Gear Manufacturer & Supplier – EMD 645 & 710 Parts

Overview

EMD 645/710 engines run two connected gear trains off the crankshaft: the accessory drive gear train (turbo, water pump, and other accessories) and the camshaft gear train, linked through idler gears. Everything downstream of the crankshaft — valve events, injector timing, accessory speed — depends on these gears staying in correct mesh.

How It Works in the Engine

Idler gears step the camshaft down to run at half crankshaft speed, which is what keeps valve and injector timing phased correctly against piston position through every cycle. Because the whole train is one connected system, wear or backlash in a single gear doesn't stay isolated — it shows up as drift across the timing-dependent systems it drives.

Signs You Need a Replacement

• Tooth wear, pitting, or spalling visible on inspection
• Backlash increasing beyond tolerance, causing valve or injector timing to drift
• Gear noise or whine under load that wasn't there before
• Uneven wear pattern suggesting the gear was running slightly out of mesh

Why Source This From Apex International

Tooth profile and bore dimensions are checked against EMD/DLW references so a replacement gear meshes correctly with the rest of the train on day one, instead of needing a break-in period to wear itself into tolerance.