Zeus timing gears for 2.5 Landies are all gears.
The principle of gears is fine, but the execution is dismal, and failures are probable. In the old Autin diesel taxi engine the timing was by gears, and I can tell you those were GEARS compared to the wimp Zeus stuff.
From the crankshaft gear the drive is taken to a larger idler gear, so this runs much slower than the crankshaft, about half-speed in fact.
This gear meshes with a gear on the camshaft with twice as many teeth as the crankshaft gear, so the camshaft turns at half engine speed.
An identical gear is fitted to the injection pump, but because it and the camshaft MUST turn in the same direction (both the same way as the crankshaft) these two gears cannot be allowed to mesh directly. So there is a second idler gear fitted between them, which is about the same size as the crankshaft pulley. Bad plan .....because the drive is taken from a BIG gear to a small gear the small gear has to go twice as fast, AND it gets badly distributed forces and increased forces applied to it. Basically, it all looks like a recipe for disaster to me.
Change belts as required, and save the money, especially as Zeus seem to have a shocking reputation for "service" when their product fails.
CharlesY
