Hydraulic Breaker Inner and Outer Bushings
Product Description
SLYM MACHINERY supplies replacement inner and outer bushings for selected hydraulic breaker models. These wear components guide the working tool and help control excessive lateral movement within the front-head assembly.
Bushing dimensions, material requirements and installation designs vary by breaker model. Correct fit depends on the applicable component specifications, including the bushing dimensions and working-tool size.
Material options may include 40Cr or 42CrMo alloy steel, depending on the product specification. Machining and heat treatment should follow the applicable drawing or order requirements.
To help confirm compatibility, please provide your hydraulic breaker brand and model, part number, working-tool diameter, existing bushing dimensions or clear photos of the component.
1. Product Function
Hydraulic breaker inner and outer bushings support and guide the working tool during operation. They are wear components that require periodic inspection according to the maintenance requirements of the specific breaker model.
Bushing condition and clearance can affect working-tool movement and wear patterns. Excessive wear, scoring or an incorrect fit may require further inspection and replacement.
When replacing bushings, the working tool, bushing seat and related front-head components should also be checked. Installing a new bushing may not resolve the problem if the housing or supporting components are damaged.
2. Material and Manufacturing
Material and production requirements depend on the breaker model and the applicable component specification.
Material options: 40Cr or 42CrMo alloy steel, where specified for the selected component.
Machining: Dimensions should conform to the applicable drawing or confirmed sample.
Heat treatment: The process and acceptance requirements should follow the relevant product specification.
Dimensional inspection: Inner diameter, outer diameter and overall height should be checked against the required dimensions.
Specific hardness values, heat-treatment depths and mechanical properties should be confirmed from the relevant technical or inspection records before being quoted.
3. Reference Bushing Dimensions
Bushing Dimensions (Inner Diameter * Outer Diameter * Height)
| Size(mm) | Size(mm) | Size(mm) | Size(mm) |
| 30*50*30 | 65*80*80 | 90*100*100 | 110*135*100 |
| 35*45*45 | 70*80*80 | 100*115*70 | 110*135*120 |
| 40*50*45 | 70*90*90 | 100*115*100 | 120*135*110 |
| 45*60*50 | 71*86*60 | 100*116*90 | 120*140*100 |
| 50*60*60 | 75*90*90 | 100*130*100 | 120*140*120 |
| 55*70*50 | 80*95*70 | 100*130*120 | 125*140*90 |
| 60*75*60 | 80*100*85 | 110*130*120 | 45*55*50 |
Outer Bush Compatible Models & Weight Reference
| No. | Compatible Model | Weight (kg) | Design / Mark |
| 1 | HB10G | 13 | Standard |
| 2 | HB20G | 31/14 | Available WITH COLLAR or WITHOUT COLLAR |
| 3 | HB30G | 44/19 | Available WITH COLLAR or WITHOUT COLLAR |
| 4 | HB40G | 59 | Standard |
| 5 | F22 | 28 | High-Wear Resistant |
| 6 | F35 | 38 | High-Wear Resistant |
| 7 | F45 | 53 | High-Wear Resistant |
| 8 | FS37 | 27 | Standard |
| 9 | DMB140 | 8 | Standard |
| 10 | DMB210 | 16 | Heavy Duty |
| 11 | SB50 | 11.5/8 | Available WITH COLLAR or WITHOUT COLLAR |
| 12 | SB70 | 25/14 | Available WITH COLLAR or WITHOUT COLLAR |
| 13 | SB81 | 25/14 | Available WITH COLLAR or WITHOUT COLLAR |
| 14 | SB121 | 30 | Standard |
These dimensions are not interchangeable. Please confirm the required bushing type, part number and breaker application before ordering. Actual availability should be checked against the current product list.
Custom dimensions may be reviewed according to drawings or samples, subject to technical confirmation.
4. Model Compatibility and Configuration
Bushing designs vary between hydraulic breaker models. Some configurations may use a collar, while others use a different external profile or installation arrangement.
When selecting a replacement, confirm:
Hydraulic breaker brand and model
Inner or outer bushing requirement
Working-tool diameter
Inner diameter, outer diameter and height
Collar or non-collar configuration, where applicable
Existing part number or technical drawing
A similar-looking bushing should not be assumed to fit without checking the required dimensions and installation details.
