Diesel World – October 2019

Themostcommonwasthe“hot-bulb,”wherethecombus-

tionchamberwasexternalandboltedtothetopofthehead

likea projectingglobewitha chimneyoverit.Theexteriorof

theglobewouldbeheatedbya kerosenetorchforstarting,

butafterrunninga while,it couldretainenoughheatto

sustainignition.Sometimestheexhaustsystemwasrouted

aroundtheglobetoapplymoreheat.Therewerealso“hot-

tube,”“hot-cylinder,”and“hot-head”combustionchambers

thatwerea differentmeanstothesameend—namely

vaporizingthefuelenoughsoit couldbeignitedatlower

temperatures(700Forless).

Englishman Herbert Akroyd-Stuart designed the first com-

mercially available hot bulb engine and the manufacturer,

Richard Hornsby and Sons, added a primitive “jerk-pump”

fuel injection system, making it the first mass-produced fuel

injected engine. These hot-bulb engines predated Dr. Diesel

by a few years, but Diesel’s upgrade to the oil engine was a

drastic increase in compression that could sustain ignition

by heat of compression alone. The big problem Diesel faced

was injecting fuel into the highly pressurized combustion

chamber, and the jerk-pumps used by the hot-bulb engines

couldn’t do it—at least initially.

Diesel’s oil engine wasn’t suited to every engine application.

Plus, it was expensive to build and buy. Companies building

Diesel engines also had to pay a licensing fee. All this made

the low compression oil engine an attractive alternative,

even if it was less efficient and economical than the Diesel.

When the Diesel patent expired in the U.S. in July 1913,

many existing engine builders began the transition into

lowercase diesels. By then the non-Diesel oil engine had

become common and practical, and it took a while for the

diesel to replace them.

 As with many of the large early diesels, the Y-V is a

two stroke without valves. Shown is a Model 32 diesel,

which is similar in design. The engine breathes through the

crankcase, either via an underground channel or a breather

on the crankcase. It was called crankcase scavenging. Being

a two stroke, it didn’t have any “suck” to fill the combustion

chamber. The crankcase for each cylinder was individually

sealed, and there was a large reed valve (Arrow 1) for each

one. When the piston moved up, it created slightly negative

pressure in the crankcase, so the reed valve was pulled

open and air pulled in. When the piston descended, it

slightly pressurized the crankcase, closed the reed valve,

and pushed air up the intake channel (Arrow 2) into the

ports, putting fresh air into the cylinder and pushing

exhaust out of the exhaust ports (Arrow 4).

Theflywheelonthisbadboyweighsthreetons—notincludingtheclutchandbeltpulley. The pulley drove a 36-inch belt. The clutch allowed the engine to also be coupled to another piece of machinery independently. The

engineis mountedona veryburly,twin-axle,dual-wheeltrailer.

SEMI-DIESEL

VINTAGE SMOKE 1923 FAIRBANKS-MORSE Y-V SEMI-DIESEL

124 OCTOBER I 2019 • DIESEL WORLD http://www.dieselworldmag.com

SOURCES

TRI-STATE GAS ENGINE AND TRACTOR ASSOCIATION

WWW.TRISTATEGASENGINETRACTOR.COM

VINTAGE DIESEL SECTION, SMOKSTAK ANTIQUE

GAS ENGINE BULLETIN BOARD

WWW.SMOKSTAK.COM