
The table contains representative industry selection data. Final model designation, dimensions, tolerances, ball profile and mechanical performance must be confirmed using Jiujin Power’s approved product drawing and corresponding test report.
Connection Structure
Upper Eye Connection
The circular eye at the upper end connects the ball eye to a compatible U-type shackle, clevis, link plate or other tower-side hardware. The eye diameter and body thickness must match the pin diameter and clevis opening of the adjacent fitting.
Lower Ball Connection
The lower ball end is inserted into a compatible socket component. Its coupling designation must match the corresponding socket and locking device. Similar-looking ball fittings with different coupling designations are not automatically interchangeable.
Locking Device
The locking device is normally installed in the socket component rather than on the QP ball eye itself. Depending on the socket design, a W-type or R-type locking pin may be used to prevent the ball end from leaving the socket.
Typical Applications
- Suspension insulator strings
- Strain and dead-end insulator strings
- Composite-insulator assemblies
- Porcelain and glass disc-insulator strings
- Connections between tower-side hardware and insulators
- Overhead transmission-line hardware sets
- Distribution-line and substation connection assemblies
Material and Manufacturing
QP-type ball eyes are commonly manufactured from steel using a controlled forging and machining process. Forging helps create a continuous load-bearing structure, while machining controls the eye hole and critical ball dimensions.
The exact steel grade, heat-treatment condition and manufacturing route must be defined by the approved drawing and mechanical performance requirements. The finished part should be inspected for cracks, laps, excessive seams, deformation and other defects that may affect mechanical performance.
Hot-Dip Galvanized Surface
The steel body is normally hot-dip galvanized after forming and machining. The zinc coating protects the fitting against atmospheric corrosion during outdoor service.
Coating appearance may range from bright silver to matte grey and may show minor variations caused by steel composition, component geometry and galvanizing conditions. These visual differences do not alone determine coating thickness or performance.
The required zinc-coating thickness, coating mass, adhesion and test method should be specified in the purchase contract. Enhanced corrosion protection may be required for coastal, tropical, industrial or highly polluted environments.
Product Selection
The following parameters must be checked before selecting a QP-type ball eye:
- Required nominal failure load
- Ball-and-socket coupling designation
- Upper eye-hole diameter
- Thickness of the eye section
- Overall connection height
- Pin diameter of the adjacent shackle or clevis
- Clevis opening of the adjacent fitting
- Type of insulator or socket fitting
- Required hot-dip galvanized coating
- Applicable utility standard and assembly drawing
A ball eye must not be selected according to visual appearance or voltage level alone. The complete mechanical interface must be checked against the approved insulator-string drawing.
Installation Guidance
- Verify the product model and permanent marking before installation.
- Confirm the coupling designation and ball dimensions match the socket component.
- Inspect the ball surface, eye hole and galvanized coating for damage.
- Connect the upper eye to the specified shackle, clevis or link fitting.
- Insert the ball end into the socket using the approved assembly direction.
- Install the correct locking device in the socket component.
- Confirm that the ball is retained securely and cannot leave the socket unintentionally.
- Check that the assembled connection can articulate without abnormal binding.
- Replace any fitting showing cracks, permanent deformation, excessive wear or severe corrosion.
Quality Inspection
- Raw-material verification
- Forging and surface-defect inspection
- Model and permanent-marking inspection
- Eye-hole diameter and thickness inspection
- Ball profile and coupling-gauge inspection
- Overall dimensional inspection
- Hot-dip galvanized coating inspection
- Nominal failure-load test when specified
- Assembly compatibility inspection with the corresponding socket
- Packaging, quantity and traceability inspection
Reference Standards
- DL/T 759-2023 – Link fittings
- GB/T 2314-2008 – General technical requirements for electric power fittings
- GB/T 4056-2019 – Dimensions of ball-and-socket couplings of string insulator units
- IEC 60120:2020 – Ball-and-socket couplings of string insulator units — Dimensions
- IEC 61284 – Overhead-line fittings — Requirements and tests
- ISO 1461:2022 – Hot-dip galvanized coatings on fabricated iron and steel articles
- Applicable utility specifications and approved project drawings
Reference to a standard does not constitute certification. Compliance claims must be supported by drawings, inspection records and test reports covering the exact model supplied.
Ordering Information
Please provide the following information when requesting a quotation:
- Required QP model
- Nominal mechanical load
- Ball-and-socket coupling designation
- Upper eye-hole diameter and thickness
- Required connection height
- Adjacent shackle, clevis or socket model
- Steel grade and manufacturing requirements
- Hot-dip galvanized coating requirement
- Applicable standard and required test documentation
- Quantity, marking and packaging requirements
Frequently Asked Questions
What is a QP-type ball eye used for?
It connects an eye-type overhead-line fitting to a ball-and-socket insulator or socket fitting within a suspension or strain insulator-string assembly.
Can the ball end connect directly to a W or WS socket fitting?
Yes, provided that the ball and socket have the same coupling designation and the correct locking device is installed.
Can QP-7 and QP-16 be used interchangeably?
No. They may have different ball sizes, coupling designations, eye dimensions and mechanical load classes. Compatibility must be checked using the approved drawings.
Does a QP ball eye have a voltage rating?
The fitting is primarily selected by mechanical load and interface dimensions. The voltage rating applies to the complete insulation and hardware assembly, not to the ball eye alone.
Is the locking pin included?
The locking pin normally belongs to the corresponding socket fitting. The exact supply scope must be confirmed in the quotation and packing list.
Can custom models be manufactured?
Custom production is possible according to an approved drawing. Mechanical load, eye dimensions, ball profile, material, coating and test requirements must be agreed before production.
