Bearing material data only makes sense when the product construction and lubrication condition are identified. This comparison brings together selected GGB bronze plain-bearing properties for one grease-lubricated CuSn8 product and three cast-bronze self-lubricating material configurations. The values are manufacturer-published limits or reference properties for those specific products; they are not universal allowable pressures for bronze bushings.

Keep the product families separate

GGB LDD is a CuSn8 bronze bearing with grease reservoirs and integrated lip seals. The manufacturer describes it for greased applications, relatively high loads and low speeds. Its listed speed and pU factor apply on the stated grease-lubricated basis. The DB entries are cast bronze with solid lubricant inserts. The suffix matters: the data sheet publishes different mechanical and tribological values for DB-B/11, DB-C/11, and DB-D/11.

The table lists each configuration separately because changing the bronze grade or insert arrangement changes the manufacturer’s rating. B/11, C/11, and D/11 are not simply interchangeable capacity classes. GGB describes C as having high load capacity with maximum corrosion resistance, while D offers the highest load capacity of the three but less corrosion resistance than C. Choose based on the actual environment and duty, not the largest number in one column.

Pressure, speed, and pU are linked

Projected bearing pressure is commonly estimated from load divided by the projected bearing area. Sliding speed depends on shaft diameter and relative motion. The pU factor combines pressure and surface speed, so the published maximum must be interpreted with the other limits and the exact lubrication mode. Reaching the maximum pressure, maximum speed, and maximum pU simultaneously should not be assumed valid unless the product documentation expressly supports that operating point.

Temperature, shaft finish and hardness, clearance, alignment, contamination, duty cycle, and start-stop behavior also affect wear and friction. GGB’s DB guidance notes that operating conditions and mating surface influence tribological performance. A nominally acceptable pressure can still produce poor service life when speed, temperature, edge loading, or lubrication is unfavorable.

How to use the values

First identify the exact GGB product and configuration. For the LDD family, confirm that grease is present and that the integrated reservoirs and seals suit the installation. For DB, confirm the B, C, or D bronze and the /11 graphite insert specification rather than assuming the values apply to a /16 PTFE insert. Then calculate the actual projected pressure, sliding speed, and pU for the operating cycle using consistent units. Check both steady and transient conditions.

Review the housing and shaft tolerances, shaft hardness and finish, installation method, thermal expansion, and the required lubrication. Ask the manufacturer to review cases involving shock, oscillation, contaminated or submerged service, elevated temperatures, or long life requirements. The table is not a bearing-life calculation and it does not set a universal fit or safety factor.

For a cylindrical journal bushing, projected area is conventionally based on bore diameter multiplied by bearing length, not the curved contact area. Use the reaction load carried by that bearing and its actual dimensions, then evaluate speed from shaft surface velocity. Oscillating motion may need a different interpretation of average and peak speed than continuous rotation. If load is eccentric or alignment concentrates contact near an edge, a simple average pressure can conceal local loading.

Limits and current documentation

Do not use these selected ratings as design allowables for another bronze alloy or supplier. Do not transfer dry-operation values to a greased or oil-lubricated case without checking the corresponding manufacturer basis. Product data may change; use the current GGB data sheet and application guidance before finalizing a drawing or releasing a replacement part.

Sources: GGB’s current LDD product specifications, the official GGB-DB data sheet, revision 003 (January 2023), and GGB’s data sheet index. Check the current product documents for the exact material and lubrication conditions.