MMS Looks Back: 1930s - Machine Shops Take a Belting in the Depression
Even when harsh economic conditions have business at a creep, manufacturing methods and shopfloor practices must move forward. The means of powering machine tools is a case in point. This article is part of our 90th anniversary series.
With business way off because of the Great Depression, shops and plants were pulling back. However, the editor’s column in the July 1932 issue of Modern Machine Shop advised readers to take advantage of the lull to plan and prepare for “the next cycle of prosperity by laying out the steps that can be taken to bring the plant to its highest point of efficiency.” The specific steps he recommended are ones we would recognize today as lean manufacturing practices and refer to as value-stream mapping, cellular manufacturing and 5S. Some things never change.
But other things do. The best way to power machine tools was changing radically, for example. In his column, the editor also called for plans to replace worn-out tools, machine parts, belts, pumps and other equipment.
The belts he was referring to were, in fact, the leather belts that connected a rotating overhead jackshaft to the spindle drive on the machine by means of ceiling-mounted pulleys. Machining speed could be controlled roughly by moving the belt from one step to another on a cone-shaped pulley attached to the outer end of the machine’s driveshaft. At the time, these belts represented the primary means of powering most machine tools and production equipment.
So important and prevalent were these leather belts, that the lead article in that issue was devoted to the care and maintenance of belt-driven equipment. The article, part of an extensive three-part series, was authored by the chairman of the Engineering Commission of the American Leather Building Association, along with two professors in machine design from the Massachusetts Institute of Technology, which was then, as now, one of the top technology schools in the country and a leading developer of industrial innovations.
All three articles are a mix of practical dos and don’ts, technical guidelines and explanations of best practices. They are illustrated with tables, diagrams and numerous photos. Clearly, this was a serious topic deserving serious treatment. As the first paragraph in the second article states, “the engineering requirements and the successful use of leather belts are just as rigid and necessary as in any branch of science.”
Eventually, line shafts and leather belts disappeared as machines powered by electric motors became the norm. Numerous examples of motor-driven machine tools already appeared in the ads running in that issue. However, even into the 1980s, it was not unusual to see a machine shop in a building where the jackshafts were still in place between the joists of the ceiling. (I saw this myself during several of my earliest plant visits.) The exposed belts, of course, were long gone.
Yet the general issue of power transmission remains a vital concern to builders and users of machine tools in the present. We are still debating the merits of direct-drive versus geared systems. The energy consumed in power machines and the means to minimize it are now the focus of many “green” initiatives and sustainability programs. Sensors are becoming widely used for detecting and measuring conditions in power-transmission components, so digital signals can be sent to machine-monitoring systems and beyond to the cloud. Power-transmission systems are now some of the most important “things” under the watch of the Industrial Internet of Things.
Likewise, delivering reliable, insightful and expert knowledge remains a vital concern for the editors of Modern Machine Shop. We still strive to zero in on the technology topics our readers will find the most useful, whether it is emerging technology such as machine learning, urgent issues such as cybersecurity, or enduring matters of plant and people management. This is a relentless, unending pursuit because technology and management practices are constantly changing.
Economic conditions also change. The Depression dragged on for years after the July 1932 issue was published. Modern Machine Shop, in fact, would have to skip an issue early the next year for want of adequate advertising revenue (the only time that has occurred in its long history). Not until 1938 did some stability and growth return to the U.S. economy. Then it seemed that the belting most businesses and factories had endured was finally over. However, the world was already headed toward war, and U.S. manufacturing soon would be put to its greatest test in the following decade.