In-House Pre-Assembly of Split Girth Gears and the Nine-Step Assembly Method

Why Split Girth Gears Should Be Pre-Assembled In-House

The large girth gear uses a four-segment structure. The four segments are first assembled in-house into two half-gears, lifted separately and bolted to the shell, then the full ring is closed into a complete large gear and adjusted for concentricity with the shell.

Keeping pre-assembly and trial running in-house means tooth alignment, concentricity and bolt-hole registration have already been verified before shipment, so on-site assembly steps are fewer and rework risk is lower.

Sequence of the Nine-Step Assembly Method

Jacking device layout → multi-section shell assembly (spigot location on end faces plus connection bolts tightened) → split girth gear assembly → shell lifting → end cover and hollow shaft bolting → bearing seat assembly → stepwise lowering of the shell assembly → girth gear installation → accessory installation and trial running.

After each step, measure before proceeding to the next; the coaxiality of the hollow shafts at both ends is checked with a laser tracker, and the bearing seats are also adjusted for equal height and concentricity with the laser tracker.

Synchronous Jacking and Lowering: Installation Without Large Lifting Equipment

Using synchronous jacking devices together with square boxes, square stools and shim plates in alternating layers, the shell is lowered as a whole onto the bearing seats, reducing the lifting capacity required; this also suits installation sites where the user has no large lifting equipment. Flush the bearing seats before each lowering step to prevent scoring of the copper bush; flush again when the clearance between the hollow shaft journal and the copper bush reaches 5 mm. As a reference for our capabilities, the maximum outer diameter for gear machining is Ø10 000 mm and the maximum module is within M60.