• Goff's Curtain Walls

Improving Profitability Through Flexible Space Separation



Case Study: Gearbox Express works with Storage Systems Midwest to use
Goff’s Enterprises’ Roll-up Curtain Walls & High Speed Doors to Adjust the Size of their Facility.

By: Marcus Mohwinkel, Vice President of Sales & Marketing: Goff’s Enterprises, Inc.

When Gearbox Express, LLC signed a lease on a formerly distressed 43,164 square-foot industrial building in, Mukwonago, Wis., the build-out plans for the production area didn’t include one thing: solid walls. Instead, the company opted for flexible curtain walls from Goff’s Enterprises, Inc., of Pewaukee, Wis., so that they could adjust the size of the shop’s “clean” and “dirty” areas.

Just a few months into operation, the decision paid off when Gearbox Express had the opportunity to acquire several wind turbine gearboxes for their exchange inventory from the field. Thanks to the flexibility of the Curtain Walls, there’ll be no problem expanding the dirty area to accommodate these 16-ton, minivan-sized components.

Why Gearbox Express?

Bruce Neumiller (CEO), Brian Hastings (CFO) and Brian Halverson (COO) combined their 40 years of experience in the gearbox manufacturing and remanufacturing business to found Gearbox Express to better serve the wind turbine and industrial gearbox market segments.

Gearbox Express focuses on “down-tower” services and is one of the first companies in the United States to remanufacture wind turbine gearboxes using an exchange inventory model. The company keeps a stock of remanufactured gearboxes ready to exchange, helping ensure a quick turn-around and getting the gearbox back uptower.

“Our business model is rooted in efficiency, quality, speed and a passionate attitude towards excellent customer service. The sooner our customers have their gearbox uptower and operational, the better it is for their business. We work together to make it happen,” said Neumiller.

Keep ‘em Separated

While gearbox manufacturers don’t operate clean rooms to ISO standards like a hospital or semi-conductor manufacturer does, they do follow many of the same climate control practices. Dust, dirt and other contaminants can cause premature wear in these high tech gearboxes. Because removing and replacing a 32,000-lb. gearbox on top of a 300-ft. tower can cost upwards of $500,000, separating dirty and clean work areas helps maximize gearbox life cycle. (Gearbox Express tests every wind turbine gearbox on its 3.1 megawatt test stand, which is located in the clean area of the shop).

The GBX production area covers 35,000 sq. ft. and is divided into north, center and south bays, with the dirty area at the east end of the building (see diagram). Operations in the dirty area include truck docks, disassembly area, paint booth, parts washer and industrial storage. The clean side of the shop stores the cleaned, re-useable parts and includes the assembly and testing areas.

“I originally looked at a building with hard partitions, but then started feeling a little uneasy about how much space we had to work with,” says COO Halverson, who was primarily responsible for establishing workflow and designing the production area. A single gearbox may have as many as 10 pallets of parts when disassembled. Gearbox Express usually works on three to five gearboxes at any time, either in disassembly or reassembly.

“I was talking about this situation with our property manager and the construction manager, and they recommended Goff’s Curtain Walls as a flexible solution,” he continues. “We wanted soft walls that you could see through. We needed to dodge our overhead cranes, and we wanted to raise and lower the walls, among other requirements.”

A Clear Vision

To help develop a solution, GBX worked with Tim Weidenfeller of Storage Systems Midwest, a Goff’s distributor and leading supplier of storage and material handling solutions based in nearby Waukesha.

To separate the dirty and clean areas in the north and center bays, Weidenfeller specified motorized roll-up curtains made from 20 mil clear PVC and 14 oz solid vinyl. The 59-foot-wide north bay uses three curtains, while the 39-foot-wide center bay uses two curtains, all of which are 21-feet tall and feature a floor sweep to block dust from sliding underneath. One curtain in each bay contains a 3- x 7-foot replaceable strip door, which is attached to the curtain.

“One of our primary considerations was that our two 20-ton P&H cranes need to go in both the clean and dirty areas,” says Halverson. Normally, the company keeps one in each area. “If we need to move them to complete a process, we reel up the walls and pass the crane through. One of my happiest days as far as this facility was concerned was when I learned how tightly the walls roll up. I was concerned that the material would bunch up and the crane wouldn’t be able to pass underneath, but it all went very well.”

