Split Steel Bushing
Split Steel Bushing
Self-lubricating bronze bearings are engineered for applications where external lubrication is impractical. Solid lubricants are compressed and molded directly into the bearing to guarantee a maintenance-free product. No additional lubrication is necessary.
Split Steel Bushings with Embedded Graphite Solid Lubricant
A split steel bushing combines three features that rarely come together: a steel body for strength and cost, a two-piece split construction for installation around a shaft that cannot be removed, and embedded graphite plugs that lubricate the contact for life. This page covers the material system, the standard dimensions and the applications where the design earns its place. For the cast-bronze equivalent, see the split bronze bushing with solid lubricant; for one-piece steel bushings, see the steel bushing page.
Key points
- Steel body (GCr15 bearing steel or HT250 cast iron) — higher load capacity and lower material cost than bronze
- Graphite plugs embedded at 25–35% surface coverage — no grease fittings, no relubrication
- Split in two halves — mounts around an installed shaft without disassembling the machine
- Standard sizes from small guide bushings to heavy mill housings; custom halves machined to drawing
What Is a Split Steel Bushing?
The bushing body is steel rather than bronze, formed in two half-shells that close around the shaft. Holes drilled through the steel wall in a regular pattern carry plugs of solid lubricant — typically high-purity graphite, sometimes a graphite composite — which smear a thin dry film onto the mating surface during the first rotations. After running-in, the pair slides on that solid film for the rest of the service life.
Split and one-piece versions share the same lubrication principle; the difference is mechanical. A split bushing can be installed or replaced by opening the two halves, so the shaft, coupling and gearbox stay in place. On long line shafts, rolls and marine stern tubes, that single feature cuts replacement time from days to hours.
Steel vs Bronze for Split Bushings
Both materials work; the choice follows load, corrosion exposure and budget. Steel scores on strength and cost — a GCr15 steel bushing runs harder and carries higher projected pressure than a tin-bronze equivalent, at a noticeably lower material price. Bronze scores on corrosion resistance, conformability and emergency dry-running behavior. Where the housing already exists in bronze, keep bronze; where the design is new, the load is heavy and the environment is dry or oiled, steel is the cost-effective default.
| Aspect | Cast Iron Bushing (Hiking Boot) | GCr15 Steel Bushing (Running Shoe) |
|---|---|---|
| Material | HT250 cast iron (sturdy, absorbs vibrations) | GCr15 steel (harder than a diamond ring, heat-treated) |
| Strength | Good for moderate loads, dampens shakes (like engine parts) | Handles extreme pressure (e.g., mining crushers) |
| Environment | Loves heat, hates chemicals | Tough in dust/heat, but rusts in water/acid without a coat |
| Cost & Use Case | Cheaper, great for farms or factories | Pricier, for critical roles (trains, ships, aerospace) |
| Durability | Wears gracefully over time | Lasts longer under brutal stress but cracks if mishandled |
Material Data: GCr15 and HT250 Steel Grades
Two steel families cover the range. GCr15 bearing steel (equivalent to AISI 52100) is the standard for machined split bushings under high contact pressure; HT250 cast iron is the economical option for large, heavily sectioned halves where the loading is compressive and speeds are moderate. The graphite plug system is identical in both.
| Technical Data | |||||
|---|---|---|---|---|---|
| Performance index/Type | Oilless Bearing | Graphite Plugged Bushing | Oil-free Bearing | HT250 Steel Bushing | GCr15 Steel Bushing |
| Max Move Load Capacity | 100 | 60 | 70 | 250 | 60 |
| Max Sliding Speed | dry0.4 oil0.5 | 2 | 2 | 0.1 | 0.5 |
| Max PV Value Limit | 3.8 | 0.5 | 0.6 | 2.5 | 0.8 |
| Density | 8 | 8 | 7.6 | 7.8 | 7.3 |
| Tensile Strength | >600 | >250 | >500 | >1500 | >250 |
| Elongation | >10 | >4 | >10 | – | – |
| Hardness | >210 | >80 | >80 | HRC>55 | 160 |
| Max Working Temperature | 300 | 350 | 300 | 350 | 400 |
| Friction coefficient | Oil Lubrication:0.03 | ||||
| Dry Friction:0.16 |
For the full chemical composition limits and the SL1/SL2 lubricant codes behind these grades, refer to the material tables on the steel bushing page.
