Technician demonstrates the expanding and closing sidewall canvas of Sherman Tank Duplex Drive at a factory

Sherman Medium M4 Tank Duplex Drive. The Sherman DD- A report to the Commanding General, European Theater of Operations. Sherman Duplex Drive (DD) in water. Four soldiers on Sherman. Sherman covered with canvas. Technician at Metropolitan Cammel Midlands factory works on the Sherman. Gauges on tank. Machines on tank. Canvas side wall goes up. Technician puts struts into place. The canvas expands. He pushes a lever and the canvas goes down. Barrel of artillery visible. He turns its barrel. (Note: filmed at Metropolitan Cammel Midlands factory, Birmingham, England who built and designed the DD equipment to be fitted to US built Sherman tanks. As it is a prototype, the air controls are not in the same place as on production machines.)