TBM Thrust Cylinders

You are 500 meters into a drive, the ground conditions have just shifted from clay to abrasive granite, and suddenly the operator reports a pressure drop in Zone B. You check the propulsion system and see it: the trunnion ear on the number 12 cylinder has cracked, or...

Shotcrete Hopper Agitator Cylinders

You know the sound. You are standing in a damp tunnel, the shotcrete machine is humming, and suddenly the rhythm breaks. The hopper stops churning. The concrete, which was supposed to be flowing smoothly into the pumping cylinders, starts to bridge and harden. In my...

Shotcrete Feeding Cylinders

If you have spent any time around a wet-mix shotcrete machine, you know that sound. It’s not the engine humming; it’s that subtle, grinding noise of the feeding system struggling against a harsh, dry aggregate mix. In my 18 years of designing and fixing hydraulic...