Request Sizes & Pricing
Email your drawing or list the bore, OD, length and split type you need. Standard halves ship from stock; custom steel split bushings are machined per drawing with the mill certificate for each lot.
Why the Split Design
Split bushings exist because shafts often cannot be removed. Typical triggers:
- Continuous line shafts — conveyors, roller tables and paper machines where the shaft passes through many housings
- Coupled drivetrains — gearboxes and couplings that would need full disassembly for a one-piece bushing
- Marine and hydropower — stern tubes and gate mechanisms where the shaft stays in the hull or the gate
- Maintenance-driven replacements — worn bronze or babbitted bearings converted to self-lubricating split halves during overhaul
The split line can run axial (two semicircular halves) or stepped/doweled for positive location, depending on housing design and load direction.
Standard Dimensions
The split series follows the standard bushing dimension conventions: bore in H7, length in standard steps, and flange or plain OD per the housing design. The table below lists the common part-number series; intermediate bores and asymmetric halves are machined to drawing.
| Part No. | 1.D. φd H7 | O.D. φD | φF d11 | L h12 | L1+0.1 0 | t | C | |
|---|---|---|---|---|---|---|---|---|
| split bearing | 30 | 38 | s6 | 48 | 34 | 22 | 6 | 1 |
| split bearing | 35 | 45 | “ | 55 | 45 | 32 | 6.5 | “ |
| split bearing | 40 | 50 | “ | 60 | 50 | 35 | 7.5 | “ |
| split bearing | 45 | 55 | “ | 65 | 55 | 40 | 7.5 | “ |
| split bearing | 50 | 60 | “ | 70 | 60 | 45 | 7.5 | “ |
| split bearing | 60 | 70 | “ | 80 | 70 | 50 | 10 | 2 |
| split bearing | 70 | 85 | “ | 95 | 80 | 60 | 10 | “ |
| split bearing | 80 | 95 | “ | 110 | 95 | 70 | 12.5 | “ |
| split bearing | 90 | 105 | “ | 120 | 105 | 80 | 12.5 | “ |
| split bearing | 100 | 115 | “ | 130 | 115 | 90 | 12.5 | “ |
| split bearing | 110 | 125 | r6 | 140 | 125 | 100 | 12.5 | “ |
| split bearing | 120 | 135 | “ | 150 | 140 | 110 | 15 | “ |
| split bearing | 140 | 160 | “ | 175 | 160 | 120 | 20 | “ |
| split bearing | 160 | 180 | “ | 200 | 180 | 140 | 20 | “ |
Length-to-bore ratios of 1:1 to 1.5:1 cover most guide and support duties; longer ratios are used where shaft alignment is imperfect and the load spreads over the full length.
Applications by Industry
Split steel bushings with embedded graphite are specified where heavy load, awkward access and relubrication cost meet:
- Steel and rolling mills — roller table shafts, shear auxiliaries, furnace door mechanisms
- Hydraulic engineering — gate hinges, sluice bearings, dam machinery
- Mining and crushing — screen shafts, crusher auxiliaries, conveyor drives
- Marine — rudder and deck machinery supports in non-submerged positions
- Mold and die — large press guide positions retrofitted from greased bronze
Installation and Maintenance
Fit the halves into the housing with the split line at 45 degrees to the load direction where the housing allows it, so neither half edge carries the concentrated load zone. Check the running clearance after closing the housing — the steel body does not close up as much as a split bronze shell under bolt load. A thin assembly paste on the outer surface prevents fretting between bushing back and housing.
During the first hours the graphite film builds on the shaft; expect a brief settling period in friction and wear, then stable dry-running values. No grease nipples, no lubrication schedule — inspection intervals follow the machine’s own overhaul plan.
