C93200 Oil-Grooved Bronze Sleeve Bearings for Gear-Reducer Intermediate Shafts
A C93200 oil-grooved sleeve bearing for a gear-reducer intermediate shaft should be selected as part of a complete lubricant circuit. The alloy designation does not specify the groove, and a visible spiral does not prove that oil reaches the working clearance. Confirm the load direction, feed connection, groove ends, installed bore and startup supply before approving a replacement.
Define the shaft support and lubricant circuit
This guide concerns a drawing-defined plain journal support inside a gear reducer, where the shaft carries an intermediate gear and receives oil through a housing passage or a specified reservoir. It does not recommend replacing an existing rolling bearing with a bronze sleeve. Gear alignment, shaft deflection, heat removal and the housing design remain assembly-level decisions.
Concast identifies C93200 as leaded tin bronze and lists bearing and bushing applications. Its casting specification is useful for identifying the base metal; it does not rate a finished grooved bearing.[1]
On a purchase order, specify the alloy, applicable casting standard and edition, manufacturing route and certificate requirements. RG7/CC493K and C93200 must not be treated as automatic equivalents. Groove geometry is a separate drawing requirement, not part of the UNS number.
Compare grooves by their job
National Bronze distinguishes oil holes, axial, annular and oval grooves, and explains that a circumferential groove interrupts the bearing into shorter working regions. It also places axial feed grooves in the unloaded area.[2]
| Arrangement | Potential reason to use it | What must be checked |
|---|---|---|
| Local feed hole | Introduce oil with little interruption of the bore | Distribution across the actual bearing length and operating clearance |
| Axial distribution groove | Carry lubricant along the sleeve | Clocking relative to the load, end margins and connection to the feed |
| Central annular groove | Distribute pressure-fed lubricant or accommodate changing load direction | Interrupted load-supporting length, leakage and the required supply |
| Spiral or oval route | Distribute lubricant along a defined path | Pitch, handedness, ends, working lands and intended return or drainage path |
These are review questions, not interchangeable groove specifications. A spiral cuts across different angular positions; its appearance alone cannot establish a hydrodynamic load capacity or oil delivery rate. The selected topology needs a lubrication analysis for the reducer duty. A grease-distribution pattern should not be copied into an oil-fed journal merely because both are called lubrication grooves.
A registered feed is an assembled feature
Trace oil from the source to the running interface: supply passage, housing port, sleeve external feature, cross-hole, internal distribution and exit or return. A correct bore and outside diameter can coexist with a blocked feed. Record which shoulders control the axial position and which feature controls angular orientation.
Consider an illustrative axial-registration check. Assume the housing and sleeve have two equal 4 mm circular ports, their axes remain parallel, and the centre offset can reach 1.5 mm. Their openings overlap, but the common area is approximately 6.71 mm², compared with 12.57 mm² for an unobstructed port. About 53% of the nominal aperture remains. This is geometry only: it does not predict that oil flow falls to 53%, because pressure losses depend on the full circuit.
This example explains why “the holes overlap” is an incomplete acceptance statement. Agree a minimum opening or an appropriate assembled flow check, with lubricant, temperature, pressure and cleanliness conditions defined. An external annular collector may accommodate angular variation, but it cannot repair an excessive axial mismatch or a blocked internal drilling.
Startup, reversal and oil return
Separate running duty from startup after a long standstill. Provide shaft speed, gear-load direction, starts per hour and any reversing operation. Identify whether the oil supply begins before the journal turns, whether oil can drain away during shutdown, and how the specified bearing is wetted before load is applied.
A shallow groove and an inlet hole do not create a pump with a guaranteed delivery. For a helical route, specify the viewing direction used to define handedness and the intended shaft rotation. Reversing rotation requires its own review. Do not assume that a groove intended to retain lubricant should be opened through both ends; do not assume that a retained-end groove provides adequate flushing. Retention, leakage and debris removal can lead to different end details.
Oil viscosity at the working temperature, contamination, supply stability and heat rejection must be considered together with load and speed. A material tensile-strength value cannot be converted directly into allowable journal pressure. Where the design relies on a fluid film, use the actual clearance, bearing geometry and operating conditions in the bearing calculation.
Installation and acceptance sequence
- Clean the housing and supply circuit, remove burrs at cross-holes and groove intersections, and protect the finished shaft.
- Use the specified fit and aligned installation tooling. Do not drive through a thin groove land or strike the running surface.
- Verify feed registration after the sleeve reaches its installed shoulder. Use drawing datums rather than a visual estimate from an exposed edge.
- Measure the installed bore and alignment, including changes caused by housing interference and fastening. Check the agreed operating-clearance budget.
- Confirm lubricant arrival and the return path before commissioning. Observe temperature, noise, supply and wear during the agreed startup procedure.
Reject a replacement investigation that only measures the worn bore. Preserve the original groove and port positions, record the unworn datums, and distinguish intended sizes from wear. A new sleeve with a larger groove can change the lubrication system even when its main dimensions match.
Frequently asked questions
Does a spiral groove make C93200 self-lubricating?
No. This guide covers an externally lubricated solid-bronze journal. A groove distributes lubricant; it does not replace the specified supply.
Can I enlarge a groove to improve oil delivery?
Only after reviewing the working lands, wall section, leakage, supply and bearing calculation. More groove area is not automatically better.
Is an overlapping oil hole acceptable?
Acceptance depends on the agreed assembled opening or flow criterion. Partial overlap alone does not establish adequate delivery.
Should I order C93200 as RG7?
Specify the required alloy and standard explicitly. A regional comparison is not approval to substitute the material.
Technical sources
- Wieland Concast: C93200. Base-alloy identification and casting reference; no finished-bearing rating adopted.
- National Bronze: Oil Grooves for Bronze Bushings. Manufacturer guidance on groove purpose, location and end arrangements; its numerical rules are not BONIU specifications.
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 reducer assembly section, bearing drawing and revision, C93200 casting requirement, shaft and housing tolerances, groove section and end positions, port datums, oil conditions, load/speed history, quantity and inspection requirements. Identify the required feed-registration acceptance separately from bore-size acceptance. BONIU confirms manufacturing scope and the quoted specification after review.