In the summer of 2002, the Wisconsin Department of Transportation (WisDOT) and the city of Milwaukee were assembling a team to build a new vertical-lift bridge over the Milwaukee River. As part of an expressway rerouting project, the bridge would connect the Knapp Street and McKinley Avenue arteries of downtown Milwaukee. Considered a fast-track project, the Knapp Street Bridge would require precision coordination among its builders to ensure rapid and efficient development.
Once a design firm and construction company had been chosen, the Oilgear Co. (Milwaukee) was selected as a subcontractor to supply both the hydraulic- and electronic-control components of the bridge. The fact that Oilgear could functionally serve as both a mechanical and an electrical subcontractor meant that traditional coordination challenges between the two disciplines would be covered by a single source that housed both engineering and manufacturing functions.
“Controlling the bridge should almost be a discipline in and of itself,” said Tom LaCombe, systems sales manager for Oilgear. “There are a lot of integration nuances that can be overlooked if hydraulic and electrical scopes of supply are awarded to separate subcontractors.” This unconventional philosophy won over Zenith Tech (Waukesha, Wis.), the primary contractor on the Knapp Street Bridge project. Working with a bridge design rendered by HNTB Corp. (Kansas City, Mo.), Oilgear supplied all of the hydraulic components (e.g., hydraulic cylinders, power units and all of the valving), as well as all of the electrical components (e.g., electronics, operator interface devices and control desks).
The bridge has a dead load of 735,000 lb, about 89% of which is leveraged by counterweights when raised. Oilgear’s hydraulics effectively lift the remaining 11% (79,000 lb) to a height of 12 ft 3 in. A 100-hp main motor is accompanied by a 25-hp emergency drive.
In accordance with Oilgear’s performance assurance program, the entire hydraulic/electronic system underwent an exhaustive factory system test at Oilgear’s facility prior to installation on the bridge.
The system was fully piped and wired on the shop floor, and using various devices Oilgear conducted a simulation of the bridge’s operation for the customer.
Following a successful demonstration, Oilgear adhered to a strict shipping timeline designed for optimal efficiency at the work site. Once the system was all piped and wired on the bridge itself, it took Oilgear just one week to commission the bridge according to the project’s specifications. Final commissioning occurred in July 2004.
The Knapp Street Bridge project wasn’t the first time Oilgear had demonstrated the efficiency of its multidisciplinary approach on bridges.
It was actually the company’s second opportunity on the Milwaukee River alone. Just downstream of Knapp Street, the Wells Street Bridge is controlled with Oilgear hydraulics and electrical components.
A bit north of Milwaukee, in Sheboygan, a bridge over the Sheboygan River marks an exceptional achievement for Oilgear and its collaborators on the project. In 1995, the South 8th Street Bridge in Sheboygan became the first non-counterweighted bascule highway bridge in the Western hemisphere. As such, the bridge’s hydraulics—supplied by Oilgear—were designed to lift the entire weight of the structure. Insufficient counterweight space was compensated by four very large (26-in. bore x 11-ft stroke), trunnion-mounted cylinders and drives totaling close to 1,000 hp. Oilgear added to the bridge’s uniqueness by supplying a triple-modular-redundant PLC control system with a user-friendly graphic touchscreen operator interface and automatic report generation capabilities.
“Sheboygan was a successful project for us,” recalled LaCombe. “It was complicated, both hydraulically and electronically, but the fact that we designed both elements and were able to perform an integrated test proved a significant benefit to our customer.”
With both mechanical and electrical proficiencies, Oilgear’s multidisciplinary approach to supplying fluid power continues to yield new levels of efficiency on bridges as well as countless other applications.
Oilgear’s broader perspective of project requirements is proven to facilitate greater coordination, ultimately resulting in conformance to established schedules and performance that meets or exceeds specifications.
