Front Heads, Cylinders & Back Heads
Heavy machined breaker bodies, bored and honed to the piston fit, with bushing seats and bolt holes machined in the same set-up where possible.
Heavy parts, cylinder-shop tolerances
A breaker cylinder body is a thick-walled bore held to a running fit against a hardened piston, with cross-drilled oil passages that must break through cleanly and be deburred. That is deep-hole boring and honing work, which is the core of our cylinder line.
Front heads add the bushing seats and the retainer pin bores, and their alignment to the cylinder bore is what determines whether the tool runs straight. Where the drawing allows, we machine the bushing seat and the bolt holes in the same set-up as the main bore.
Specification
| FIELD | UNIT | ORISE VALUE |
|---|---|---|
| Maximum part length | mm | 1800 |
| Maximum bore diameter | mm | 400 |
| Maximum part weight | kg | 1200 |
| Bore tolerance | ISO class | H8 standard · H7 where the piston fit requires it |
| Bore roughness Ra | µm | 0.4, honed |
| Bore straightness | mm/m | 0.3 |
| Piston-to-bore running clearance | mm | 0.05 to 0.07 total, set against the mating piston |
| Material | — | 42CrMo front and back head · 20CrMo cylinder body · 40CrMo, to drawing |
| Heat treatment | — | Forge, quench and temper, stress relieve before final boring |
| Cross-hole deburring | — | Mechanical deburring and pressure washing, with borescope check of every oil passage |
| Cleanliness | — | Washed, dried and oiled. A written cleanliness limit can be agreed and verified by filtered flush and particle count |
Cleanliness matters more than it looks. Swarf left in a cross-drilled oil passage will destroy a rebuilt breaker in hours. State your cleanliness requirement and we will quote the washing and inspection step visibly rather than absorb it.
What we need from you
- Brand, model and whether the body is the front head, cylinder or back head
- Drawing, or a serviceable sample for measurement
- Bore tolerance and the piston it must run against
- Oil passage layout and any cleanliness requirement
- Surface protection required for shipping and storage
Send the part, the drawing or the model
A photograph with a scale rule and the machine model is usually enough to begin.