The slide valve, simply explained by William John Tennant
"The slide valve, simply explained by William John Tennant" is a technical engineering guide from the late 19th century, within the Victorian era. Aimed at students and practitioners, it explains how steam-engine slide valves work and how to set and modify them, using clear diagrams and a simple hands-on model to visualize motion. The book focuses on valve motion fundamentals—lap, lead, travel, eccentric advance, compression, and expansion—while also surveying practical valve types
and gears used on locomotives and stationary and marine engines. The book progresses from the plain D-slide valve to a cardboard-disc model that treats the eccentric as a crank, letting readers trace admission, cut-off, release, and compression. It introduces lead and cushioning at dead centres, then shows how outside lap yields expansion and how inside lap or inside lead changes exhaust timing; “free exhaust” is explained by widening ports without changing events. It then covers double-ported valves (and similar forms like the Giddings), multiple-admission designs (such as the Straight Line/Sweet and Woodbury), and piston valves with external or internal admission (including types used on the Ide/Ideal engines). A central section demonstrates how advancing the eccentric, shifting the valve, or adding lap alters timing and duration of events. The link motion is treated as a variable eccentric—contrasting open and crossed rods, full gear, linked up, mid-gear, and back gear—with concise distribution diagrams. Finally, it addresses very early cut-off using separate cut-off gear (Meyer, Buckeye) and the Allen/Trick passage, and closes with a clear explanation of why reversing gears are needed, plus a template to build the instructional model. (This is an automatically generated summary.)
deaurider, Matthew Everett and the Online Distributed Proofreading Team at https://www.pgdp.net (This file was produced from images generously made available by The Internet Archive)
Reading Level
Reading ease score: 61.1 (8th & 9th grade). Neither easy nor difficult to read.
