ARNOLD AIR FORCE BASE, Tenn. -- Five Arnold Engineering Development Complex team members created a device to help reduce cost and time in maintaining equipment for the von Kármán Gas Dynamics Facility, or VKF, at Arnold Air Force Base.
Bruce Jones, Eddie Lee, Carlos Bussche, Gary Jarrell and Joel Sizemore helped to design, fabricate and build a device that allows the user to surface new brushes for the sync motors in the VKF Compressor Drive.
“It takes two craftsmen approximately one hour to prep and surface one brush to the contour of the slip ring,” said Jones, an engineering technical specialist at Arnold. “But with this brush surfacing device, one craftsman can surface over 120 brushes in the same amount of time.”
Using the current method, labor cost is more than $5,000 to surface all of the S1-S5 sync motor brushes.
“The new brush surfacing device has the potential to allow one craftsman to be able to surface the brushes for all S1-S5 sync motors in less than 25 minutes, which will be a significant cost savings,” Jones added.
The brush surfacing device assists with maintaining the five motor drives that provide the airflow for the VKF wind tunnels.
“The carbon brushes rub the slip rings, causing electricity to go in the rotor,” Jones said.
Jarrell, an operations engineer, added, “These brushes are regularly checked, and if cracked or worn, they are replaced.”
Fabricating the brush surfacing device was originally an idea Lee and Bussche, electricians at Arnold, had when discussing the difficulty of the brush surfacing process.
“Being able to get in place to do it can be hazardous, and it takes an hour for two people to complete just one,” Jones said. “I got on a computer and designed the device according to the dimensions needed, Gary Jarrell located the materials and then Joel Sizemore did the machining, fabrication and assembly.”
In July 2021, the group put the brush surfacing device to use for the sync motor brushes.
“The first time that we used it, it worked,” Jones said. “With the old process we used, the craft guys would surface the brushes in place and would have to crouch down or be in an awkward position. It would create a bunch of dust, so completing the task, along with cleanup, would take an hour or more at a time. This way is a lot easier and safer, in addition to saving labor costs and time.”
Another plus about the brush surfacing devices is that they may be utilized in other AEDC test facilities.
“I have been talking to an engineer at the Propulsion Wind Tunnel, and he is interested in using the same concept,” Jones said. “As long as the diameter of the slip rings is the same, it will work. If not, the surfacing wheel could be custom made to fit.”