How to Rebuild a Swing Drive
If you’ve spun around in an excavator cab, you know that an important part making that happen is the swing drive and, if you’ve worked in an excavator long enough, you know that the swing drive is a part that often comes with an expiration date. A good swing drive will have a long life, but due to the nature of its work, it just won’t last forever.
Not every swing drive that passes through our salvage shop is able to be saved, but often heavy worn parts can be replaced and combined with original OEM parts to create a perfect rebuilt part. In this case, our Part Technician Matt puts his skills to work on a Komatsu PC490LC-11 swing drive. Watch the video to see our process or read the detailed steps below.
Want to see how a swing drive is disassembled? Watch that process in our How to Dismantle a Swing Gearbox post.
Rebuilding a Swing Drive Step-by-Step Process
- Every rebuild in the H&R Recon and Rebuild shops starts with a mix of salvaged and new parts.
- In the video the tech starts with a new lower bearing, new retainer plate, and new oil seal.
- Using an extra plate on top of the seal helps the seal move evenly into the retainer plate without damaging the seal.
- In the video, notice the tech uses extra spacers on top of the pinion shaft to account for the top height of the press.
- Throughout the process, lifting eye bolts are used for moving parts. In this case, a lifting eye bolt attaches to a forklift and later an overhead crane to help the tech return the freshly-pressed parts to his working area, the same way it was brought to the press.
- To prevent the inside of the housing from rusting while it is heated in the oven the tech oils the inside of the housing.
- The tech transports the swing drive to the oven for heating. The process will expand the steel just enough to fit the bearing, and when the parts cool, the fit of the two parts will be sealed.
- While the housing bakes for 20 minutes, the tech starts with the planetary. Before installing the pins, a taper punch is used to open the holes.
- Previously they had been closed to prevent the pins from backing out.
- Expanding the upper bearing with heat will help the parts properly fit together.
- In the video, notice how small the tolerance of the parts is.
If you’re planning your own swing drive rebuild we hoped a look at our process was helpful, if you’re just inquisitive about parts we hoped you found our process interesting, and if you’re in search of a replacement swing drive we’re, of course, always here as a resource for you.