5. Inspection and Replacement
Inspect the working tool and bushings in accordance with the manufacturer's maintenance schedule.
Pay attention to excessive tool movement, uneven wear, scoring, galling and abnormal contact marks. Where necessary, measure the working-tool diameter and bushing internal diameter using suitable equipment, following the specified measurement procedure.
Compare the measured clearance with the service limit for the particular breaker model. There is no single wear limit that applies to every hydraulic breaker.
Before installing a replacement, inspect the bushing seat and surrounding front-head area for damage or deformation. Follow the applicable service procedure during removal and installation.
For more information, read our Hydraulic Breaker Bushing Maintenance Guide.
6. Ordering Information
To help identify the suitable replacement, please send SLYM MACHINERY the following information:
Breaker brand and model
Required inner or outer bushing
Part number, if available
Existing bushing dimensions
Clear photos of the component and its installation position
Our team can review the provided information and confirm the applicable specifications before an order is placed.
For related components, visit our Hydraulic Breaker Spare Parts category. If the bushing locking system is also damaged, see our Hydraulic Breaker Bushing Lock Pin Troubleshooting Guide.
Contact SLYM MACHINERY for bushing specifications, model compatibility and replacement part inquiries.
Technical FAQ
Q1: How does a worn inner bushing cause catastrophic piston and cylinder scoring?
A: When the inner bushing wears beyond maximum allowable limits (typically exceeding 5 mm radial clearance), the chisel tool no longer stays aligned vertically. Under impact, the chisel tilts at an angle inside the housing. This off-axis tilt forces the piston to strike the chisel shank unevenly (off-axis contact), generating severe torsional stress across the piston face. Over time, this angular impact chips the piston striking edge and creates deep axial scratches (scoring) along the precision-honed cylinder bore, resulting in severe internal hydraulic oil bypass.
Q2: What causes galling and metal seizure between the chisel shank and the inner bushing?
A: Galling occurs when high-frequency friction creates localized temperatures above 200°C, causing micro-welding and metal transfer between the tool shank and the bushing wall. This is primarily caused by two maintenance errors:Using incorrect grease: Standard chassis grease lacks solid lubricants and breaks down under heat. Always use heavy-duty lithium grease containing 3% to 5% Molybdenum Disulfide (MoS₂).Greasing in horizontal/suspended positions: Greasing while the breaker is laying flat allows grease to enter the upper strike chamber rather than coating the bushing wear surface. Upon the next stroke, trapped grease causes a hydraulic lock that destroys dust seals and starves the lower bushing of lubrication.
Q3: Why do lower bushings deform into an oval shape ("egg-shaping"), and how can operators prevent it?
A: Ovalization occurs when excavator operators use the breaker chisel as a crowbar to pry or leverage embedded rock. Hydraulic rock breakers are designed strictly for perpendicular, downward impact (90° angle). Applying lateral leverage puts massive bending force against the bottom lip of the lower bushing and the top shoulder of the thrust ring, deforming the circular inner diameter into an oval. This binding traps the chisel, increases internal friction heat, and risks cracking the front head casting.
Q4: Why do inner bushings crack or flake (spalling) under heavy demolition work?
A: Bushing fracture and surface flaking are primarily driven by blank firing (activating the hammer without firm tool down-pressure against rock) and shock-fatigue micro-cracks. Blank firing forces the chisel to drop violently against the stop pins and bushing shoulders without rock resistance, transmitting un-dampened recoil shock directly through the bushing metallurgy. SLYM bushings combat brittle fracture by utilizing precision-forged high-density alloy steel with deep induction hardening on the wear surface, backed by a shock-absorbing ductile core.
Q5: What is the maximum wear limit, and when should breaker bushings be replaced?
A: Bushing clearance should be measured weekly using calipers or a feeler gauge. As a general rule, when the radial play between the chisel shank and the inner wear wall exceeds 5 mm (or manufacturer specs for smaller micro-breaker classes like SM40/TB20), the inner bushing must be replaced immediately. Replacing worn bushings promptly costs a fraction of a full cylinder re-hone or piston replacement. Additionally, inspect retaining pins daily for flat spots and rotate them 90° during reinstallation to ensure even wear distribution across the bushing pin slots.