6D108 - 2 Diesel Used Engine Blocks For Excavator PC300 - 6 Water Cooling

Specification

Description

Pinning Techniques

Straight threaded pins won’t seal a crack unless a heat-resistant, ceramic-based thread sealer is applied to the threads and the tops of the pins are peened over. Don’t use ordinary anaerobic thread sealer on pins in or around the combustion chamber or exhaust ports because it can’t take the heat.

straight threaded pin

Another type of straight threaded pin uses a special directional thread with a shoulder at the top of the pin. The upward rake of the threads produces a pinching or clamping effect when the pin is tightened. This allows the pin to grip the adjacent metal more tightly, which works well with thin wall castings. Special taps are required with this type of locking pin to form the threads in each drilled hole. It’s a two-step process, starting with a roughing tap and followed by a finishing tap.

Tapered pins or plugs are installed in essentially the same manner except that the depth of the pin is more critical for a proper fit. A tapered pin is narrower at the bottom and wider at the top. It works like a threaded pipe plug and wedges itself into the hole as it is tightened. Tapered plugs require a special tap. Once each plug has been installed, the top must be cut or ground off.

Some threaded pins have tops that are designed to snap off when the plug is tightened. This saves the extra step of having to trim off the top of the plug, but the torque on the plug can vary depending on the diameter of the plug and the thickness of the casting.

For cracks that may spread under heat or load, “locks” can be placed at intervals along the crack to stitch and hold the crack together. Some locks have a bowtie shape while others are shaped like a string of flattened beads. Locks are installed across the crack (perpendicular to the crack) like shoe laces, with the remainder of the crack filled in with overlapping pins.