Why Do Through Bolts Snap? Importance of Torque Settings
26 November 2025
The parts that clamp the three main blocks of the hydraulic breaker (Front Head, Cylinder, Back Head) together are called Tie Rods (Through Bolts). These parts are the backbone of the breaker.
The most common "bolt snapping" issue on site is usually caused not by metal quality, but by lack of maintenance (loosening). When one bolt snaps, the others are subjected to extreme load, causing a chain reaction of damage.
1. Why Do Tie Rods Snap?
The breaker stretches at a micron level with every strike. This vibration loosens the nuts over time.
- Loosening: The moment a bolt loosens, the tensile load becomes unbalanced, and it snaps due to metal fatigue.
- Blank Firing: If the piston energy hits the housing instead of the rock, this shockwave stretches and snaps the bolts.
- Over-tightening: Bolts tightened without a torque wrench exceed their elastic limit and "stretch their necks".
2. Maintenance and Torque Check
Follow this routine to protect your bolts:
| Action | Frequency | How to Do? |
| Visual Check | Daily | Check for loose nuts or cracks. |
| Torque Check | Weekly (50 Hours) | Tighten to factory specs with a torque wrench. |
| Replacement | Yearly (Recommended) | Replace as a set to prevent fatigue failure. |
3. Compatible Brands
As HKM, we support the following models with our high-strength steel aftermarket tie rods:
- Atlas Copco (Epiroc): SB 102, SB 202, MB 1200, HB 2000, HB 3000.
- Rammer: S 23, S 25, E 68, G 80, G 100.
- Furukawa (FRD): F 5, F 9, F 22, F 35, F 45.
- Montabert: SC 36, V 1200, V 32.
- Soosan: SB 81, SB 121, SB 151.
- Others: MSB Saga, Daemo DMB, Toku, Indeco, DNB, MTB.