Wicket Gate Servo Motor Refurbishment

Power House Unit 1 Wicket Gate
Servo Motor Refurbishment


Location: Butte County
Completed: February 2020

A longtime client of TCB contacted our Hydro Division about an excessive oil leak both internal and externally on the wicket gate servo motors. TCB jumped into action, performing as found alignment measurements of the wicket gate elevations and shutter clearances. It was determined that the wicket gate measurements were out of specification tolerances and would need to be corrected in parallel to the Servo refurbishment. TCB’s crew disassembled the servo motors and transported them to one of our trusted vendors for further, in depth disassembly and investigation. During this process we found that the piston rods needed new bushings and piston rings. In addition to that, the pistons themselves were cracked and deemed unusable. TCB along with Machine Shop fabricated two new heads, one for each servo.

Along with TCB’s in-house confined space team, we successfully realigned each gate to ensure all shutter clearances were at zero. While on site for these repairs, TCB was also contracted to remove and install new rotor lower fan blades and fabricate/install new guardrails on top of the rotor air housing. Upon refurbishment completion, both servo motors were then transported back to site to be reassembled and properly aligned to the gate ring. The PRV was linked up, and restored to the original position. Team TCB ran a successful final inspection with the system primed to ensure that there were no leaks.