If the Breaker Runs Irregularly: Control Valve Failures
26 November 2025
The Control Valve (Distributor Valve) is the "brain" of the breaker, directing oil flow to move the piston up and down. If your breaker is running irregularly, skipping beats, or not starting at all, the problem is usually here.
Faults in the valve system are often caused by microscopic scratches or jamming. Valve cleanliness is crucial, especially in sensitive breakers like Rammer and Montabert.
1. Why Does the Breaker Skip or Stop?
Common valve problems on site:
- Valve Jamming: Particles in dirty oil get stuck between the valve spool and housing. The breaker "locks up".
- Valve Cover Scratch: Scratches on the Valve Cover cause pressure loss. The breaker slows down and loses power.
- Broken Spring: If the return spring inside the valve breaks, the valve cannot change position, and the breaker stops.
2. Valve Repair and Maintenance
Part replacement is not always necessary for valve failures:
| Issue | Solution | Note |
| Jamming | Sanding & Cleaning | Can be fitted with very fine water sandpaper. |
| Scratched Cover | Lapping | Surface can be corrected with special paste. |
| Excessive Wear | Replacement | If the valve body is worn, it must be replaced completely. |
3. Compatible Brands
HKM provides support for valve seals, valve covers, and complete valve groups for the following brands:
- Rammer: S 23, S 25, E 68 (Sandvik).
- Montabert: SC 36, V 32, V 1200.
- Furukawa (FRD): F 5, F 22, F 35.
- Soosan: SB 40, SB 81, SB 121.
- Others: Atlas Copco, MSB, Daemo, Indeco, Toku, MTB.