A tri-bundle yoke plate is the load-distribution head of a three-conductor bundle suspension or tension assembly. Its three attachment bores are arranged in a triangular pattern, one per subconductor, all positioned on the same radius from the string axis so each subconductor hangs level and shares the bundle tension equally. On high-capacity transmission lines using triple-bundle conductor, this single casting is the reference point from which the whole bundle geometry — clamp heights, spacer damper spacing, jumper routing — is established.
Three-point load sharing is a harder problem than two. With a twin bundle, an unlevel plate is easy to see; with three subconductors, small geometry errors distribute load unevenly in a pattern that only shows up later as spacer wear and bundle galloping. That is why we machine all three bores from a single setup after casting, hold the triangular spacing to drawing tolerance, and verify symmetry at inspection rather than trusting the as-cast position alone. The plate is cast in ductile iron ASTM A536 for ductility at the lugs and hot-dip galvanized per ASTM A153 to match the corrosion life of the strand, clamps, and insulators in the string.
| Item | Typical Value |
|---|---|
| Material | Ductile iron ASTM A536 (65-45-12 typical); malleable iron option |
| Strength Rating | Ultimate tensile strength typically 30,000–60,000 lbs class for the three-point assembly |
| Hole Diameter | 13/16"–1" bores typical, sized to bundle clamp hardware |
| Hole Spacing | Triangular subconductor spacing typically 18"–20" sides per bundle design |
| Finish | Hot-dip galvanized per ASTM A153 |
| Suitable Insulator String | Suspension insulator strings and polymer long-rod assemblies with tri-bundle clamps |
| Weight Range | Approx. 5–11 kg per piece |
| Casting Process | Green sand casting, shot-blasted, all bores machined in one setup |
| Standard | Manufactured to ANSI C29-series bundle hardware conventions |
Suspend the plate from the string's tongue or ball fitting, then pin each of the three subconductor clamps to its bore. Field practice from customer crews:
Hang the bundle with all three clamps pinned before final tensioning; tensioning on two points twists the third subconductor into the plate.
Confirm side lengths of the triangular hole pattern against the bundle drawing — typically 18"–20" — since spacer damsper intervals are referenced to these dimensions.
On long spans, inspect the plate's center lug and coating annually; galloping bundles drive the highest alternating loads through this fitting.
Typical applications include triple-bundle reconductoring projects, river and strait crossings where large conductor bundles carry high capacity, and substation entrances where three-conductor feeders drop into gantry structures. The tri-bundle plate often works alongside yoke tension adjusting fittings and the string's disconnect hardware for maintenance access.
We cast tri-bundle yoke plates to customer drawings or samples. Customizations include alternate triangular spacings, unequal-leg layouts for compact bundle designs, twin apex lugs for double-tongue strings, drilled auxiliary holes for spacers or grounds, and heavier web sections for severe ice districts. Sample lead time is typically 3–4 weeks for this larger casting class, with CMM first-article reports.
Inspection includes: CMM verification of triangular bore positions and symmetry; bore diameter gauging; web and lug section measurement; hot-dip galvanizing thickness checks per ASTM A153; and scheduled tensile sampling to confirm the rated assembly strength. Large-section castings are screened for internal shrinkage before coating, with radiographic sampling available on request. Plates ship individually wrapped with corner protection, crated and palletized for export.
Q: How is a tri-bundle yoke plate different from a delta plate?
A: The delta plate is a three-point fitting for string stability (V-strings, rigid supports); the tri-bundle plate is purpose-shaped for holding three subconductors of a bundle at matched spacing.
Q: What bundle spacings can you cast?
A: Standard triangular spacings around 18"–20" side length, but any spacing is machinable to your bundle drawing.
Q: Can it be supplied with spacer hardware?
A: We quote the yoke plate casting; matched spacer and clamp hardware can be sourced through our supply network on request.
90° Base Elbow — example of our broader ductile iron casting range
Send your bundle design — subconductor spacing, string hardware, and load class — and we will confirm the tri-bundle yoke plate casting with samples and reports.
WhatsApp: +86 185 6156 7088, or submit the RFQ form for a full quote package.
Need a formal quotation? Send your Tri-Bundle Yoke Plate drawing, quantity and target price through our quotation request form — it goes straight to the foundry inbox, and we reply with a priced offer, material certificate draft and production lead time within one business day.
Professional technical research and development team to provide customers with the best solution.
Jimo District, Qingdao City, Shandong Province, China
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