C86300 Graphite-Plugged Sleeve Bushings for Radial-Gate Trunnions
For a radial-gate trunnion, a proposed C86300 graphite-plugged sleeve must be reviewed against the gate’s friction-moment allowance as well as bearing pressure. A low sliding speed does not remove the opening load after a long dwell. Specify the complete alloy–solid-lubricant–pin system, assess adverse friction conditions and keep radial and thrust contacts separate.
What C86300 and JDB/500# establish
C86300 identifies a manganese-bronze base alloy. Concast lists slow-speed, heavy-load bearings among its applications, but its material sheet does not qualify a graphite-plugged trunnion system.[1]
JDB/500# is a product-family description used in enquiries; it does not establish a particular C86300 casting, plug formulation, pattern, friction coefficient or submerged-service approval. In this guide, C86300 is a proposed drawing material, subject to confirmation. No BONIU gate installation, service life or project qualification is claimed.
The procurement question is specific: can the proposed sleeve, counterface and environmental protection satisfy the gate designer’s approved load and friction criteria? Generic catalogue pressure and PV values cannot answer that question on their own.
Compare pressure, radial friction and thrust friction
| Check | Useful first calculation | What it leaves unresolved |
|---|---|---|
| Projected journal pressure | Radial reaction divided by pin diameter × engaged sleeve length | Pin bending, edge loading, plug interruptions and allowable material-system duty |
| Radial friction moment | Screening estimate μr × radial reaction × pin radius | Actual breakaway behaviour, alignment, corrosion and spatial pressure distribution |
| Thrust friction moment | Screening estimate μa × axial reaction × effective sliding radius | Contact distribution, thrust-face geometry and load sharing |
Use reactions from the gate analysis, not just gate weight. Specify whether loads are per trunnion, per sleeve or for the complete gate. If a thrust face is present, identify its working pair and effective radius. A plain cylindrical sleeve does not, by itself, define where axial load is carried.
USACE Risk Management Center explicitly treats trunnion friction as a radial-gate failure mode and notes that its typical event trees require adjustment for site-specific conditions.[2] That supports examining adverse friction; it does not supply a universal friction coefficient for a BONIU bushing.
An original friction-moment sensitivity example
Assume, solely for illustration, one trunnion has a 400 kN radial reaction on a 160 mm diameter pin and a 30 kN axial reaction on a separate thrust face with an assumed effective radius of 110 mm. Use μr = μa for this screening exercise. Neither load nor friction assumption is a BONIU rating.
Radial term: μ × 400,000 N × 0.080 m = μ × 32,000 N·m.
Thrust term: μ × 30,000 N × 0.110 m = μ × 3,300 N·m.
Total for these two contacts: μ × 35,300 N·m. At assumed μ = 0.10, 0.20 and 0.30, the totals are 3.53, 7.06 and 10.59 kN·m respectively.
These three coefficients are sensitivity inputs, not prescribed design values or measured graphite-bearing performance. The upper result is three times the lower result although the pin diameter and reaction loads have not changed. Selecting an optimistic coefficient can therefore alter the apparent gate-operating margin without improving the physical assembly.
This is not a complete hoist-sizing calculation. Seal friction, other pivots, gate geometry, operating direction, hydrodynamic effects, load combinations and mechanical efficiency remain outside the example. The gate designer must establish the governing criteria and transfer the friction moment into structural and operating-system calculations.
Long dwell and water exposure need their own evidence
Describe the longest loaded dwell, first movement, operating angle, cycle frequency, water chemistry, silt, splash and wet–dry exposure. A short dry oscillation test cannot be assumed to represent a trunnion that sits under load and is then opened after months of environmental exposure.
OILES’ metallic-bearing selection guide distinguishes its own lubricant variants and their water-service suitability. Its tabulated application scope also identifies atmospheric shaft rotation as the basis for the listed performance values.[3] This is evidence that formulation and test environment matter; its material names, environmental classifications and ratings are not transferred to BONIU.
For the proposed system, agree evidence for the actual exposure and friction duty: material documents, counterface specification, lubricant identification, representative conditioning and an appropriate acceptance method. Where commissioning torque or force is measured, define the gate position, hydraulic loading and other friction contributions. A hoist reading is not automatically the coefficient of a single bearing.
Fit, pin support and maintenance access
- Show the complete pin, housing, sleeve and thrust arrangement. Identify the member that rotates and the surfaces intended to remain fixed.
- Review alignment under assembly and service loads, including pin deflection and housing distortion. Extra nominal sleeve length is not proof of uniform load sharing.
- Specify installed clearance, fit, retention, corrosion protection and compatible seals or covers. Keep debris away from the running contact.
- Protect plug edges and bearing faces during installation. Do not add grooves, machine the working surface or apply an unreviewed lubricant to a finished self-lubricating system.
- Provide access for inspection and the agreed maintenance or monitoring plan. Self-lubricating does not mean the complete trunnion needs no inspection.
The bushing RFQ and gate-operating approval are separate decisions. A component quotation can define material, dimensions and inspection scope; it cannot certify an unreviewed gate structure or hoist.
Frequently asked questions
Can I use a low catalogue friction value to size the hoist?
Use the gate designer’s approved criteria and relevant evidence for the complete bearing system and exposure. A generic value cannot replace the gate analysis.
Is C86300 automatically suitable for an immersed gate bearing?
No. Base alloy, solid lubricant, pin, water chemistry and protection must be considered together. Confirm project-specific suitability.
Does low PV prove acceptable breakaway?
No. PV describes load–speed duty; it does not establish the friction after a long loaded dwell or environmental conditioning.
Is the sensitivity example a recommended design coefficient?
No. The three inputs illustrate the effect of an assumption. The responsible gate designer selects and validates the governing criteria.
Technical sources
- Wieland Concast: C86300. Base-alloy reference; no graphite-bearing friction or gate qualification inferred.
- USACE Risk Management Center: Radial Gate Failure Due to Trunnion Friction. Primary institutional context for the failure mode and site-specific analysis.
- OILES: Metallic Bearing Selection Guide. Manufacturer-specific formulation and environmental distinctions; no numerical rating adopted.
Source documents describe their own materials, products or engineering scope. The application analysis and illustrative calculations above are not BONIU test results or guaranteed performance.
Request a drawing review
Send the gate and trunnion assembly sections, exact proposed alloy and casting standard, plug-system requirement, pin and housing details, radial and axial load cases, designer-approved friction criteria, water exposure, maximum dwell, operating history, quantity and inspection scope. Mark proposed substitutions explicitly. BONIU reviews component manufacturing requirements before confirming supply.