Page:Motors and motor-driving (1902).djvu/142

110 the cylinder through the exhaust valve into the exhaust pipe, the exhaust valve is held open by a mechanical contrivance.

The simplest form of exhaust-valve mechanism is to be found in engines of the De Dion type, as illustrated in fig. 6.



is the end of the crank-shaft (fly-wheel shaft) on to which the small gear wheel is fixed. This wheel engages with another wheel, which revolves on the shaft. The gear wheel is double the size of, consequently  only revolves once for every two revolutions of the crank shaft. In the solid with wheel is mounted an eccentric cam, which raises the exhaust valve  against the pressure of the spiral spring , thus allowing the exploded gases to escape from the cylinder. The mode of working