← Vermont Locomotive Worksthe shop's working tool for the Case 30 HP restoration · build 18811e6 2026-08-12
Steam engine valve gear simulator
Vermont Locomotive Works · kinematics after Dalby, Valves and Valve Gear Mechanisms (1906) · steam practice checked against Kent's Power, 11th ed. (1936)
Engine solved
Case 30 HP - right side, proportions measured off erecting dwg 2160-1/-2 (1½ in = 1 ft; printed 113 in stack top, 29⅜ axle setback, 97⅞ wheelbase); coachwork after the prototype photos, illustrative · clutch in turns the train at the printed teeth · tap the headlamp
crank & piston plane — side
valve-gear plane — side
plan — the two planes, stations from dwg 1255
live steamexhaustforward eccentric & rodbackward eccentric & rodlink, die block, valve rod
full backmid-gearfull forward
Boiler two-state
Model: Åström & Bell (2000) §4.1 two-state global balances on
IAPWS-IF97 — pressure and water volume; no shrink-and-swell (that
needs the fourth-order model). Vessel: illustrative barrel 26 in
× 8.5 ft, 900 kg metal mine —
not the Case boiler; its drawings are on the request list. Fire: 4.3 ft²
grate at 15 lb/h·ft² limit, bituminous 13,000 Btu/lb,
efficiency 0.61 calibrated from the Brandon 1909 band (5.5–7.9 lb
water per lb coal). Safety valve 175 psia set, 5 psi blowdown (Case
manual: about one-eighth turn per five pounds). Steam demand is taken at the
engine's live speed and pressure; per the record it is trustworthy at
full gear only until the compressible-flow stage lands.