PIN ASSY

264 388 01 TAPER PIN is essentially the muscle inside your rock drill or a heavy-duty feed cylinder. It’s what takes that hydraulic pressure you’re pumping into the system and turns it into actual work – either slamming into the shank adapter to break rock or pushing the feed beam to advance the drill. Think of it as the primary mover, really. It cycles back and forth, driving the impact mechanism, or extending and retracting a cylinder, depending on where it’s fitted. Without it, you’re just circulating oil.

When this piston starts wearing out, you’ll usually notice a drop in impact power if it’s in the rock drill. The penetration rate goes down, and the operator might complain about the hammer 'feeling soft' or just not hitting like it used to. If it's in a feed or positioner cylinder, you might see drift, or the cylinder just won't hold its position under load, slowly creeping. Sometimes, you'll hear a different, more 'slapping' sound from the hammer, or the hydraulic pressure might fluctuate more than it should, indicating internal leakage past worn seals or grooves on the piston itself.

Replacing this isn't usually a quick job, so make sure you've got the right tools and a clean workspace. When you pull the old one, always check the cylinder bore for scoring or damage – a new piston won't last long if it's running in a grooved bore. And don't forget to properly lubricate the new piston and its seals before installation; a dry start can ruin new seals pretty fast, leading to premature failure and another breakdown.