He also notes that each curtain rolls up independently, which is an important feature because, “The middle curtain in the north bay gets the biggest workout, as it’s the fork truck aisle.”


Storage Systems Midwest installed the roll-up curtains to the bottom of the roof trusses in a manner that enables them to be removed and relocated to another truss, creating the flexible work area Gearbox Express desired.

Currently, Gearbox Express has the ability to add or subtract a total of 2,352 sq. ft. from its dirty or clean areas. It created this space by combining the roll-up curtains with a 24-foot-wide standard curtain wall that runs perpendicular to these curtains and forms a wall between the center and south bays. The standard curtain has floor sweeps, wind-ties to anchor the curtain to the floor and a walk-through strip door. Should Gearbox Express wish greater flexibility, it can easily install another section of standard curtain wall.

The 49-foot-wide south bay did not require east-to-west size flexibility, but Halverson also wanted a clear PVC standard curtain wall because, “We wanted to be able to see through the wall, as good visibility enhances safety. We have all clear PVC walls because in the dirty area we could be working with a 100-ton press, heat, heavy parts or a fork truck. Visibility enhances safety, but it’s also handy to see what’s going on through the walls.” The workers feel more connected when they can see each other, and the entire curtain can be pulled aside like a gymnasium divider if necessary.

The south bay curtain wall also has a 10 x 10 foot G2 3600 high-speed solid vinyl door that raises and lowers at a rate of 36 inches per second, or up to 12 times faster than a conventional overhead door. As personnel and fork trucks pass through this door to convey washed parts to the clean storage area, high-speed operation helps minimize the time dirt can blow through, as well as controls temperature and air pressure loss.

A remote control that functions like a garage door opener allows drivers to stay in the fork truck, a convenience they enjoy. Should one of those drivers accidentally “blow out” the door, the G2 design enables the door to automatically reset itself.

Staying Positive

Maintaining “clean” status means that Gearbox Express cleans the floor with water (vs. just sweeping) to minimize dust. It also means filtering the air and maintaining positive air pressure on the clean side of the production area. As a test, an auditor will hold a piece of paper by a man door opening between the clean and dirty sides and drop it…and the paper had better blow in the direction of the dirty side.

Halverson worked with Midwest Storage Systems to strategically locate the curtain walls in a way that accommodates the location of the building’s six air conditioners and make-up air unit.

“When we turn on our paint booth and its ventilation system, we turn on the make-up air unit to keep the clean area pressurized,” says Halverson.

Currently, the truss space area above the curtain walls remains open, and Halverson plans to monitor air pressure to ensure that it remains positive. He is not concerned in the long run, however, as Goff’s custom-manufactures valance panels to any dimension so Gearbox Express can create a permanent barrier above the Curtain Wall.

Open House

Gearbox Express held its formal opening on May 1, 2012, and about 175 people from industry and government attended, as well as the Milwaukee Journal-Sentinel. “I don’t think they expected our facility to be this clean or organized. They could tell we took quality very seriously, as there’s not a lot of difference in appearance between our clean and dirty sides,” says CEO Bruce Neumiller. “At the time, we only had a handful of wind gearboxes in-house. It’s just three months later, and now we have more than 15, plus several industrial gearboxes. Things are progressing nicely toward our goal of becoming a 100-person company from the eight we have today.”

Overall, Halverson has been impressed with the products and service from Storage Systems Midwest and Goff’s Enterprises. The curtains were installed in less than three days at a fraction of the cost, time or construction mess that would have been required to install hard walls.

“We’ve actually had many people from the industry in here, and they were impressed with the flexibility and clean appearance of Goff’s Curtain Walls,” he says. “The only mistake I made was not putting one of the man doors right next to my desk. Now I have to walk an extra 25 feet.”

Case Study:

Goff’s – Gearbox Express Case Study

Gearbox Express works with Storage Systems Midwest to use Goff’s Enterprises’ Roll-up Curtain Walls & High Speed Doors to Adjust the Size of their Facility.

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