Hardened steel bushings
Heat-treated steel sleeves, HRC 58–62, for lubricated, slow-moving, high-load pivots on excavators, rotary drilling rigs, large loaders and diaphragm-wall grabs. Metric and inch, 20–150 mm nominal bore, made to order.
- HRC 58–62Hardness
- 250 N/mm²Maximum load
- 0.1 m/sMaximum speed
- 20–150 mmNominal bore range
A hardened steel bushing is a plain-bearing sleeve made from carbon, alloy or bearing steel and heat treated so that its bore resists wear from a hardened pin under heavy, slow, lubricated motion.
- Materials: Grade 45 carbon steel, 40Cr and 20CrMo alloy steel, GCr15 bearing steel
- Hardness HRC 58–62; maximum load 250 N/mm²; maximum sliding speed 0.1 m/s; maximum PV 1.5 N/mm²·m/s
- Working temperature −100 °C to +350 °C
- Bore machined with oil grooves and radial feed holes to your pattern
- Standard metric and inch dimensions, 20–150 mm nominal bore, plus sizes to drawing
Four steel grades, one heat-treated bore
Each grade is heat treated to produce the HRC 58–62 running surface. The grade is chosen against the pin material, the load and the temperature; when in doubt, state the pin and let us propose the sleeve.
Grade 45 carbon steel
The economical route for general pins and pivots under moderate shock.
Carbon steel40Cr alloy steel
Higher core strength for heavier loads and larger sections.
Alloy steel20CrMo alloy steel
Case-hardening grade: hard surface over a tough core for impact-loaded joints.
Alloy steelGCr15 bearing steel
Bearing-quality steel for the highest hardness and wear resistance.
Bearing steel
Steel grades and heat treatment
JBM-ST bushings are made from four listed steel grades: Grade 45 carbon steel, 40Cr alloy steel, 20CrMo alloy steel and GCr15 bearing steel. Other steels can be quoted when the application calls for them; the four listed grades cover the great majority of construction-machinery joints.
All grades are heat treated to a bore hardness of HRC 58–62. The hardness is what lets the sleeve run against a hardened pin under 250 N/mm² without galling; the steel grade sets how much core strength sits behind that surface. Grade designations are quoted as supplied, without assumed SAE, EN or JIS equivalents.
Put the pin material and hardness on the enquiry. Sleeve and pin are specified as a pair.
Performance limits
The reference values below are the JBM-ST published limits. Each row is a separate limit: a joint may run at the maximum load or at the maximum speed, not at both together, and the PV value is the boundary that ties them.
| Parameter | Unit | JBM-ST |
|---|---|---|
| Hardness | HRC | 58–62 |
| Maximum load | N/mm² | 250 |
| Maximum linear speed | m/s | 0.1 |
| Maximum PV | N/mm²·m/s | 1.5 |
| Working temperature | °C | −100 to +350 |
| Linear thermal expansion | °C⁻¹ | 1.1 × 10⁻⁵ |
Series reference values. Load, speed, PV and temperature are separate limits; they are not simultaneously achievable.
Oil grooves and feed holes
JBM-ST is a lubricated bushing. Grease or oil reaches the bore through radial feed holes that line up with the housing lubrication point, and a machined groove pattern carries it away from the feed point across the loaded arc. Without the groove the lubricant stays where it entered and the far side of the bore runs dry.
Groove patterns are machined to the application: straight, spiral, figure-of-eight or a customer pattern. Specify the groove and the feed-hole position relative to the principal loaded arc and to the housing lubrication point, or send the pin-and-housing drawing and we will propose one.
Sizes and tolerances
JBM-ST sleeves are manufactured in standard metric and inch dimensions with a nominal metric bore range of 20–150 mm, and to drawing outside that range. Complete legacy references are 55 × 65 × 45 mm and 60 × 70 × 70 mm (bore × outside diameter × length); every size is made to order and confirmed at quotation.
Bore and outside-diameter tolerances, housing retention, running clearance, chamfers and groove geometry are set for the quoted part from the customer drawing. Nominal size alone does not fix them.
The size chart lists the references and explains how to write and measure a steel bushing size.
What to put in the enquiry
Five items let us quote within 12 hours and machine a sample without a second round of questions.
Dimensions
Bore, outside diameter and length, with tolerances if you have them, or the drawing.
Pin and housing
Pin diameter and hardness, housing bore and material. Sleeve fits are set against these.
Steel grade
Grade 45, 40Cr, 20CrMo, GCr15, or leave it to us with the load and temperature stated.
Lubrication features
Groove pattern, oil-hole diameter and angular position, or the housing feed point.
Quantity and programme
Sample, batch and annual quantity. Samples are free; there is no minimum order.
Where hardened steel bushings are used
Heavy, slow, greased joints in abrasive surroundings: the pivots of construction and foundation machinery.
Frequently asked questions
What hardness are JBM-ST hardened steel bushings?
HRC 58–62 after heat treatment, on all four listed grades: Grade 45, 40Cr, 20CrMo and GCr15.
Do hardened steel bushings need lubrication?
Yes. JBM-ST is a lubricated bushing for slow, heavy motion; grease or oil is fed through radial holes and distributed by machined bore grooves. For joints that cannot be relubricated, look at graphite-plugged bronze or PTFE composite bushings instead.
What sizes are available?
Standard metric and inch dimensions with a nominal metric bore range of 20–150 mm, and sizes to drawing outside that range. All sizes are made to order and confirmed at quotation; samples are free.
Which steel grade should I choose?
Grade 45 for general pivots, 40Cr for heavier loads and larger sections, 20CrMo where a hard case over a tough core is wanted for impact, GCr15 for the highest wear resistance. State the pin material and hardness and we will confirm the pairing.
Can you match my existing pin bushing part number?
We quote against an OE or supplier part number after comparing dimensions and material; interchangeability is confirmed part by part. Send the drawing or the dimensions you have measured on a new part.
Send the pin, the housing and the size.
Our engineers confirm the steel grade and groove pattern and quote within 12 hours. Samples are free and there is no minimum order.