3 Scale Model Case

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Ernest H. Casson
Courtesy of Ernest H. Casson, 909 Naperville Road, Wheaton, Illinois 60187.

909 Naperville Road Wheaton, Illinois 60187.

A 3′ Scale Model Case Engine built and owned by Gerald
Carruthers, Lenox, Iowa, in 1965, and exhibited by him at the Mt.
Pleasant reunion in 1967. Boiler description; locomotive, dry
firebox bottom type, all welded construction, boiler shell
8’Dia., 29′ long plus smokebox and firebox, six
11/4‘ tubes 25’ long, firebox
61/2‘ wide, 10-3/8’ long,
61/2‘ grate to crownsheet. The boiler has
6.33 Sq. Ft., of heating surface, 0.47 Sq. Ft., of grate surface,
0.25 Cu. Ft., of firebox volume. The boiler when burning 20 lbs.,
of 8,500 Btu., wood per hour, operating at 68% efficiency and 100
lbs., steam pressure and 60°F., feed water temperature will produce
62 lbs. of steam per hour.

A 3′ Scale Model Case Engine owned by Gerald Carruthers,
Lenox, Iowa. Built in 1967.

The engine is a single cylinder simple, 2
1/2‘ bore, 2
3/4‘ stroke with ‘D’ slide valve
and Woolf valve gear with steam cutoff set at 9/10 stroke, with
governor control speed set at 275 RPM. The indicated H. P.
developed at 81 lbs., mean effective pressure is 1.5. The brake H.
P. at 74% mechanical engine efficiency woulddfcf

The engine traction system is a two shoe band or flywheel
clutch, a 2.2′ 10 pitch crankshaft pinion, a 6.4′ 10 pitch
intermediate gear, a differential spur gear l0′-10 pitch,
2.25′-8 pitch countershaft pinions, 11.25’8 pitch bull
gears, and 18′ Dia., drive wheels with 5
1/2‘ rims. The gear hubs turning on
shafts are bronze-bushed. The engine will travel at 0.65 MPH., with
275 RPM., engine speed and deliver 0.70 H. P., to the drive wheel
rims equal to 403.8 lbs., gross tractive effort. The engine weighs,
with fuel and water supply 750 lbs., and on traction on smooth dry
clay road the tractive effort to move the engine is about 56 lbs.,
which will leave about 348 lbs., drawbar pull equal to 0.60 net
drawbar horsepower. This is a neat working model very typical of
its Case big brothers except the firebox volume is small and the
piston speed of the engine is very low, 63 rpm, and the
9/10 cutoff point is later than those. Engine
construction features through the courtesy of Mr. Carruthers.
Engine performance calculations and submission by Ernest H.
Casson.

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