CuSn8 / FB090 Wrapped Bronze Bushings for Hydraulic-Cylinder Clevis Pins
For a CuSn8 / FB090 wrapped bronze bushing in a hydraulic-cylinder clevis, specify the strip material, pocket geometry, supported inspection condition and grease route together. FB090 is a bearing-series description, not a complete material or fit specification. A pocketed rolled sleeve, a graphite-plugged solid sleeve and an SF-1 composite need different acceptance criteria even when their nominal sizes match.
Identify the sleeve before choosing the inspection method
This position is the external cylinder mounting-eye or clevis pivot. It is separate from the internal rod guide, piston bearing and cylinder pressure boundary. The approved joint drawing should identify the rotating member, pin retention, eye support and any axial side-contact surfaces.
CSB’s CSB-090 material information describes a sleeve wrapped from CuSn8 bronze with diamond lubricant indentations and requires initial lubrication.[1] Its published specification uses the CSB-090/FB090 naming. Treat the series name as a construction reference; specify the actual strip grade, product standard and condition on the order.
GLT’s BRO-MET is another manufacturer-specific example: a wrapped CuSn8P bronze bearing with lubricant pockets and an initial oil or grease requirement.[2] Neither source establishes automatic equivalence between suppliers, and their dimensional fits and load ratings are not BONIU specifications. The current BONIU catalogue does not by itself confirm supply of a CuSn8/FB090 wrapped product; request a separate manufacturing and material review.
Compare the lubricant reservoir, not just the colour
| Construction | What the visible feature means | What the purchaser must define |
|---|---|---|
| Pocketed CuSn8 rolled sleeve | Indentations retain externally supplied lubricant | Strip condition, pockets, seam, initial fill and replenishment |
| Through-hole rolled sleeve | Reservoirs pass through the wall | Exact series, housing coverage and lubricant access; not a pocketed sleeve by default |
| Graphite-plugged solid copper-alloy sleeve | Specified solid-lubricant inserts form part of the bearing system | Base alloy, plug formulation, shaft and any commissioning lubricant |
| SF-1 PTFE composite sleeve | A layered sliding surface works against the pin | Backing, lining formulation, outside finish and installed fit |
A grease pocket is not a graphite plug. Changing from pockets to a solid-lubricant sleeve can also change wall stiffness, housing fit and the required pin clearance. Retain the existing grease system until a reviewed replacement design explicitly changes it. A cylindrical sleeve of any of these constructions does not supply the angular articulation of a spherical joint.
Separate free-sleeve handling from controlled bore acceptance
A wrapped sleeve is not a rigid machined ring in its free state. Its seam and thin wall make the measurement condition part of the result. A two-point reading taken while squeezing the loose sleeve should not become the sole basis for rejecting its working bore.
ISO 3547-6 identifies checking of wrapped-bush inside diameter and its necessary measuring methods and equipment; the ISO catalogue also distinguishes wall-thickness and outside-diameter checks.[3] The public abstract establishes that these are separate checking subjects. Obtain and agree the applicable full standard and edition before specifying a gauge method or tolerance; this guide does not reproduce a standard procedure.
For a useful inspection plan, distinguish supplier acceptance in the agreed checking fixture from acceptance in the actual cylinder eye. Record fixture or housing identity, housing bore condition, seating position, measurement locations and instrument. An accepted test-ring result does not certify a damaged or distorted eye bore.
An investigation can therefore have three different outcomes: the sleeve fails its agreed controlled inspection; the sleeve passes but the eye is outside its drawing limits; or both pass individually while the assembled alignment or pin condition remains unacceptable. Keep these findings separate so a replacement order corrects the actual cause.
Prove that grease can reach the working contact
Map the feed from the accessible grease fitting through the pin or eye to the sleeve. Show whether a cross-hole or groove is required in the sleeve, and identify which faces or seals allow replenished grease to move. The presence of many pockets does not prove connection to the fitting.
For limited-angle motion, describe the angular sweep, dwell, load direction and reversal rate. Confirm a replenishment plan appropriate to the contact and contamination. Mud and water exclusion, lubricant compatibility and maintenance access remain important even if the bronze itself resists some environmental exposure.
Do not cut a circumferential groove into a thin wrapped wall merely to match an old solid bushing. Such a change can affect support and the reservoir pattern. Any machining allowance and resulting geometry must belong to the specified product design, not be inferred from the general name FB090.
Release a supported joint, not only a loose part
- Inspect the pin for scoring, taper and wear; record the housing bore and alignment before pressing in a new sleeve.
- Confirm installation chamfers, seam orientation, seating depth and tooling from the approved drawing. Protect pocket edges and avoid striking the sleeve directly.
- Check that the thin wall is supported as intended, including around feed passages and relieved portions of the eye.
- Apply the agreed initial lubricant and confirm that the intended feed is open after installation.
- Inspect installed clearance, axial side clearance and free pivot movement without using the bushing to pull misaligned clevis cheeks into position.
Agree any first-article joint check before production: controlled dimensions, grease arrival, articulation through the working range and the relevant load conditions. A smooth unloaded hand movement alone cannot release a heavily loaded pivot.
Frequently asked questions
Is FB090 a chemical grade?
No. Specify the actual bronze grade, product form, condition and governing requirements separately from the commercial series description.
Can I measure the loose split sleeve like a solid bronze ring?
Use the agreed inspection condition and equipment for the wrapped product. Free-state handling and controlled bore acceptance answer different questions.
Are diamond pockets a dry lubricant?
No. The pocketed examples cited here require an initial lubricant supply. Confirm the exact product and replenishment plan.
Can a CuSn8 sleeve replace a graphite bush solely by size?
No. Review wall construction, housing support, pin, installed fit, lubrication and complete joint duty before approving the substitution.
Technical sources
- CSB Sliding Bearings: CSB-090. Wrapped CuSn8 pocket construction and initial-lubrication requirement; associated manufacturer specification uses FB090 naming.
- GLT Bearings: BRO-MET. Manufacturer-specific CuSn8P pocketed sleeve example; no dimensional fit or performance limit transferred.
- ISO: Wrapped bushes, checking the inside diameter. Public scope reference for ISO 3547-6; full contracted inspection requirements must be agreed separately.
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 clevis and eye section, nominal and measured pin/housing dimensions, CuSn8 strip specification, wrapped-series requirement, pocket and feed details, inspection fixture requirement, installed clearance, lubrication and contamination history, loads, movement, quantity and drawing revision. Identify a proposed change of construction explicitly. BONIU will confirm whether the requested wrapped construction and documentation can be supplied before quotation.