Backtalk - 03/20/2008

March 20, 2008
Last Remaining Dredge
The Bay City Walking Dredge is the last one remaining in the U.S. of some 145 walking machines.

The dredge was used to construct a portion of U.S. 41, called the Tamiami Trail, that connects Tampa with Miami through the Everglades and Big Cypress Swamp.

Built by the Bay City Dredge Works of Bay City, Mich., the dredge had a unique propulsion design that let it handle drainage problems in wetlands environments. The machine dug a canal to provide rock fill for roadbed drainage for the road. The dredge, running on a 50-hp Charter internal-combustion engine, moved over rough, swampy, and slippery ground and through close-cut stumps, something that was difficult for other earth excavators.

The walking mechanism was patented by Vincent G. Anderson, Thief River Falls, Minn., on July 2, 1918. According to the Michigan Historical Review, Fall 1986, the first walker was designed by Albert N. Cross of Grand Rapids, Wis., in 1902. His design was modified in 1916 by Carl F. Wilson at Bay City in a form similar to Anderson’s patent.

Wilson’s walker consisted of identical pairs of 30-ft bridge frames and weight-supporting runners on each s ide of the dredge. The bridge frame eased forward along the ground with the weight of the frame s moving from the corner runners to intermediary runners, using hoists and the motion of the bucket, until the corner pads could be repositioned. Once relieved of its load, the intermediary runners would be drawn forward and repositioned for another step. Each step covered 5 to 8 ft in 30 sec. The machine could be turned and backed up and required one operator and helper, which was one less than dredges on portable tracks.

Dredges followed drilling rigs, which bored holes into limestone. The holes were then filled with cypress posts and dynamite that were electrically detonated.

Blog Bytes

Go to and check out:

It’s a Materials World

* The world’s largest rubbish dump: Kathy Marks, Asia-Pacific Correspondent for the U.K. journal, The Independent, along with Daniel Howden report that “A ‘plastic soup’ of waste floating in the Pacific Ocean is growing at an alarming rate and now covers an area twice the size of the continental United States. The vast expanse of debris — in effect the world’s largest rubbish dump — is held in place by swirling underwater currents. This drifting “soup” stretches from about 500 nautical miles off the Californian coast, across the northern Pacific, past Hawaii, and almost as far as Japan.”

*North by Northwest: The Earth’s geographic poles are fairly stable, wobbling back and forth across the landscape only a few meters every year or so, reports Sid Perkins in a recent Science News Online article. The north and south magnetic poles are far more mobile. They move independently of one another. The north magnetic pole is moving northwest toward Siberia by about 50 km each year and now sits in the Arctic Ocean just north of Canada.

From Lee Teschler

* Shades of intellectual property problems –Why you don’t post your ideas on YouTube: If you check out this demo of a prize winning video game,, I think you’ll agree it’s a pretty cool idea.

*Internet, communications technologies boost energy efficiency: An American Council for an Energy Efficient Economy (ACEEE) study states that it takes the U.S. less than half the energy to produce a dollar of economic output now that it did in 1970.

According to ACEEE, every extra kilowatt-hour demanded by Internet and communications technologies produces a tenfold energy savings in the U.S. economy.

Just a reminder . . .
, the feature- length documentary about George Westinghouse, will be available on Tues., April 8. Inecom Entertainment Co., a subsidiary of Algor Inc., produces historical documentaries that are available through DVD and electronic distribution.

Walking Dredge, Collier-Seminole State Park, photo by Linda Cohen

Sponsored Recommendations

The entire spectrum of drive technology

June 5, 2024
Read exciting stories about all aspects of maxon drive technology in our magazine.


May 15, 2024
Production equipment is expensive and needs to be protected against input abnormalities such as voltage, current, frequency, and phase to stay online and in operation for the ...

Solenoid Valve Mechanics: Understanding Force Balance Equations

May 13, 2024
When evaluating a solenoid valve for a particular application, it is important to ensure that the valve can both remain in state and transition between its de-energized and fully...

Solenoid Valve Basics: What They Are, What They Do, and How They Work

May 13, 2024
A solenoid valve is an electromechanical device used to control the flow of a liquid or gas. It is comprised of two features: a solenoid and a valve. The solenoid is an electric...

Voice your opinion!

To join the conversation, and become an exclusive member of Machine Design, create an account today!