At the connection between an excavator house and its undercarriage sits a swing motor and swing gearbox with a short pinion shaft connected to a slewing ring. Every time that hard-working swing motor engages it sends the house swinging in a circle. Because its work is hard, frequent, and often fast-moving, a swing motor is under intense pressure and when it stops working it takes one of the most critical functions of an excavator with it.

While not every swing motor that comes from our salvage teams can be rebuilt, for those that can there’s always an experienced parts technician ready to rebuild and reassemble this part. So when someone’s swing motor fails, there’s a replacement swing motor ready and waiting.

To see the reassemble process for this part, take a trip into one of the H&R Recon and Rebuild shops as a parts tech reassembles a Komatsu PC300-7 swing motor.

How to Reassemble a Swing Motor (Step-by-Step Process)

• The housing for the swing motor is placed into an industrial parts oven to expand.
  • The oven will gently expand the housing, allowing parts to be mounted into it without applying an abundance of force.
• The rotating shaft is inserted into the housing.
• Clutches are placed around the rotating assembly.
• The brake piston is fastened on top of the rotating assembly.
• Pistons are inserted into the brake piston.
• A spring is positioned over the center piston.
• A barrel is placed on top of the spring.
• The top of the housing is placed onto the base of the housing using an overhead crane.
• The pistons are propped into the top of the housing before bolting both halves together.
• The main relief valve is set into the housing.
• Poppet valves are placed into the front and back of the housing and tightened firmly into the housing.
• The equalizer valve is fastened to the top of the swing motor.
• The technician tests the swing motor to ensure that it performs to a working standard.
• The swing motor is primed, painted, palleted, and ready to ship to a customer.

Whether you’re just the kind of person who loves to watch a video from the shop, you’re looking for tips on how to reassemble your own swing motor, or you’re trying to solve a swing motor problem, hopefully you found our video interesting. If you’re in the last category, we’re always here to help you find a replacement swing motor for your excavator.

When you call, we’ll search our deep inventory of parts from the machines we salvage, our own new parts inventory, and even our national connected parts networks.